A Swedish researcher, Staffan Lindeberg, has been studying the inhabitants of Kitava, one of the Trobriand Islands of Papua New Guinea. He claims that sudden cardiac death, stroke, and exertion-related chest pain never occur in Kitava; and he attributes this to their eating a Paleolithic diet.
2,250 people live on Kitava. They are traditional farmers. Their dietary staples are tubers (yam, sweet potato and taro), fruit, fish, and coconut. They don’t use dairy products, alcohol, coffee, or tea. Their intake of oils, margarine, cereals, and sugar is negligible. Western foods constitute less than 1% of their diet. Their activity level is only slightly higher than in Western populations. 80% of them smoke daily and an unspecified number of them chew betel. The macronutrient composition of the Kitavan diet was estimated as 21% of total calories from fat, 17% from saturated fat, 10% from protein, and 69% from carbohydrates.
Lindeberg’s Kitava study examined a sample of 220 Kitavans aged 14-87 and compared them to healthy Swedish populations. They found substantially lower diastolic blood pressure, body mass index, and triceps skinfold thickness in the Kitavans. Systolic blood pressure was lower in Kitava than in Sweden for men over 20 and women over 60. Total cholesterol, LDL cholesterol, and apolipoprotein B were lower in men over 40 and in women over 60. Triglycerides were higher in Kitavans aged 20-39 than in Swedes of the same age. HDL was not significantly different.
Another study examined how the Kitavans’ risk factors changed with age.
I am always suspicious of initial reports of unusually healthy or long-lived groups in remote areas, because I have so often seen such reports disconfirmed by subsequent investigations. Lindeberg’s studies were done in the early 90’s and have not been confirmed by other studies in the ensuing two decades. In the Kitava study, the ages of subjects were not objectively verifiable, but were estimated from whether or not they remembered significant historical events. The absence of heart disease and stroke was deduced by asking islanders if they had never known anyone who had the symptoms of either condition. This was reinforced by anecdotal reports from doctors who said that they didn’t see those diseases in islanders. EKGs were done on the Kitavans, but a normal EKG does not rule out atherosclerosis or cardiovascular disease. I’m not convinced that we have enough solid data to rule out the presence of cardiovascular disease or other so-called “diseases of civilization” in that population.
But even supposing those diseases don’t exist in Kitava, what could we deduce from that? Lindeberg thinks it constitutes evidence to support the Paleolithic diet of meat, fish, vegetables, fruit and nuts that our ancestors ate 2,000,000 to 10,000 years BP. We aren’t really sure what our Paleolithic ancestors ate, but we can be reasonably sure they didn’t typically eat what Kitavans eat. The Paleolithic diet included meat and was probably much higher in protein than the Kitavan diet. Most of our Paleolithic ancestors probably did not have access to coconuts or taro or to an abundance of fish. Our ancestors were hunter-gatherers, while the Kitavans are farmers; agriculture did not develop until around 10,000 BP.
I don’t see how we could assume the absence of those diseases was due to the Kitavan diet. Other causes would have to be ruled out, including heredity and environmental factors. Even if it was due to the diet, how could we possibly know whether it was due to the diet as a whole or to some specific aspect or component of the diet?
What can we conclude?
The Kitava study serves as a disconfirming example to discredit the claims made for low-carb diets. Kitavans eat a very high-carb diet, with lots of saturated fat and little protein, and they appear to thrive on it without becoming obese or developing a high incidence of metabolic syndrome as the low-carb theorists would predict.
It is evidence against the hypothesis that low-fat diet recommendations caused the obesity “epidemic” simply because people replaced fat with carbohydrates. It shows that a diet high in carbohydrates does not necessarily lead to obesity, especially if they are complex carbohydrates and the total calorie intake is not excessive.
It supports the general consensus of most diet experts that a predominately plant-based diet is healthy. It supports Mom’s admonishments to eat our vegetables.
It suggests that saturated fat need not be avoided, especially if it is of vegetable rather than animal origin.
It tends to confirm the health benefits of weight control and the principle that weight can be controlled simply by limiting calories. The Kitavans are not overweight, and their intake of calories is lower than the conventional Western diet.
It tends to support advice to avoid processed foods and refined carbohydrates.
It reinforces the concept that humans can thrive on a wide variety of diets.
The Kitava Study provides food for thought; it doesn’t provide enough justification to recommend either a Kitavan diet or a standard “Paleolithic diet” over other healthy diets.
This article was originally published in the Science-Based Medicine blog.