What symptoms indicate vitamin D deficiency?

Common symptoms include persistent fatigue and exhaustion, depressive moods, frequent infections, muscle and bone pain, and delayed wound healing. However, these symptoms are nonspecific; only a blood test (25-OH-vitamin D) can reliably detect a deficiency.

How much vitamin D do I need daily?

The German Society for Nutrition (DGE) recommends 800 IU (20 µg) daily for adults when adequate sun exposure is not possible. For infants, 400 IU applies. With confirmed deficiency, significantly higher doses (e.g., 2000–4000 IU) can be prescribed under medical supervision.

Can I get vitamin D without sun through diet?

Only to a limited extent. Good sources include fatty fish (salmon, herring, mackerel), egg yolk, liver, and vitamin D-fortified foods. The requirement can hardly be met through diet alone; approximately 80–90 % of vitamin D is produced by the skin itself through sun exposure.

Can you take too much vitamin D?

Yes. Hypervitaminosis D is possible with very high supplementation and manifests through nausea, vomiting, calcium deposits in organs, and kidney stones. Overdosing is not possible through diet and normal sunlight; with high-dose supplements, serum levels should be monitored.

When should I take vitamin D supplements?

Supplementation is advisable with confirmed deficiency (< 30 nmol/l in blood), during winter months (October–March), for people over 65, people with dark skin, those with little outdoor time, and people with fat absorption disorders. Discuss dosage with your doctor.

Vitamin D Deficiency: Symptoms and Treatment

Vitamin D is a vital nutrient that the body produces mainly through sunlight. However, in Germany, an estimated 60 percent of the population does not have adequate vitamin D levels. Particularly during the winter months from October to March, the sun's radiation in our latitudes is insufficient to produce enough vitamin D. A deficiency can have far-reaching consequences for health.

What is Vitamin D and why is it important?

Strictly speaking, vitamin D is not a classic vitamin, but a hormone. The body produces approximately 80 to 90 percent of it itself when UV-B rays hit the skin. The remaining 10 to 20 percent are obtained through food. Vitamin D is essential for calcium metabolism and thus for strong bones and teeth. Furthermore, it influences the immune system, muscle function, heart health, and mental well-being.

Symptoms of Vitamin D Deficiency

Vitamin D deficiency develops gradually and often goes unnoticed for a long time. Typical symptoms include general fatigue and exhaustion, muscle weakness and muscle pain, increased susceptibility to infections, bone pain especially in the back and legs, depressive moods particularly in winter, hair loss, and delayed wound healing.

In severe and prolonged deficiency, adults may develop osteomalacia (bone softening). In children, a pronounced deficiency leads to rickets, a disorder of bone growth. Elderly people have an increased risk of osteoporosis and bone fractures with vitamin D deficiency.

Risk Groups for Vitamin D Deficiency

Certain groups of people are particularly at risk. These include elderly people, as skin's own vitamin D production decreases with age. Residents of nursing homes are particularly affected because they spend little time outdoors. Other risk groups include people with dark skin, as melanin filters UV-B radiation, people who spend little time outdoors, severely obese people, as vitamin D is stored in adipose tissue, as well as pregnant and nursing women with increased requirements.

Diagnosis: Testing Vitamin D Levels

The safest method to determine vitamin D deficiency is a blood test. The 25-hydroxyvitamin D level (25-OH-D) in the blood is measured. The assessment of values is as follows: Below 12 ng/ml is considered severe deficiency, 12 to 20 ng/ml is deficiency, 20 to 30 ng/ml is suboptimal, and 30 to 60 ng/ml is the optimal range. Values above 150 ng/ml are considered toxic.

The blood test is performed by your general practitioner. The costs of 20 to 30 euros are usually covered by health insurance only if there is a justified suspicion. Use the physician search to find a suitable doctor near you.

Treatment and Supplementation

Treatment depends on the severity of the deficiency. With mild deficiency, increased sun exposure and adjusted diet are often sufficient. With more severe deficiency, the doctor will recommend supplementation. The German Society for Nutrition recommends a daily intake of 800 IU (International Units) of vitamin D when there is no adequate self-production.

With confirmed deficiency, doctors often prescribe an initially higher loading dose to replenish stores, followed by a lower maintenance dose. Vitamin D is fat-soluble and should therefore always be taken with a meal containing some fat. Overdosing is not possible with normal diet and sun exposure, but can occur with uncontrolled intake of high-dose supplements.

Vitamin D Through Diet

Only a few foods contain significant amounts of vitamin D. The best sources are fatty fish such as salmon, herring, and mackerel, fish liver oil, egg yolk, liver, and certain mushrooms like button mushrooms that have been exposed to UV light. Foods fortified with vitamin D such as margarine or dairy products can be helpful as a supplement. However, the requirement can hardly be met through diet alone.

Vitamin D Through Sunlight

The most effective method of vitamin D supply is self-production through sunlight. During the summer months, 15 to 25 minutes of sun exposure to the face, hands, and forearms – without sunscreen – is sufficient. The correct UV index is important, which in Germany is sufficiently high between April and September. Sunscreen with a sun protection factor of 15 already reduces vitamin D production by about 99 percent. Nevertheless, sunburn should be avoided at all costs.

Prevention of Vitamin D Deficiency

Use the summer months to replenish your vitamin D stores. Spend time outdoors daily and pay attention to a vitamin D-rich diet. During the winter months, targeted supplementation can be worthwhile, especially if you belong to a risk group. Have your vitamin D levels checked regularly, especially if symptoms occur. Information on local counseling services can be found through your health department.

Frequently Asked Questions

What symptoms indicate vitamin D deficiency?: Common symptoms include persistent fatigue and exhaustion, depressive moods, frequent infections, muscle and bone pain, and delayed wound healing. However, these symptoms are nonspecific; only a blood test (25-OH-vitamin D) can reliably detect a deficiency.
How much vitamin D do I need daily?: The German Society for Nutrition (DGE) recommends 800 IU (20 µg) daily for adults when adequate sun exposure is not possible. For infants, 400 IU applies. With confirmed deficiency, significantly higher doses (e.g., 2000–4000 IU) can be prescribed under medical supervision.
Can I get vitamin D without sun through diet?: Only to a limited extent. Good sources include fatty fish (salmon, herring, mackerel), egg yolk, liver, and vitamin D-fortified foods. The requirement can hardly be met through diet alone; approximately 80–90 % of vitamin D is produced by the skin itself through sun exposure.
Can you take too much vitamin D?: Yes. Hypervitaminosis D is possible with very high supplementation and manifests through nausea, vomiting, calcium deposits in organs, and kidney stones. Overdosing is not possible through diet and normal sunlight; with high-dose supplements, serum levels should be monitored.
When should I take vitamin D supplements?: Supplementation is advisable with confirmed deficiency (< 30 nmol/l in blood), during winter months (October–March), for people over 65, people with dark skin, those with little outdoor time, and people with fat absorption disorders. Discuss dosage with your doctor.

Note: This article is for information purposes only and does not replace medical advice.