Ringer T V, DeLoof M J, Winterrowd G E, Francom S F, Gaylor S K, Ryan J A, Sanders M E, Hughes G S
Upjohn Research Clinics, Upjohn Company, Kalamazoo, MI 49007.
Am J Clin Nutr. 1991 Mar;53(3):688-94. doi: 10.1093/ajcn/53.3.688.
Doses of beta-carotene for cancer-prevention trials have been chosen based on epidemiologic data. Mechanisms of the putative antineoplastic effects by beta-carotene are unknown but may involve modulation of the immune system. We measured plasma carotenoid concentrations and selected immunologic indices at baseline and at 2 and 4 wk in 50 healthy humans (5 groups of 10 each) ingesting 0, 15, 45, 180, or 300 mg beta-carotene/d for 1 mo in this randomized placebo-controlled, open-label, parallel study. Plasma beta-carotene concentrations were markedly increased by 2 wk and were correlated with dose. Beta-carotene concentrations plateaued between 2 and 4 wk except for the 300-mg group. Thus, we developed a dose-concentration curve to optimize beta-carotene-dose selection to achieve target plasma concentrations. We were unable to identify any effects of beta-carotene ingestion on the immunologic indices studied, but modest increases in high-density-lipoprotein cholesterol were observed in all beta-carotene-treated groups.
癌症预防试验中β-胡萝卜素的剂量是根据流行病学数据选定的。β-胡萝卜素假定的抗肿瘤作用机制尚不清楚，但可能涉及免疫系统的调节。在这项随机、安慰剂对照、开放标签、平行研究中，我们测量了50名健康人（每组10人，共5组）在基线以及摄入β-胡萝卜素0、15、45、180或300毫克/天，为期1个月后的第2周和第4周时的血浆类胡萝卜素浓度，并选取了免疫指标进行检测。2周时血浆β-胡萝卜素浓度显著升高，且与剂量相关。除300毫克组外，β-胡萝卜素浓度在第2周和第4周之间趋于平稳。因此，我们绘制了剂量-浓度曲线，以优化β-胡萝卜素剂量选择，从而达到目标血浆浓度。我们未能发现摄入β-胡萝卜素对所研究的免疫指标有任何影响，但在所有β-胡萝卜素治疗组中均观察到高密度脂蛋白胆固醇有适度升高。
