In addition to calcium supplementation, vitamin D supplementation is also necessary to prevent osteoporosis. The most direct and simple way to supplement vitamin D is to get sunlight. However, the daylight hours are short in winter, making it easy to become deficient in vitamin D. Therefore, special attention should be paid to supplementing vitamin D in winter.

　　Experts say that to supplement vitamin D, one should sunbathe for about 15-30 minutes every day. Older people have a weaker ability to absorb sunlight due to skin aging, so they should sunbathe for a slightly longer time than younger people. In addition, since window glass blocks some ultraviolet rays, it is recommended to take a walk outdoors to sunbathe.

　　Besides sun exposure, dietary sources are also an important way to supplement vitamin D. Foods that provide vitamin D are mainly fish and mushrooms. Even dried shiitake mushrooms, because they are exposed to sunlight, can produce their own vitamin D, just like the skin, so eating dried shiitake mushrooms is highly recommended.

　　The Information Center of the National Institute of Health and Nutrition in Japan points out that, under normal circumstances, as long as a balanced diet is maintained, it is possible to obtain enough vitamin D from food. However, if there is a picky eating habit, vitamin D deficiency is likely to occur. In particular, white-collar workers who often eat out may have insufficient vitamin D intake due to an unbalanced diet if they order similar foods for each meal.

　　It's also important to emphasize that even if a certain nutrient is considered very healthy, overeating it can lead to a decrease in the intake of other nutrients. Therefore, maintaining a balanced diet is the most important principle. Even though it's difficult to control and calculate nutrient intake, consciously modifying the menu for each meal and eating different foods every day can effectively maintain a balanced intake of different nutrients.