Vitamin D belongs to the fat-soluble vitamins. It is mainly produced when the ultraviolet rays in sunlight react with specific cholesterol under the skin. It is also found in animal foods such as deep-sea fish, animal livers, cheese, as well as plant-based foods such as grains and mushrooms. As a “multitasker,” vitamin D not only promotes the absorption of calcium and phosphorus by the intestinal mucosal cells, thereby promoting bone formation and calcification but also plays an important role in regulating immune function and promoting skin growth. In addition, although the exact mechanism is not yet clear, research has found that vitamin D deficiency is also associated with the occurrence of diseases such as Alzheimer’s disease, diabetes, and breast cancer.
Despite the importance of vitamin D, statistics show that about 50% to 80% of the global population lacks this nutrient, and there are 5 types of people who are particularly prone to deficiency: the first type is people who lack sunlight exposure, such as office workers who spend long periods indoors, residents living in high latitudes, people who excessively use sunscreens, as well as pregnant and lactating women, and so on. The second type is people with dark skin. They have more melanin in their skin, which absorbs and scatters a part of the ultraviolet rays, thereby reducing the synthesis of vitamin D. The third type is elderly people over 65 years old, who have a weaker ability to synthesize vitamin D in their bodies. The fourth type is obese individuals because excessive fat binds to vitamin D, hindering its entry into the bloodstream. The last type is people who engage in long-term dieting or have insufficient intake of animal-based foods.
When the body lacks vitamin D, it may send out some signals, such as joint pain, muscle soreness, weakness in the limbs, and so on. However, these symptoms can only serve as a reference. If you want to accurately identify whether you have a deficiency, regular medical check-ups are still necessary. For those who need supplementation, you can try the following 3 methods: First, sunlight exposure in a scientific manner. It is generally recommended that adults have 30 minutes to 1 hour of sun exposure daily, while children and individuals with weaker constitutions can shorten it to 15 to 30 minutes. You can go for a walk outdoors during relatively mild sunlight hours, such as 10 a.m. or 4 p.m., and expose areas such as forearms and lower legs to increase the contact area between the skin and sunlight. In addition, you can eat more deep-sea fish, animal livers, mushrooms, and other foods rich in vitamin D. According to the ” Dietary Reference Intakes” it is recommended that individuals aged 1 to 60 ensure a daily intake of 10 micrograms of vitamin D, while individuals over 65 years old should increase it to 15 micrograms per day. This is approximately the amount provided by 100 grams of salmon, 300 grams of sardines, or 700 grams of yogurt. Finally, friends with specific needs can also take vitamin supplements. It is important to note that vitamin D is a fat-soluble vitamin, which is more difficult to excrete from the body compared to water-soluble vitamins such as vitamin C. If taken excessively, it may accumulate in the liver and harm health. Therefore, it is necessary to supplement it under the guidance of a doctor.