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近年来,维生素的概念发生了新的变化。Folke-rs等认为,维生素是一种有机物,是由外源性摄取,或是在体内内源性生成的最终活性物质,为酶系统的成分之一,以促进机体的代谢反应,是一种极微量的营养素。如维生素D,机体以前维生素D_2或D_3的形式摄取,经紫外线照射在体内转变为维生素D_3,并经肝脏和肾脏羟化形成最终活性物质1,25(OH)_2D_3后才具有维生素的作用。又如,抗糙皮病的烟酸(N-AD)在体内由色氨酸途径合成,但生成量很少,所以在NAD需要量增多时亦出现烟酸缺乏症。前列腺素等在体内也可由必需脂肪酸内源性合成,因此认为也是一种维生素。
In recent years, the concept of vitamin has undergone a new change. Folke-rs and other that vitamin is an organic matter is exogenous uptake, or in vivo endogenous generation of the final active substance, as one of the components of the enzyme system to promote the body’s metabolic response is a Trace amount of nutrients. Such as vitamin D, the body before the intake of vitamin D_2 or D_3 form, the UV irradiation in the body into vitamin D_3, and the liver and kidney hydroxylation to form the final active substance 1,25 (OH) _2D_3 only after the role of vitamins. In another example, nicotinic acid (N-AD) against pellagra is synthesized in the body by the tryptophan pathway, but is produced in a small amount, so niacin deficiency occurs when the NAD requirement increases. Prostaglandins, etc., can also be endogenously synthesized in the body by essential fatty acids and are therefore considered to be also a type of vitamin.