The Inuit, a group of people who make the Arctic their home, have benefited from a handy set of genetic adaptations that help them survive in some of Earth's harshest conditions. Scientists said a study of the genomes of Inuit from Greenland revealed unique genetic variants related to fat metabolism that ward off cardiovascular disease that otherwise could be caused by a diet traditionally high in fat from blubbery seals and whales.
These genetic mutations, which the researchers said arose perhaps 20,000 years ago, help lower "bad" LDL cholesterol and fasting insulin levels, limit the height of the Inuit, keep down their weight and help them adapt to a cold environment. "Our study is perhaps the most extreme example to date of a genetic adaptation to a specific diet," said computational biology professor Rasmus Nielsen of the University of California, Berkeley and the University of Copenhagen.
"The mutations we find seem to compensate physiologically for a large intake of animal fat and are largely an adaptation to a lifestyle in which you have a high-caloric intake of fat from marine mammals, and possibly also from other mammals." The Inuit, formerly called Eskimos, are indigenous people in Greenland and Arctic regions of Canada and Alaska. The researchers examined genomes of 191 Inuit, 60 Europeans and 44 Han Chinese. The genetic variants found almost universally in the Inuit were much rarer in the Europeans (2 percent) and Chinese (15 percent).
The research, published in the journal Science, is the latest to illustrate human genetic adaptation to environmental conditions. "One of the best examples is the Tibetans' adaptation to high altitude," said University of Copenhagen computational biology professor Anders Albrechtsen, referring to a study showing that many Tibetans possess a rare variant of a gene involved in carrying oxygen in the blood, helping them in high-altitude, low-oxygen conditions. The Inuit findings may shed light on the value of diet supplementation with omega-3 fatty acids and fish oils. Nielsen noted such supplementation was originally motivated by observations that Inuit people had a high intake of fat but low cardiovascular disease incidence, so the particular form of fat they got in their diet might be healthier than other kinds. "Our study shows that lessons from the Inuit cannot be extrapolated to other populations. The Inuit have special genetic variants that might allow them to function better on a diet rich in omega-3s than other populations," Nielsen said.