Isoflavones sources

Hendrich S, Murphy SP. Isoflavones Sources and Metabolism. In Wildman REC, editor. Handbook of neutraceuticals and functional foods. Boca Raton CRC Press, 2001. p. 55-72. 

Genovese MI, Barbosa AC, Pinto Mda S, Lajolo FM. 2007. Commercial soy protein ingredients as isoflavone sources for functional foods. Plant Foods Hum Nutr 62 53-58. 

Hendrich S, Murphy PA. Isoflavones, source and metabolism. In Wildman REC, ed. Handbook of Nutraceuticals and Functional Foods. Boca Raton, FL CRC Press, 2001 55-75. 

Anderson et al., 1998 OVX, lactating rats low calcium diet genistein-rich protein source 3 doses isoflavones (0.5, 1.6, 5.0 mg/d) for 2 weeks A biphasic response to genistein was observed for bone weight (femur ash) low dose more protective than high dose... 

Similar to the human studies, the animal studies are not entirely consistent, due to the different study designs (source and dose of soy protein/isoflavones time, method and length of administration age of rats, etc.). Nevertheless, a certain number of conclusions may be drawn. Overall, soy extracts or pure isoflavones show an osteoprotective effect in the ovariectomized rat model of menopausal bone loss. The time of administration is important and they must be given at the time of ovariectomy which allows prevention but not reversal of bone loss. Although the OVX-induced bone loss in the rat is a... 

An overall osteoprotective effect is associated with soy diets, the major active component being the isoflavones although the contribution (if any) of soy protein has to be clarified. The spine, rather than the femur, appears to be the most consistently protected bone site. The average daily intake in Japanese women is around 50 mg/day and appears to be sufficient to have a long-term protective effect on the spine. In non-Asian, postmenopausal women, the demonstrated effective dose is 80-90 mg/day. In future clinical studies, investigating the effect of isoflavones on bone metabolism, larger scale, randomized, controlled, intervention trials for longer time periods (1-3 years) will be necessary with a standardized source of soy protein/isoflavones and... 

In order to produce soy protein, soybeans are first dehulled, flaked, and defatted to make white flakes . Soy protein concentrates are obtained by removing a portion of the carbohydrates from defatted and dehulled soybeans. Alcohol extraction is the method most commonly used to manufacture soy protein concentrates even though it results in the loss of isoflavones. Soy protein concentrates retain most of the fiber in the original soybean and must contain at least 65% protein on a moisture-free basis to meet quality standards. The most concentrated source of soy protein is soy protein isolates (or isolated soy protein, ISP), which is required to be at least 90% protein on a moisture-free basis. It is heat-treated during processing to insure inactivation of trypsin inhibitors. Most isolated soy protein is manufactured by water extraction from defatted and dehulled soybeans and it retains the natural isoflavones. 

Y (1999) Dietary intake and sources of isoflavones among Japanese. iVnlr Cancer. 33 (2) 139 5. 

The three main classes of phytoestrogens (and common food sources) are isoflavones (soybeans), lignans (cereals and oilseeds such as flaxseed), and coumestans (alfalfa sprouts). The biologic potency of phytoestrogens varies and is less than that of synthetic estrogen. 

Soybeans (Glycine max) are protein-rich legumes widely grown around the world as a food crop. They are the major dietary source of isoflavones, which are broken down in the intestine into the phytoestrogens genis-... 

Keki, S. et al., Post-source decay matrix-assisted laser desorption/ionization mass spectrometric study of peracetylated isoflavone glycosides cationized by protonation and with various metal ions, J. Mass Spectrom., 38, 1207, 2003. 

The anticancer effect of soy, the only relevant dietary source of isoflavones and the main candidate foodstuff responsible for the cancer protection conferred by Asian diets, has been tested in a number of animal studies. Messina et al. [204] reviewed 26 such studies published up to 1994 (gastrointestinal and non gastrointestinal). Seventeen of them (65%) reported a protective effect and none found a potentiation of carcinogenesis. One study has examined the effect of feeding a soy protein diet in a genetic... 

The value of antioxidant protection by way of natural food sources has been pointed out in the literature with considerable frequency. Among the components of soy flour known to have some antioxidant properties are isoflavones and phospholipids. Amino acids and peptides in soybean flour also possess some antioxidant activity. There also may be some antioxidant impact from aromatic amines and sulfhydryl compounds. 

Table 11.6.3 Commercial Sources of Soy Isoflavone Reference Standards"...

Source Data from USDA-lowa State University Isoflavone Database, 2002. 

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