Human beings lost the ability to detoxify uric acid millions of years ago. What implications does this have for our health today?
Our story starts about 15 million years ago. It was the Miocene epoch. Things seemed to be going pretty good until, it seems, two flaming meteorites smashed into what's now Germany with an estimated power of a couple million Hiroshimas. As you can see in my 3-min. video Miocene Meteorites and Uric Acid, the crater looks quaint now, but at the time, there was a mass extinction event, wiping many animals out. Thankfully, the common ancestor of human beings and other great apes developed a mutation that may have helped them survive. We lost the ability to detoxify uric acid. Why was that a good thing?
Uric acid is naturally produced by the body and may help us hold onto fat, which is good when there's not a lot of food around thanks to pesky asteroids. Uric acid also helps us retain sodium, which is good if there aren't a lot of salt shakers out on the savannah, and it also acts chemically as an antioxidant, which is good since green tea hadn't been invented yet.
Fast-forward 15 million years. When salt and calories abound, the last thing we need is more sodium and fat retention.
But the antioxidant part we like. Unfortunately, not all antioxidant compounds are necessarily good for us. For example, the preservative chemical BHA works by preventing the oxidation of foods, but is reasonably anticipated to be a human carcinogen.
Similarly, uric acid is chemically an antioxidant, but when you have too much in your blood it can crystallize in your joints, causing a painful disease called gout. High uric acid levels may also put us at risk for high blood pressure, stroke, heart disease, diabetes, and death. So keeping one's uric acid levels low is an important dietary goal. How do we do that? By avoiding meat and sugar (see my 2-min video Flesh and Fructose).
No surprise that the meat and sugar industries both got upset with the latest round of dietary guidance from the federal government. See Dietary Guidelines: Pushback From Sugar, Salt and Meat Industries and Dietary Guidelines: Corporate Guidance.
Gout is one of the diseases of royalty that used to only affect the "1%," the tiny minority eating rich diets. Now we can all dine like kings and queens three times a day and suffer from the same diseases. The "peasant food" choices, the cheapest plant foods, are often the healthiest. See Eating Healthy on the Cheap and Biggest Nutrition Bang For Your Buck.
For more on the dangers of excess sodium consumption see Dietary Guidelines With a Grain of Big Salt and Salt OK if Blood Pressure is OK?. For more on eating based on our evolutionary heritage, see Paleolithic Lessons.
-Michael Greger, M.D.
Image credit: Rachel from Cupcakes Take the Cake / Flickr