The Inuit People of the Arctic Circle have always had a diet that consisted primarily of eating what they could hunt, which was whales, seals, fish, and the few plants that could be gathered from the tundra. Yet, despite this very fatty diet, the Inuit do not suffer many heart attacks. In past decades, researchers chalked it up to the protective effect of high amounts of omega-3 fatty acids from fish. But a new study suggests that what protects them may actually be genetic adaptations that reduce the risk of their high-fat diet.
The idea that fish oil offers protection from cardiovascular disease fueled a boom in fish oil supplements. Yet, studies have failed to confirm that fish oil helps prevent heart attacks or stroke. The new finding about the Inuit raises questions about whether omega-3 fatty acids and fish oil really are protective.
The study, published in the journal Science, reported that over millennia the Inuit evolved genetic adaptations for metabolizing omega-3s and other fatty acids. Those gene variations also reduced their height and weight.
Researchers in Denmark, England, Greenland, and the United States studied the DNA of more than 190 Greenlanders whose ancestry was almost completely Inuit. The researchers looked at the DNA of these people for variations in genes related to metabolism.
The found several gene variations that are unusually common in Inuit DNA compared with people in Europe or China. Several of these variations occurred within a cluster of genes that direct the creation of enzymes called fatty acid desaturases. One gene variant was in almost all of the Inuit, but is found in only 2% of Europeans.
The researchers then compared Inuit people who had the variant gene to those who had the European version. People with two copies of the Inuit gene had different blood levels of fatty acids than who did not have them, they found. They were also on average an inch shorter and 10 pounds lighter than those without a copy, which is an extreme difference for one gene to make.