July 9, 2019

Walnuts: The Big Question Answered

Over the years we have seen a long line of studies published suggesting that people who eat more nuts have a lower risk of heart disease. It started years ago when studies found that eating a serving of nuts each day lowered cholesterol levels after a month or so. Then there were studies that found that people, such as vegetarians or Seventh Day Adventists who ate more nuts seemed to have a lower risk of heart disease. It was all well and good for us to know that people who had always eaten nuts during their life had gained some protection but what about the rest of us, the casual nut eaters who had only gotten serious about eating more nuts as we aged and became more interested in improving our risk ratios against all those infirmities and morbidities that were on the horizon?

Just recently we saw the outcomes reported in a study done by a group of researchers from Harvard’s T.H. Chan School of Public Health. They had finally asked the right question: Will eating more nuts now, later in life, decrease our risk of heart disease down the road? Or put another way: Will it be worth the bother to try and change our eating habits (something that doesn’t come easy)?

Harvard’s researchers have the ability to ask questions like this as they have data from several large patient cohorts at their disposal and are skilled at accessing it. In this study, they analyzed data pulled from 34,222 men enrolled in the Health Professionals Follow-up Study, 77,957 women from the Nurses' Health Study, and 80,756 women from the Nurses' Health Study II. Not quite 200,000 participants were followed for a mean of 17.2 years. This adds up 2,818,760 person-years of data; more than enough data to ask some very specific questions. Nut consumption had been assessed every four years. Using some sophisticated statistics, the researchers examined the difference shifting nut consumption had on risk of having a heart attack or dying of coronary artery disease, or stroke. Their findings both confirmed those earlier, weaker studies and assured us that making even slight changes in our diets now, such as increasing nut consumption, will pay off in the long run.

For each half-serving of walnuts per day that people added to their diets, the relative risk of cardiovascular disease over the following 4 years dropped by 14%. For other tree nuts and for peanuts, the relative risk dropped only 7%. Regular and consistent nut consumers had a significantly lower risk for cardiovascular disease, coronary heart disease and stroke.

While these numbers do not come as a great surprise, the strength of this study is striking. The fact that changing consumption patterns change outcome risk in a relatively short period of time is perhaps the most striking. That and the fact that walnuts appear to provide substantially more benefit than other types of nuts.

What counts as a serving of nuts? The answer is one ounce of nuts or 28 grams. This study looked at the effect that half a serving a day has, or 14 grams of walnuts. There are 12 -14 walnut halves in an ounce, so we are talking about just half a dozen walnuts halves per day.

Once again, I feel an urge to take my hat off to the fine researchers at T.H. Chan who have provided with information that can make a difference.

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