25-hydroxyvitamin D is the main form of vitamin D in the body, and its concentration in the blood is an ideal indicator of the body’s vitamin D nutritional status. low 25-hydroxyvitamin D values reflect vitamin D deficiency, which can easily occur due to insufficient sunlight exposure, low vitamin D intake, or lesions involving the gastrointestinal tract, resulting in impaired absorption, as well as the use of drugs that affect vitamin D metabolism. 1. Insufficient sunlight exposure: Vitamin D is a steroid derivative, which can be synthesized by the skin under UV irradiation, and after entering the circulating blood, the synthesized vitamin D will be hydroxylated into 25-hydroxyvitamin D by the action of liver microsomal 25-hydroxylase. If the sunshine time is not enough, the body cannot absorb and synthesize enough vitamin D, which may lead to low 25-hydroxy vitamin D. 2, too little vitamin D intake: the main vitamin D cycle in the body is 25-hydroxy vitamin D that is hydroxylated in the liver, which is the main storage form of vitamin D in the body. Inadequate intake of vitamin D caused by factors such as unreasonable diet structure and malnutrition may lead to insufficient 25-hydroxyvitamin D. Especially pregnant women and children who are still growing and developing need to pay particular attention to adequate vitamin D supplementation; 3, vitamin D absorption disorders: for example, Crohn’s disease patients with vitamin D deficiency, or other lesions involving the gastrointestinal tract, digestive dysfunction vitamin D can not be effectively absorbed, may also appear 25-hydroxy vitamin D low performance; 4, taking drugs that affect vitamin D metabolism: if you take some drugs that affect vitamin D metabolism, such as anti-epileptic drugs, will make the body vitamin D decomposition too fast, affecting the body’s vitamin D content. Therefore, in daily life, pay attention to appropriate outdoor activities and more sunshine to promote the synthesis of vitamin D in the skin. Also pay attention to a balanced diet and avoid picky and partial eating, so as not to cause malnutrition. In addition, if you suffer from gastrointestinal diseases, etc., you need to actively treat them.