Handelman G J
Department of Health and Clinical Science, University of Massachusetts, Lowell, MA 01854, USA.
Nutrition. 2001 Oct;17(10):818-22. doi: 10.1016/s0899-9007(01)00640-2.
The growth of our knowledge of carotenoid biochemistry has opened new and divergent paths for research. The earliest role established for beta-carotene in animals was as a vitamin A precursor, a role it shares with several other pro-vitamin A carotenoids. Additional studies have continued to refine our understanding of this function. Because carotenoids are excellent scavengers of singlet oxygen and respectable scavengers for other reactive oxygen species, substantial work was done concerning their potential role as antioxidants. In an unexpected twist, the ability of radicals in cigarette smoke to degrade carotenoids might be responsible for the finding that high-dose dietary beta-carotene increased the incidence of lung cancer in smokers. A new role for the polar carotenoids lutein and zeaxanthin was identified, when those carotenoids were found to constitute the macular pigment (the yellow spot at the center of the human retina). Many different carotenoids can be metabolized to products with retinoid activity, which might affect gene expression and cell differentiation. The formation of retinoids from diverse carotenoids might account for a portion of their activities as anticancer agents. Studies of lycopene in prostate cancer prevention have been very promising, and clinical studies of lycopene are underway. Carotenoids have emerged as the best single tissue marker for a diet rich in fruits and vegetables, and measurements of plasma and tissue carotenoids have an important role in defining the optimal diets for humans.
我们对类胡萝卜素生物化学知识的增长为研究开辟了新的、不同的途径。动物体内最早确定的β-胡萝卜素的作用是作为维生素A前体，它与其他几种维生素A原类胡萝卜素共同具有这一作用。更多的研究不断完善我们对这一功能的理解。由于类胡萝卜素是单线态氧的优秀清除剂，也是其他活性氧物种的良好清除剂，因此人们围绕它们作为抗氧化剂的潜在作用开展了大量工作。出人意料的是，香烟烟雾中的自由基降解类胡萝卜素的能力可能是高剂量膳食β-胡萝卜素会增加吸烟者肺癌发病率这一发现的原因。当发现叶黄素和玉米黄质这两种极性类胡萝卜素构成黄斑色素（人视网膜中心的黄斑）时，它们的新作用被确定了。许多不同的类胡萝卜素可以代谢为具有视黄醇活性的产物，这可能会影响基因表达和细胞分化。多种类胡萝卜素形成视黄醇可能是它们作为抗癌剂发挥部分活性的原因。番茄红素在预防前列腺癌方面的研究前景十分广阔，相关临床研究正在进行。类胡萝卜素已成为富含水果和蔬菜的饮食的最佳单一组织标志物，血浆和组织类胡萝卜素的测量在确定人类最佳饮食方面具有重要作用。
