A South American tribe living in an almost complete isolation without any Western dietary influences showed no increase in average blood pressure from one to 60 years of age, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health. For comparison, a nearby tribe, whose diet contains some processed foods and salt, showed higher blood pressure in late middle age.
In the US and most other countries, blood pressure rises with age, from the early years of life. The results of this study support the view that the trend in Western societies to increase blood pressure with age is not a natural part of aging, but may be due to the cumulative effect of exposure to the Western diet and lifestyle.
Arrangements appear on November 14 in the journal JAMA Cardiology.
"The idea that an increase in blood pressure is the result of aging is a common belief in cardiology, but our findings confirm that an increase in blood pressure can be avoidable by the consequences of the Western diet and lifestyle, not by aging itself" – says Noel Mueller, Dr. , MPH, epidemiology adjunct at Bloomberg School and member of the Welch Center for Prevention, Epidemiology and Clinical Research.
In the course of the study, the researchers took blood pressure measurements from 72 Yanomami from one to 60 years old and did not find any tendencies to higher or lower readings, as in the age of the participants. Researchers also measured the blood pressure of 83 members of the nearby Yekwana tribe, which is more vulnerable to Western influences, including diet – and here they found a clear tendency for higher pressure with age.
Yanomami live as hunter-gatherers and gardeners in a remote region of rainforests in northern Brazil and southern Venezuela. Their diet has low fat and salt content as well as high fruit and fiber content. Adult studies of Yanomami since the 1980s have shown that atherosclerosis and obesity are virtually unknown and that they have moderate low blood pressure, with no visible increase with age.
A new study reveals that this age stability in the Yanomami blood pressure range begins in early childhood. He is the first to compare Yanomami with a geographically colonized population – Yekwana – which had a different exposure to Western diet and other influences of Western lifestyle.
Researchers, studying members of the Yanomami village in southern Venezuela, found that their blood pressure measurements were on average 95 (mm Hg) of contraction over 63 diastolic. (In adults in the US, the systolic mean is 122 and diastolic 71). This low number among Yanomami is consistent with previous studies in adult Yanomami, but researchers measured approximately the same blood pressure in Yanomami children. In fact, the data suggest that the blood pressure in this population remains close to the same low level from the first century, at least to 60 years, with no tendency to increase or decrease.
Unlike the Yanomami, Jekwana was exposed to certain aspects of Western lifestyle and diet, including processed food, through interaction and trade with the industrialized world. While the blood pressure readings in the youngest ages were virtually the same as for their Yanomami peers, there was a statistically significant tendency to increase with age – about 0.25 mm Hg per year – so that the Yekwana level was on average 5.8 mm Hg higher at the age of 10 and 15.9 mm Hg higher at the age of 50.
"This age-related increase in blood pressure begins in early childhood – which suggests that early childhood may be a" window of opportunity "to lifestyle interventions to prevent later high blood pressure," says Mueller.
To account for these findings in context, systolic blood pressure in the United States increases by approximately 1.5 mm Hg and 1.9 mm Hg per year in boys and girls and 0.6 mm Hg per year in adults, respectively.
Mueller and his colleagues plan to continue research on intestinal bacteria with Yanomami and Yekwana to determine if the intestinal microbiome corresponds to the differences in blood pressure between the two tribes with age.
The financing was provided by the National Heart, Lung and Blood Institute (K01HL141589), the Alfred P. Sloan Foundation, the C & D Fund and the Emch Fund for microbiological diversity.