There are multiple studies on various indigenous populations, and the relationship of their diet to hypertension and cardiovascular disease. Some of these indigenous groups include the Tarahumara, Yanomamo, Cuna, and Inuit. Before these populations changed their diets by exposure to the Western diet, they had a very low incidence of hypertension.
Transition To Western Life
As they transitioned to a Western life, these populations developed more hypertension and cardiovascular disease. Of course, there are many factors beyond diet involved in Westernization. It is not necessarily the potassium to sodium ratio that caused the increase in hypertension and cardiovascular disease. When they transition to a Western life, indigenous people take on all the habits of Western life. This includes smoking, alcohol consumption, less physical activity, and the Western diet.
The Western diet has a much lower potassium to sodium ratio than any of the traditional indigenous diets. We have discussed how this led to more hypertension in the Tarahumara and Kenyan Luo indigenous groups as their diet became Westernized.
Effect Of The Western Diet On The Inuits
Studies on the Inuits show a similar result. The Greenland Inuits studied in the 1920s had an almost purely carnivorous diet. In the 1970s, studies of the Inuits' diet tried to discover how the Inuits could have such a low incidence of heart disease and hypertension, while getting so many calories from meat.
Because such a high percentage of calories came from fats in their diet, the nature of those fats became the focus of subsequent studies. This focus on the polyunsaturated fatty acids (PUFAs) found in the Inuit diet led to many findings about how PUFAs aid cardiovascular health.
One such finding was how PUFAs bring about favorable effects on blood lipids, inflammation and health. As an example of one such discovery, we discussed in the recent post how DHA aids the potassium channels in the mitochondria. As a result, this action by DHA allows better health results from a slightly lower potassium sodium ratio than would be obtained otherwise.
Potassium to Sodium Ratio Ignored Until Recently
Sadly, the potassium to sodium ratio of the Inuit diet was ignored until recently, though. But two relatively recent studies of the Inuits show how important the potassium sodium ratio is.
The first study (1) was done on Greenland Inuits in 2002. Specifically, the Inuits staying in Greenland were compared to those migrating to Denmark. The Inuits in Greenland had a more traditional lifestyle and diet.
In contrast, those who migrated took on a more modern lifestyle, including a Western diet. The Greenland Inuits ate twice as much fish and seal, and half as much fruit and vegetables as the migrant Inuits. Nonetheless, across all age groups the Inuits in Greenland had lower blood pressure than the Inuits migrating to Denmark. Yes – despite eating more meat and fewer fruits and vegetables, the more traditional Inuits had lower blood pressure. And the older the Inuit age group, the bigger the difference between the blood pressure of the Greenland group and the blood pressure of the age matched migrant group.
In the second study (2) this difference in diet between age groups was examined. In particular, the older Inuits got approximately twice as many calories as the younger Inuits got from traditional food sources. No Inuits have a purely traditional diet today. Consequently, in the Inuits studied in the second report, a traditional diet comprised only 28% of total calories. For those Inuit men between 20 and 40 years of age, only 15 to 18% of calories came from traditional food. In contrast, for those between 40 and 60, 29 to 36% came from traditional food.
Dietary Potassium and Sodium Measured
This second study did something else quite rare for a study of an indigenous group. Namely, it measured the amount of potassium and sodium in the diets of the Inuits. In most of the earlier studies of indigenous cultures, researchers estimated the amount of dietary sodium and potassium from the foods eaten.
The Inuits in the second study had days that included more of the traditional diet than other days. Researchers measured many of the micronutrients and minerals, including potassium and sodium, on both the more traditional days and the more modern days. Notably, the potassium to sodium ratio for the more traditional diet was approximately 1.5. In contrast, the potassium to sodium ratio for the more modern diet was approximately the same as a typical Western diet. It was 0.67.
So although the studies starting in the 1970s led to useful knowledge about PUFAs, the health results from only increasing PUFA are limited. Specifically, increasing the potassium sodium ratio is far more important. The early Inuit diet was purely carnivorous. The Inuits trimmed the visible fat from their meat. The remaining meat, although high in PUFAs, more importantly had a high potassium to sodium ratio. The ratio found in the meat of all wild game is above 4.5. Accordingly, this potassium sodium ratio was far more responsible for the early Inuits' lower blood pressure than the polyunsaturated fat content.
Will The Real Paleo Diet Please Stand Up?
For those who feel the Paleo diet is the healthiest diet, it is difficult to choose which Paleo diet they are referring to. Is it the diet of the early, purely carnivorous Inuit? Or is it the diet of the early Tarahumara, who were mostly vegetarian?
Rather than try to duplicate a healthy diet, it is better to determine what aspect of a particular diet is healthy. To duplicate the food practices of unfamiliar cultures is very difficult. Today's domesticated animals and plants differ in many ways from wild animals and plants. They even differ from domesticated animals and plants of just a century ago.
Tests, Tests And More Tests
But if you can find the crucial factors in the diet of a particular group of people that led to their health, you can duplicate those factors in a modern diet. By testing suspected factors to determine how they work biologically, you can develop a model that explains the health effects.
In this instance, the common factor in indigenous diets was a high potassium to sodium ratio. As shown in these two studies of the Inuits (as well as multiple studies of other indigenous groups), the higher the potassium to sodium ratio, the lower the blood pressure.
Of course, all the studies of indigenous groups only show an association. They do not show causation. Studies, such as those we discussed previously about the cell biology and physiology of potassium and sodium, tested the potassium sodium model to show that the potassium sodium ratio is key to determining blood pressure.
It's Even In Medical Textbooks
Doctors Guyton, Young, Hall and their associates demonstrated the basic physiology of how this ratio leads to hypertension in a definitive manner through an extensive body of work. It is so definitive that it is now in the medical physiology book originally authored by Dr. Guyton, now authored by Dr. Hall.
Where Are The Tables?
To find tables of the amounts of potassium and sodium in foods, click on the “Links to Food Potassium Tables” tab at the top of the page. It will take you to a page with links to multiple tables of foods with their sodium and potassium content.
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1. Higher blood pressure among Inuit migrants in Denmark than among the Inuit in Greenland. Bjerregaard P1, Jørgensen ME, Lumholt P, Mosgaard L, Borch-Johnsen K; Greenland Population Study. J Epidemiol Community Health. 2002 Apr;56(4):279-84.
2. Arctic indigenous peoples experience the nutrition transition with changing dietary patterns and obesity. Kuhnlein HV1, Receveur O, Soueida R, Egeland GM. J Nutr. 2004 Jun;134(6):1447-53.
