Vitamin D deficiency: Prophylaxis in the winter time

The longer the dark season lasts, the more our health and mood can suffer. There is an increase in infections and depressive moods. One reason for this is the vitamin D deficiency that develops during the winter months. You can find out how your vitamin D level is with a simple blood test at your dermatologist. A few tips and suitable supplement measures help to counteract a deficit – so that you remain healthy and radiant even in the dark season.

The body can generally produce vitamin D itself – provided it gets enough sunlight. With the help of UV-B rays, vitamin D is synthesized in the skin and converted into its active form calcitriol in the body. However, at our latitude where sunlight is scarce in winter and the sun is very low, the supply is critical.

Reservoirs used up during the winter

Even those who still get a lot of sun from an extended beach holiday in autumn often cannot protect themselves from a vitamin D deficiency in winter. The “sun vitamin”, which is actually not a vitamin but the precursor of the hormone calcitriol, has only a short half-life. If the sun is insufficient, the body uses up its reservoirs within a few weeks and runs into a deficit. This increases more and more in the course of the dark season. While we can still defend ourselves against infectious diseases quite well in October and November, we become much more vulnerable in January and February.

Vitamin D: Numerous functions in the body

The so-called killer cells of the body’s immune system need vitamin D in order to effectively combat invading viruses and bacteria. However, vitamin D is not only of central importance for the immune system. The prohormone is involved in all metabolic processes and has numerous functions in the body. These are just a few of them:

Strengthens bones:

Vitamin D is indispensable for strong bones. It influences their health in many ways. Vitamin D not only regulates the absorption of calcium in the intestines, but also increases its recovery from the blood via the kidneys. It also helps the cells to absorb calcium and store it in the bones. It thus promotes bone growth and the continuous development of the skeleton. A lack of calcium and vitamin D can increase the risk of osteoporosis. Therefore, these two nutrients should always be considered together and, if necessary, supplemented in consultation with your doctor.

Protects skin and tissue:

Sunlight not only stimulates our skin to produce vitamin D, an adequate supply of vitamin D in turn also protects the skin from being damaged by UV radiation. In addition, it protects all tissues in the body against ageing processes. The fact that all body tissues have vitamin D receptors shows that every tissue needs vitamin D to function optimally. This illustrates how important vitamin D is for the metabolic processes of our cells.

Maintains balanced mental health:

There are many causes of depression – difficult living conditions, stress, burn-out and genetic predisposition. Their development usually involves several factors. The focus is increasingly on nutritional deficiencies. Such deficiencies are also increasingly frequent in our society. With today’s low-sun lifestyle, where many people eat high energy foods with too few nutrients, deficiencies can easily arise. Depressed people, for example, have particularly low vitamin D levels. It is also noteworthy that depressions occur more frequently in the dark season – “winter depression” has now become an established term. Studies have shown that the decisive factor for this is not only the general lack of sunlight, but also the associated vitamin D deficiency. In these cases, depression improved after an adequate administration of vitamin D, whereby “sunlight therapies” alone (= irradiation with “sunlight lamps”) were less successful. The connection becomes all the more plausible when we look at the biochemical processes: Among other things, vitamin D helps to convert the amino acid tryptophan into serotonin – one of the most important messenger molecules for a good mood. Tryptophan is found in eggs, tuna and walnuts.

Secondary diseases: Consider studies with caution

Like many nutrients, there are also quite a number of studies on vitamin D that suggest that a deficiency is related to certain diseases – such as multiple sclerosis, asthma and certain types of cancer. As with all studies of this kind, these should also be considered in a differentiated way. They merely indicate that a disease correlates with a vitamin D deficiency. This does not automatically mean that the deficiency is also the cause. It should also be taken into consideration that people with certain diseases spend less time in the sun or outdoors, which in turn leads to a vitamin D deficiency. Nevertheless, one thing is certain: Vitamin D is not a substance that is optional for our bodies, but absolutely essential to our health.

Uptake in winter: Use every ray of sunshine

From October to March in Germany, the body usually doesn’t get enough sun to produce enough vitamin D. Even when the sun shines in winter, it is usually not high enough to provide us with UVB radiation. The situation is different in the high mountains or the southern regions. A skiing holiday or a trip to the Mediterranean is therefore also a real benefit for the vitamin D reservoir. Since this is of course not possible for everyone, alternatives are needed. In general: As soon as the sun shows up, you should use every ray of sunshine. Hold your face to the sun, roll up your sleeves and trouser legs. It is important to know that a sun protection factor of just ten inhibits vitamin D synthesis and that windows and car windows also prevent UVB rays from reaching the skin. In contrast to winter, it is, of course, essential that you protect yourself well from the sun in summer.

Mindfulness exercise:

Beware of the solarium: Due to the damage to the skin caused by UVA light, sunbeds should be used with absolute caution. Many sunbeds also use only the rapidly tanning UVA light and no UVB radiation which is needed for vitamin D synthesis. Therefore, solariums are not an effective alternative for your vitamin D provision. If you still want to use the artificial sun in winter, it is essential to consult your dermatologist.

Food with vitamin D

In addition to sunlight, you can also support your vitamin D reservoirs with an appropriate diet. While we produce about 80 % of our vitamin D in the skin on average, we take in about 20 % through food. You should therefore choose the following foods, especially in the low-sun season:

  • Herring: 100 g contain 25 mg
  • Salmon: 100 g contain 16 mg
  • Egg yolk: 100 g contain 5.6 mg
  • Cep: 100 g contain 3.1 mg
  • Button mushroom: 100 g contain 1.9 mg
  • Avocado: 100 g contain 3.75 mg
  • Emmental cheese: 100 g contain 1.1 mg

It is admittedly much harder for vegetarians and vegans to find food containing vitamin D. Vitamin D is only present in very small amounts in fruit and vegetables. The aforementioned fungi and avocados only contain it if they have previously been exposed to sunlight or UVB light. But even if nutrition only makes a small contribution, you should still use this resource. The omega-3 fatty acids from fish also support a balanced mood in winter and prevent inflammation.

Vitamin D deficiency despite sun and diet

Those who make every effort to catch every ray of sunshine and also eat plenty of fatty fish can still find themselves in a deficient state. In fact, most people in Germany have an inadequate amount. According to studies, 60 to 90 percent of the population has less than 20 ng per ml of vitamin D in their blood – and not only in winter. A deficit can also develop in the sunny months if we do not spend enough time outdoors.

Supplementary products: Blood test by the doctor beforehand

It makes sense to take supplements if there is a proven deficiency. Although you can’t find out for yourself whether you have enough vitamin D, your doctor can determine this with a simple blood test. The test may cost you 20 to 25 euros.

The desired level of vitamin D is 40 to 80 ng/ml; a deficiency already exists at 30 ng/ml.

Who is particularly at risk?

  • Pregnant women and nursing mothers
  • Breastfed babies whose mothers suffer from vitamin D deficiency
  • Elderly people
  • People with illnesses
  • People who are highly obese
  • People who hardly spend any time outdoors

Do not self-dose:
Generally applies to all dietary supplements: Too much can upset the body and even make it ill. Without a test, you can never know what concentration is present in the blood, fatty tissue and liver cells or how much you need to supplement. An overdose of vitamin D over a prolonged period of time, for example, causes the bones to release vitamin D and calcium into the blood. Lime can form in the blood vessels, which in turn can lead to consequential damage. Always take supplements in consultation with your doctor. He or she can tell you exactly how much you need for the optimum care of your body.