Oat bran is not special?

Oat bran is not special?

Since 1981, scientists have touted the cholesterol-lowering effects of soluble fiber--especially oat bran. But a Boston research team now asserts that experimental evidence of oat bran's benefits probably results more from reductions in dietary fat content than from concurrent fiber increases.

Frank M. Sacks and his colleagues at the Harvard University School of Medicine and Brigham and Women's Hospital gave specially prepared "supplements"--in the form of muffins and entrees--to 20 healthy hospital employees. For six weeks, half the group received high-fiber supplements containing oat bran while the rest received similar foods in which low-fiber Cream of Wheat and white flour replaced the oat bran. After a two-week break, the supplements were switched.

Neither diet affected blood pressure, and both lowered the volunteers' mean serum cholesterol to levels 7 to 7.5 percent below prestudy values. The researchers found "no significant difference" between diets in terms of changes in cholesterol and in the lipoproteins that transport cholesterol in the bloodstream. In the Jan. 18 NEW ENGLAND JOURNAL OF MEDICINE, they write that "oat bran has little inherent cholesterol-lowering action" in people with normal cholesterol levels -- nor, apparently, in those with elevated levels, based on the limited range of values represented by this study group. People worried about serum cholesterol would probably benefit by increasing their intake of complex carbohydrates, "whatever the fiber content," the researchers conclude.

The subjects' low prestudy cholesterol levels (averaging a healthy 183 milligrams per deciliter of blood) provide the "simplest explanation" of why the Boston team found no difference between the two diets, maintains nutrition researcher David Kritchevsky of Philadelphia's Wistar Institute. Fiber seldom exerts much influence on serum cholesterol in people whose cholesterol levels are already low, he notes.