Which nuts are best? The definitive answer to this question is currently unknown. In the Adventist Study about about 32 percent of the nuts eaten were peanuts, 29 percent almonds, 16 percent walnuts, and 23 percent other types. These researchers did not ascertain whether the nuts were fresh, oil-roasted, or dry-roasted. The Nurses’ Study found that peanuts, which are legumes, appeared to be just as effective in reducing the risk of coronary heart disease as tree nuts6. Experiments where volunteers were fed nuts as part of their diet for several weeks have found that walnuts20-23, almonds23-26, hazelnuts26, peanuts27, pecans29, pistachio nuts30 and macadamia nuts31 all alter the composition of the blood in ways that would be expected to reduce the risk of coronary disease. Chestnuts, a nut unusually low in fat, do not yet seem to have been studied. The best advice currently is probably to eat a variety of nuts. Walnuts though, because they contain n-3 fatty acids, may be particularly beneficial 32, but this requires further study. Coconuts, on account of their high saturated fat content, should probably be avoided.
It is not completely understood just why nuts are so consistently found to be healthy32. Nuts contain low levels of saturated fats and high levels of unsaturated fats. Consequently, as would be expected, studies have clearly shown that nut consumption lowers blood cholesterol levels. No doubt the lower cholesterol lowers the risk of heart disease.
Interestingly though the cholesterol is lowered by a larger amount than would be expected just from the favourable fatty acid composition of nuts31. However the reason for this is not clear. Nuts though are good sources of fibre, vitamin E, folic acid, copper, magnesium and the amino acid arginine, for each of which there is evidence of a role in preventing heart disease32. Nuts are the best dietary source of manganese and contain plant sterols, the compounds now added to some margarines to reduce cholesterol adsorption from food, and are a good source of boron33. The nutrient composition of nuts has been reviewed by King34 and by Chen35.
Even peanuts seem to work!
Per this article..