New Study Of Yanomami and Yekwana Tribes Points To Role Of Diet On Blood Pressure

A newly released study sheds insight into the role Western-influenced diets may play in blood pressure levels throughout our lives.

Credit: webmd.com

Researchers from the Johns Hopkins Bloomberg School of Public Health measured blood pressure levels of two native tribes in South America. One tribe, the Yanomami, lives in near-total isolation and has had no Western influence on their diets. The researchers found that there was no increase in average blood pressure in tribe members from childhood into adulthood and middle age. The second tribe, the Yekwana, have diets partially influenced by Westernized societies, including processed foods. Their blood pressure levels were shown to increase into late middle age.

The researchers took blood pressure measurements from 72 members of the Yanomami tribe, aged 1 to 60 years. They found no trend either higher or lower as the participants aged. Researchers also measured blood pressure levels of 83 members of the nearby Yekwana tribe. Western society has impacted the Yekwana much more than the Yanomami, particularly when it comes to diet. The Yekwana had a clear trend towards higher blood pressure as they aged.

The Yanomami are hunter-gatherers and gardeners that live in northern Brazil and southern Venezuela. Their diet is low in salt and fat, and high in fiber and fruits. The Yekwana, on the other hand, have been in more contact with the Western world. Through trade and interaction, they have come to include processed foods in their diets.

The Yanomami people and their health have been studied before. Studies since the 1980s have shown that obesity and atherosclerosis are rarities among them. Very low blood pressure levels have been apparent throughout these studies as well. The new study however is the first to compare the Yanomami people to a nearby tribe that has been more exposed to Western civilization.

Researchers found that members of Yanomami villages in southern Venezuela have blood pressure averages of 95 (mm Hg) systolic over 63 diastolic. (The average among U.S. adults is 122 systolic over 71 diastolic.) These numbers are consistent with previous studies of Yanomami adults. The study also found roughly the same numbers among children of the tribe. As mentioned earlier, these low levels were consistent between people aged 1 to 60 years.

Yanomami man with children
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Blood pressure levels among Yekwana children were similar to those of the Yanomami children. But the Yekwana showed a clear trend of increased blood pressure as the population aged. The Yekwana had levels roughly 5.8 mm Hg higher by age 10 and 15.9 mm Hg higher by 50.

“This age-related rise in blood pressure,” said Noel Mueller, PhD, MPH and assistant professor of epidemiology at the Bloomberg School, “begins in early childhood — which suggests that early childhood may be a ‘window of opportunity’ for lifestyle interventions to prevent later rises in blood pressure.”

Challenge To A Widely-Held Belief

The findings of this study are significant largely because they seem to challenge the common thought that blood pressure rises as we age. This is certainly the case in the U.S. and many other countries. In the United States, systolic pressure rises by about 1.5 mm Hg per year in boys and 1.9 mm Hg per year in girls. Levels rise by roughly 0.6 mm Hg per year in American adults.

It’s fascinating that people of a native tribe with no Western influence on its diet maintains similar blood pressure levels throughout their lives. This certainly adds to the discussion surrounding our food system and the diets we choose.

“The idea that rising blood pressure is a result of aging is a widely held belief in cardiology,” says professor Mueller, “but our findings add to evidence that rising blood pressure may be an avoidable consequence of Western diet and lifestyle rather than aging itself.”

It’s hard to say what influence this study could have on people in Western societies and their diets. Countless research points to the importance of a diet low in salt and processed foods, something most people probably know. This study reinforces this idea quite strongly, it seems.