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Isoflavone content of the soy based supplements
1Department of Clinical Chemistry, Folkhälsan Research Center, University of Helsinki, PO Box 63, Fin-00014 Helsinki, Finland. tarja.nurmi@uku.fi
Journal of Pharmaceutical and Biomedical Analysis
|February 28, 2002
Summary
Soy isoflavone product labels often misrepresent actual content. Analysis revealed significant discrepancies between stated and measured isoflavone levels in most soy supplements.
Area of Science:
- Nutritional Science
- Analytical Chemistry
Background:
- Soy isoflavones are compounds found in soy products with potential health benefits.
- Numerous soy isoflavone supplements are commercially available, making accurate labeling crucial for consumers.
Purpose of the Study:
- To verify the accuracy of isoflavone content claims on soy product labels.
- To compare manufacturer-provided data with independently measured isoflavone levels.
Main Methods:
- Fifteen soy-based products were analyzed.
- High-performance liquid chromatography (HPLC) with a coulometric electrode array detector was used.
- Isoflavones were quantified in aglycone form after hydrolysis to identify different conjugate forms.
Main Results:
- Only one product accurately matched its label for isoflavone content.
- Measured total isoflavone (aglycone) amounts varied widely, from 0.121 to 201 mg/g.
- Most products showed lower measured isoflavone levels than indicated on labels.
Conclusions:
- Significant inconsistencies exist between soy product labels and actual isoflavone content.
- Consumers may find it difficult to ascertain the true amount of isoflavones due to confusing product data.
- Independent verification of soy isoflavone content is recommended.