Michael Greger MD's Blog

Latest in Nutrition vol. 9 DVD now available (proceeds to charity)

2012-05-21T12:00:00Z

The current batch of videos from volume 8 are set to run out soon, and so starting this week, and running up until August here on NutritionFacts.org, I'll be rolling out the videos off my new Latest in Clinical Nutrition DVD, volume 9. The DVDs give folks the opportunity to sneak preview videos months ahead of time, watch them all straight through, and share as gifts, but there's nothing on the DVDs that won't eventually end up here for free at NutritionFacts.org.

The Latest in Clinical Nutrition volume 9 DVD is available for purchase now, with all proceeds going to The Humane Society of the United States.

Here's the list of chapters off the new DVD, a preview of what's to come on NutritionFacts.org:

SAD states
Amnesic seafood poisoning
A fine kettle of fluoxetine
Red fish, white fish; dark fish, atrial fibrillation
Hair testing for mercury before considering pregnancy
Nerves of mercury
Which brand of tuna has the most mercury?
Health food store supplement advice
Bad advice from health food store employees
Dangerous advice from health food store employees
Pharmacists versus health food store employees: who gives better advice?
Dietary supplement snake oil
Heavy metals in protein powder supplements
Some dietary supplements may be more than a waste of money
Handwashing compliance of retail deli workers
Don’t put your money where your mouth is
Tongue worm in human eye
Viral meat spray
Maggot meat spray
Not so delusional parasitosis
Unsafe at any feed
Zero tolerance to acceptable risk
Arterial acne
Blocking the first step of heart disease
Making our arteries less sticky
Chamomile tea may not be safe during pregnancy
Is hydroponic basil as healthy?
Boosting immunity through diet
Anti-inflammatory effects of purple potatoes
Fighting inflammation in a nut shell
Achieving remission of Crohn’s disease
The leaky gut theory of why animal products cause inflammation
The exogenous endotoxin theory
Dead meat bacteria endotoxemia
Antimutagenic activity of green versus white tea
Is caffeinated tea dehydrating?
Treating Gorlin syndrome with green tea
Treating genital warts with green tea
Preventing kidney failure through diet
Treating kidney failure through diet
Kiwifruit for irritable bowel syndrome
Kiwifruit and DNA repair
Plant-based diets and cellular stress defenses
What women should eat to live longer
Americans are living longer but sicker lives
The benefits of caloric restriction without the actual restricting
New mineral absorption enhancers found
Risk associated with iron supplements
How do nuts prevent sudden cardiac death?
Mineral of the year: magnesium

Remember, you are what you eat, so please--eat healthy,
-Michael Greger, M.D.

Poultry and Penis Cancer

2012-05-17T12:00:00Z

One of the reasons it’s so difficult to study the relationship between diet and cancer is because many dietary behaviors are associated with non-dietary behaviors. For example, one of the reasons we used to think coffee-drinking caused cancer was because people who drink coffee are more likely to have a cigarette in the other hand, which led to spurious conclusions. When you factor in those considerations, we find that coffee consumption may actually decrease cancer risk, as I detailed in Coffee and Cancer.

The reason it was so difficult to study cancer among coffee-drinkers is the same reason it’s so difficult to study cancer among meateaters. Historically, those eating vegetarian have been noted to have lower cancer rates, but maybe it’s just because they exercise more, or smoke less, or inhale less diesel fumes because they all own a Prius :)

In my 3 min. video Vegetarians Versus Healthy Omnivores I profiled new data that attempts to control for non-dietary factors by effectively comparing vegetarians only to meateaters who are as slim as vegetarians, exercise as much, smoke as little, and even eat roughly the same amount of fruits and vegetables. After all, maybe the reason vegetarians have been shown to be healthier is less about eating less meat, and more about eating more plants. Though these rigorous controls undercut key vegetarian advantages, such as lower obesity rates, even when vegetarians were compared in effect only to healthy meateaters with healthier diets, researchers still found “the incidence of all cancers combined was lower among vegetarians."

The most striking difference between the dietary groups was in the risk for cancers of the blood and bone marrow, such as non-Hodgkins lymphoma, various leukemias, and myeloma (more details in my 2 min. video EPIC Findings on Lymphoma). Chicken consumption appeared the most hazardous, associated with up to triple the cancer rates for every 50 grams of daily poultry consumption—that's just a quarter of a chicken breast worth!

Why was there so much more lymphoma and leukemia risk among those eating just a small serving of chicken a day? As detailed in my 2 min. video Chicken Dioxins, Viruses, or Antibiotics?, the association between poultry and cancer may be explained by the presence in chickens' and turkeys' flesh of drugs that were fed to the birds, industrial carcinogens such as dioxins, and/or the presence of oncogenic (cancer-causing) viruses.

In Poultry and Penis Cancer I present the largest study to date on poultry workers and cancer mortality, which found a whopping 8-fold increased risk of dying from penile cancer compared to controls, a finding thought due to chicken virus exposure, raising broader food safety concerns. If chickens can be infected with viruses linked to cancer in consumers, then what about eggs? Find out in Carcinogenic Retrovirus Found in Eggs.

These cancer-causing viruses found in chicken and eggs are utterly destroyed by proper cooking, so the primary risk of infection would presumably be associated with cross-contamination, such as when mixing cake batter, handling raw poultry, or even just touching meat in the supermarket.

-Michael Greger, M.D.

Image credit: Kate Tomlinson / Flicker

Coffee Caveats

2012-05-10T12:00:00Z

Last month in the American Journal of Clinical Nutrition, an editorial entitled "Coffee consumption and risk of chronic diseases: changing our views" reviewed the growing evidence that for most people, the benefits of drinking coffee likely outweigh the risks. For example, a recent analysis of the best studies published to date suggests coffee consumption may lead to a modest reduction in overall cancer incidence, as detailed in my 1-min. video Coffee and Cancer. Each daily cup o' joe was associated with about a 3% reduced risk of cancers, especially bladder, breast, mouth, colorectal, endometrial, esophageal, liver, leukemic, pancreatic, and prostate cancers.

What about the caffeine, though? Glad you asked! Check out What About the Caffeine?

There are a few caveats. Some health conditions may be worsened by coffee, such as insomnia, anxiety, gastroesophageal reflux (heartburn), high blood pressure, and certain heartbeat rhythm irregularities. There are also compounds in coffee that increase cholesterol levels, but are effectively removed when filtered through paper, so drip coffee is preferable to boiled, French press and espresso. Pregnant women should restrict caffeine consumption to less than two cups of coffee a day.

Despite the growing evidence of health benefits associated with coffee consumption, I still don't recommend people drink it—not because it's not healthy, but because there are even healthier choices. In this way, coffee is like a banana, another common convenient plant product. If you have a choice, I'd encourage you to make healthier fruit choices (apples are better, berries are best). Similarly, when it comes to beverages, I'd encourage you to choose an even healthier one, like green tea.

One final note: not all routes of administering coffee are benign. Consider the title of a case reported in a medical journal last month: "Rectal Perforation…Caused by Rectal Burns Associated With Hot Coffee Enemas."

-Michael Greger, M.D.

Image credit: Urban Hafner / Flickr

Stool Size and Breast Cancer Risk

2012-05-03T12:00:00Z

Women eating plant-based diets may have lower breast cancer rates because they have larger bowel movements. In The Best Detox, I described the role of the liver in removing toxins from the blood stream, which can then be jettisoned through the bile into the digestive tract, and eliminated. Our gut is our body's disposal system; anything it wants to get rid of, it throws down the trash chute. One can imagine our enterocytes, the cells lining our intestinal wall, as a vast array of trash pickers, resource recovery workers. They’re sifting through the river of garbage flowing past and picking up anything of use—a vitamin here, a mineral there, such that by the end there isn’t much left that’s desirable—and what's left truly gets, ahem, dumped.

The digestive tract is also how we get rid of excess hormones and cholesterol. Our body expects there to be an ever-flowing torrent of intestinal contents to flush this stuff out to sea. We did, after all, evolve over millions of years on a diet centered on unrefined plant foods. We aren't designed for burgers and milkshakes; we are designed for fiber, and lots of it. Anthropologists estimate we evolved eating 100 grams of fiber a day or more!

So our body is counting on a massive, quick-flowing stream of contents through our digestive tract, and when there's excess estrogen in the trash, our body expects it to just zip right out. But what if we don't consume an adequate amount of fiber to soften and bulk up that intestinal flow? What if that river dries up into just a slow trickle of sludge? We still have the same number of trash pickers, but the volume and speed of the flow is way down, so they’re finding all sorts of stuff that otherwise would have been lost. Uh oh—that means they're picking back up the estrogen that your body intentionally dumped, and thrusting it right back into the system. Fiber, on the contrary, dilutes, speeds, and bulks up the flow, so lots of stuff never even makes it to banks of the river to be picked at and inappropriately saved. My 4-min video Relieving Yourself of Excess Estrogen explains that this may be why women who eat lots of plants (the only place fiber is found) have lower estrogen levels and a lower risk of breast cancer.

As I show in my 1-min video Food Mass Transit, meat-eating women average a four-day mouth-to-anus transit time, likely too long to meet the target 200 gram (half pound) minimum fecal output for cancer prevention. People don't realize you can have daily bowel movements and still be effectively constipated. You can be regular, but four days late. In other words, what you’re flushing today you may have eaten last week. If you want to test it for yourself, all you need to do is eat a big bowl of beets and see when things turn pretty in pink. Ideally, to reach that half-pound target, your intestinal transit time should be down in the 24 to 36 hour range.

Small bowel movements are also associated with a variety of other diseases such as appendicitis, colon cancer, constipation, and diverticulitis. See my 2-min. video Stool Size Matters. Just eating antioxidant-rich foods can improve stool weight. See Bulking Up on Antioxidants (2 min). And finally, check out Bowels of the Earth (2 min) to find out which country has the largest (and smallest) average stool size. Find out who's #1 at number 2!

-Michael Greger, M.D.

Image credit: Taylor McConnell / Flickr

Breast Cancer Survival and Soy

2012-04-26T12:00:00Z

In my last two posts, The Best Detox and Breast Cancer Stem Cells vs. Broccoli, I documented ways to 1) boost our liver's ability to clear carcinogens, 2) make our DNA more resistant to toxins that make it past our first line of defense, and 3) then ramp up immune surveillance of any budding tumors—all in hopes of preventing cancer. But what about for those who already have it?

Though small consolation, one consequence of the fact that breast cancer is now the #1 cancer killer of young women is that breast cancer survival is a very active area of research. For example, a major study was recently published that followed 4,000 women with breast cancer for 7 years. Not all of them made it to the end. The researchers tried to figure out if there was anything about the diets of the non-survivors that may have played a role in their deaths. Two dietary components in particular were associated with an early death: saturated fat and trans fat.

Breast cancer survivors may decrease their risk of dying by 41% simply by avoiding saturated fat, found primarily in the American diet in cheese, chicken, and junk food (see my 3-minute video Breast Cancer Survival, Butterfat, and Chicken). And breast cancer survivors may improve their survival 78% by avoiding trans fat, found primarily in junk food and animal products (see my 1-minute video Breast Cancer Survival and Trans Fat). Ideally, everyone should try to minimize the intake of both, as explained in Trans Fat, Saturated Fat and Cholesterol: Tolerable Upper Intake of Zero.

On the other hand, the two foods expected to improve breast cancer survival are flax seeds and soy products. Breast cancer is initially so slow-growing that women may have tumors for years or even decades before they’re diagnosed (see my 1-minute video Cancer Prevention and Treatment May Be the Same Thing). So one might expect that the same dietary factors that helped grow the tumor in the first place would keep goading it on after diagnosis. This may not always be the case, though. Alcohol, for example, is strongly associated with breast cancer risk, but the data has been mixed as to whether once you already have a full-blown tumor, it makes a difference if you continue to drink or not. Still, in general, the diet that helps prevent breast cancer is the same diet that’s going to help prolong survival. And that certainly seems to be the case for the phytonutrients found in flax and soy.

Flax seeds are the most concentrated source of lignans, a class of cancer-fighting compounds that may cut breast cancer mortality risk in half (see my 3-minute video Breast Cancer Survival and Lignan Intake). Interestingly, there are no lignans actually found in the seeds, just precursors that the good bacteria in our gut turn into lignans. This may explain why women who have frequent urinary tract infections have higher breast cancer rates—the courses of antibiotics wipe out the gut flora critical to the production of these anti-cancer compounds (see my 2-minute Flax and Fecal Flora).

Soy foods appear to help prevent breast cancer and prolong survival more directly, though. In Breast Cancer Survival and Soy I review the only three human studies to date, all of which suggest soy is beneficial. Before we had any human data, rodent studies found conflicting results, and we just found out why. It turns out rats and mice metabolize the phytoestrogens in soy up to 150 times less efficiently than humans. The faulty old lab rat data continue to be cited by soy detractors, however, even though we now have studies published on thousands of actual breast cancer survivors. While the jury may still be out on whether to feed tofu to your pet rat, the verdict is in on soy in human beings: not guilty.

-Michael Greger, M.D.

image credit: imgdive / Flickr and MesserWoland / Wikimedia Commons

Mad Cow California: Is the Milk Supply Safe?

2012-04-25T16:00:00Z

In announcing the detection of a new case of mad cow disease in California, the USDA emphasized that her carcass never made it into the food supply. The fact that the infected animal was a dairy cow, though, raises the question about the disposition of her milk. There's currently no direct evidence that cow's milk poses any mad cow risk, but when it comes to this mysterious class of diseases, we've learned time and time again that absence of evidence of risk, does not equal evidence of absence of risk.

The USDA flatly declared that milk doesn't transmit mad cow disease, but that's what we used to think about scrapie, the parallel disease in sheep, before research in the last 5 years unequivocally demonstrated that milk could indeed become contaminated with prions, the infectious proteins that cause these transmissible sponge-like (spongiform) brain diseases (encephalopathies). Similar experiments have not detected infectivity in mad cow milk, but this may be a function of the limited sensitivity of testing methods.

If prions are present at low levels in bovine milk, then this could present a particular problem in the United States, since inflammation has been shown to dramatically boost the infectivity of prion-infected milk and there is an epidemic of mastitis in the U.S. dairy herd. Last year researchers demonstrated that the ingestion of as little as 1 to 2 quarts of milk from scrapie-infected sheep stricken with mastitis could cause prion infection in lambs at an attack rate of 86%. This is thought to be because the prions may concentrate in the blood and pus cells sloughed into milk from inflamed udders.

Today’s dairy cows endure annual cycles of artificial insemination, pregnancy and birth, and mechanized milking for 10 out of 12 months (including 7 months of their 9-month pregnancies). This excessive metabolic drain overburdens the cows, who are considered “productive” for only two years and are slaughtered for hamburger when their profitability drops, typically around their fourth birthday, a small fraction of their natural lifespan. Turning dairy cows into milk machines has led to epidemics of so-called “production-related diseases,” such as lameness and mastitis, the two leading causes of dairy cow pre-slaughter mortality in the United States.

Because 1 in 6 dairy cows in the United States suffers from mastitis, the dairy industry continues to demand that American milk retain among the highest allowable “somatic cell” concentration in the world. When a cow's udder is inflamed, greater than 90% of the somatic cells in her milk are neutrophils, the inflammatory immune cells that form pus. As the dairy industry points out, the accumulation of pus is a natural part of an animal’s defense system. So pus itself isn’t a bad thing, we just may not want to drink it, especially if it can increase the risk of transmission of cellular pathogens that can survive pasteurization such as paratuberculosis and, in theory at least, prions.

-Michael Greger, M.D.

Breast Cancer Stem Cells vs. Broccoli

2012-04-19T12:00:00Z

In my post The Best Detox last week, I detailed how a phytonutrient in broccoli boosts the detoxifying enzymes in the liver, but helping to clear carcinogens isn't the only way greens protect our DNA. A study of the DNA of broccoli-eaters found that eating broccoli appears to make DNA more resistant to damage, as I explore in my 1-minute video DNA Protection from Broccoli.

That was just one of several extraordinary studies published lately on cruciferous vegetables. Kale and the Immune System compares the immune system-boosting effect of cooked versus raw kale, a follow-up on my Best Cooking Methodvideo. Smoking Versus Kale Juice looks at the Japanese health fad of doing shots of kale juice. Seems kale can boost our good cholesterol, like amla and cocoa. Is there anything kale can't do?

Broccoli Versus Breast Cancer Stem Cells documents the most important study of the lot, though, exploring the role phytonutrients in certain greens play in a new theory of cancer biology, cancer stem cells, which explains why breast cancer can relapse 25 years after you thought it went away.

Sure, cruciferous vegetables produce a compound that appears to target breast cancer cells, but that's in a test tube. How do we even know we absorb broccoli phytonutrients into our bloodstream? And even if we do, how much do we have to eat to arrive at the test tube concentrations featured in the studies where it counts—in breast tissue itself? An innovative group at Johns Hopkins figured it out. They found women scheduled for breast reduction surgery, and an hour before they went into the operating room, had them drink some broccoli sprout juice. Check out my 2-minute video Sulforaphane: From Broccoli to Breast to see what they found.

Breast cancer is the leading cancer killer of young women, but lung cancer is the #1 cancer killer of women overall. In my 3-minute Lung Cancer Metastases and Broccoli I talk about some fascinating new research on the effects of broccoli on cancer cell migration, suggesting that broccoli and broccoli sprouts may decrease the metastatic potential of lung cancer.

Worried about the safety of raw sprouts? You’re probably thinking about alfalfa (Don’t Eat Raw Alfalfa Sprouts and Update on Alfalfa Sprouts). Broccoli sprouts appear much safer in terms of the risk of food poisoning (as noted in Broccoli Sprouts).

We know this family of vegetables helps prevent cancer, but once you already have cancer, what dietary changes can one make to improve survival? Raw Broccoli and Bladder Cancer Survival completed my 13-video series on the latest research on cruciferous vegetables.

I previously covered a bit of the prevention side of the story in The Healthiest Vegetables. Wasn’t there some report downplaying the role of fruits and vegetables in cancer prevention, though? Watch my 2-minute take on it in EPIC Study.

Oh, and eat your greens!

-Michael Greger, M.D.

Image credit: Annie Cavanagh. Wellcome Images

The Best Detox

2012-04-12T12:00:00Z

As detailed in my 3-minute video The Best Detox, there’s lots of talk these days about detoxing, but talk is cheap—our liver is actually doing it, all day, every day. If we want to detoxify our bodies, the best thing we can do is to boost our liver’s own detoxifying enzymes, and one of the most potent such inducer is a phytonutrient called sulforaphane. So where do we find this stuff? Broccoli, which produces more than any other known plant (with the silver going to kohlrabi and bronze to cauliflower; broccoli raab, on the other hand, produces about 500 times less than broccoli).

Broccoli is an exceptional source of sulforaphane, but the surprising thing is that there’s none actually in the vegetable—until you bite it. You know those chemical flares, or glow sticks, where you snap them and chemicals in two different compartments mix and set off a reaction? Broccoli does the same thing. In one part of the cell it keeps the enzyme myrosinase, and in another part it keeps something called glucoraphanin. There is no sulforaphane, which is what we want, anywhere in broccoli—not until some herbivore starts chewing on it. At that point, plant cells get crushed, the enzyme mixes with the glucoraphanin and sulforaphane is born. And the herbivore is like, "Ew, this tastes like broccoli!" and runs away. The plant uses this as a defense against nibblers and noshers. Little did broccoli count on a little lemon juice and some garlic—maybe a little tahini dressing? It’s our counterattack.

A similar enzymatic "glow stick" reaction happens in garlic. Both the enzymes in both these cases are inactivated by cooking, so there's a secret to preserving the benefits. See Sometimes the Enzyme Myth Is True for my "hack & hold" strategy (or maybe I should call it whack & wait?).

Broccoli sprouts are even healthier, and can be a cost-effective way to eat on the cheap if you make your own. That's the subject of my 2-minute video Biggest Nutrition Bang for Your Buck, in which broccoli sprouts beat out purple cabbage (Superfood Bargains) for the most one could get nutritionally for one’s money. Another good cost-saving tip can be found in Are Goji Berries Good For You?.

Can you overdo it? Yes, four cups of broccoli sprouts a day may exceed the safe dose of sulforaphane, for example. See Liver Toxicity Due to Broccoli Juice? and How Much Broccoli Is Too Much? There is also the issue of the goitrogenic compounds in raw cruciferous. See Overdosing on Greens. We can also drink too much tea (see Overdosing on Tea), eat too much of the spice turmeric (see Oxalates in Cinnamon), too much of the seaweed kelp (see Too Much Iodine Can Be As Bad As Too Little), and overdo coffee when pregnant (see Caffeine During Pregnancy). And in a nod to my Care2 post Stomach Staples or Healthy Kitchen Staples, I relate a cautionary tale of gastric bypass surgery in The Dangers of Broccoli?

-Michael Greger, M.D.

Ask the Doctor: Q&A with Michael Greger, M.D. (#21)

2012-04-05T12:00:00Z

This is another sampling of the nearly 1,000 comments and questions I’ve responded to on the site NutritionFacts.org (so far!). Please feel free to leave any follow-up questions here or on any of the hundreds of videos on the more than a thousand topics covered on NutritionFacts.org. And remember, there’s a new video posted every weekday, so to make sure you don’t miss any:

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veggiechick asked on Preventing Allergies in Adulthood: What would you recommend for nasal allergies? Hubby and I are both on a plant based diet and our allergies are better since going vegan, but it’s spring & it’s bad this year already lol.

Oh, I’m so sorry you’re suffering! There was a new study published last week on diet and allergic rhinoconjunctivitis (runny nose/itchy eyes) that confirmed that meat is associated with increased risk (in this case 71% higher), but that’s no help to a couple vegans! There are four plant foods, however, associated with cutting one’s risk in approximately half:
1. Seaweed. An ounce of sea vegetables appears to lower risk 49%–just make sure to avoid kelp and hijiki.
2. Dark green leafy vegetables. Greens of the land may protect as much as greens from the sea. A study found that those with the highest level of total carotenoids in their blood stream (alpha-carotene, beta-carotene, lutein/zeaxanthin, canthaxanthin and cryptoxanthin) had a significantly lower prevalence of seasonal allergies. See my video Egg Industry Blind Spot for a list of some of the best sources and Raw Food Nutrient Absorption and Forgo Fat Free Dressings? for the best ways to boost bioavailability.
3. Flax seeds. Similar to the carotenoid finding, those with higher levels of both long and short chain omega-3 fatty acids in their blood stream were found to have less allergic rhinitis in a cross-sectional study.
4. Miso. A teaspoon of miso a day was associated with about 41% lower prevalence. So try my favorite dressing on those greens: Blend until smooth in high-speed blender 3 T white miso. 1/4 cup brown rice wine vinegar, 1/4 cup water, 2 carrots, a small beet, an inch of fresh ginger root, and 1 T freshly toasted sesame seeds. Just watch your clothing as it comes out BRIGHT purple!

scorpiomoon asked on The Dangers of Broccoli?: I have seen several health experts talk about the benefits of coconut water that comes straight from a young Thai coconut. However, I have read conflicting information about the coconut water one can get in packages (such as Vita CoCo).

Obviously packaged coconut water is pasteurized and not as good as fresh, so from that perspective it isn’t as beneficial. The thing I am wondering about is the sugar content. It’s my understanding that sugar is not added to coconut water, yet there is a high amount of sugar per serving. Is the sugar in coconut water bad for you? Is packaged coconut water something we should stay away from?

These days, coconut water is hugely popular. Is it just another form of unhealthy empty calories marketed as something healthy?

Vita Coco just settled a $10 million class action lawsuit for claiming its coconut water was “super-hydrating” “nutrient-packed” “mega-electrolyte” “super-water,” yet independent testing showed that the actual electrolyte levels were a small fraction of what the label advertised. Earlier this year a study in the Journal of the International Society of Sports Nutrition compared coconut water to a manufactured sports drink and found no difference between the two in terms of hydration or exercise performance, and in fact those drinking the coconut water reported feeling more bloated and experienced greater stomach upset–and the study was funded by the Vita Coco!

vetstud asked on Amalgam Fillings vs. Canned Tuna: How did you come up with your calculation about how many mercury-containing dental fillings are equivalent to eating a can of tuna once a week?

Three national brands of canned tuna were recently tested for mercury. They averaged 600 ppb of mercury, exceeding the U.S. Environmental Protection Agency’s safety level for human consumption (500 ppb). The drained solids in a can of tuna weigh about 170 grams, so that comes out to be about 100 mcg of mercury per can of tuna. A conservative estimate of the amount of mercury we’re exposed to on a daily basis per amalgam-filled tooth is 0.5 mcg, so eating a single can of tunafish a week is like having 29 teeth filled with mercury-based fillings day in and day out.

Poxacuatl asked on Is Yerba Maté Tea Bad For You?: Whoa! Really?! It seems there must be a lot of problems for the South Americans who consume loads of this daily? I haven’t read anything negative — any other info on how this is affecting people who have been drinking it for years?

The latest review suggests that the drying method (using firewood) may be to blame for the high levels of carcinogenic polycyclic aromatic hydrocarbons found in maté drinks, so a different production method may obviate this problem. That would be great since new evidence suggests that yerba maté may protect bone strength and improve blood sugar and cholesterol control in diabetics. I’ll let you know if I find more research in this evolving area.

Data asked on A Harmless Artificial Sweetener: What is your take on the following substances? Gurmar…jamun… bitter melon…[and] fenugreek? Lastly, Dr. Greger what do you think of Citruline and L Argenine in their role as helping out in repairing the endothelium cells ( Citruline ) and the later helping in promoting Nitrous Oxide formation if one used the drug versions instead of Citruline absorbed thru Watermelon rind where a large portion of citulline is usually discarded?

I’ve often wondered about bitter melon myself (Momordica charantia, also known as karela, or bitter gourd). I’m glad you brought it up to give me an excuse to look into it. I’ve seen it at the Indian spice stores I frequent (looks kind of like a ridged warty cucumber), but never tried it. I hear it lives up to its name, though. In fact the more ripe it gets, the more inedibly bitter it evidently becomes! But with enough heavy spicing I guess anything can be made palatable (the best way to mask the taste appears to be tomato-based sauces).

A study published just a few days ago found that an extract of the fruit appeared to slow the growth of a rare cancer in a petri dish (adrenocortical carcinoma, an aggressive 1 in a million cancer of the adrenal gland), something that extracts of blueberries, zucchini, and acorn squash couldn’t do. Similar findings were reported in 2011 with prostate cancer cells and in 2010 with breast cancer cells. Traditionally, bitter melon has been used to lower blood sugars in diabetics, though most of the studies to support this use have been small and methodologically weak. There was a randomized controlled study published in 2007 that found no significant improvement in long-term blood sugar control in diabetics, but there have also been case reports of children having hypoglycemic seizures (and one even sinking into a coma) after drinking bitter melon tea, so presumably there is some blood-sugar-lowering effect there somewhere. If you are going to try it, I would recommend eating the fruit itself, not some extract. For example, there is a published report of a man who started throwing up blood after chugging two cups of bitter melon juice, which apparently ate through the wall of his stomach.

I'll have to look into gurmar and jamun; as for citrulline and watermelon, I cover that in my video Watermelon as Treatment for Erectile Dysfunction, which is chapter 33 of my Latest in Clinical Nutrition DVD, volume 8, and should air here at NutritionFacts.org by the end of the month. I’ve also got upcoming videos on fenugreek, so I leave you in suspense (*spoiler alert*: fenugreek seeds appear to have both muscle-building and anti-cancer properties, but do have an unusual side effect: they may make your armpits smell like maple syrup!).

-Michael Greger, M.D.

Using Greens to Improve Athletic Performance

2012-03-22T12:00:00Z

Earlier this month on NutritionFacts.org I completed a 17-part video series on the performance-enhancing effects of certain vegetables. It started with Doping with Beet Juice, which described how beets were the first to be found to significantly improve athletic performance while reducing oxygen needs, upsetting a fundamental tenet of sports physiology. How is that possible? Check out Priming the Proton Pump to nerd out on a bit of biochemistry.

Next up was Don’t Use Antiseptic Mouthwash, which describes the role the natural good bacteria flora on our tongue plays in the performance-boosting effect of high nitrate vegetables, and Out of the Lab onto the Track, which documented the randomized, double-blind, placebo-controlled crossover studies that convinced the scientific establishment of the real-world effect.

Asparagus Pee and Pretty in Pee-nk go off on a tangent to delve into the phenomenon of "beeturia," the chief side effect of beet consumption--though not all are affected, akin to the malodorous urine that sometimes results from asparagus consumption.

If our bodies can turn the nitrate in vegetables into the vasodilator nitric oxide, then performance enhancement may be just the tip of the iceberg. Indeed, as I explain in Hearts Shouldn’t Skip a Beet, this may help explain the role dark green leafy vegetables play in the prevention and treatment of hypertension and heart disease. So which vegetables have the mostest? Find out in Vegetables Rate by Nitrate.

If the nitrates in vegetables such as greens are health-promoting because they can be turned into nitrites and then nitric oxide inside our bodies, what about the nitrites added to cured meats such as bacon, ham, and hot dogs? This is the apparent conundrum I present in Is Bacon Good or Is Spinach Bad? and then solve in Are Nitrates Pollutants or Nutrients? but not before laundry-listing the health concerns associated with processed meats.

In When Nitrites Go Bad I describe how nitrites added to processed meat form nitrosamines, a class of potent cancer-causing agents found in cigarette smoke that may explain why hot dog consumption has been associated with the two leading pediatric cancers, brain tumors and childhood leukemia. So which meat has the highest level of these carcinogens? In Prevention Is Better Than Cured Meat the levels of nitrosamines are compared across an array of processed meats including chicken, turkey, and pork.

And finally, bacon. Carcinogens in the smell of frying bacon is pretty self-explanatory. In Bacon and Botulism I talk about the incredible story of regulators forced to strike a balance between the risk that consumers will get cancer, and the risk that they'll get a deadly form of food poisoning. Part of that balance is the legal mandate to add certain antioxidants to processed meats, though I explore the irony in Vitamin C-Enriched Bacon that this may make the meat even more carcinogenic. Finally, in Meat Additives to Diminish Toxicity, I feature an article published in the journal Meat Science revealing how meat scientists continue to justify promoting foods associated with promoting cancer.

I ended the series with So Should We Drink Beet Juice or Not?, in which I describe the safest ways for athletes to nitrate load, which involve lots of dark green leafy vegetables.

Maybe Popeye was onto something.

Michael Greger, M.D.

Harvard's Meat and Mortality Studies

2012-03-15T12:00:00Z

On Monday, the results of two major Harvard studies were published, following more than 100,000 men and women—and their diets—for up to 22 years. They found that red meat consumption was associated with living a significantly shorter life—increased cancer mortality, increased heart disease mortality, and increased overall mortality. The studies were featured in the NutritionFacts.org video-of-the-day yesterday, Harvard's Meat and Mortality Studies.

The American Meat Institute immediately sent out a press release: "A new study in today’s Archives of Internal Medicine tries to predict the future risk of death from cancer or cardiovascular disease by relying on notoriously unreliable self-reporting about what was eaten and obtuse methods to apply statistical analysis to the data." Alas, yes, the Harvard researchers were not telepathic and did indeed have to ask people what they were eating. The Meat Institute criticized the esteemed researchers for using "survey data – not test tubes, microscopes or lab measurements...." No beakers either, I bet! Nor sizzling electric arcs, nor panels with pretty flashing lights. No, just cutting edge epidemiological science, however "obtuse" this may be to the American Meat Institute.

The Meat Institute asserted that "nutrition decisions should be based on the total body of evidence, not on single studies…." If two prospective cohort studies—the gold standard of observational studies—following more than 100,000 people for two decades published by one of the most prestigious institutions in the world isn't good enough for the Meat Institute, how about the largest such study ever—the NIH-AARP study, "Meat Intake and Mortality: A Prospective Study of Over Half a Million People." What does the largest forward-looking study on diet and disease in human history have to say on the subject? Watch Meat & Mortality for a distinct sense of déjà vu.

I think the most interesting finding in the new Harvard studies is that even after factoring out known contributors of disease, such as saturated fat and cholesterol, they stillfound increased mortality risk, raising the question: what exactly is in the meat that is so significantly increasing cancer death rates, heart disease, and shortening people's lives? A few possibilities include heme iron, nitrosamines, biogenic amines, advanced glycation end products, arachidonic acid, steroids, toxic metals, drug residues, viruses,heterocyclic amines, PCBs, dioxins, and other industrial pollutants.

-Michael Greger, M.D.

Ask the Doctor: Q&A with Michael Greger, M.D. (#20)

2012-03-08T13:00:00Z

This is another sampling of the more than 900 comments and questions I’ve responded to on the site NutritionFacts.org (so far!). Please feel free to leave any follow-up questions here or on any of the hundreds of videos on the more than a thousand topics covered on NutritionFacts.org. And remember, there’s a new video posted every weekday, so to make sure you don’t miss any:

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Amy Freudenberg Dover asked on the NutritionFacts.org Facebook page: Not necessarily related to beets, but related to how certain veggies and fruit cause skin colorations. My palms and soles of my feet are orange. I know this is from beta carotene. Is it cause for concern? It got better for awhile, but I noticed they are very orange again :(

Sounds like you have carotenoderma, caused by the buildup of carotenoid phytonutrients in your skin. The condition itself is harmless, but if you haven't increased your vegetable intake in the last month or two (juicing carrots is a common cause) and there's still a significant increase in coloration then you should check with your doctor to make sure you're not suffering from secondary carotenoderma, in which the high levels in your skin are not because you're eating a lot, but because there may be an underlying disease state such as hypothyroidism, anorexia, diabetes, or kidney disease that is increasing levels in your blood stream. Carotenoderma can also sometimes be confused with jaundice, a sign of liver dysfunction, but the two can be differentiated by looking at the whites of the eyes; they which remain white in carotenoderma, but turn yellow in jaundice. For more on carotenoid deposition in the skin see Golden Glow and Produce, Not Pills.

Duke asked on Ask the Doctor (#19): I started being plant based after Thanksgiving. The principal reason is for my health and hopes to reduce or eliminate some day all my meds. One area that I’ve never seen any reference to is diet and atrial fibrillation. Is there any connection? Can diet begin to replace cumadin or pradaxa?

Atrial fibrillation is the most common clinical cardiac arrhythmia, an irregularity of our heart beat rhythm, which can set you up for a stroke, increase your risk of dementia and heart failure, and significantly shorten our lifespan. Previous findings on the effect of diet have been conflicting. Some studies have found alcohol, caffeine and fish consumption to be good in terms of preventing or resolving atrial fibrillation, and other studies have shown them all to be bad. It’s when this kind of situation arises in nutritional science, you pull out the big guns and put it to the test in one of the bigger better studies, like the famous Framingham Heart Study population, which is what was recently done. They found no effect either way in general from the consumption of alcohol, caffeine, or fish, but when they looked closer they observed an association between the consumption of dark fish and atrial fibrillation. A 6-fold higher hazard ratio for those eating a lot of fish like salmon, swordfish, bluefish, mackerel, and sardines. They conclude that their findings may suggest a “true adverse effect of dark fish and fish oil on certain subtypes of atrial fibrillation,” proposing that “potential toxins such as dioxins and methyl mercury accumulated in certain fish may have a negative effect on cardiac arrhythmia.”

There’s less out there about treatment, but a recent study did find that those with atrial fibrillation with higher intakes of antioxidants did have 80% greater odds of spontaneously reverting back to a normal heart rhythm. Until that happens your physician will likely want you to continue to take those two anticoagulants. My video Antioxidant Power of Plant Foods Versus Animal Foods offers an overview on which foods to choose to maximize antioxidant intake, though since you’re already eating a plant-strong diet, check out Antioxidants in a Pinch for a tip on taking it to the next level. Just make sure not to increase your dark green leafy vegetable consumption while on coumadin without your physician helping you titrate your drug dose.

azwildcat76 asked on So Should We Drink Beet Juice Or Not?: As an endurance athlete I thought that beets/beet juice was my little secret but now you’ve let the cat out of the bag so to speak. I am curious if you had any comments on Dr. Ferenczi’s early Hungarian studies on the use of beets/beet juice to combat cancer?

I see Dr. Ferenczi has published papers in both Hungarian and German. Anyone out there willing and able to translate them for me if I send you the PDFs? For an overview of my beet videos, see my blog yesterday at One Green Planet: Using Greens to Improve Athletic Performance.

CapeBreton asked on So Should We Drink Beet Juice Or Not?: I was surprised to see you reference a paper by Eaton on so called “Paleolithic nutrition.” These folks are part of a group who argues that we (humans) need to eat lots of meat to be healthy because that is built into our genes…..despite the overwhelming evidence that eating less (or no) meat promotes better health and that there are no nutrients except B12 not effectively obtained from a plant based diet.

David Jenkins is more convincing in arguing our genetic heritage is more likely rooted in the Miocene, with a diversity of plant foods at the root of our diet.

I have tremendous respect for Dr. Jenkins and his “ape diet” (also known as the Portfolio Diet) that I refer to in Low Fat or Whole Food. He was the guy who came up with the glycemic index concept. He was a co-author of the seminal review I covered in Egg Cholesterol in the Diet and my zombie-themed Avoiding Cholesterol is a No-Brainer. He’s also the one behind the plant-based “Eco-Atkins” diet (Plant-Based Atkins Diet). The full text of the commentary you mention is available at The Garden of Eden: Plant-Based Diets.

mercman40 asked on The Best Nut: Been drinking as replacement for cow milk, love the taste, etc. However, I do buy the Vanilla sweetened flavor…is that bad? Am I taking away from the good of it all?

Almond milk is certainly superior to calf’s milk, if only because of the lack of saturated animal fat, cholesterol, and hormones (see, for example, my videos Acne & Cancer Connection and Trans fat, saturated fat, and cholesterol: Tolerable upper intake of zero), but is unflavored, unsweetened almond milk preferable to sweetened vanilla? In general, I’m in favor of cutting down on intake of empty calories whenever possible. We only get about 2,000 in the calorie bank every day–why not try to make them count? So almond milk versus almond milk with added sugar is a no-brainer decision for me, but I guess it depends on what you’re using it for. If the only way you would drink green tea is with the sweetened variety, then overall it would be healthier for you to stick with the added sugar (though your taste buds would probably adapt to the unsweetened variety, or you could try adding a harmless noncaloric sweetener such as erythritol (see A Harmless Artificial Sweetener). The vanilla question is interesting, though. Given its popularity, I was surprised there wasn’t more science published on the health effects of vanilla orchid fruit phytonutrients. There are two in vitro studies that suggest vanillin, one of the many aromatic compounds in vanilla, may be protective against colorectal and cervical cancer, but no clinical or epidemiological studies have been published to my knowledge. There was also a study showing that vanilla extract may interfere with bacterial communication, concluding vanilla “might promote human health by…preventing bacterial pathogenesis.”

The most unusual vanilla study may be one published out of Germany in 1999. Researchers wanted to know how if our olfactory memory goes back even further than our verbal memory. Do we subconsciously remember tastes and smells from our infancy before we could even put them into words? They realized that there was a time certain German infant formulas were flavored with vanilla, so they challenged a group of adults with a vanilla-containing food. But they couldn’t just use your typical vanilla flavored confection because it could introduce too many other new variables. They had to choose something that no one would have ever associated with vanilla. So they concocted… vanilla-flavored ketchup! And guess what? Two-thirds of those bottle fed with vanilla as infants preferred the vanilla ketchup, whereas two thirds of the rest were like “blech!” and chose the regular ketchup. The moral of the story is that perhaps if breastfeeding women eat lots of healthy foods, their broccoli-flavored breast milk might get remembered years down the road.

Latest in Nutrition vol. 8 DVD now available (all proceeds to charity)

2012-03-01T13:00:00Z

The current batch of videos from volume 7 are set to run out soon, and so starting next week, and running through May here on NutritionFacts.org, I'll be rolling out the videos off my new Latest in Clinical Nutrition DVD, volume 8. The DVDs give folks the opportunity to sneak preview videos months ahead of time, watch them all straight through, and share as gifts, but there's nothing on the DVDs that won't eventually end up here for free at NutritionFacts.org.

The Latest in Clinical Nutrition volume 8 DVD is available for purchase now, with all proceeds going to The Humane Society of the United States.

Here's the list of chapters off the new DVD, a preview of what's to come on NutritionFacts.org:

Is there anything kale can’t do?
Smoking versus kale
Smoking versus broccoli
From stem to stern
From broccoli to breast
Liver toxicity due to broccoli juice?
How much broccoli is too much?
The best detox
Sometimes the enzyme myth is true
Have broccoli, won’t travel
Biggest nutrition bang for the buck
The dangers of broccoli?
Raw broccoli and bladder cancer survival
Breast cancer survival, butterfat, and chicken
Breast cancer survival and trans fat
Breast cancer survival and lignan intake
Flax and fecal flora
Breast cancer survival and soy
Coffee and cancer
What about the caffeine?
Vegetarians versus healthy omnivores
EPIC findings on lymphoma
Dioxins, viruses, or antibiotics?
Poultry and penis cancer
Carcinogenic retrovirus found in eggs
Poultry exposure and neurological disease
Poultry and paralysis
Cross-contamination risks
Meat-borne infection risk from shopping carts
A treatment for chronic fatigue syndrome
Cholesterol and female sexual dysfunction
Cholesterol and lower back pain
Watermelon as treatment for erectile dysfunction
The safer cinnamon
Raw veggies versus cooked for heart disease
The fruit whose juice is healthier
Preventing COPD with diet
Treating COPD with diet
Eating healthy on the cheap
When meat can be a lifesaver
Creatine brain fuel supplementation
Cheese mites and maggots
Cow’s milk-induced infant apnea
Cow’s milk casomorphin and crib death
Cow’s milk casomorphin and autism
National Dairy Council on acne and milk
Skim milk and acne
The acne-promoting effects of milk
Apples and oranges: dietary diversity
Garden variety anti-inflammation
Preventing macular degeneration with diet
How to see 27 miles farther
Preventing cataracts with diet

Springtime is almost here!
-Michael Greger, M.D.

Ask the Doctor: Q&A with Michael Greger, M.D. (#19)

2012-02-16T13:00:00Z

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Ionestamot asked on Toxins in Cooked Potatoes?: [...] what’s the verdict on gold, red & purple potatoes?

The healthiest potatoes are probably sweet potatoes (see my video about sweet potatoes), but if you are going to eat plain potatoes, the varieties with colored flesh (not just skin) do appear healthier. A new study published this month found that the consumption of 6-8 microwaved purple potatoes a day (they’re pretty small) resulted in a boost in antioxidant capacity of the blood (whereas the plain potato starch control acted as a pro-oxidant) and a drop in blood pressure in overweight individuals. “Thus,” they concluded, “purple potatoes are an effective hypotensive agent and lower the risk of heart disease and stroke in hypertensive subjects without weight gain.” Last year a study found that purple potatoes appeared to suppress both early and late stage human colon cancer cells in vitro, but only if they were fresh. After being in storage a few months their anti-cancer properties diminished. And finally, another study published last year (and this one available full-text), found a trend towards lower inflammation in men eating purple potatoes than white, concluding “Pigmented potato consumption reduced inflammation and DNA damage in healthy adult males. This offers consumers an improved nutritional choice in potato consumption.” Purple sweet potatoes may offer the best of both worlds, as suggested in an in vitro study last year on human fat cells that suggested anti-obesity, anti-oxidant, and anti-inflammatory benefits.

Berryman asked on Preventing childhood allergies: I’d be interested in your opinion of this study I found online at http://www.finola.com/FinolaOilandAtopy.pdf. This is regarding hempseed oil, not necessarily for children but for adults with eczema. Have you seen other studies looking at hempseed oil and eczema? Is it ok to take so much oil every day for a month?

I was surprised to find so few articles published in the human medical literature on hempseeds, but maybe I shouldn’t be given the lack of much of an industry lobby and the stigma attached to the plant. Only 4 popped up in a pubmed search (excluding articles written by a “Dr. Ian D. Hempseed.”). The latest (available full-text) was a double-blind placebo-controlled comparison of fish, flax and hempseed oil supplementation that lasted 3 months and found no significant effects of any of them on lipid profile, LDL oxidation or measures of inflammation. This result is similar to what was found in my video Is Distilled Fish Oil Toxin-Free? Before that a study comparing daily tablespoons of flaxseed to hempseed oil similarly didn’t find much effect. The third was the study you cited, which found that 2 daily tablespoons of hempseed oil improved atopic dermatitis (an itchy skin rash) better than the same amount of olive oil. The researchers suggest it may be because of the gamma linoleic acid content of hempseeds, an omega 6 fatty acid that paradoxically appears to have an overall anti-inflammatory effect. Instead of downing the oil, as always I’d suggest eating the whole food–hempseeds–directly (same with flaxseeds, see my video Just the Flax Ma’am). And the final study, “Anaphylaxis to ingestion of hempseed” soundly debunks the wikipedia claim that “In fact, there are no known allergies to hemp foods.”

veggie4every1 asked on Priming the proton pump: What about the oxalic acid in beets? Is it good for you to take in large amounts?

As noted in my video about the oxalates in turmeric versus cinnamon (Oxalates in Cinnamon), it’s not just the amount that matters but also how well particular oxalates are absorbed, and the bioavailability of oxalates in beets is relatively poor (6 times less so than spinach, for example). Cooking the beets could cut levels about 25% but for the rare person with a condition like idiopathic calcium nephrolithiasis (a type of kidney stones) that needs a low-oxalate diet, a better high-nitrate vegetable choice would be arugula.

Toxins asked on Ask the Doctor (#18): Hello Dr. Greger. Latest in nutrition Volume 8 was a fantastic DVD. It was very informative and applicable to my lifestyle. I especially liked the healthy ice cream idea, I’m going to try that! I don’t want to pester you with an email, so I thought id post it here. In regards to creatine, you mentioned that most creatine supplements are contaminated with heavy metals, yet consuming a creatine supplement as a vegetarian increased cognitive function. Now my question to you is this: Is there any safe creatine supplement and if there was one, would you recommend consuming it? Also in reference to caffeine, you mentioned it has positive health benefits. This study shows that the caffeine in coffee caused impaired endothelial function: http://www.clinsci.org/cs/109/0055/1090055.pdf I know Dr. Esselstyn also brings up this study. What are your thoughts?

I’m so glad you liked it! (note: volume 8 won’t be available publicly until March; I’m still rolling out volume 7). So everyone understands the context, I’ll leave the creatine question until the video airs (sometime in early May), but let me address the caffeine question, since I’ve been such an outspoken advocate of green tea consumption (see, for example, The Healthiest Beverage and Dietary Brain Wave Alteration). As I detailed in my video The Power of NO, endothelial dysfunction is the first step towards atherosclerosis–our #1 killer–and so we need to keep the inner lining of our arteries healthy by any means necessary. Last year, a study entitled “Impact of Acute Caffeine Ingestion on Endothelial Function in Subjects With and Without Coronary Artery Disease” was published in the American Journal of Cardiology. They performed the most rigorous investigation to date, a randomized, double-blind, placebo-controlled cross-over study that found that caffeine significantly improved endothelial function. They concluded “In conclusion, acute caffeine ingestion significantly improved endothelial function assessed by brachial artery FMD in subjects with and without CAD and was associated with lower plasma markers of inflammation.” That was for the amount of caffeine found in about 2 cups of coffee, 4 cups of black tea, or 8 cups of green. Similar benefits were found previously at a higher dose (3, 6, and 12 cups respectively). So why do studies on brewed coffee, espresso, and energy drinks show negative effects? Well, there are a lot of other substances in these beverages besides caffeine, some of which may also be removed in the decaffeination process. Since there appear to be compounds in coffee that both impair and improve endothelial function (whereas in tea, both green and black, it appears to be all improvement), one might turn to epidemiological studies to look at overall risk and benefit of coffee consumption (see, for example, my Update on Coffee). Though filtered coffee may be good, the evidence supporting the benefits of green tea are much stronger and more consistent. So I continue to recommend people drink tea instead of coffee, not because coffee is bad for you, but because green tea appears to be much better.

JTodd asked on Medical school nutrition education: I’m afraid I’m one of those guilty docs who never filled in the nutrition knowledge gap that medical school left me with. NutritionFacts.org has been such an eye-opener, and I am already seeing some quasi-miraculous changes in some of my more motivated patients. Where else would you suggest I go to supplement my training in nutrition?

My favorite source for continuing medical education credit is nutritionCME.org. It’s co-sponsored by the George Washington University School of Medicine and Health Sciences and the Physicians Committee for Responsible Medicine. In fact they currently have my swine flu presentation up as one of the featured offerings!

-Michael Greger, M.D.

PS: If anyone lives in northern California, I'm giving a free open-t0-the-public presentation on the latest in clinical nutrition this weekend, and just added four new speaking dates in March. See my speaking schedule here.

Ask the Doctor: Q&A with Michael Greger, M.D. (#18)

2012-02-09T13:00:00Z

This is another sampling of the more than 800 comments and questions I’ve responded to on the site NutritionFacts.org (so far!). Please feel free to leave any follow-up questions here or on any of the hundreds of videos on the more than a thousand topics covered on NutritionFacts.org. And remember, there’s a new video posted every weekday, so to make sure you don’t miss any:

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CapeBreton asked on Evolutionary argument for optimal vitamin D level: I assume the lifeguards were caucasian? With a “built in” SPF of 15 what blood level of Vit D does the lifeguard of African descent attain? Perhaps that is a better clue for evolutionary “normal”.

You’re absolutely right, CapeBreton. Considering the average vitamin D levels of clothed high latitude office workers “normal” for our species doesn’t make much sense and though lifeguards are at least outside all day and half naked, they were still both Caucasian and Missourian. A more representative normal level of the “sunshine vitamin” could be gleaned measuring levels in those with black skin who live scantily clad in equatorial Africa. The problem is that such a study has never been done–until now.

This month researchers published results from the Maasai and the Hadzaben and the title says it all: “Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l.” So lower than the pale St. Louisans, but still nearly twice the levels found in most Americans. No change to my recommendations, though, summarized in the culmination of my two week vitamin D series: Resolving the vitamin D-bate.

Toxins asked on Ask the Doctor (#16): Dr. Greger, I have heard some talk about the dangers of fluoride. When I research this all I stumble upon are propagandists websites without scientific backing. Is there any truth to these claims that fluoride in our water supply and toothpaste is damaging our health?

The proposed EPA changes to water fluoridation have sparked a resurgence of many of the old anti-fluoridation arguments, which as far as I can tell were successfully debunked over 50 years ago. According to the CDC, fluoridation of drinking water joins vaccination (another unjustly vilified practice) as one of the greatest public health achievements in the last last century.

MarkB asked on Dragon's blood: Is any research available on astaxanthin which seems to be touted as a wonderful antioxidant?

Astaxanthin is the reason flamingos are pink (or at least flamingos in the wild; in the zoo they may be fed artificial dyes like farmed salmon–see my video Artificial Coloring in Fish). Astaxanthin is also the reason some crustacean shells turn red when boiled. One need not eat flamingo feathers or lobster exoskeletons, though. You can go right to the source and get it from green algae such as chlorella (I recommend against blue-grean algae and spirulina–see for example my videos Is blue-green algae good for you? and Another Update on Spirulina). A review last month suggests a wide range of beneficial effects, though one should note the author is listed as a dietary supplement industry consultant. With a few exceptions, I recommend against taking supplements as they have been found in some cases to be less effective (see, for example, my Produce Not Pills) or even deleterious (see Is vitamin D the new vitamin E? and my other 60 videos on supplements).

Georgel asked on Ask the Doctor (#17): I’ve seen a number of blog posts about some food scientists stating that if you avoid ANY food, canned tomato products and non-organic root vegetables should be at the top of your list? Do you know anything about these statements? Is it just the opinion of a few researchers or is there a lot of weight behind the recommendation to avoid those products?

Did they offer any rationale? With canned tomato products are they concerned about the BPA? (see my video Which Plastics are Harmful?). A recent study found that it was canned tuna that had the highest levels, whereas concentrations in canned vegetables was relatively low. And pesticides in root vegetables? Only one even made it into the Environmental Working Group’s top twenty list. If I had to pick a worst food it would probably be Crisco, processed meat, or some of the mentions in my blog post about Paula Deen.

Joanne Irwin asked on Ask the Doctor (#16): Class participant heard that celery should be avoided for colon cancer patients. Only thing I’ve read about celery is to consume only ‘organic’ as conventional grown veggie is extremely high in pesticides. Do you know any other reason it should be avoided? Thanks.

Celery avoidance makes no sense to me. In fact celery may have a “strong protective effect against colorectal cancer.” And in terms of for people already fighting the disease, a study was just published a few weeks ago elucidating the mechanism by which one of the key phytonutrients in celery (luteolin) arrests the growth of human colon cancer cells in vitro. For a comparison of the anti-cancer activity of a variety of vegetables, see my videos Veggies vs. Cancer and the follow-up, #1 Anticancer Vegetable.

For some reason the subject of nutrition appears especially wrought with myths, exaggerations, and baseless opinions. That’s in fact one of the reasons NutritionFacts.org was started. When it comes to what we put in our bodies, critical thinking is, well, critical. Any time anyone hears anything like that I would encourage you to ask what their source was for their information. If there really is science backing up their assertions I’d be happy to review it and offer my thoughts.

-Michael Greger, M.D.