A Mediterranean diet high in olive oil, nuts, fish and fresh fruits and vegetables may help prevent heart disease and strokes, according to a new large study from Spain

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Past research suggested people who eat a Mediterranean-like diet have healthier hearts, but those studies couldn’t rule out that other health or lifestyle differences had made the difference.

For the new trial, researchers randomly assigned study volunteers at risk of heart disease to a Mediterranean or standard low-fat diet for five years, allowing the team to single out the effect of diet, in particular.

“This is good news, because we know how to prevent the main cause of deaths – that is cardiovascular disease – with a good diet,” said Dr. Miguel Angel Martinez-Gonzalez, who worked on the study at the Universidad de Navarra in Pamplona.

He and colleagues from across Spain assigned almost 7,500 older adults with diabetes or other heart risks to one of three groups.

Two groups were instructed to eat a Mediterranean diet – one supplemented with extra-virgin olive oil and the other with nuts, both donated for the study – with help from personalized advice and group meetings. The third study group ate a “control” diet, which emphasized low-fat dairy products, grains and fruits and vegetables.

Over the next five years, 288 study participants had a heart attack or stroke or died of any type of cardiovascular disease.

People on both Mediterranean diets were 28 to 30 percent less likely to develop cardiovascular disease than those on the general low-fat diet, the researchers reported Monday in the New England Journal of Medicine.

The new study is the first randomized trial of any diet pattern to show benefit among people initially without heart disease, said Dr. Dariush Mozaffarian, who studies nutrition and cardiovascular disease at the Harvard School of Public Health in Boston.

NOT DUE TO SINGLE INGREDIENT

It’s the blend of Mediterranean diet components – not one particular ingredient – that promotes heart health, according to Martinez-Gonzalez.

“The quality of fat in the Mediterranean diet is very good,” he told Reuters Health. “This good source of calories is replacing other bad sources of calories. In addition, there is a wide variety of plant foods in the Mediterranean diet,” including legumes and fruits as desserts, Martinez-Gonzalez added.

“I think it’s a combination of what’s eaten and what’s not eaten,” agreed Mozaffarian, who wasn’t involved in the new research.

“Things that are discouraged are refined breads and sweets, sodas and red meats and processed meats,” he told Reuters Health. “The combination of more of the good things and less of the bad things is important.”

Martinez-Gonzalez suggested people seeking to improve their diet start with small changes, such as forgoing meat one or two days per week, cooking with olive oil and drinking red wine with meals rather than hard alcohol.

Replacing a high-carbohydrate or high-saturated fat snack with a handful of nuts is also a helpful change, said Teresa Fung, a nutrition researcher at Simmons College in Boston who also wasn’t on the study team.

“All of these steps are making, at the end of the day, a big difference,” Martinez-Gonzalez said.

Fung pointed out many people in the new trial were already on medications, such as statins and diabetes drugs.

“The way I see it is, even if people are on medication already, diet has substantial additional benefit,” she told Reuters Health.

That’s likely the case for people without heart risks – including high blood pressure or cholesterol – as well, Fung added.

“This is a high-risk group, but I don’t think people should wait until they become high-risk in order to change,” she said.

SOURCE: New England Journal of Medicine, online February 25, 2013.

Weekly Abstracts:

Mediterranean Diet and Non-Enzymatic Antioxidant Capacity

CARDIOVASCULAR DISEASE, ANTIOXIDANT CAPACITY – Mediterranean Diet

“Mediterranean diet and non-enzymatic antioxidant capacity in the PREDIMED study: Evidence for a mechanism of antioxidant tuning,” Zamora-Ros R, Serafini M, et al, Nutr Metab Cardiovasc Dis, 2013 Feb 25; [Epub ahead of print]. (Address: Nutrition and Food Science Department, XaRTA INSA, Pharmacy School, University of Barcelona, Av/Joan XXIII s/n, 08028 Barcelona, Spain).

In a study involving 564 subjects with a high risk of cardiovascular disease, adherence to a Mediterranean diet for one year was found to increase plasma total antioxidant capacity levels in subjects at high risk of cardiovascular disease, and the effects were related to baseline levels of plasma non-enzymatic antioxidant capacity. Plasma levels of ferric reducing antioxidant potential (FRAP) increased after 1 year of adherence to the Mediterranean diet plus virgin olive oil (72 micromol/L) and the Mediterranean diet plus nuts (48.9 micromol/L), while no such benefits were found after adhering to a low-fat diet which served as the control, and similar results were found for levels of total radical-trapping antioxidant parameter (TRAP). These results suggest that adherence to a Mediterranean diet may benefit persons at high risk of cardiovascular disease.

Omega-3 Fatty Acids and Fish and Asthma Risk

ASTHMA – Omega-3 Fatty Acids, Fish

“Intakes of long-chain omega-3 (n-3) PUFAs and fish in relation to incidence of asthma among American young adults: the CARDIA study,” Li J, Xun P, et al, Am J Clin Nutr, 2013 Jan; 97(1): 173-8. (Address: Departments of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA).

In a study involving 4,162 young adult subjects between the ages of 18 and 30 years, with a history of asthma at baseline, who were followed up with for 20 years, during which time 446 incident cases of asthma were identified, long-chain omega-3 polyunsaturated fatty acid intake was found to be significantly inversely associated with incidence of asthma. Comparing the highest to the lowest quintiles of omega-3 fatty acid intake, the multivariable HR was 0.46. A greater inverse association was found for DHA as compared to EPA, and nonfried fish consumption was not associated with risk. The authors conclude, “This study showed that intakes of LC[omega]3PUFAs are inversely longitudinally associated with the incidence of asthma in American young adults.”

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