Research Centre for Food and Nutrition, Council for Agricultural Research and Economics (CREA-AN), Rome, Italy.
Antioxidants Research Laboratory, Jean Mayer USDA Human Nutrition Center on Aging, Tufts University, Boston, MA, USA.
Oxid Med Cell Longev. 2018 May 9;2018:4637861. doi: 10.1155/2018/4637861. eCollection 2018.
Vegetables and fruits contain non-provitamin A (lycopene, lutein, and zeaxanthin) and provitamin A (-carotene, -cryptoxanthin, and -carotene) carotenoids. Within these compounds, -carotene has been extensively studied for its health benefits, but its supplementation at doses higher than recommended intakes induces adverse effects. -Carotene is converted to retinoic acid (RA), a well-known immunomodulatory molecule. Human interventions suggest that -carotene and lycopene at pharmacological doses affect immune functions after a depletion period of low carotenoid diet. However, these effects appear unrelated to carotenoids and retinol levels in plasma. Local production of RA in the gut-associated lymphoid tissue, as well as the dependency of RA-induced effects on local inflammation, suggests that personalized nutrition/supplementation should be considered in the future. On the other hand, the differential effect of RA and lycopene on transforming growth factor-beta suggests that lycopene supplementation could improve immune functions without increasing risk for cancers. However, such preclinical evidence must be confirmed in human interventions before any recommendations can be made.
蔬菜和水果含有非维生素 A（番茄红素、叶黄素和玉米黄质）和维生素 A（β-胡萝卜素、β-隐黄质和β-胡萝卜素）类胡萝卜素。在这些化合物中，β-胡萝卜素因其对健康的益处而被广泛研究，但在推荐摄入量以上补充β-胡萝卜素会引起不良反应。β-胡萝卜素可转化为视黄酸（RA），这是一种众所周知的免疫调节分子。人体干预研究表明，β-胡萝卜素和番茄红素在药理剂量下，在低类胡萝卜素饮食的消耗期后，会影响免疫功能。然而，这些影响似乎与血浆中的类胡萝卜素和视黄醇水平无关。肠道相关淋巴组织中 RA 的局部产生，以及 RA 诱导作用对局部炎症的依赖性，表明未来应考虑个性化营养/补充。另一方面，RA 和番茄红素对转化生长因子-β的不同作用表明，番茄红素补充剂可以改善免疫功能，而不会增加癌症风险。然而，在提出任何建议之前，这种临床前证据必须在人体干预中得到证实。
