The traditional diet of the Inuit Greenland natives is considered an example of how high levels of omega-3 fatty acids can counterbalance the bad health effects of a high-fat diet, but it may not work for everybody.
A new study has revealed that the Inuit and their Siberian ancestors have special mutations in genes concerned with fat metabolism. These mutations help to partly counteract the effects of eating marine mammal fat, largely from seals and whales that eat fish with high levels of omega-3 polyunsaturated fatty acids. While the mutations occur in nearly 100 percent of the Inuit, they only happen in 2 percent of Europeans and 15 percent of Han Chinese, meaning that these groups would synthesize omega-3 polyunsaturated fatty acids differently from the Inuit.
According to project leader Rasmus Nielsen, professor of integrative biology at the University of California, Berkeley, “The original focus on fish oil and omega-3s came from studies of Inuit. On their traditional diet, rich in fat from marine mammals, Inuit seemed quite healthy with a low incidence of cardiovascular disease, so fish oil must be protective. We’ve now found that they have unique genetic adaptations to this diet, so you cannot extrapolate from them to other populations. A diet that is healthy for the Inuit may not necessarily be good for the rest of us.”
Genetic mutations in the Inuit also lower “bad” LDL cholesterol and fasting insulin levels, likely protecting against cardiovascular disease and diabetes, and have a significant effect on height, because growth is partly controlled by a person’s fatty acid profile. Mutations determining shorter height in the Inuit are also linked to shorter height in Europeans.
According to Ida Moltke, associate professor of bioinformatics at the University of Copenhagen, “The mutations we found in the Inuit have profound physiological effects, changing the whole profile of fatty acids in the body, plus it reduces their height by 2 centimeters: nearly an inch. Height is controlled by many genes, but this mutation has one of the strongest effects on height ever found by geneticists.”
The study, which was published in the journal Science, analyzed the genomes of 191 Greenlanders with a low admixture of European genes (less than 5 percent) and compared them to the genomes of 60 Europeans and 44 Han Chinese. One cluster of mutations, in genes that code for enzymes that desaturate carbon-carbon bonds in fatty acids, stood out strongly.
Thus, human populations appear to be adapted to particular diets, differing in the way they physiologically respond to diets. “Just as genome sequencing can lead to personalized medicine tailored to an individual’s specific set of genes, so too may a person’s genome dictate a personalized diet,” explained an article in
Futurity.
