"People would get the wrong message if they think that they can continue eating unhealthy fats provided they add walnuts to their meals," said Emilio Ros, MD, PhD, director of the Lipid Clinic at Hospital Cl?nico in Barcelona, Spain, the principal site where the research was conducted.
"Instead, they should consider making walnuts part of a healthy diet that limits saturated fats.
"Each time we eat a high-fat meal, the fat molecules trigger an inflammatory reaction that, among other ill effects, reduces the elasticity of the arteries," Dr. Ros
"Over time, this repeated damage is thought to contribute to hardening of the arteries and, in turn, to heart disease.
Our latest research shows that eating walnuts helps to maintain the elasticity of the arteries."
For the study, Dr. Ros
colleagues recruited 24 nonsmoking adults with normal body weights and blood pressures.
"The inner lining of the arteries produces a substance called nitric oxide that is needed to keep the arteries flexible," Dr. Ros
"When we eat high-fat meals, the fat molecules temporarily disrupt the production of nitric oxide, preventing the arteries from increasing blood flow in response to physical activity."
One of the nutrients found in walnuts, he
said, is arginine, an amino acid used by the body to produce nitric oxide.
Walnuts also contain antioxidants and alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid.
Olive oil does not contain ALA, a specific type of healthy, polyunsaturated fat.
Currently, Dr. Ros
is beginning a new trial to determine whether the ALA in walnuts will help people with abnormal heart rhythms.
The ALA, although from plants, is similar to the omega-3 fatty acids found in fish.
These fatty acids already have been shown to help prevent atrial fibrillation in some people.
For people worried about gaining weight from adding walnuts or olive oil to their diets, Dr. Ros
said no evidence exists that links healthy fats to increases in body weight.
Eating more saturated fats, such as butter or lard, however, often leads to weight gain because these fats usually are consumed with simple sugars, he
Dr. Ros serves on the scientific advisory board of the California Walnut Commission.