Walnuts may do a better job than olive oil at keeping arteries healthy

Credit: Nick Frey

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SYDNEY: Walnuts may help prevent heart disease, according a team of Spanish researchers.

In a recent study, the group, working at the University of Barcelona, found that a handful of walnuts after a fatty meal prevented arteries from hardening up as much as they might. Clogged arteries can lead to heart attacks, so these findings could have big implications for future heart-healthy diets.

When eaten regularly, walnuts are known to help lower 'bad' cholesterol levels. The study, funded by walnut growers and the Spanish government, and reported in this week's Journal of the American College of Cardiology, is the first to suggest they have immediate benefits, as well.

"Each time we eat a high-fat meal, the fat molecules trigger an inflammatory reaction that … reduces the elasticity of the arteries," said Emilio Ros, one of the authors of the study. "Over time, this repeated damage is thought to contribute hardening of the arteries and, in turn, to heart disease."

"The inner lining of the arteries produces a substance called nitric oxide that is needed to keep the arteries flexible," he said. "When we eat high-fat meals, the fat molecules temporarily disrupt [its] production."

According to Ros, walnuts help the body maintain artery flexibility by providing the building blocks for nitric oxide.

He cautions that people shouldn't substitute walnuts for a healthy diet and exercise, however.

"People would get the wrong message if they think that they can continue eating unhealthy fats provided they add walnuts to their meals," said Ros. "Instead, they should consider making walnuts part of a healthy diet that limits saturated fats."

The study has already received attention from other researchers concerned with cardiac health. Robert Vogel, from the University of Maryland, says the research questions some long-standing assumptions about the reasons why some diets help lower cholesterol.

Doctors often prescribe 'Mediterranean' diets for patients trying to lower their cholesterol. It has long been thought that Mediterranean diets owe their health benefits to their high olive oil content. But according to Dr. Vogel, this research suggests it's not true. "There are probably other factors in the diet, including that it is a relatively rich source of nuts."

More research is needed to determine how cooking affects walnuts' artery-protecting properties, according to Vogel. The nuts may need to be eaten raw in order to provide the greatest health benefit, he said.

Ros and his colleagues receive funding from the Spanish Ministry of Health, Fundación Carolina, and the California Walnut Commission. Ros serves on the scientific advisory board of the latter.