Tymchuk C N, Tessler S B, Barnard R J
Department of Physiological Science, University of California, Los Angeles 90095, USA.
Nutr Cancer. 2000;38(2):158-62. doi: 10.1207/S15327914NC382_3.
Dietary factors including fat and fiber have been reported to play a role in the development of breast cancer, possibly mediated by changes in estradiol. Diet and exercise have been shown to affect levels of sex hormone-binding globulin (SHBG), which in turn regulate the bioavailability of estradiol. Diet and exercise also affect insulin levels, which play a role in the synthesis of SHBG, and the hormone itself is a potent mitogen for many cancer cell lines. This study was designed to measure the effects of a low-fat, high-fiber diet, combined with regular aerobic exercise, on the levels of SHBG, insulin, and serum lipids in postmenopausal women with or without hormone replacement therapy (HRT). Two groups of postmenopausal women, 11 on HRT and 11 not on HRT, underwent a low-fat (1O% fat calories), high-fiber (65-70 g/day) diet-and-exercise intervention for three weeks. Serum SHBG, insulin, and lipids were measured before and after the regimen. After the intervention, SHBG levels were significantly increased for the women on HRT (44.5 +/- 3.4 vs. 62 +/- 6.4 nmol/l) and the women not on HRT (32.1 +/- 4.6 vs. 45.5 +/- 6.1 nmol/l, both changes p < 0.01). Also after the intervention, insulin levels were significantly reduced for the women on HRT (196 +/- 44.4 vs. 119.8 +/- 28.7 pmol/l) and the women not on HRT (144.2 +/- 17.9 vs. 115.5 +/- 20.8 pmol/l, both changes p < 0.01). Body mass index and total cholesterol were significantly reduced for both groups of women (all changes p < 0.01). Although the exact mechanism for the change in SHBG is not known, the increases in SHBG and reductions in insulin as a result of this lifestyle intervention should reduce the risk for breast cancer in postmenopausal women.
据报道，包括脂肪和纤维在内的饮食因素在乳腺癌的发生发展中起作用，可能是通过雌二醇的变化介导的。饮食和运动已被证明会影响性激素结合球蛋白（SHBG）的水平，而SHBG反过来又调节雌二醇的生物利用度。饮食和运动还会影响胰岛素水平，胰岛素在SHBG的合成中起作用，而且该激素本身对许多癌细胞系来说是一种强效的促有丝分裂原。本研究旨在测量低脂、高纤维饮食结合规律有氧运动，对接受或未接受激素替代疗法（HRT）的绝经后女性的SHBG、胰岛素和血脂水平的影响。两组绝经后女性，11名接受HRT，11名未接受HRT，进行了为期三周的低脂（脂肪热量占10%）、高纤维（65 - 70克/天）饮食和运动干预。在该方案前后测量血清SHBG、胰岛素和血脂。干预后，接受HRT的女性SHBG水平显著升高（44.5±3.4对62±6.4纳摩尔/升），未接受HRT的女性SHBG水平也显著升高（32.1±4.6对45.5±6.1纳摩尔/升，两者变化p<0.01）。同样在干预后，接受HRT的女性胰岛素水平显著降低（196±44.4对119.8±28.7皮摩尔/升），未接受HRT的女性胰岛素水平也显著降低（144.2±17.9对115.5±20.8皮摩尔/升，两者变化p<0.01）。两组女性的体重指数和总胆固醇均显著降低（所有变化p<0.01）。虽然SHBG变化的确切机制尚不清楚，但这种生活方式干预导致的SHBG升高和胰岛素降低应该会降低绝经后女性患乳腺癌的风险。
