“Observational” studies are interesting but “interventional” studies are the nuts and bolts of nutritional science. And talking about nuts, a study just published in the New England Journal of Medicine is sure to generate a plethora of nutty headlines about nuts reducing the risk of death. Well, the risk of death cannot be reduced, it is 100%, save perhaps for one questionable example two thousand years ago. But the risk of death during a specific period can be reduced, and that is just what happened in this study. In an observational study researchers attempt to glean information by observing the habits of a population over a period of time. In a long term study monitored by Harvard scientists, nurses and physicians filled out dietary questionnaires every couple of years. When the subjects were divided into groups based on their nut consumption, it turned out that there were fewer deaths among the nut eaters even when other factors such as exercise habits and calorie consumption were taken into account. Of course this doesn’t mean that nuts have some special health benefit, it may be that they just replaced some less healthy components of the diet.
Interesting, especially given that a number of other observational studies have come up with similar results and that nuts are rich in antioxidants which conceivably could have benefits. When evidence from all studies is combined, subjects consuming nuts at least 4 times a week show an almost 40% reduced risk of coronary heart disease compared with those who never or seldom eat nuts. Each additional serving of nuts per week is associated with an average of 8% reduced risk of coronary heart disease. Only an intervention study would clarify the situation. This would involve following two groups of subjects for years and years with the only difference between the groups being nut consumption. Since this would be far too challenging to organize and monitor, we are left to make an educated guess. A handful of mixed unsalted nuts is definitely a better snack than chips, cookies or Twinkies. Will it reduce your risk of death? Nothing can do that. But it may help put it off. Especially if you use the nuts as a reward for your taste buds after exercise.