Dietary Intervention of Flaxseed: Effect on Serum Levels of IGF-1, IGF-BP3, and C-Peptide.
Dietary Intervention of Flaxseed: Effect on Serum Levels of IGF-1, IGF-BP3, and C-Peptide.
Year: 2011
Authors: Sturgeon, S.R. Volpe, S.L. Puleo, E. Bertone-Johnson, E.R. Heersink, J. Sabelawski, S. Wahala, K. Bigelow, C., Kurzer, M.S.
Publication Name: Nutr. & Cancer
Publication Details: Vol 63; No. 3; Pages 376-380.
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 post-intervention 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)
High blood levels of insulin and insulin-like growth factors (IGFs) have been implicated in the development and progression of cancer. Elevated C-peptide levels have also been associated with increased risk of several cancer types, including pancreatic and colorectal cancers. Flaxseed lignans have been shown to lower plasma IGF-1 concentrations. In the present study of postmenopausal women, the authors hypothesized that a 12-wk supplementation of usual diet with flaxseed would lower circulating levels of IGF-1 and C-peptide, a marker of long-term insulin secretion. The results showed that 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 IGF-1, IGF-BP3, or C-peptide. In exploratory sub-analyses, the authors report that flaxseed supplementation resulted in declines in serum C-peptide levels only in normal weight women a finding that should be considered in future studies. Findings from studies that have focused on flaxseed constituents, such as flaxseed oil, flaxseed-derived lignan capsules, and flaxseed fiber supplements on fasting glucose and insulin concentrations have been inconsistent. 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 lacks 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. Overall, the results of this 3-mo intervention did not suggest that flaxseed favorably alters markers of insulin or IGF-1 physiology in a direction that would lower breast cancer risk. Further work is necessary in a larger population group, higher levels of flaxseed and over a longer duration of time. (Editor's comments)
High blood levels of insulin and insulin-like growth factors (IGFs) have been implicated in the development and progression of cancer. Elevated C-peptide levels have also been associated with increased risk of several cancer types, including pancreatic and colorectal cancers. Flaxseed lignans have been shown to lower plasma IGF-1 concentrations. In the present study of postmenopausal women, the authors hypothesized that a 12-wk supplementation of usual diet with flaxseed would lower circulating levels of IGF-1 and C-peptide, a marker of long-term insulin secretion. The results showed that 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 IGF-1, IGF-BP3, or C-peptide. In exploratory sub-analyses, the authors report that flaxseed supplementation resulted in declines in serum C-peptide levels only in normal weight women a finding that should be considered in future studies. Findings from studies that have focused on flaxseed constituents, such as flaxseed oil, flaxseed-derived lignan capsules, and flaxseed fiber supplements on fasting glucose and insulin concentrations have been inconsistent. 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 lacks 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. Overall, the results of this 3-mo intervention did not suggest that flaxseed favorably alters markers of insulin or IGF-1 physiology in a direction that would lower breast cancer risk. Further work is necessary in a larger population group, higher levels of flaxseed and over a longer duration of time. (Editor's comments)
