Vitamin D is actually a hormone, and its production begins in the skin by exposing to ultraviolet (UV-B) rays, which are part of sunlight. Theoretically, it takes only a few minutes of sun exposure per day to produce enough vitamin D. But many people, especially in the winter, are not exposed to sun enough.
The ability to produce that vitamin with age is reduced, which also contributes to a more severe deficiency in the elderly people. However, there may be a deficiency in young people who do not have adequate supplies of that substance. One study conducted on 300 hospitalized patients due to various diseases showed that 57% did not have enough vitamin D levels. A particular concern was caused by the fact that the deficiency was present in one third of those who took enough of this vitamin, either with food or with dietary supplements. This may mean that the current recommended doses are not large enough.
How does it work?
The basic function of vitamin D is to regulate calcium and phosphorus concentrations in the blood and help build healthy and strong bones and teeth.
PREVENTION: research has shown that this vitamin is important for preventing osteoporosis, porous bone disease, in which the risk of fracture is increased. If the amount of vitamin D is not enough, enough calcium from the food or dietary supplements can not be absorbed, no matter how large the intake is. When the level of calcium in blood drops, the organism takes it from the bone to make it sufficient for the function of the muscles (especially the heart) and the nerves. Over time, due to withdrawal of calcium from the bones, the bone mass is reduced.
ADDITIONAL USEFUL EFFECTS: scientists are constantly coming up with new insights into the functioning of vitamin D in the body. Research suggests that it is important for the normal functioning of the immune system; it can help prevent prostate, colon and breast cancer. One study has shown that an adequate amount of vitamin D can slow the progression of knee osteoarthritis, although it does not prevent the onset of the disease.
How much vitamin D is needed?
The recommended amount of daily intake of this vitamin for adults is not determined because it is considered that sufficient amount is generated by the action of sunlight on the skin. But for people over the age of 65, pregnant and breastfeeding women, 10 μg per day is recommended.
IF YOU TAKE TOO LITTLE: vitamin D deficiency harms the bones – it causes rickets (weakiening of bones) in children, and in adults increases the risk of osteoporosis. Diarrhea, insomnia, nervousness and muscle spasms may also appear. Today, the likelihood of rickets is not large because children usually spend enough time in the sun.
IF YOU TAKE TOO MUCH: although the excess of vitamin D is easily excreted, taking too much dietary supplements with this vitamin can cause problems. Intake of 25 to 50 μg over six months may cause constipation or diarrhea, headache, loss of appetite, nausea and vomiting, improper heartbeat and severe fatigue. If too much of vitamin D is taken over time, the balance of calcium and phosphate can be disturbed, bone can weaken, and calcium can accumulate in soft tissues, such as muscles.
How to take it?
DOSAGE: if you spend only 10 to 15 minutes on sun, two or three times a week, bathing you face and hands around noon, you will have enough of that vitamin. However, if you are older than 50, if you do not go out too much between 8 and 13 o’clock or if you constantly use sunscreen creams, you may need to take dietary supplements. Many therapists advise that people after age 50 take 10 to 15 μg of vitamin D per day, while for younger people 5 to 10 μg is enough.
USE GUIDELINES: these dietary supplements can be taken at any time of the day, regardless of diet. Most multivitamin preparations contain up to 10 μg of vitamin D, and dietary supplements with calcium often contain it, too.
Many wheat flakes that are eaten for breakfast are enriched with 1 to 2.5 μg of vitamin D per meal. Fatty fish, such as herring, salmon and tuna, is a natural and rich source of this vitamin.
IMPORTANT: taking excessive amounts of vitamin D can lead to increased levels of calcium in the blood. Possible consequences include loss of body mass, nausea, and heart and kidney damage.