Key Findings:
A reduction on diabetic symptoms has been shown with secoisolariciresinol diglucoside (SDG) feeding. SDG appears to inhibit the expression of the phosphoenolpyruvate carboxykinase gene, which codes for a key enzyme responsible for glucose synthesis in the liver. In 48 postmenopausal women, the incorporation of 7.5 g of flaxseed daily for 6 wk. and 15 g of flaxseed for an additional 6 wk. into the diet of healthy postmenopausal women has little short-term effect on blood levels of insulin-like growth factor 1 (IGF-1), insulin like growth factor binding protein 3 (IGF-BP3), and C-peptide, a marker of insulin production. Flax feeding resulted in decreases in serum C-peptide levels only in normal weight women in subgroup analysis. The present study was relatively small and thus small changes in serum levels of IGF-1, IGF-BP3, and C-peptide due to flaxseed were difficult to detect. In addition, the study lacked a placebo control group, and flaxseed-related changes in serum levels of these markers may have been offset by temporal changes in lifestyle or other factors. In addition the amount of flaxseed used was quite low and further research is necessary to ascertain the effects using higher dosages.
ABSTRACT:
Higher levels of insulin and insulin-like growth factor 1 (IGF-1) increase cancer risk by stimulating cell proliferation and increasing survival of DNA-damaged cells through anti apoptotic mechanisms. Laboratory studies suggest that flaxseed added to the diet may lower circulating levels of insulin and IGF-1, but there is limited information on the effects of dietary flaxseed on these biomarkers of cancer risk in humans. The aim of this study was to determine the effect of flaxseed supplementation in postmenopausal women on serum levels of insulin-like growth factor 1 (IGF-1), insulin like growth factor binding protein 3 (IGF-BP3), and C-peptide, a marker of insulin production. Forty-eight postmenopausal women participated in this 12-wk baseline to postintervention study. Participants were asked to consume 7.5 g per day of ground flaxseed for 6 wk and 15 g per day for an additional 6 wk. No significant changes were observed in blood levels of IGF-1, IGF-BP3, or C-peptide over the study intervention. Flaxseed supplementation did not impact circulating levels of IGF-1, IGF-BP3, or C-peptide. Longer duration of intake may be necessary to observe changes in these biomarkers of cancer risk. (Author’s abstract)
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