食物中含有的糖类、蛋白质、脂肪以及矿物质等,都是人体所必需的营养素,然而在人们的生活中,仅仅满足了这些营养素,还是不能维持正常的生活,甚至还会产生某种疾病。维生素也是人体所必需的物质,虽然所需的量不多,但却不可缺少。人类存在许多疾病,其致病的原因是多种多样的,有些病是由细菌、病毒以及微生物和动物致病,有的病如脚气病、坏血病等则是由于缺乏某些维生素所引起。人们发现缺乏维生素 The sugars, proteins, fats, and minerals contained in foods are all essential nutrients for the human body. However, in people’s lives, only by satisfying these nutrients, can not maintain a normal life, and even produce some kind of disease. . Vitamins are also essential for the human body. Although the amount required is not large, it is indispensable. There are many diseases in humans. The causes of the diseases are various. Some diseases are caused by bacteria, viruses, microorganisms and animals. Some diseases such as beriberi and scurvy are caused by lack of certain vitamins. . People find a lack of vitamins