Feeling tired, run down and exhausted? Then, it may be because your body is deficient in vitamin D. Vitamin D is both a nutrient and a hormone. It is essential for the human organism. It contributes to the mineralization of bones and plays a vital role in producing certain messenger substances that regulate activity, mood and stress levels.
It is not uncommon for an undersupply of vitamin D to be associated with increased susceptibility to infections, hair loss and the so-called “winter depression.” A deficiency can also have an impact on bone health. For adults, weight-bearing bones may become deformed, and pain and muscle weakness may accompany this. Older people are also at risk of osteoporosis.
Usually, the body can produce a large amount of vitamin D itself with the help of sunlight. But in the fall or winter, when the sun is only in the sky for a few hours, it is advisable to provide the body with an additional supply of the messenger substance. This is ideally achieved through diet, but it can also be done using dietary supplements.
How much vitamin D does the body need?
The human body usually forms 80 to 90 percent of the vitamin itself in the skin. This happens with the help of sunlight—UV-B radiation, to be precise. Diet contributes about 10 to 20 percent of the supply. However, vitamin D serum levels are subject to seasonal fluctuations.
A simple blood test can determine if a person has a vitamin D deficiency. A specific value in the blood is usually measured. This is expressed in nanomoles per litre (nmol/l). Doctors speak of a “deficient supply” when blood values are below 30 nmol/l. This is called “suboptimal supply”. We speak of “suboptimal supply” in the 50 to 30 nmol/l range, and “adequate supply” is when the values are above 50 nmol/l.
The German Nutrition Society (DGE) and the German Federal Office for Risk Assessment (BfR) recommend that adults get a maximum of 20 micrograms of vitamin D daily.
The best sources of vitamin D
- fish: eel, kippers, maties, herring, trout, salmon, sardines, tuna and mackerel
Eel: 90 µg/ 100 g
kipper: 30 µg/ 100 g
maties: 28 µg/ 100 g
Herring: 26 µg/ 100 g
Trout: 18 µg/ 100 g
Salmon: 16 µg/ 100 g
Sardines: 11 µg/ 100 g
Tuna: 6 µg/ 100 g
Mackerel: 4 µg/ 100 g
Beef liver: 1.7 µg/ 100 g
Chicken liver: 1.3 µg/ 100 g
- dairy products
Gouda 45% fat: 1.3 µg/ 100 g
Butter, 1.2 µg / 100 g
Cream 30% fat: 1 µg/ 100 g
Whole milk 3.5% fat: 0.09 µg/ 100 g
Morels: 3,42 µg/ 100 g
Porcini mushroom: 3,1 µg/ 100 g
Chanterelles: 2.1 µg/ 100 g
Mushrooms: 1.9 µg/ 100 g
- vegetable products
Vegetable drinks: 0.75 µg/ 100 g
Margarine: 2,5–7,5 µg/100 g
Cod liver oil provides the most vitamin D. Light to brownish-yellow oil is obtained from cod, hake or haddock liver. Thus, 100 g of cod liver oil contains 300 µg of vitamin D.
How helpful are dietary supplements?
Before taking vitamin D supplements, you should consult a doctor and have your blood values checked. Only those not spending enough time outdoors should take this dietary supplement. People (or risk groups), such as older people over 65, are also advised to take supplements.
The German Society for Nutrition also recommends taking additional vitamins only if a deficiency is proven.
Is there too much vitamin D?
Yes, there is too much vitamin D. Overconsumption can lead to poisoning. This is because vitamin D, as a fat-soluble vitamin, can be stored in both fat and muscle tissue.
Poisoning via the body’s vitamin D formation or natural nutrition is impossible; however, using supplements, high-dose medications, or eating highly fortified foods.
Symptoms of overdose leading to increased calcium levels are nausea, loss of appetite, abdominal cramps and vomiting. In severe cases, it can lead to kidney damage, cardiac arrhythmias, unconsciousness or even death.