A study of two isolated South American tribes has shed light on the influence of diet in the onset of hypertension, upending the common consensus that higher blood pressure is a direct, and inevitable, consequence of aging.

The fascinating research focused on two remote tribes living around the border of Brazil and Venezuela – the Yanomami and the Yekwana. The Yanomami tribe has proved particularly compelling to scientific researchers as several decades of study has revealed they have significantly low blood pressure levels, which do not seem to rise as they age.

The new study set out to examine the blood pressure of Yanomami subjects in comparison to a nearby tribe called the Yekwana. The big difference between the two tribes is that while the Yanomami have been able to remain significantly isolated with little exposure to Western influences, the Yekwana have been much more exposed to Western diets and lifestyles since the construction of an airstrip in the middle of their territory in 1969, which introduced trading and foreign food to their communities.

Over 70 Yanomami tribe members, aged from one to 60, revealed remarkably stable low blood pressure readings, with no trend towards a blood pressure increase as they aged. However, the nearby Yekwana tribe displayed a statistically clear trend of rising blood pressure as they aged, displaying systolic measurements on average 15 mm higher than their Yanomami counterparts by the age of 50.

"This age-related rise in blood pressure 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," says Noel Mueller, one of the researchers on the project.

While the study inevitably has several limitations, including a relatively small sample set, the unique opportunity to compare two distinct tribal populations in similar geographical locations allows for relatively solid conclusions to be made about the influence of a Western diet on certain health factors.

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

The next step for the researchers is to turn their sights on the two tribes' gut bacteria. Examining the differences between their microbiomes will hopefully elucidate whether differences in gut microbiota can account for the variations in the age-related blood pressure readings between the two tribes.

The new study was published in the journal JAMA Cardiology.