Friday Facts: The Power of Nuts

Some fun facts about nuts from Dr. Michael  Greger’s excellent book “How Not to Die.” This book has lots of information about specific foods — I highly recommend it!

  • women at high risk for heart disease who ate nuts or a tablespoon of peanut butter five or more days a week appeared to nearly halve their risk of suffering a heart attack compared to women who ate a serving or less per week
  • people who increased their nut increase from a half ounce per day to one ounce per day appear to cut risk of stroke in half
  • while nuts are high in calories, studies have shown that through a combination of dietary compensation mechanisms, your body’s failure to absorb some of the fat, and increased fat-burning metabolism, adding nuts to your diet does not tend to cause weight gain

Here is a an excerpt that goes into more detail about the studies on nuts. One note: in this excerpt he mentions “red light” and “yellow light” foods, which in the book are what he calls foods to avoid and foods to eat in moderation.

From “How Not to Die”:

Sometimes it feels like there just aren’t enough hours in a day to get everything done. So instead of trying to make your day longer, why not make your life longer by an extra two years? That’s about how long your life span may be increased by eating nuts regularly— one handful (or about a quarter of a cup) five or more days a week. Just that one simple and delicious act alone may extend your life.

The Global Burden of Disease Study calculated that not eating enough nuts and seeds was the third-leading dietary risk factor for death and disability in the world, killing more people than processed meat consumption. Insufficient nut and seed intake is thought to lead to the deaths of millions of people every year, fifteen times more than all those who die from overdoses of heroin, crack cocaine, and all other illicit drugs combined.

[…]

Which nut is healthiest? Normally, my answer is whichever you’re most willing and able to eat regularly, but walnuts really do seem to take the lead. They have among the highest antioxidant3 and omega-34 levels, and they beat out other nuts in vitro in suppressing cancer cell growth. But how do walnuts fare outside the laboratory in real life?

PREDIMED is one of the largest interventional dietary trials ever performed. Interventional studies, if you remember, are those in which participants are randomized to different diets to see who fares better. This helps researchers avoid the problem of confounding variables when trying to determine cause and effect in cohort studies. For example, in major study after study after study, people who eat nuts tend to live longer and suffer fewer deaths from cancer, heart disease, and respiratory disease. There was a lingering question, though: Did these findings show causation or merely correlation? It could be possible, after all, that nut eaters also tend to have other healthy lifestyle behaviors. Maybe those who eat nuts are more likely to be, well, health nuts. On the other hand, if scientists randomly assign thousands of people to various levels of nut consumption and the nuttier group ends up the healthiest, we could have more confidence that nuts aren’t just associated with better health but actually cause better health. This is what PREDIMED ended up doing.

More than seven thousand men and women at high cardiovascular risk were randomized into different diet groups and followed for years. One of the groups received a free half pound of nuts every week. […] At baseline, before the study even started, the thousands assigned to the nut group were already eating about half an ounce of nuts a day. Thanks to the ensuing freebies, they ended up bumping up their consumption to a whole ounce (about a handful). As a result, the study was able to determine what happens when people at high risk for heart disease following a particular diet eat an extra half ounce of nuts every day.

With no significant differences in meat and dairy intake, there were no significant differences in saturated fat or cholesterol intake. So, unsurprisingly, there were no significant differences in their blood cholesterol levels or the subsequent number of heart attacks. However, the added-nuts group did end up having significantly fewer strokes. […F]or those not willing to make major shifts in their diet, just the minor tweak of adding nuts appeared to cut stroke risk in half.

[…]

Regardless of which group participants were assigned to, those eating more nuts each day had a significantly lower risk of dying prematurely overall. Those who consumed more red- and yellow-light sources of fat— olive oil or extra virgin olive oil— failed to have any survival benefit. This is consistent with the way Ancel Keys, the so-called father of the Mediterranean diet, viewed olive oil. He thought of its benefit more as a means of replacing animal fats — that is, anything to get people to eat less lard and butter.

Of all the nuts studied in PREDIMED, the researchers found the greatest benefits associated with walnuts, particularly for preventing cancer deaths. People who ate more than three servings of walnuts per week appeared to cut their risk of dying from cancer in half. A review of the scientific literature concluded that “the far-reaching positive effects of a plant-based diet that includes walnuts may be the most critical message for the public.”

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