The liver can synthesize niacin from the essential amino acid tryptophan, requiring 60 mg of tryptophan to make one mg of niacin.

The idea that cardiovascular disease is not associated with high fat diets is also shown by comparison study of matched groups of twenty-eight railwaymen from North India and twenty-eight from Southern India.(53) The consumption of fats, mostly of animal origin, was ten times higher among the North Indians than the South Indians, but there were no significant differences between their lipid and cholesterol levels. Among the South Indian population, the incidence of heart disease is said to be fifteen times as high as among the North Indians where the fat content of the diet is ten times higher. Dietary factors are doubtless very important in connection with the incidence of heart disease, but fat is only one factor, and other dietary factors are considerably more important.

This is also corroborated by a study of 400 Masai men in Tanganyika.(54) In spite of the fact that the diet of these men is almost exclusively milk and meat (consumption of whole blood is relatively rare), both of which contain much fat and plenty of cholesterol, the cholesterol levels in the blood of the Masai are extraordinarily low, and there was "no evidence of arteriosclerotic heart disease." It should be noted that a diet containing large quantities of meat is free from "naked calories," and is certain to supply an assortment of amino acids, minerals, and vitamins in liberal amounts. Though the Masai have other health disorders - many of infective origin - they probably escape heart disease because their body cells are furnished with an environment that is adequate enough to protect their hearts and blood vessels.

A corollary of the notion that saturated fats are archvillains is the idea that one should eat substantial amounts of polyunsaturated fats. (The phrase "polyunsaturated fatty acids" has become virtually synonymous with "heart protection" in both popular and orthodox medical thinking.) While everyone should have unsaturated fats in his diet, their presence does not by any means afford adequate protection against atherosclerosis and heart disease. The current consumption of polyunsaturated fatty acids in the USA is higher than it has ever been, yet this does not curb heart disease.(55) There are many reasons on which to base our conclusion that other factors are far more important.(56) When other deficiencies are eliminated, the amount of unsaturated fat is of secondary importance. If there is plenty of vitamin B6 in the diet, fat metabolism tends to take care of itself.
I have said a good deal about vitamin B6, but I do not mean to imply that it is, by itself, the answer to heart disease. All the nutrients contribute to the prevention of heart trouble.