Infertility affects 10–15 percent of couples attempting to conceive, and in about half the cases the problem is in the man. A recent Harvard study found that increasing saturated fat intake just 5 percent was associated with a 38 percent lower sperm count, but why? It may be because of endocrine-disrupting industrial pollutants that build up in animal fat, particularly fish, as I describe in my video Xenoestrogens & Sperm Counts, but male fertility is not just about the number of sperm, but also how well they work.
A recent study, featured in my 5-min video Male Fertility and Diet, found that successful pregnancy and fertilized egg implantation outcomes are decreased in patients reporting a more frequent intake of meat. The researchers blame industrial pollutants and steroids present in animal products. They conclude that couples having trouble conceiving must be advised about the dramatic effects diet may play on treatment success for both men and women, consistent with previous findings that “frequent intake of fat-laden foods like meat products or milk may negatively affect semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.” Vegetable consumption was also found protective in this new study, which may be because of the antioxidant and nutrient content.
The reason why maternal beef consumption may alter a man’s testicular development and adversely affect his future reproductive capacity is thought to be due to the anabolic steroids implanted into the animals. However, as an accompanying editorial to a study exploring this phenomenon pointed out, the steroids could also be interacting with other xenobiotics—industrial chemicals present in meat—such as pesticides and dioxin-like pollutants, and even chemicals that may be present in the plastic wrap (see Dioxins in the Food Supply). For more on the hormones used in meat production, see my video Anabolic Steroids in Meat.
Heavy metals may also play a role. Lead and cadmium exposure, as measured by levels in the bloodstream, were associated with a significantly longer time to conceive. Where might exposure be coming from? Common types of seafood from fish markets and supermarkets were sampled. The highest cadmium levels were found in tuna; highest lead levels in scallops and shrimp. The greatest risk from different metals resided in different fish. Thus, the risk information given to the public (mainly about mercury) does not present a complete picture. There are other toxic metals in fish as well.
For more on heavy metal exposure (dietary as opposed to auditory), see:
- Cannibalistic Feed Biomagnification
- Dietary Theory of Alzheimer’s
- Drug Residues in Meat
- Filled Full of Lead
- Get the Lead Out
- Heavy Metals in Protein Powder Supplements
- Nerves of Mercury
- Some Ayurvedic Medicine Worse Than Lead Paint Exposure
The only beverage associated with infertility in women was soft drinks, though this may be from an indirect route, since soda is linked to obesity and obesity is then linked to reduced fertilization rates. However, Harvard researchers conducted a study on one really direct route: “The Effectiveness of Coca Cola As a Spermicidal Agent in Vaginal Douching.” Diet coke apparently had the strongest effect. What about Coke versus Pepsi? Tax-payer money hard at work for this head-to-head test. Neither of them really worked—Coke nor Pepsi—though they explain their methods for preparing the "sperm-cola mixtures" differed from the Harvard group. Bottom line: soda probably isn’t good for you going into any orifice.
-Michael Greger, M.D.
Image credit: Jug Jones/ Flickr