By E.J. Mundell
NEW YORK, Oct 04 (Reuters Health) -- Recent study findings have suggested that risks for heart attack or stroke rise in the hours following a high-fat meal. Now researchers report that the consumption of oatmeal and other high-fiber foods, or antioxidants such as vitamin E, may help reduce that increase in cardiovascular risk.
The soluble fiber found in oats, beans and other foods may help prevent blood vessel constriction by "slowing absorption of fat and carbohydrates into the bloodstream," according to study lead author Dr. David L. Katz of the Yale School of Medicine in New Haven, Connecticut. He presented the findings Saturday at the annual meeting of the American College of Nutrition, held in Washington, DC.
The study, funded by The Quaker Oats Company, focused on 50 healthy adults fed high-fat (50 grams of fat) meals once a week for three weeks. Each meal was accompanied by one of three 'side dishes' -- a bowl of oatmeal, a bowl of whole-wheat cereal, or an 800 IU vitamin E supplement.
The researchers used ultrasound to measure the diameter of each subject's blood vessels 3 hours before and 3 hours after each meal. Restriction in blood vessel diameter is a risk factor for heart attack and other heart problems.
Katz and colleagues report that -- compared with pre-meal levels -- post-meal blood vessels were restricted by 13.4% in subjects who ate high-fat meals combined with whole-wheat cereal.
However, post-meal vessel diameters remained unchanged from pre-meal levels in subjects who ate high-fat meals in combination with either oatmeal or vitamin E.
In an interview with Reuters Health, Katz explained that vitamin E -- a potent antioxidant -- helps 'mop up' free radical molecules that form as a byproduct of the breakdown of foods. Experts believe that free radicals can damage the cells that line blood vessels, affect the ability of arteries to dilate in response to changes in blood flow, and raise the risk for heart attack.
While vitamin E appears to help reduce the number of free radicals, the soluble fiber found in oatmeal "prevents fewer of those free radicals from forming in the first place," Katz explained, by blocking the gastrointestinal absorption of fat and carbohydrate into the bloodstream.
"In many ways, it's alarming that a fatty meal causes this abnormal (cardiovascular) response," Katz said. But, "it's reassuring to know that certain foods that we eat quite regularly seem to prevent that effect."
Other foods besides oats -- especially beans, lentils, whole-grain rice, and fruits and vegetables -- contain moderate to high levels of soluble fiber, Katz added. However, wheat-based products do not -- explaining why blood flow restrictions occurred in study subjects who ate whole-wheat cereal along with their high-fat meals.
Short-term fluctuations in blood flow may impact on more than just cardiovascular health. Vasoconstriction "could potentially affect the brain" according to Katz, and "impact on cognitive function or intellect as we age." He believes it could also affect sexual function, "since that too is very dependent on the vascular system."
In 1997, the US Food and Drug Administration granted The Quaker Oats Company the right to labeling asserting that oat products might help reduce risks for heart disease.
Those claims were based on the results of long-term studies. But according to Katz, the new findings suggest that "we need to begin to pay attention not just to the health effects of diet over time, but the health effects of diet in short periods of time -- including a single day or even a single meal." He believes that health-conscious consumers should "try to... balance foods that could at least potentially stress our blood vessels with the consistent consumption of foods that clearly are protective, such as oats."
