Effect, deficiency, dosage, side effects, overdose
Contrary to what the name suggests, vitamin D is actually not a vitamin, but a hormone that the body can produce using sunlight. It is particularly important for building bones, teeth and joints and also involved in the following processes in the body:
Scientific studies have led to the assumption that vitamin D also plays a role in the prevention of a variety of diseases. This includes:
Many people have a higher need for vitamin D, e.g. the elderly, children and also people who hardly spend time outdoors, who have dark skin tones or who are veiled. The health experts advise in these cases to use nutritional supplements. In England they go one step further: Now that many people are staying at home, the health authority in England is advising everyone to take additional vitamin D supplements every day. (Source: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/)
Vitamin D is the only vitamin that can not only be absorbed through the diet, but can also be produced by the body itself. Since vitamin D is only present in very small amounts in food, an adequate supply of the vitamin alone through food is extremely difficult. According to the German Nutrition Society (DGE), adolescents and adults in Germany only consume 10 to 20 percent of their daily needs with food - the body produces the majority of the vitamin using sunlight in the skin.
In the summer, 15 minutes of sunlight a day are enough for the body to produce the daily requirement of the vitamin. Even on cloudy days, UV radiation is usually sufficient to ensure adequate production. Nevertheless, studies have shown that up to 60 percent of people in Germany have insufficient vitamin D levels. The reasons for this are varied and are related to lifestyle, habitat or diseases that impair vitamin D intake. Several unfavorable factors can also come together and make an adequate supply of the vitamin difficult.
A vitamin D deficiency is particularly common in northern Europe in the winter months. One reason for this is that the majority of the population spends less time outdoors during that time than in the warm season. However, the low position of the sun between October and March in all areas north of the 40th parallel, e.g. north of Rome, prevents sufficient UV rays from reaching the skin even on regular walks. Although it is advisable to replenish the vitamin D depot in the summer months by spending a lot of time outdoors, the vitamin D level drops drastically after just a few weeks without sufficient vitamin intake.
Low vitamin D levels are initially manifested by atypical symptoms such as fatigue and exhaustion, pessimism and depressed mood, listlessness, nervousness, easy excitability, sleep disorders, cravings for sweets or tooth decay and gum infections. In the further course, respiratory tract infections, an increased susceptibility to allergies or pain in the musculoskeletal system may occur.
Vitamin D deficiency means that calcium is no longer sufficiently stored in the bones and they become soft and flexible. If the vitamin D deficiency persists over a longer period of time, children's bones, particularly the skull and spine, may deform. In adults, a calcium deficiency can lead to a decrease in bone density, which favors the development of osteoporosis. Autoimmune diseases, loss of body functions, rheumatic complaints or personality changes can also be symptoms of a vitamin D deficiency.
The DGE recommends adolescents and adults between the ages of 15 and 65 to ingest 800 international units (IU) of vitamin D per day if the body can't produce vitamin D itself. This corresponds to around 20 micrograms of the vitamin. According to various vitamin D experts, however, this dose is only sufficient to meet the minimum requirements and to protect against vitamin deficiency diseases. In order to keep the vitamin D level constant at the required level, experts therefore advise adults with a body weight of 70 kg to take a daily dose of 5,000 IU on average.
Babies, children, pregnant women and people with various diseases have different needs for vitamin D. In addition, many other factors play a role in the intake of vitamin D. This includes the age, body weight, skin color, intensity of sun exposure, lifestyle and absorption capacity of vitamin D and its metabolism. The recommended guidelines for calculating the optimal vitamin D dosage are therefore only indicative. A blood test is essential to find out how high your vitamin D level is.
Especially in the winter months, it is difficult to keep the vitamin D level constant at a sufficiently high level. Since the sun is not enough and the need for vitamin D can't be covered by the diet alone, taking vitamin D in the form of dietary supplements is recommended.
Taking vitamin D as a dietary supplement can be useful:
As with most substances, an overdose can also occur with vitamin D if the intake is very high. In this case, it is a vitamin D poisoning. For this, however, very high doses of the vitamin must be taken in the long term. Instead of the recommended 5,000 units daily, more than at least 10,000 IU, probably even up to 40,000 IU, of vitamin D would have to be added daily over a period of 3 months or longer to cause vitamin D poisoning. In order to avoid an overdose, it is advisable to have your individual needs checked with a doctor.
Different organizations recommend varying doses of vitamin D. For example, in cases where vitamin D formation through sunlight is deficient, the DGE currently recommends a dose of 400 IU for infants up to 1 year of age and 800 IU for children, adolescents, adults, seniors, and pregnant and nursing women.
According to vitamin D experts this recommendation is too low and only represents the minimum daily intake required to stave off rickets.
Recent studies clearly demonstrate that vitamin D3 and vitamin K2 are essential to good health. Deficiencies in both these vitamins are extremely common, which is why more and more people are taking vitamins D3 and K2 as a daily dietary supplement.
It's very important to know that if you take vitamin D3 regularly over a long period, you definitely need to take vitamin K2 as well. This raises the question of how these two key vitamins should best be combined in order to promote health and vitality.
You can measure your vitamin D levels by using a blood test to determine if you have enough vitamin D in your body. In fact, not the active form of vitamin D is measured, but the concentration of 25(OH)D (25-hydroxyvitamin D) in the blood.
The 25 (OH)D value is a precursor of vitamin D, in which form is is transported in the blood. If necessary, this form is converted into the active form of vitamin D (calcitriol).
The 25 (OH)D value shows how much vitamin D you got through nutrition or produced during sun exposure. But this value does not tell you anything about your vitamin D levels throughout the year, which will vary depending on the sun exposure and vitamin D uptake from food.
The half-life of 25(OH) Vitamin D is 2 month. This means, that the vitamin D level will fall to half of its value, provided that you no longer get any vitamin D at all.