Buckwheat protein shows potential for cholesterol reduction
cholesterol levels in rats on a high cholesterol diet by at least
25 per cent, report Japanese researchers.
If the results can be reproduced in humans, the proteins may offer an alternative for functional food formulators and dietary supplements to tap into the burgeoning cholesterol reduction market, currently dominated by phytosterols and stanols. The research, published in the Journal of Food Science, reports that supplementation of a high cholesterol diet with protein from common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tataricum Gaertn) reduced serum cholesterol levels in rats by 32 and 25 per cent, respectively. In a second experiment, the researchers looked at the effect of the proteins to reduce the formation of gallstones (lithogenesis), measured by the lithogenic index. Supplementation with common (BWP) and tartary buckwheat (TBP) led to reductions of the lithogenic index of 62 and 43 per cent, respectively. "Taken together, these results suggest a potential source of TBP as a functional food ingredient as well as BWP," wrote the authors. High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year. Analysis of the chemical composition of TBP was found to be 45.8 per cent protein, 7.8 per cent lipids, and 2.7 per cent dietary fibre, while BWP was composed of 65.8 per cent protein, 22.0 per cent lipids, and 7.0 per cent dietary fibre. TBP was also found to contain more rutin and quercetin than BWP, with 5.3 and 4.4 mg of rutin per 100 grams, respectively, and 1710 and 5.4 mg of quercetin per 100 grams, respectively. "In this study, TBP contained much amount of quercetin, and its concentration is much higher than BWP, while the content of rutin was very low in both TBP and BWP," wrote the authors. "The results imply that the rutin in tartary buckwheat flour might be largely degraded to quercetin during the alkali extraction process." The researchers note that a synergy might exist between quercetin and tartary buckwheat protein, both of which have been reported to offer protective benefits to the colon. "A large amount of quercetin in TBP might transfer to large bowel together with indigestible protein. It is possible that quercetin in the TBP may exert potentially beneficial effects on protecting colon oxidative damage," they stated. Additional studies need to be performed, with human interventions a priority, before the potential benefits for cholesterol reduction and colon health can be accepted, but the initial results from animal studies appear promising. The study is a collaboration between researchers from Iida Women's Junior College, Hiroshima University, Takano Co., Ltd, Prefectural University of Hiroshima, and Food Technology Research Institute of Nagano Prefecture Source: Journal of Food Science (Blackwell) Published online ahead of print, 23 Aug 2007, doi: 10.1111/j.1750-3841.2007.00474.x "Preparation of Tartary Buckwheat Protein Product and Its Improving Effect on Cholesterol Metabolism in Rats and Mice Fed Cholesterol-Enriched Diet" Authors: H. Tomotake, N. Yamamoto, H. Kitabayashi, A. Kawakami, J. Kayashita, H. Ohinata, H. Karasawa, and N. Kato