Selenium Bioavailability from Soy Protein Isolate and Tofu in Rats Fed a Torula Yeast-Based Diet

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• 作者：Lin Yan ; George L. Graef ; Philip G. Reeves ; LuAnn K. Johnson
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2009
• 出版时间：December 23, 2009
• 年：2009
• 卷：57
• 期：24
• 页码：11575-11580
• 全文大小：727K
• 年卷期：v.57,no.24(December 23, 2009)
• ISSN：1520-5118

文摘

Selenium (Se) is an essential nutrient, and soy is a major plant source of dietary protein to humans. The United States produces one-third of the world’s soybeans, and the Se-rich Northern Plains produce a large share of the nation’s soybeans. The present study used a rat model to determine the bioavailability of Se from a protein isolate and tofu (bean curd) prepared from a soybean cultivar we recently developed specifically for food grade markets. The soybean seeds contained 2.91 mg Se/kg. Male Sprague−Dawley rats were depleted of Se by feeding them a 30% Torula yeast-based diet containing 5 μg Se/kg; after 56 days, they were replenished of Se for an additional 50 days by feeding them the same diet supplemented with 20, 30, or 40 μg Se/kg from soy protein isolate or tofu. l-Selenomethionine (SeMet) was used as a reference. Selenium bioavailability was determined on the basis of the responses of Se-dependent enzyme activities and tissue Se contents, comparing those responses for each soy product to those for SeMet using a slope-ratio method. Dietary supplementation with the protein isolate or tofu resulted in dose-dependent increases in glutathione peroxidase activities in blood and liver and thioredoxin reductase activity in liver, as well as dose-dependent increases in the Se contents of plasma, liver, muscle, and kidneys. These responses indicated an overall bioavailability of approximately 97% for Se from both the protein isolate and tofu, relative to SeMet. These results demonstrate that Se from this soybean cultivar is highly bioavailable in this model and that high-Se soybeans can be good dietary sources of Se.