Research with Isoflavones

Isoflavones belong to the best-researched plant constituents, with more than 10,000 publications covering all areas of interest, among others

• Examinations of effects of isoflavones at receptors and enzymes in vitro;
• Effects of isoflavones on patterns of gene expression;
• Effects in animal models of bone health, cardiovascular health, cancer or estrogenic effects, just to mention a few;
• Toxicological and safety studies in animals;
• Bioavailability and kinetics of isoflavones;
• Clinical studies ranging from observational to randomized controlled trials examining the health-related benefits;
• Clinical safety studies on specific hypothetical risks (e.g., cancer or thyroidal gland);
• Dietary surveys; and
• Epidemiologic studies.

Health benefits related to menopausal complaints, bone and cardiovascular health, cancer prevention and cognitive effects have been amply observed in human application, and confirmed through animal experiments and/or in vitro studies.

Much of the research was dedicated to safety, with soy being a major staple in human nutrition. Overall the safety of isoflavones at doses corresponding to the range of dietary intakes has been found excellent. Recent official safety assessments were performed by the French Agency for Food Safety (Anon 2005), the Japanese Ministry of Health (Anon 2006) and the German Federal Institute of Risk Assessment (Anon 2007). Currently, the EFSA is re-examining the safety and efficacy of isoflavones (EFSA 2009).

Whereas the French agency did not find a risk up to a safe dose of 60 mg isoflavone (aglycones) per day in 2005, the Japanese MOH concluded on a safe dose of 100-105 mg/day (as aglycones) in 2006. The German BfR did not define a safe dose – a task left to the EFSA in the current assessment.

References

Anon. (2005). Sécurité et bénéfices des phyto-estrogènes apportés par l'alimentation - Recommendations. Paris: AFSSA.
Anon. (2006). Fundamental concepts in the safety assessment of foods containing isoflavones for the purpose of specified health use. Tokyo: Japanese Ministry of Health.
Anon. (2007). Isolierte Isoflavone in Nahrungsergänzungsmitteln und bilanzierten Diäten. Gesundheitliche Bewertung des BfR vom 30. 11. 2007
EFSA (2009). The use of dietary isoflavones and isolated isoflavones from soy or red clover in food and food supplements. Parma: European Food Safety Authority (EFSA).