Vitamin D is actually a hormone linked to calcium metabolism and bone growth. Vitamin D is also an important vitamin linked to calcium concentration in the blood. If the calcium level in the blood is reduced, vitamin D will re-absorb more calcium from the small intestine and kidneys. In addition, the blood’s calcium level will rise when calcium is released from bones. When the calcium level in the blood increases, a hormone called calcitonin is secreted, and calcium is absorbed into the bones. As the body manages blood calcium levels very sensitively, you will get muscle cramps when the level is too low, or calcium will stick to your arteries when the level is too high.
The point is that calcium cannot be absorbed well if you don’t get enough vitamin D.
Vitamin D is a key element in bone growth, as it promotes the production of a protein contained in bones and teeth. It enhances the function of the bone-forming cells that are essential for new bone growth.
Vitamin D is also important for DNA function, because a deficit of vitamin D affects the differentiation, proliferation and growth of cells. Recent research shows that vitamin D supplements help prevent and treat cancer and psoriasis. Vitamin D boosts your immune system so it can fight bacteria and virus. Another study shows that high doses of vitamin D work effectively to battle autoimmune diseases such as rheumatoid arthritis. Vitamin D also affects the production of other hormones, like estrogen and testosterone. Many studies show that vitamin D helps reduce cardiovascular disease and inflammation of joints.
Because of these reasons, vitamin D is a necessity for people of all ages.
Sources of vitamin D
Vitamin D has two sources. One is food. Egg yolks and fatty fish such as salmon, sardines, and mackerel contain large amounts of vitamin D. You can find vitamin D-fortified milk or cereals in stores.
Another source is sunlight. Exposing your skin to the sun produces vitamin D naturally. By exposing your face and hands to the midsummer sun for 10 minutes, the necessary amount of vitamin D will be synthesized in your skin. However, sunscreen rated SPF8 or higher will inhibit 95% of the synthesis of vitamin D.
If you’re aged 65 or older, longer sunbathing is needed. It takes 3 times longer for older people to synthesize vitamin D in the skin than it takes young people.
Since the midday sunlight accelerates aging, it’s better to expose your face and arms in the morning or the evening sun for 15 minutes. This will give you enough sunlight for vitamin D synthesis. It is recommended that you sunbathe often before the arrival of winter, because vitamin D can be stored in fat.
Lack of Vitamin D
Vitamin D that comes from food or is synthesized in the skin does not become effective until it is metabolized in your liver and kidneys. If your liver and kidney function is impaired, you’re more likely to have a vitamin D deficiency. In addition, people who are not exposed to the sun, always use sunscreen, who have digestive system problems, and vegetarians are prone to vitamin D deficiency. Vitamin D deficit can cause rickets, osteomalacia, and osteoprorsis.
People are more likely to suffer winter depression in cities like Seattle, where the daylight hours are short and there are a lot of rainy days. But Vitamin D can be acquired from supplements; the limit is generally 2000IU a day.
Overdosing on vitamin D
Taking too much vitamin D can produce toxicity, which builds up the calcium level in your blood. The calcium can accumulates in the kidneys, heart, lungs and veins, which could become sclerotic.
If you use vitamin D for therapeutic purposes – such as for treating psoriasis, cancer, an autoimmune disease, osteoporosis, or polycystic ovary syndrome – make sure your doctor is familiar with nutrition. Test your vitamin D level every three months to avoid a vitamin D overdose.
You can never get too much vitamin D from sunlight – so enjoy yourself sunbathing every day!