The fact that man is an OMNIVOROUS HUNTER-GATHERER is sometimes taken as an argument that western foods would be without adverse health effects. But then an important point is missed: For a typical Westerner at least 70% of calories are provided by foods that were practically unavailable during some period of their human evolution, namely dairy products, oils, margarine, refined sugar and cereals.
These typical western foods are low in minerals, vitamins and soluble fibre but high in fat and salt. There is much evidence indicating that some of these dietary factors are important causes of common western disorders like CORONARY HEART DISEASE, STROKE and DIABETES which furthermore appear absent or rare in populations pursuing a traditional subsistence lifestyle.
Every traditional population so far studied has, after adopting the western lifestyle, developed a more or less typical western morbidity pattern where cardiovascular diseases play the dominant role.
Fully developed ARTERIOSCLEROSIS of the coronary vessels of the heart is part of normal ageing in westernised populations but has not been demonstrated in other free-living mammals. Every studied case of mature atherosclerosis in animals (laboratory animals, domestic swine etc) has been preceeded by a diet which is not eaten by the animal in its natural context. Among lifestyle interventions it is only dietary changes that has been shown to lead to regression of arterioschlerosis.
It is apparently only in westernised humans that ageing is accompanied by increased WEIGHT and BLOOD PRESSURE as well as several other alterations.
CANCER rates may have been low due to a high intake of fruits and vegetables which apparently prevent some common forms of cancer in western populations.
Expectedly, hunter-gatherers would furthermore be protected from OSTEOPOROSIS, another modern epidemic, since their lifestyle implied lots of walking, much sunlight and plenty of vegetables fairly rich in calcium that was highly available due to the low cereal intake. The low sodium intake would probably minimize renal losses of calcium. Some data indicate higher bone mass in ancient human skeletons, although osteoporotic fractures are commonly found in archeological Eskimo skeletons.
As for children, the possible absence of RICKETS in preagricultural skeletons, its apparent increase during medieval urbanization and its epidemic explosion during industrialism can hardly be explained only in terms of decreasing exposure to sunlight. An additional possible cause is an increasing inhibition of calcium absorption by phytate from cereals which took increasingly greater part during the Middle Ages, and since old methods of reducing the phytate content such as dampening and heat-treatment may have been lost during the emergence of large-scale cereal processing.
IN CONCLUSION, atherosclerosis, cardiovascular disease, diabetes, osteoporosis, rickets and other common western diseases can probably to a large extent be prevented by diets resembling those of hunter- gatherers.
THE KITAVA STUDY Against the above background we have made a survey on cardiovascular disease incidence and related risk factors among 2300 subsistence horticulturists in the tropical island of Kitava, Trobriand Islands, Papua New Guinea. Semi-structured interviews concerning disease patterns were performed among 213 Kitavans aged 20-96 years. Age estimations were based on known historic events as reference.
Our most important findings so far published are that sudden cardiac death, stroke and exertion-related chest pain were non-existent or extremely rare in the Kitavan population. Infections, accidents, complications of pregnancy and senescence were the most common causes of death. All adults had low diastolic blood pressure (all below 90 mm Hg) and were very lean (weight decreased after age 30), while serum cholesterol was somewhat less favourable, probably due to a high intake of saturated fat from coconut.
Tubers, fruit, fish and coconut were dietary staples in Kitava. The intake of western food and alcohol was negligible. Saturated fat intake from coconut was high (mainly lauric and myristic acid), and the estimated proportions of energy derived from total, saturated, monounsaturated and polyunsaturated fatty acids were 21, 17, 2 and 2% of dietary energy (en%) compared with 37, 16, 16 and 5 en% in Sweden. The intake of n-3 PUFA, soluble fibre, minerals and vitamins was high, while salt intake approximated 40-50 mmol/24h, as compared to 100-250 in the West.
The level of physical activity was roughly estimated at 1.7 multiples of the basal metabolic rate, which is slightly higher than the levels of sedentary western populations. Eighty per cent of both sexes were daily smokers, supporting the concept that smoking alone is not sufficient to cause cardiovascular disease. Our survey methods preclude any speculation as to the role of psychosocial factors.
The only available migrant was a 44 year-old urbanized businessman who had grown up on Kitava and who came for a visit during our survey. He differed markedly from all other adults regardless of sex: he had the highest diastolic blood pressure (92 mm Hg), the highest body mass index (28 kg/m2) and the highest waist to hip ratio (1.1), indicating that Kitavans are not genetically protected from hypertension or abdominal obesity.
IN CONCLUSION, the virtual absence of cardiovascular disease in Kitava further emphasizes the potential of its prevention. Among the analysed cardiovascular risk factors, leanness and low diastolic blood pressure appeared to be the most important modifiable ones in this population. Our findings are supported by clinical experience by three medical doctors working in the Trobriand Islands since the 1960s.
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