HONG KONG--Two studies from the February issue of The American Journal of Clinical Nutrition (www.ajcn.org) examine the impact of dietary compounds on cholesterol levels. The first, a meta-analysis including 23 randomized controlled trials, reviewed the impact of soy protein containing isoflavones on the lipid profile (81, 2:397-408, 2005). Researchers from the Chinese University of Hong Kong and Peking University, Beijing, found soy protein with intact isoflavones was associated with significant decreases in total cholesterol, low-density lipoprotein (LDL) cholesterol and triacylglycerols, as well as increases in the beneficial high-density lipoprotein (HDL). The impact was greater in men and appeared dose-dependent, with intakes over 80 mg/d with the best effects on the lipid profile. However, tablets with extracted soy isoflavones were not found to impact cholesterol levels.
In the second study, conducted at St. Michael's Hospital, Toronto, 34 hyperlipidemic patients underwent three one-month treatments to determine the impact of diet on cholesterol levels (81, 2:380-87). The diets included a very-low-saturated-fat diet (control), the control diet plus 20 mg/d lovastatin, or a "portfolio diet" including plant sterols, soy protein foods, almonds and viscous fibers from oats, barley and psyllium. While the statin diet showed a greater impact on LDL cholesterol concentrations at four weeks (33 percent reduction) compared to the portfolio treatment (29 percent reduction), nine participants showed the best results on the statin diet. In addition, there was no significant difference between the statin and portfolio diets in ability to reduce LDL cholesterol below the recommended primary prevention cutoff.
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