Some years ago a medical paper was published that caused a run on Brazil nuts throughout the western world. For a time they disappeared entirely from supermarket shelves; for Brazil nuts contain a high level of selenium and the medical paper had suggested that the high rate of heart attacks in a certain province of China was caused by the exceptionally low level of selenium in the inhabitants’ diet.
But of course for every panacea there is an equal and opposite health scare. Brazil nuts concentrate radium and give off more radiation than any other food; they also often contain relatively high levels of aflatoxin, produced by a fungus of the Aspergillus genus. Aflatoxins are very carcinogenic, leading to cancer of the liver.
So where Brazil nuts are concerned, the question boils down to whether you would prefer to die of heart attack or cancer.
A paper in a recent edition of the New England Journal of Medicine suggests that, overall, nuts are very good for you. The authors compared the death rates among female nurses and male health nurses according to their self-reported consumption of nuts. They divided nut consumption into true nuts and peanuts, the latter being legumes rather than nuts.
I never cease to be amazed at the organizational feat of such studies: 76,464 women and 42,498 men were followed up between 1980 and 2010 and 1986 and 2010, respectively. After various statistical manipulations which 99 percent of the readership of the NEJM would not understand it was found that the more nuts people ate (including the false nuts known as peanuts), the lower their all-cause mortality. They didn’t just die less of such illnesses as heart attack, stroke and cancer, but of all illnesses whatsoever. At last, then, the panacea!
People who ate nuts more than seven times a week(!), hunter-gatherer style, had a 20 percent less chance of dying in the period of follow up than those who never ate nuts. This is a very big effect, for me almost too big to be believed.