USDA updates composition data for isoflavones in food

The food composition database, launched last week, gives a break-down of three isoflavone compounds – genistein, daidzein and glycitein.

Compiled by scientists as USDA’s Agricultural Research Service (ARS), the Isoflavone Database is necessary to assess the effects of the intake of isoflavones on various biological parameters, said the agency.

Benefits​

Isoflavones are a subclass of the antioxidants flavonoids. They have weak estrogenic and other biological properties that may contribute to the reduction of the risk of some chronic diseases.

A study published in 2007 found that soy isoflavones alone and along with soy proteins lower serum total and LDL cholesterol in humans (Taku et al., 2007). In addition, a review of clinical trials of soy isoflavones suggests some skeletal benefits in younger postmenopausal women (Messina et al., 2004).

Other studies have indicated that isoflavones could have prostate cancer benefits (Messina et al., 2006), while the non-hormonal properties of isoflavones may reduce the risk of some cancers (Sarkar and Li, 2004).

Isoflavone database​

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The first Special Interest Database on isoflavones was released in 1999 by ARS’ Nutrient Data Laboratory (NDL) in collaboration with the Iowa State University. It was since updated based on feedback on new values for certain foods.

The agency said the current update, compiled by the agency’s David Haytowitz and Seema Bhagwat at NDL, was necessary as the launch and demand of new soy products has increased further to the approval of a health claim for soy proteins from the Food and Drug Administration (FDA) in 1999.

Haytowitz and Bhagwat conducted an extensive review of a range of data sources, and evaluated scientific articles published in peer-reviewed journals since 1999. All data were evaluated by a data quality evaluation system developed by the NDL scientists.

To access the isoflavone database, click here​.

Other databases ​

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The isoflavone database is one of a number of Special Interest Databases produced by NDL with the aim of providing data on bioactive compounds for selected foods.

Other databases include ones on flavonoids, proanthocyanidins and ORAC.

ARS updated its flavonoid database last year, providing industry with an expanded and up-to-date research tool for quantification of the flavonoid content of 26 flavonoids in 393 foods.

This added 168 new foods to the original database, while data for many of the original 225 foods were also updated.

Flavonoids are found in certain wine, fruits, vegetables, tea, nuts, and chocolate, and are thought to have potent antioxidant activity. Many have also been implicated in possible protection against diseases such as cancer and cardiovascular disease.

ARS also last year published a new database giving antioxidant values for 277 fruits, nuts, vegetables and spices. Researchers conducted ORAC tests on a number of these food products.

They also searched peer-reviewed scientific literature on the subject, and screened studies using the agency’s data quality evaluation system.