Effect of γ-Oryzanol on Serum TSH Concentrations in Primary Hypothyroidism

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A single oral dose (300mg) of γ-oryzanol extracted from rice-bran oil produced a significant reduction on the elevated serum TSH levels in hypothyroid patients. Similarly, chronic treatment with γ-oryzanol resulted in decreased serum TSH levels in 6 of 8 patients. There was no change in the serum levels of thyroxine-iodine and triiodothyronine during the study. In addition, there was no difference in the serum TSH response to TRH in hypothyroid patients and normal subjects.
These observations suggest that γ-oryzanol inhibits serum TSH levels in patients with primary hypothyroidism, possibly by a direct action at the hypothalamus rather than the pituitary.