Establishing a Safe Upper Limit for Soy Isoflavone Intake

 

Based on a long-term (5-year) clinical trial in postmenopausal women who consumed 150 mg/day of soy isoflavones, researchers observed potential health risks at this dosage. To ensure safety across different populations, an upper intake limit was determined:

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Safe Upper Limit for Daily Soy Isoflavone Intake:

• 75 mg/day (half of the 150 mg/day considered a potential "effect level" associated with health risks)

• Applies to premenopausal women, postmenopausal women, and men

• Based on clinical trials and individual differences in metabolism

 

Rationale for the 70-75 mg/day Upper Limit:

• While exceeding this level does not cause immediate health risks, prolonged intake above this range may lead to hormonal disturbances.

• Soy isoflavones exert their effects through the oestrogen hormone system, which is highly conserved across mammals.

• The limit is set based on both human clinical findings and animal studies, ensuring biological plausibility and minimizing potential harmful effects.

• Prescence of xenoestrogens in most packaged foods today make this limit more plausible as we have a lot of unwarranted hormonal exposure

 

Citation: Fundamental Concepts in the Safety Assessment of foods containing soy isoflavones, 2002