Monday, March 17, 2008
Say Hello to the Kuna
For those of you who haven't been reading the comments, we've been having a spirited discussion about the diet and health of hunter-gatherers here. I brought up the Kuna indians in Panama, who are immune to hypertension, live a good long time, do not gain excess weight, and seem to have less cardiovascular disease and cancer than their city-dwelling cousins.
I was hungry for more information about the Kuna lifestyle, so over the last few days, I've dug up every paper I could find on them. The first paper describing their lack of hypertension was published in 1944 and I don't have access to the full text. In 1997, a series of studies began, headed by Dr. Norman Hollenberg at Harvard. He confirmed the blood pressure findings, and collected data on their diet, lifestyle and kidney function. Here's a summary:
The Kuna are half hunter-gatherers, half agricultural. They cultivate plantains, corn, cocoa, yucca, kidney beans, and several types of fruit. They trade for sugar, salt, some processed cocoa and miscellaneous other foods. They drink 40+ oz of hot cacao/cocoa per day, some locally produced and some imported. A little-known secret: the Kuna eat an average of 3 oz of donut a week. They also fish and hunt regularly.
In the first recent study, published in 1997, the Kuna diet is described as 29% lower in fat than the average US diet (56 g/day), 23% lower in protein (12.2 g), 60% higher in cholesterol, and higher in sodium and fiber. The study doesn't specifically mention this, but the reader is left to infer that 65% of their calories come from carbohydrate. This would be from plantains, corn, yucca, sugar and beans. The fat in their diet comes almost exclusively from coconut, cocoa and fish: mostly saturated and omega-3 fats.
In the next study, the picture is beginning to change. Their staple stew, tule masi, is described as being 38% fat by calories (from coconut and fish), exceeding the American average. In the final study in 2006, Hollenberg's group used a more precise method of accounting for diet composition than was used in previous attempts. The paper doesn't report macronutrients as a percentage of calories, and I suspect the reason is that they aren't consistent with the previous papers. They have retreated from their previous position that the Kuna diet is low-fat and describe it instead as "low in animal fat", leaving plenty of room for saturated fats from coconut and cacao.
I was able to find some clues about their diet composition, however. First of all, they report the meat consumption of the Kuna at approximately 60 oz per week, mostly from fish. That's 8.6 oz per day, identical to the American average. They also reported the fat content of the cacao the Kuna produce locally and brew into their favorite 40-oz-a-day drink. It's 44.2% fat by weight. The low-fat cocoa drinks they used to calculate macronutrient totals are made from imported cocoa (cocoa is defatted cacao powder), ignoring the locally produced, full-fat cacao. If we assume half the chocolate they drank was locally produced, that's about 30 additional grams of fat a day, bringing their total fat intake to 8g above the average American. I suspect the authors chose to ignore the locally-produced cacao to lower the apparent fat intake of the Kuna, even though the paper states they drank both regularly.
By putting together the pieces from the later studies, a new picture emerges: a diet high in fish and moderate in protein, high in unprocessed fat (especially saturated and omega-3), and moderate in mostly unprocessed carbohydrate.
Here's my biased interpretation. The Kuna are healthier than their city-dwelling cousins for a number of reasons. They have a very favorable omega3:6 ratio due to seafood, wild game and relatively saturated vegetable fats. Their carbohydrate foods are mostly unprocessed and mostly from non-grain sources. They also live an outdoor life full of sunshine (vitamin D) and exercise. The chocolate may also contribute to their health, but I doubt it's a major effect. They're healthier than industrialized people because they live more naturally.
Another lesson to be learned from the Kuna and other exceptionally healthy indigenous peoples is that the human body can tolerate a fair amount of carbohydrate under the right conditions. Peter discusses another example of this, the Kitavans, on his blog. 50% carbohydrate while sitting in front of a desk all day, eating corn oil and getting no exercise = bad. 45% carbohydrate while hunting, relaxing and preparing whole, natural food in the sun all day = good.