On the island of Kitava there are coconuts, sweet potatoes, yams, a few other starches and fish to eat. This leads to an interesting diet. The estimated percentages of energy from protein, fat and carbohydrates are 10%, 21% and 69% in Kitava. Most of the fat is saturated. Three quarters of the population smoke.
Obviously high carb eating should mean catastrophic blood lipids. You would expect low HDL cholesterol and high triglycerides. And this is exactly what you find. HDL-C down at 1.1mmol/l (some as low as 0.5mmol/l) and triglycerides up at 1.7mmol/l (some up at 3.0mmol/l). Not a good ratio. They smoke too. Must be a hotbed of cardiovascular disease. Especially as some of the total cholesterol readings were up around the (gasp) 7.0mmol/l mark. Pravastatin in the local well water is the obvious answer.
Except they have no heart disease. On a diet of 70% carbohydrate. Life expectancy, ignoring neonatal mortality which appears to be high, is around seventy years. That's without any medical facilities. How do they do it?
BTW there were two amusing comments in the discussion of this paper. The best was:
"Evaluation of TGs and HDL-C as cardiovascular risk factors must thus be restricted to the study population"
I'll rephrase that. In Sweden "bad" lipds (and smoking!) are BAD. Not so in Kitava, here "bad" lipids are not bad. They're a product of diet composition. As there is no heart disease they must be good!
So what's happening? Do horrible triglycerides block to your arteries like hot beef fat blocks a cold sewer in Sweden, but then by magic they become non sticky in Kitava? Go figure. Hint, maybe it's not the lipids that trigger the blocked arteries.
Second comment was
"our findings lend no support to the concept that a very high intake of carbohydrates (>60% of energy) increases the risk of cardiovascular disease"
ie living on low fat doughnuts is safe for everyone. Everyone. No suggestion that you have to live in Kitava for this to be the case. So if you eat a junk diet in Sweden and get Kitava lipids in Sweden plus smoke Kitava cigarettes, will you be OK? Somehow I doubt it!
So why are the Kitavans free of heart disease?
Their average fasting glucose is 3.7mmol/l and their fasting insulin 4.0 microU/ml. They do not have any features of metabolic syndrome! Except the lipids of course. Despite eating appalling quantities of carbohydrate. If we define metabolic syndrome as carbohydrate intolerance how do the Kitavans manage this?
I think that this goes back to the main limit on population growth, which is food. Daniel Quinn is the best source of information on this subject. As the Kitavans live with minimal Western food it seems they must be living within the food production capacity of their island. The basic principle is that populations grow to the limit set by their food supply. On Kitava you cannot make babies out of thin air. No extra yams means no extra people. The fluctuations in food and population must mean there are fluctuations in hunger and plenty, but if populations really do expand to the limits of food supply, the island location must ultimately apply calorie restriction. On average.
Ad lib food on a global basis has resulted in a population explosion. On an individual basis it results in a waistline explosion. As carbohydrate is cheap, addictive and hunger generating it is what usually fuels the metabolic syndrome, hence "bad" lipids are associated with metabolic syndrome as carbohydrates are the usual tool of excess calorie intake.
Calorie restriction, intermittent fasting and once daily eating all limit the development of insulin resistance and hyperglycaemia, pretty well independent of macro nutrient ratio. On Kitava there must be accidental calorie restriction as the population is in equilibrium with with a fixed food supply, hence no metabolic syndrome. Despite the "bad" lipids, which merely reflect the composition of their restricted diet.
Can we all do the same? Probably yes, but having read about life on the calorie restricted optimal nutrition (CRON) diet this is definitely not for me. Licking the plate clean because the sauce is delicious is one thing. Doing it because you are starving is quite another! No, there does appear to be a better way.
Eating a ketogenic diet appears to mimic calorie restriction. Ketosis limits appetite so allows modest calorie restriction without any hunger. Forget any drug which may be developed to mimic eating a high fat diet. Better pile on the lard, dump the "healthy" carbohydrate and generate a few ketone bodies. Enough to keep your energy intake reasonable without that desperate dreaming of food which is reputed to go with CRON.
Or you can starve on a balanced diet.