Vitamin D Deficiency: Signs, Causes and What You Can Do

The days are getting shorter, the sun is low and you spend most of your time indoors. This is exactly when vitamin D deficiency becomes a topic for many people in Switzerland. The sunshine vitamin is involved in numerous processes in your body: in strong bones, in the function of your muscles and in a well-functioning immune system.

The tricky part: a deficiency develops gradually, and the signs are often non-specific. Many people simply blame tiredness or lack of motivation on the grey November weather. In this article you will learn where your body gets vitamin D, who is particularly at risk and what you can do in everyday life. If you are already thinking about your immune defences, also read our article on how you can strengthen your immune system.

First of all: this article does not replace medical advice. If you have symptoms or suspect a deficiency, please have it checked by a doctor. A simple blood test brings clarity.

What vitamin D does in your body

Strictly speaking, vitamin D is more of a hormone than a classic vitamin. Your body can produce it itself, namely in the skin, as soon as UVB radiation from the sun hits it. Through food, on the other hand, you only absorb a small part.

Its most important tasks include:

• Bone health: Vitamin D ensures that your body can absorb calcium from the intestine and incorporate it into the bones.
• Muscle function: It supports the strength and coordination of your muscles, which is especially important during training and with age.
• Immune system: Vitamin D is involved in regulating your immune cells.
• General well-being: A sufficient level contributes to your performance in everyday life.

The link with bones in particular is a good reason to think of vitamin D and exercise together. You can read how load strengthens your bones in the article on strength training against osteoporosis.

Why vitamin D deficiency is so common in winter

At our latitudes, from about October to March the sun is so low that UVB radiation is barely sufficient to form any meaningful amount of vitamin D in the skin. In addition, you wear more clothing in winter and spend less time outdoors. The stores you built up in summer gradually run down.

Who is particularly affected

Some groups have a higher risk of vitamin D deficiency:

• People who work a lot indoors, for example in an office or in shift work
• Older people, as the skin produces less vitamin D over the years
• People with darker skin, because more pigment slows down its formation
• People who largely cover their skin for cultural or health reasons
• People who are overweight, since vitamin D is stored in fat tissue and becomes less available
• People with certain intestinal, liver or kidney diseases

Typical signs of a deficiency

A mild deficiency often runs without clear symptoms. If it becomes more pronounced, various signals can appear. None of them is conclusive on its own, but in combination it is worth taking a closer look:

• persistent tiredness and lack of motivation
• muscle weakness or diffuse muscle pain
• bone pain, for example in the back or legs
• frequent infections
• low mood during the dark season
• slower recovery after training

Because these signs can also have many other causes, the rule is: do not diagnose yourself, but get it checked by a doctor if you suspect a problem. There, your vitamin D level in the blood can be measured, and you will receive a recommendation that suits you.

How to prevent a vitamin D deficiency

The good news: with a few habits you can do a lot for a healthy vitamin D balance. The following tips are easy to fit into your everyday life.

Tip 1: Make use of every hour of sunshine

In spring and summer, regular time outdoors with your face, arms and hands uncovered is often enough. Plan breaks outside on purpose, for example a walk at lunchtime. Fresh air is also good for you in winter, even though vitamin D formation is then low. Always make sure you use sensible sun protection and avoid sunburn.

Tip 2: Rely on foods rich in vitamin D

Diet alone hardly covers your needs, but it does make a contribution. Good sources are:

• fatty fish such as salmon, herring or mackerel
• eggs, especially the yolk
• mushrooms, particularly if they have been exposed to sunlight
• foods fortified with vitamin D

Fatty fish also provides valuable fatty acids. You can find out more in the article on omega-3 fatty acids. A good overview of vitamins and minerals is given in the article Micronutrients – what are they?.

Tip 3: Supplements only with a plan

The Swiss Federal Nutrition Commission recommends adults a daily intake of 15 micrograms (600 IU), and 20 micrograms (800 IU) from the age of 60. Whether you need a supplement and in what dose depends on your level. Do not take high doses on your own, because vitamin D can cause harm if overdosed. Raise the topic with your doctor.

Tip 4: Keep moving

Training does not replace vitamin D, but both work together on bones and muscles. Regular strength training provides the stimulus that helps your body incorporate calcium effectively. A full-body workout two to three times a week is an ideal way to start. And if you move your training outdoors on a sunny day, you combine both at once.

Frequently asked questions

Can I get vitamin D through a window in winter?

No. Window glass blocks most UVB radiation. Behind the pane, your skin therefore practically produces no vitamin D.

Does a solarium help against vitamin D deficiency?

This is advised against for health reasons, because UV exposure increases the risk of skin cancer. It is better to discuss safe alternatives with your doctor.

How quickly will I notice an improvement?

This is individual and depends on how pronounced the deficiency was. A follow-up measurement after a few months will show you whether the measures are working.

Conclusion: getting through the dark season well

A vitamin D deficiency is widespread in Switzerland, especially in winter, but it is not inevitable. Make use of sunshine hours, eat mindfully, have your level checked by a doctor if you suspect a problem and stay active. Exercise strengthens bones, muscles and mood alike. If you would like support with your nutrition, take a look at update Nutrition. And if you want to start with regular training, book your free trial session: a coach will create a training plan with you that suits your goals.