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人体对维生素的需要量是很微少的,它不是构成身体组织的原料,也不是体内热能的来源,但却是维持生命必不可少的低分子有机化合物。它参加人体中许多重要的生理过程,所以维生素与人体健康的关系极大。目前已知的维生素有20多种,它们大多数不能在体内合成,必须由食物供给。维生素按其溶解性不同,可分为两类:一类是脂溶性维生素,主要有A、D、E、K等;另一类是水溶性维生素,主要有抗坏血酸和硫胺素、核黄素,尼克酸及其他B族维生素。 1 维生素A和胡萝卜素维生素A是一种无色物质,主要存在
The human body needs vitamins is very small, it is not the material constituting the body tissues, nor is the source of heat in the body, but it is essential to maintain life of low molecular weight organic compounds. It participates in many important physiological processes in the human body, so vitamins have a great relationship with human health. Currently there are more than 20 kinds of vitamins, most of them can not be synthesized in the body, must be supplied by food. Vitamins according to their solubility can be divided into two categories: one is fat-soluble vitamins, mainly A, D, E, K, etc .; the other is a water-soluble vitamins, mainly ascorbic acid and thiamine, riboflavin , Niacin and other B vitamins. 1 Vitamin A and carotenoids Vitamin A is a colorless substance, mainly present