NEW YORK (Reuters Health) – Research published today supports the heart-health benefits of consuming vegetable oils and foods rich in omega-3 and omega-6 polyunsaturated fatty acids.

In one study, boosting intake of the omega-3 fatty acid alpha-linolenic acid was associated with a reduced risk of a heart attack in a Costa Rican population that, as a whole, has a low intake of this fatty acid. Alpha-linolenic acid is found in some vegetable cooking oils such as soybean, canola and flaxseed oils, as well as in walnuts, and in fish such as salmon, tuna and sardines.

In the other study, boosting omega-6 fatty acids (mainly linoleic acid) was linked to lower blood pressure among healthy adults from China, Japan, the UK and the US. Linoleic acid is plentiful in soybean, safflower, sunflower and corn oils, as well as tofu, nuts and seeds.

In their study, Dr. Hannia Campos of Harvard School of Public Health in Boston compared the diets of 1,819 residents of Costa Rica who had survived a first heart attack to a similar group who had not had a heart attack. They also analyzed body fat samples to determine participants’ alpha-linolenic acid content.

The investigators found that individuals with the highest amount of alpha-linolenic acid in body fat, compared to individuals with the least amount, had a 59 percent lower risk heart attack risk. This is “a large and significant reduction,” Campos and colleagues note in the American Heart Association’s journal Circulation.

“Alpha-linolenic acid was associated with a very strong protective effect, and the relationship quickly reached a plateau with most of the effect achieved after just a small intake,” Campos added in a written statement. The amount of dietary alpha-linolenic acid needed to produce this degree of protection corresponded to 2 teaspoons of soybean oil or canola oil, half a teaspoon of flaxseed oil, or 6 to 10 walnut halves, taken daily.

Meanwhile, in the AHA’s journal Hypertension, researchers with the International Study of Macro-Micronutrients and Blood Pressure Study report that a diet rich in the omega-6 fatty acid linoleic acid had statistically significant beneficial effects on blood pressure in healthy populations from different countries.

The analysis centered on 2,238 healthy adults who consumed no therapeutic diet or nutritional supplements, had never been diagnosed with heart disease, diabetes or high blood pressure and took no medication for those conditions.

“We found that a higher linoleic acid consumption of about 9 grams per day was associated with 1.4 millimeters of mercury (mm Hg) lower average systolic blood pressure and a 1.0 lower average diastolic blood pressure,” Dr. Katsuyuki Miura of Shiga University of Medical Science in Japan said in a statement.

Systolic blood pressure represents the pressure when the heart contracts to pump blood around the body and diastolic blood pressure represents the pressure when the heart relaxes between beats.

On a population-wide basis, even a small decrease in average blood pressure can have a large impact on the risk of death and disability due to heart disease within that population, Miura noted.

“Lowering the systolic blood pressure of a population by ‘small’ amounts, such as 2 mm Hg, is estimated to reduce mortality rates by 6 percent for stroke and by 4 percent for coronary heart disease,” he said.

SOURCES: Circulation, online July 7, 2008; Hypertension, online July 7, 2008.