在我国，维生素D缺乏引起的佝偻病仍是婴幼儿常见病。近年来由于看电视、玩电脑游戏等室内活动增多，一些西方发达国家的佝偻病发病率也开始回升。同时，成年人维生素D缺乏也非常普遍。由于成年人骨发育已成熟，所以成年人维生素D缺乏更加隐匿，不易被发现，导致多种慢性病的发病率升高。这些现象与维生素D的知识没有得到普及有关。近年来，维生素D的营养保健科学飞速发展，全世界几乎每天都有维生素D的报道。《TIME》周刊将“维生素D对健康的贡献”列为2007年十大医学突破之一。维生素D缺乏不但可以引起儿童佝偻病，而且可以增加肿瘤、糖尿病、肺结核、流行性感冒、小儿哮喘等多种慢性病的发病概率。但这些报道多局限于学术研究层面，在普通民众中得不到普及，更不可能从中受益。申请者课题组在国家自然基金资助下进行了近十年的维生素D研究，发现并验证了多项维生素D的新功能。深感有必要写一本普通大众能看懂的科普作品来普及维生素D知识。

Vitamin D deficiency rickets are prevalent in China. A tendency for children to stay indoors and watch TV or play on computer games increased prevalence rates of rickets in western country. Meanwhile, vitamin D insufficiency is also prevalent among adults. As adults'' bones are physically matured, vitamin D insufficiencies among adults are more difficult to be diagnosed, which leads to higher morbidity of various chronic diseases. This is resulted from the lack of prevalence of vitamin D science. Recently, nutrition science concerning vitamin D has developed rapidly. Vitamin D researches are reported almost every day in the world. The New York Time has ranked the contribution of vitamin D in health as ten of the greatest medical breakthroughs. Vitamin D not only builds strong bones, but also helps in preventing or controlling diseases such as diabetes, tumor, influenza, asthma, tuberculosis, and even heart disease. However, these scientific studies are reported only by academic researchers, ordinary people are not aware of these achievements yet and are less likely to benefit from these scientific researches. Our research group has studied vitamin D for nearly ten years, and discovered as well as confined a number of new functions of vitamin D in the sponsorship of national natural scientific foundation. We believe that it is of great significance to write a straightaway scientific reading to popularize the knowledge of vitamin D in order to benefit the public.