It’s been a rough week for some of the foods we’ve come to think of as healthy. One recent study called into question the health benefits of chocolate and red wine, while another took issue with the original research on fatty fish and heart disease. The jury is still out on how much attention we should pay these new warnings, but happily, new research in Proceedings of the National Academy of Sciences looks at the effect of the Mediterranean diet on heart health - and the verdict is favorable. But even more than that, the study lays out exactly why olive oil and greens are together so beneficial for the heart. Though the study was done in mice, the results very likely apply to humans, too.
Until now, researchers hadn’t quite been able to explain why a diet high in fat as the Mediterranean diet is linked to cardiovascular health. Researchers have wondered what exactly it is about the fats that helps the heart, and now they’ve arrived a pretty convincing mechanism to explain it.
The trick is to create a “fusion” of the healthy fats in, say, olive oil and the nitrites and nitrates in greens like spinach, celery, and carrots, which make up a large part of the Mediterranean diet. This fats-greens pairing, according to the researchers, creates a compound - nitro fatty acid - that has the effect of relaxing blood vessels and bringing down blood pressure, which are key components of heart health.
To test the theory, the team fed mice - with high blood pressure - the omega-6 fatty acids found in olive oil. They also added to their diets sodium nitrite, in order to mimic the pairing of olive oil and veggies. Indeed, not only was the level of nitro fatty acids higher in these mice, but their blood pressure was lower at the end of the 5-day intervention. And when the researchers used a strain of mice that were resistant to the effects of the nitro fatty acids, their blood pressure did not change.
Though the research was done in mice, the mechanism likely applies to people, too. Earlier research has pointed to the benefits of olive oil and nuts on cardiovascular health in humans.
“The findings of our study,” said study author Philip Eaton, “help to explain why previous research has shown that a Mediterranean diet supplemented with extra-virgin olive oil or nuts can reduce the incidence of cardiovascular problems like stroke, heart failure and heart attacks.” Avocados may work too, the team told the BBC, since they also contain healthy unsaturated fats.
The effect of the Mediterranean diet is somewhat like the “French effect” - but with the latter, a diet higher in saturated fats in linked to cardiovascular health, which is a little less intuitive. While researchers are still scratching their heads to figure out all the effects of the world’s many diets, the Mediterranean diet is probably a safe bet, since it’s better understood and more intuitive than some. Eating lots of vegetables, fruits, whole grains, nuts, fish, and very little red meat, dairy, and sweets just makes sense. And, if you’re so inclined, have a little red wine to go along with it. After all, one thing we do know about nutrition is that moderation is usually the best rule of thumb.
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