Lovejoy J C, Windhauser M M, Rood J C, de la Bretonne J A
Pennington Biomedical Research Center, Louisiana State University School of Medicine, Baton Rouge 70808-4124, USA.
Metabolism. 1998 Dec;47(12):1520-4. doi: 10.1016/s0026-0495(98)90080-4.
African-American women have been shown to be more insulin-resistant than age- and weight-matched Caucasian women, but the reasons for this difference are unclear. The purpose of the present study was to determine whether experimental manipulation of dietary fat intake has differential effects by race on insulin sensitivity (S(I)) in 20 African-American and 11 Caucasian women. Additionally, leptin levels before and after 3 weeks of an isocaloric high-fat ([HF] 50% fat, 35% carbohydrate, and 15% protein) or low-fat ([LF] 20% fat, 55% carbohydrate, and 15% protein) diet were compared. African-American and Caucasian women did not differ significantly in the body mass index (BMI) or percentage body fat at baseline. S(I) (adjusted for BMI) decreased on the HF diet and increased on the LF diet in both races combined relative to the baseline control (control, 2.42 +/- 0.22; HF, 2.29 +/- 0.22; LF, 2.75 +/- 0.21 x 10(-4) min(-1)/microU x mL; main effect of diet, P = .04). There was a 6% decrease in S(I) on the HF diet compared with the control in women of both races, while the LF diet increased S(I) by 6% in African-American and 20% in Caucasian women. Leptin levels increased by 14% on the HF versus control diet in African-Americans (35.2 +/- 3.0 v 30.8 +/- 3.0 ng/mL, P < .01), but did not change with diet in Caucasian women. Glucose and insulin administration had no effect on leptin levels. We conclude that a HF diet consumed over several weeks reduces S(I) in healthy women of both races; however, the magnitude of increase in S(I) on a LF diet is greater in Caucasian women. The HF diet significantly increased leptin levels in African-American women, although there were no other influences of diet, insulin, or race on serum leptin.
研究表明，非裔美国女性比年龄和体重匹配的白人女性更具胰岛素抵抗性，但造成这种差异的原因尚不清楚。本研究的目的是确定饮食脂肪摄入量的实验性操控对20名非裔美国女性和11名白人女性的胰岛素敏感性（S(I)）是否存在种族差异影响。此外，还比较了等热量的高脂（[HF]脂肪占50%、碳水化合物占35%、蛋白质占15%）或低脂（[LF]脂肪占20%、碳水化合物占55%、蛋白质占15%）饮食3周前后的瘦素水平。非裔美国女性和白人女性在基线时的体重指数（BMI）或体脂百分比无显著差异。相对于基线对照，两种族组合的S(I)（根据BMI调整）在高脂饮食时降低，在低脂饮食时升高（对照，2.42±0.22；HF，2.29±0.22；LF，2.75±0.21×10⁻⁴min⁻¹/μU×mL；饮食的主要效应，P = 0.04）。与对照相比，两种族女性在高脂饮食时S(I)降低了6%，而低脂饮食使非裔美国女性的S(I)升高了6%，白人女性升高了20%。非裔美国人高脂饮食与对照饮食相比，瘦素水平升高了14%（35.2±3.0对30.8±3.0 ng/mL，P < 0.01），但白人女性的瘦素水平不受饮食影响。葡萄糖和胰岛素给药对瘦素水平无影响。我们得出结论，数周的高脂饮食会降低两个种族健康女性的S(I)；然而，低脂饮食时S(I)升高的幅度在白人女性中更大。高脂饮食显著提高了非裔美国女性的瘦素水平，尽管饮食、胰岛素或种族对血清瘦素没有其他影响。
