Cholesterol-Lowering Effects of Dietary Fiber; 67 Studies Over 30 Years

Lisa Brown (et al) were uncertain about the effects of dietary fiber on cholesterol. The authors set out to research clinical studies with the objective quantifying the cholesterol-lowering effects of dietary fiber. Oat bran, guar gum, and psyllium were chosen as the fiber to test. 67 controlled clinical test were analyzed by the researchers.

Out of 162 clinical studies on fiber and choleterol, 67 were chosen for the validity based on the researchers' study criteria. 25 clinical trials focused specifically on the effects of oat bran. Articles published from 1966 to 1996 were considered as part of the research study. Studies were selected only if they met a certain criteria: they were properly controlled; or, compared to a hold out test to compare the result differences; and, had a test designed to randomly cross over partipants diets, or run two tracks of diets in parallel; they provided lipid changes for both the fiber diet group as well as the control groups (hold out comparison). For test validity, the researchers were also concerned with each test having a minimum of a 14 day lead-in period to ensure the effects to cholesterol levels were not from initial dietary changes.

After reviewing the 67 studies, the researchers concluded soluble fiber could reduce both total and LDL cholesterol. In a full dosage range, "soluble fiber significantly reduced both total cholesterol, and LDL cholesterol" (full dosage 2-30 grams per day). 1512 clinical research participants of 1600 total participated in oat bran clinical studies. Those same 1512 subject found partical dosages of oat bran, 2-10 grams per day, could lower cholesterol 1.56ml/dl per 1 gram of oat bran soluble fiber. In other words, eating 10 grams of oat bran solube fiber (i.e. beta-glucan) could lower cholesterol about 15ml/dl over a reasonable period* (*high fiber diets work best with diets low in fat).