Remember the oat bran craze? In the late 1980s, several published studies touting the benefits of oat bran for lowering cholesterol had health professionals singing its praises.
Food companies were only too happy to accommodate the newfound demand, trotting out oat bran garlic bread, oat bran muffins, oat bran animal cookies, oat bran brownies, even oat bran-dusted potato chips and doughnuts.
Research in the 1980s focused mostly on the effects of the bran, but over time, the focus shifted to the benefits of whole oats. And by 1997, the cholesterol-lowering evidence for oats was so strong that the Food and Drug Administration approved the first "food-specific claim," permitting labels of oat-rich products to bear a statement that eating oats and oat-based foods reduced the risk of cardiovascular disease. (Up until then, only nutrient-specific claims -- such as for reduced fat or salt -- had been given FDA approval.)
Findings on food and health sometimes swing back and forth like a pendulum. But in the 10 years since that claim was allowed, continued research into the reported benefits of oats has verified the link and offered new insights into how oats help the heart.
Regular oatmeal consumption lowers total cholesterol as well as "bad" -- LDL -- cholesterol, with no adverse effects on the "good" -- HDL cholesterol. It also has the potential to reduce inflammation, one of the first steps in the development of atherosclerosis.
Most studies point to beta-glucan -- the soluble fiber in oat bran that gives cooked oats their gluey texture -- as the likely active agent in cholesterol reduction. Part of the mechanism has to do with bile, a cholesterol-rich fluid that helps the body digest fats. Beta-glucan increases the excretion of bile from the gall bladder into the small intestine. This, in turn, stimulates the body to produce more bile -- pulling cholesterol out of the blood to do so.
Whole oats also contain polyphenols, a class of antioxidant compounds found in all kinds of plant foods (including berries, tea, wine and chocolate) that may play an additional role in keeping the heart healthy. Avenanthramides, polyphenols unique to oats, have been shown -- at least in a cell culture dish -- to interfere with inflammation, a key step in the development of arterial plaque.
In one 2004 study, aortic cells were pre-treated with avenanthramides and then exposed to interleukin-1 beta, a substance known to stimulate inflammation. The avenanthramide mixture greatly reduced inflammation as well as the production of molecules normally produced in the early stages of plaque formation.
The amount of avenanthramides used in the study was much more than what one would obtain in a bowl of oats, but the study does help explain how polyphenols in oats may bring about their effects.
Weight loss lowers cholesterol too -- but oats plus weight loss seem to do it even better. Two trials have shown that when oats or oat bran are incorporated into a calorie-restricted regimen, total cholesterol and LDL levels drop an additional 4% to 12% beyond what is seen in subjects who lose similar amounts of weight on an oat-free plan.
In a recent review in which data from several studies were pooled, two daily servings of oats (each serving is about an ounce) dropped cholesterol levels about 8 points on average, and LDL cholesterol levels by about 7 points.
Americans eat, on average, about 2 1/2 pounds -- 40 ounces -- of oats per year, or less than 1 ounce per week. This pales in comparison with the nearly 95 pounds of wheat we consume, most of it refined.
If you want to add oats to your diet, basic breakfast oatmeal is the best way to start -- you can choose from various types. Steel-cut oats (chopped whole oat groats with only the tough outer husk removed) are 100% whole grain, as are old-fashioned rolled oats in which the groats have been steamed, rolled and flaked.
Quick oats (thinner flakes that cook in only a minute or two) are 100% whole grain, too. And even though instant oatmeal doesn't qualify for the 100% whole grain moniker because it typically has salt and flavoring added, it can still provide nearly the same amount of healthful soluble fiber.
Sugary granola bars and cereal bars might contain some whole grain oats but won't provide even close to a serving.
If you still prefer oat bran, consider adding it to your whole grain oat cereal in the morning, since science tells us bran is only part of the oat story. As with all other plant foods, the complex mixture in the whole food offers much more than its individual parts. But it's unlikely we'll see a "whole oat" craze any time soon.
Susan Bowerman is a registered dietitian and assistant director of the UCLA Center for Human Nutrition.