It’s common for nutrition scientists to give advice to white Americans based on studies done of what is good for nonwhites to eat. For example, in the 1980s, one of the most fashionable studies was of Japanese in Hawaii. The first generation ate mostly rice with little fat, and they had relatively few heart attacks. The next generation ate cheeseburgers and had higher rates of coronary disease than their parents. From this and other studies emerged the conventional wisdom of a quarter century ago: you should eat a low fat, high carb diet.
From the New York Times, a similar tale:
Inuit Study Adds Twist to Omega-3 Fatty Acids’ Health Story
SEPT. 17, 2015
by Carl Zimmer
Children in Greenland. A new study found that Greenlanders with Inuit ancestry often have gene variants that help regulate different fats in the body, including omega-3 fatty acids.
As the Inuit people spread across the Arctic, they developed one of the most extreme diets on Earth. They didn’t farm fruits, vegetables or grains. There weren’t many wild plants to forage, aside from the occasional patch of berries on the tundra.
For the most part, the Inuit ate what they could hunt, and they mostly hunted at sea, catching whales, seals and fish. Western scientists have long been fascinated by their distinctly un-Western diet. Despite eating so much fatty meat and fish, the Inuit didn’t have a lot of heart attacks.
In the 1970s, Danish researchers studying Inuit metabolism proposed that omega-3 fatty acids found in fish were protective. Those conclusions eventually led to the recommendation that Westerners eat more fish to help prevent heart disease and sent tens of millions scrambling for fish oil pills.
Today, at least 10 percent of Americans regularly take fish oil supplements. But recent trials have failed to confirm that the pills prevent heart attacks or stroke. And now the story has an intriguing new twist.
A study published on Thursday in the journal Science reported that the ancestors of the Inuit evolved unique genetic adaptations for metabolizing omega-3s and other fatty acids. Those gene variants had drastic effects on Inuit’s bodies, reducing their heights and weights.
Rasmus Nielsen, a geneticist at the University of California, Berkeley, and an author of the new study, said that the discovery raised questions about whether omega-3 fats really were protective for everyone, despite decades of health advice. “The same diet may have different effects on different people,” he said.
An amazing insight: “the same diet may have different effects on different people!”
Shouldn’t that be the conventional wisdom?
Part of the problem is that the diet researchers want to play by the rules of Science!, which are supposed to apply everywhere. If an astronomer discovers a galaxy where Einstein’s General Theory of Relativity doesn’t apply, it would be a big deal. Thus, the search for the Perfect Diet that works for everybody.
But human biodiversity, the fact that your ancestors didn’t evolve under exactly the same conditions as my ancestors, is not a thing we are supposed to keep foremost in our minds when thinking about human sciences.
So maybe you should try different diets and see if one works better for you.
In the future, maybe you’ll be able to get your DNA analyzed and be given a list of diets in rank order of their likelihood that they will work for you. But, right now, you can still try different diets. In particular, ask your relatives about what has worked and not worked for them.