Tymchuk C N, Tessler S B, Aronson W J, Barnard R J
Department of Physiological Science, School of Medicine, University of California, Los Angeles 90095-1527, USA.
Nutr Cancer. 1998;31(2):127-31. doi: 10.1080/01635589809514691.
A diet high in fat has been linked to prostate cancer, possibly through an influence on hormones. Sex hormone-binding globulin (SHBG) binds androgens and is regulated in part by insulin. Diet and exercise can modify insulin levels, potentially affecting SHBG and the biologically available levels of androgens. To determine the effects of a low-fat (< 10% of calories), high-fiber diet plus daily exercise on insulin, SHBG, prostate-specific antigen (PSA), and serum lipids, we measured the levels of these factors in the serum of 27 obese men undergoing a three-week diet-and-exercise program. Insulin decreased from 222 +/- 30 to 126 +/- 21 pmol/l (p < 0.01), and SHBG increased from 18 +/- 2 to 25 +/- 3 nmol/l (p < 0.01). Body mass index decreased from 35 +/- 1.9 to 33.4 +/- 1.8 kg/m2 (p < 0.01). PSA levels were normal and did not change significantly, although in a small subset of men (n = 3) with slightly elevated PSA levels (> 2.5 ng/ml) all showed a decrease. The three-week diet-and-exercise intervention decreased insulin and lipid levels while increasing SHBG. The increase in SHBG would result in more testosterone being bound and, therefore, less of the androgen available to act on the prostate. The decrease in insulin might also decrease mitogenic activity in the prostate. The diet-and-exercise regimen did not have a significant impact on normal PSA levels. Although modest, these changes may be protective against the development of prostate cancer.
高脂肪饮食可能通过对激素的影响与前列腺癌有关。性激素结合球蛋白（SHBG）结合雄激素，部分受胰岛素调节。饮食和运动可改变胰岛素水平，进而可能影响SHBG及雄激素的生物利用水平。为确定低脂（热量的<10%）、高纤维饮食加每日运动对胰岛素、SHBG、前列腺特异性抗原（PSA）和血脂的影响，我们测量了27名肥胖男性在进行为期三周的饮食和运动计划期间血清中这些因子的水平。胰岛素从222±30降至126±21 pmol/l（p<0.01），SHBG从18±2升至25±3 nmol/l（p<0.01）。体重指数从35±1.9降至33.4±1.8 kg/m2（p<0.01）。PSA水平正常且无显著变化，不过在一小部分PSA水平略高（>2.5 ng/ml）的男性（n = 3）中，所有患者的PSA水平均有所下降。为期三周的饮食和运动干预降低了胰岛素和血脂水平，同时提高了SHBG。SHBG的升高会导致更多睾酮被结合，因此作用于前列腺的雄激素减少。胰岛素的降低也可能减少前列腺中的促有丝分裂活性。饮食和运动方案对正常PSA水平没有显著影响。尽管变化不大，但这些改变可能对预防前列腺癌的发生具有保护作用。
