Combined effect of vegetable protein (soy) and soluble fiber added to a standard cholesterol-lowering diet

Dietary treatment of hyperlipidemia focuses on reducing saturated fat and d ietary cholesterol. Other aspects of diet are not emphasized at present, de spite growing evidence that a number of plant components decrease serum cho lesterol. We therefore determined whether a combination of two plant compon ents, vegetable protein and soluble fiber, further reduce serum lipids when incorporated into the currently advocated low-saturated-fat diet. Thirty-o ne hyperlipidemic men and women ate two 1-month low-fat (<7% of total energ y from saturated fat), low-cholesterol (<80 mg cholesterol/d) metabolic die ts in a randomized crossover study. The major differences between test and control diets were an increased amount of vegetable protein (93% v 23% of t otal protein), of which 33 g/d was soy, and a doubling of soluble fiber. Ea sting blood samples were obtained at the start and end of each phase. On th e last 3 days of each phase, fecal collections were obtained. Compared with the low-fat control diet, the test diet decreased total cholesterol (6.2% +/- 1.2%, P <.001), low-density lipoprotein (LDL) cholesterol (6.7% +/- 1.7 %, P <.001), apolipoprotein B (8.2% +/- 1.2%, P <.001), and the ratios of L DL to high-density lipoprotein (HDL) cholesterol (6.3% +/- 2.0%, P =.004) a nd apolipoprotein B to A-I (5.4% +/- 1.5%, P =.001). A combination of veget able protein and soluble fiber significantly improved the lipid-lowering ef fect of a low-saturated-fat diet. The results support expanding the current dietary advice to include increased vegetable protein and soluble fiber in take so that the gap in effectiveness between a good diet and drug therapy is reduced. Copyright (C) 1999 by W.B. Saunders Company.