Indigenous Greenlanders are uniquely adapted to a diet rich in fatty acids

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These days, it is commonplace to incorporate omega-3 fatty acids, especially those found in fish and fish oil supplements, into our diets. However, the scientific support for an association between higher consumption of omega-3 polyunsaturated fatty acids (PUFAs) and a lower risk of cardiovascular disease is mixed, at best.¹ Recently, scientists studying populations in Greenland discovered that Indigenous Greenlanders carry particular versions of genes known to control how the body processes PUFAs.² This discovery could shed light on why large-scale trials of PUFAs in populations of mixed ancestry have been inconclusive. In particular, consuming diets rich in PUFAs might only be protective if your ancestors adapted to such diets and passed those genes on to you.

Greenland is, we know by now, not very green at all. Covered by ice, the world’s largest island is inhabited primarily by Indigenous Inuit, or Kalaallit people. Although this population has lived in Greenland for less than 1,000 years, their ancestors lived in the extreme conditions of the Arctic for thousands of years before that.³ Traditionally, they subsisted on a seafood-heavy diet, consuming large amounts of PUFAs. It probably goes without saying that diets heavy in meat — particularly fatty meats like seals, whales, and fish — and low in vegetables often result in heart disease. However, despite what you’d expect, Indigenous Greenlanders don’t have higher rates of heart attacks.

The researchers studying the Indigenous Greenlanders’ genes found that the versions of the genes in the Kalaallit population were associated with better cardiovascular health measures. These included lower body-mass index, lower fasting blood sugar, and lower fasting blood LDL cholesterol levels. The authors also looked at the frequency of these genetic variants in European populations. Though the frequencies were much lower in Europeans (about 2%) than in Greenland Kalaallit, those who did carry these gene variants also had healthier cholesterol and blood sugar levels. When they explored this connection further they discovered that people who carry two copies of one of the studied variants had lower PUFA levels and were 10 pounds lighter.

Diet is a strong force for natural selection, and this study can help explain the differences in how people metabolize fats. However, it also provides a lesson regarding claims about what is “good for us.” Before physicians and dietitians draw conclusions based on lessons learned from one population and apply them to all populations, it is important to understand the evolutionary forces that shaped them.

1. Aung T, Halsey J, Kromhout D, et al. Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: meta-analysis of 10 trials involving 77 917 individuals. JAMA Cardiol 2018;3:225–234.
2. Fumagalli, Matteo, Moltke, Ida, Grarup, Niels, Racimo, Fernando, Bjerregaard, Peter, Jørgensen, Marit E., Korneliussen, Thorfinn S., Gerbault, Pascale, Skotte, Line, Linneberg, Allan, Christensen, Cramer, Brandslund, Ivan, Jørgensen, Torben, Huerta-Sánchez, Emilia, Schmidt, Erik B., Pedersen, Oluf, Hansen, Torben, Albrechtsen, Anders, & Nielsen, Rasmus (2015). Greenlandic Inuit show genetic signatures of diet and climate adaptation. Science 349(6254):1343–1347.
3. Gulløv, H. C. (2004). Grønlands Forhistorie. Gyldendal, Copenhagen.