Studies of indigenous groups provide insight into how our ancestors ate, but do not represent exactly how our ancestors ate. Even the studies from the 1940s, 50s and 60s have indigenous groups that are only somewhat representative of Paleolithic eating patterns. We discussed the changes that have occurred over the recent decades in the Tarahumara here, and how the changes affected their rate of hypertension. Despite their efforts to retain tradition, the indigenous Kuna of Panama are undergoing similar changes in lifestyle and have yet to see a change in blood pressure.
Eating patterns of modern indigenous groups differ from pre-agricultural man in that even those who are relatively untouched by urban life are farmers rather than hunter-gatherers, with the rare exception. The Kuna are mostly farmers, but even those who have not migrated to the city have had major changes in their eating habits and lifestyle. Yet indigenous Kuna hypertension is rare.
The Indigenous Kuna
Many Kuna still live on the San Blas Islands. They trade regularly with Colombians for salt and cocoa. In the distant past they did not have access to salt, and they grew their own cocoa. Now they use salt in their meals. And after a devastating destruction of their cocoa plants in the 1950s and 60s they use mostly cocoa from Colombia.
So studies even from the period shortly after the crop destruction would show a very different eating pattern in the indigenous Kuna than would have existed prior. Cocoa would have been consumed less until they developed trade with the Colombians. This Colombian cocoa has a different composition than their prior native cocoa plants.
Kuna Cocoa Consumption
Cocoa is a major component of the Kuna diet, being consumed as a beverage 5 times a day. Some recent papers have discussed how flavonoids in the Kuna's native cocoa plant are in greater concentration than present in other cocoa. There is a dispute about how often this native plant is consumed by the Kuna compared to the Colombian cocoa. If the Colombian plant were consumed most, the flavonoid consumed would be half that from the native plant.
The composition of the two cocoa plants is given in a 2001 paper (1). The Colombian plant has a lower procyanidin content (a flavonoid) but a much higher ratio of potassium to sodium. Some of the later papers by this group of researchers relate that the native plant is the most commonly consumed by the Kuna, although the 2001 paper indicated the Colombian cocoa is most commonly consumed.
A paper by Barnes (2) also indicates that the native plant is consumed less often, being consumed less than once a week. His paper indicates that most of the cocoa consumed is Colombian. This would favor the potassium sodium ratio rather than flavonoids alone as the main factor in cocoa lowering Kuna blood pressure.
The 2001 paper also claims that the sodium consumed by the indigenous Kuna in 1997-1999 is quite high, so that the low blood pressure among the San Blas Islanders is not due to a low sodium intake. They ascribe the low blood pressure to a high flavonoid intake. A number of papers have shown blood pressure lowering effects from flavonoids, including papers showing a potential biological rationale.
Dietary Potassium Sodium Ratio
However, the series of papers by this group does not account for the dietary potassium sodium ratio, although in a 1997 paper (3) they estimate it from urinary sodium and potassium. They discuss potential inaccuracies in the type of study they have done. Such potential inaccuracies are inherent in such studies, and do not detract from their conclusions. If the researchers continue their study over the years, changes in diet and blood pressure will help to sort out the potential factors that may account for the low rate of hypertension.
Most of the food eaten by the Islanders has a high potassium sodium ratio. Because of this their daily dietary ratio is very likely to be higher than the typical Western ratio. Two exceptions to the high ratio food are a soup called Tale Masi, and a condiment that is used for dipping fish. The study indicates that the fish is eaten in small amounts, so the condiment would not contribute much sodium to the diet. The soup is salted according to individual taste. The samples the researchers measured had approximately twice as much sodium as potassium. The soup is reported to be eaten once daily. These two exceptions may not contribute much sodium to the diet.
The Kuna Diet Is Changing
The amount of sodium the San Blas Islanders consume is growing though. Over the past several years it has grown from 2.6 tsp per day just prior to 1997, to 7 tsp per day in 2006. As the potassium sodium ratio shrinks, the amount of hypertension in a population will grow.
It takes time for hypertension to develop. In Western society, where a dietary ratio of 0.6 is consumed from childhood on, the percentage of hypertensives grows from 7.3% at age 18-39 to 32% at age 40-59 and 65% for those over 60 (4). With the present trend in their potassium sodium ratio, the indigenous Kuna will take a number of years before developing a Western prevalence of hypertension.
Urbanized Kuna Hypertension
The Kuna migrating to the city already show blood pressure changes. The 1997 paper discusses the rise of blood pressure in the Kuna as they become urbanized. In addition to the San Blas Island Kuna, their study includes 2 other groups of Kuna. The study relates the blood pressure and diet of Kuna who moved into Panama City, and of Kuna with an intermediate lifestyle who moved into a community, Kuna-Nega, just outside the city.
The Kuna in the transitional location, Kuna-Nega, have not fully adapted a Western diet. They have fewer hypertensives than the Kuna who have become fully Westernized. The fully Westernized Kuna have the same percentage of hypertensives as other Western societies. Thus this aspect of the study agrees with studies of other migratory indigenous groups.
If the dietary potassium sodium ratio in the San Blas Island Kuna continues to shift, it can be expected that the next two decades will show the same percentage of hypertensives in the indigenous group as in the urban Kuna. This happened with the Tarahumara, as discussed here. Increased physical activity, lack of alcohol intake, lack of smoking, and increased flavonoid intake can only postpone the inevitable.
We hope the Kuna will continue to be studied into the future. If there is truly something unique about this group that allows them to escape the fate that a huge body of scientific studies shows to be inevitable, the discovery of the cause of this unique biological difference would be invaluable.
1. Proximate, mineral, and procyanidin content of certain foods and beverages consumed by the Kuna Amerinds of Panama. Chevaux KA, Jackson L, Villar ME, Mundt JA, Commisso JF, Adamson GE, McCullough ML, Schmitz HH, Hollenberg NK. J Food Comp Anal. 2001; 14:553–63.
2. Where Chocolate Begins and Research Methods End: Understanding Kuna Cacao Consumption. Barnes J. Human Organization. 2013; 72(No 3):211-19.
3. Aging, acculturation, salt intake, and hypertension in the Kuna of Panama. Hollenberg NK, Martinez G, McCullough M, Meinking T, Passan D, Preston M, Rivera A, Taplin D, Vicaria-Clement M. Hypertension. 1997 Jan; 29(1 Pt 2):171-6.
4. Hypertension Among Adults in the United States: National Health and Nutrition Examination Survey, 2011–2012. Tatiana Nwankwo, M.S.; Sung Sug (Sarah) Yoon, Ph.D., R.N.; Vicki Burt, Sc.M., R.N.; and Qiuping Gu, M.D., Ph.D. NCHS Data Brief, No. 133, October 2013.