Vitamin D deficiency symptoms in adults: the most important questions and answers

Vitamin D Mangel Symptome bei Erwachsenen: Die wichtigsten Fragen und Antworten

Have you ever wondered how the body absorbs vitamin D and what can happen in the body with a vitamin D deficiency? Is an acute vitamin D deficiency responsible for possible hair loss or even seriously dangerous? Are tiredness or frequent headaches caused by a vitamin D deficiency?

With this article we would like to give you clarity about the topic of vitamin D deficiency and possible symptoms by means of neutral reporting, and show you which measures you can take preventively or in an acute case to keep your vitamin D level at a healthy level or rebuild.

the essentials in brief

  • Vitamin D is a group of different fat-soluble vitamins that are related to the regulation of calcium balance and bone mineralization (calciferols).
  • Vitamin D deficiency can be detected by a doctor during a routine examination and regulated accordingly. However, various lighter or more serious symptoms can also indicate that there is an acute vitamin D deficiency in your body.
  • As a preventive measure, you should know how the body can absorb vitamin D and how you can influence the natural intake in everyday life.

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Vitamin D deficiency in adults: What you should know about the causes and symptoms

Below we have researched the most important questions regarding possible causes and symptoms of a vitamin D deficiency in order to be able to give you a compact and informative overview.

Where can vitamin D deficiency come from?

Vitamin D deficiency (vitamin D3 deficiency) is becoming more common and is most common in people who spend a lot of time indoors without sunlight and little outdoors.(1)

The body covers the greatest need for vitamin D with the help of sunlight through its own production.(2) However, if the skin cannot absorb sufficient UV rays, the necessary vitamin D must be supplied more through food or through dietary supplements.

Woman is standing in a meadow

Sunlight is the most important natural source of vitamin D for the human body. (Image source: Alexander Shustov / Unsplash)

A vitamin D deficiency can often be the result of a lifestyle that takes place too much indoors than outdoors in the fresh air, coupled with the low vitamin D occurrence in food.

Other causes of a low vitamin D level can also be illnesses, the use of certain medications or the increased excretion of vitamin D through the kidneys (kidney failure).

Is there an optimal vitamin D level in the body?

According to the most frequently represented expert opinion in recent times, values ​​in the range between 40 and 80 ng/ml would be optimal. Bone experts demand that the vitamin D level in the blood should be at least 30 ng/ml, especially in people over the age of 60.

Many labs classify levels below 20 ng/mL as mild vitamin D deficiency and levels below 12 ng/mL as severe vitamin D deficiency.

Can vitamin D deficiency be dangerous for the body?

Vitamin D deficiency can only become really dangerous when it falls below 12.5 nanomoles per liter. Then we speak of a severe deficiency which can lead to osteoporosis, osteomalacia (softening of the bones) and rickets in adults.

This is because vitamin D is involved in bone health, among other things, by maintaining physiological levels of calcium in the blood.(3)

Symptoms such as tiredness, headaches or hair loss are not directly dangerous but should be taken seriously.

These can also be attributed to a too low vitamin D value. We will go into more detail about this below in order to give you a comprehensive overview.

Does Vitamin D Deficiency Cause Headaches?

Vitamin D is believed to play a role in various neurological disorders. Too little vitamin D could also cause increased headaches or migraines.

Various studies on the connection between vitamin D deficiency and headaches have already indicated that there are possible connections. However, this has not yet been scientifically proven.(4)

Are depression and fatigue due to a vitamin D deficiency?

The studies available to date show that the risk of depression decreases significantly from a blood level of 30 ng/ml.

Vitamin D plays an important role in the regulation of the brain messenger substance serotonin and influences the utilization of dopamine and the synthesis of noradrenaline.

All of these messengers have an impact on mood and mental health.

Furthermore, vitamin D has various protective functions for the nerve cells. People with depression are more likely to have low (below 30 ng/ml) vitamin D levels. So there may be a connection here. A vitamin D cure is therefore often recommended in depression treatments.(5)

Woman sits on the edge of the window

Depression is an increasingly common disease in society. Therefore, the vitamin D level should be checked and increased if there is a deficiency. (Image source: Free-Photos / pixabay)

In the case of persistent fatigue, the vitamin D balance usually plays a role. It has been scientifically proven that persistently tired people had a low vitamin D value and that the tiredness could return to a normal state after concentrated treatment with vitamin D preparations.(6)

Is Vitamin D Deficiency Linked to Hair Loss?

Hair loss can have many causes. Hair loss can also be promoted by a vitamin D deficiency, which may cause a disruption in the hair growth process. However, the connection has not yet been scientifically proven, but studies show that the severity of hair loss can correlate with the severity of the vitamin D deficiency. (7)

Research on animals has also found that better results can be achieved in a hair transplant with prior vitamin D value treatment.(8)

Can Vitamin D Deficiency Lead to Weight Gain?

Being overweight can be linked to a vitamin D deficiency. Support for diets with vitamin D preparations has also been examined in various studies. Here it was shown that the weight loss in people who treated their vitamin D household parallel to the diet progressed faster. However, the connection has not yet been fully scientifically proven.

img src="" alt="Woman weighing herself">

A large increase in body weight can possibly be caused by an acute vitamin D deficiency. (Image Source: I Yunami / Unsplash)

Scientists assume that vitamin D receptors, which are located on the fat cells, tell the cell whether they should store the fat or burn it as energy. If there is a vitamin D deficiency, this function could be less active.

Vitamin D receptors are also found on the brain cells that control satiety, hunger and metabolism. Thus, a vitamin D deficiency could negatively affect the feeling of satiety.(9,10)

Which skin symptoms indicate a vitamin D deficiency?

The vitamin D deficiency in skin diseases such as acne, psoriasis and neurodermatitis has been intensively researched. People with these clinical pictures often also have a lower vitamin D level. In the following we would like to clearly illustrate the three skin symptoms and the corresponding effect of vitamin D.

skin symptom clinical picture Function of vitamin D
acne Malfunction of the sebaceous glands, which are responsible for moisturizing the skin. When these glands become blocked, bacterial growth leads to the well-known symptoms of acne acts as a steroid hormone and regulates many other hormones, relieves skin inflammation, fights off bacteria better, supports the regulation of the sebaceous glands
Psoriasis (psoriasis) Triggered by an autoimmune reaction. The body attacks its own skin cells, which leads to excessive skin formation, cornification and inflammation of the skin Has a strong anti-inflammatory effect and can counteract exactly this defense reaction of the body
neurodermatitis Defects in the skin barrier and defense reaction in which inflammatory messenger substances (cytokines) are released Helps regulate cytokines by reducing the inflammatory response

Doctors often recommend successful UV radiation therapies for the treatment of these diseases. In certain cases, the intake of cortisone could even be reduced in patients who tolerated the vitamin D therapy well.

What treatments are there to remedy or avoid a vitamin D deficiency?

In the following we would like to show you the various ways in which your body can absorb vitamin D in order to maintain the best possible vitamin D value and how you can possibly achieve positive effects with certain clinical pictures or symptoms by building up your vitamin D household in a concentrated manner.


80 to 90% of the fat-soluble vitamin D is synthesized in the skin through exposure to sunlight (UV-B). Sunlight is considered the most important vitamin D producer in the body and it is therefore of great health importance to exercise outdoors whenever possible.

However, you should keep in mind to apply the necessary sun protection to the skin, because too much UV radiation can also be harmful.

Do your bones a favor

  • Our vitamin D3 helps to strengthen
    of bones, teeth, muscles and joints at 💪
  • It's also vegan 🌿
  • Get an automatic 21% discount when you buy now 💸*

Sunt Icon

*The discount is automatically applied to the product


With the appropriate diet, 10 to 20% of the total requirement can be ingested as D3 (cholecalciferol) or D2 (ergocalciferol). This is therefore a rather insignificant part of covering the vitamin D household, but should not be neglected.

It is primarily fish and sea creatures, eggs and fats that have a relatively high vitamin D content. But other foods such as meat and fruit also make a small contribution to the vitamin D balance.

dietary supplements

If the body cannot get enough vitamin D from sunlight and food, it is possible to take vitamin D from vitamin D supplements. These preparations are usually available in capsule form.

However, since concentrated vitamin D is released into the body in this way, it is advisable in any case to first obtain a doctor's recommendation. In this way, a possible overdose can be avoided and the preparation can be used sensibly.

Vitamin D syringe

In certain cases, vitamin D cannot be absorbed by taking supplements through the digestive tract. Here, the vitamin D injection for concentrated intake is a possible alternative.

However, vitamin D injections should only be used and checked by a doctor to avoid overdosing. Normally, an injection is given here once a year.

Vitamin D cure

A vitamin D cure makes sense as an initial therapy for acute undersupply of vitamin D. In such cases, the high-dose supply offers advantages compared to long-term supplementation with smaller doses.

A vitamin D deficiency can put a significant strain on the body and pose a serious health risk. This should be fixed as soon as possible. Here, too, it is essential to discuss the therapy with a doctor in advance and to tailor it accordingly.

If a vitamin D deficiency is determined, there are various ways of remedying this, depending on the intensity of the deficiency, and bringing it back to a target value.


The vitamin D balance is therefore an important health issue, which should be considered seriously, especially with increasing age. Irrespective of the corresponding symptoms, which can indicate a deficiency, it is advisable to have the vitamin D level tested during routine medical examinations and to correct this if necessary.

From a scientific point of view, the individual connections between vitamin D deficiency and the corresponding clinical pictures cannot yet be proven in detail, but a stable vitamin D level in the body can contribute to general well-being and health and can possibly prevent the onset of various diseases.


  1. Authors: Michael F Holick The Vitamin D Deficiency Pandemic and Implications for Non-Skeletal Health: Mechanisms of Action
  2. Authors: Matthias Wacker, Michael F. Holick Sunlight and Vitamin D A Global Perspective on Health
  3. Authors: Omeed Sizar, Swapnil Khare, Amandeep Goyal, Pankaj Bansal, Amy Givler Vitamin D deficiency in alopecia areata
  4. Authors: Jyrki K. Virtanen, Rashid Giniatullin, Pekka Mäntyselkä, Sari Voutilainen, Tarja Nurmi, Jaakko Mursu, Jussi Kauhanen, Tomi-Pekka Tuomainen Low serum 25-hydroxyvitamin D is associated with a higher risk of frequent headaches in middle-aged and elderly men connected to men
  5. Authors: Sue Penckofer, Joanne Kouba, Mary Byrn, Carol Estwing Ferrans
  6. Authors: Albina Nowak, MD, Lukas Boesch, Erik Andres, Edouard Battegay, Thorsten Hornemann, Christoph Schmid, Heike A. Bischoff-Ferrari, Paolo M. Suter, Pierre-Alexandre Krayenbuehl Effect of vitamin D3 on self-perceived fatigue A double-blind, randomized, placebo-controlled study
  7. Authors: Aksu Cerman, Sarikaya Solak, Kivanc Altunay Vitamin D Deficiency in Alopecia Areat
  8. Authors: Noriyuki Aoi, Keita Inoue, Toshihiro Chikanishi, Ryoji Fujiki, Hanako Yamamoto, Harunosuke Kato, Hitomi Eto, Kentaro Doi, Satoshi Itami, Shigeaki Kato, Kotaro Yoshimura 1α,25-dihydroxyvitamin D3 modulates the hair-inductive capacity of dermal papilla cells: therapeutic potential for the hair regeneration
  9. Authors: Caitlin Mason, Liren Xiao, Ikuyo Imayama, Catherine Duggan, Ching-Yun Wang, Larissa Korde, Anne McTiernan Vitamin D3 supplementation during weight loss: a double-blind, randomized, controlled trial
  10. Authors: Zujaja-Tul-Noor Hamid Mehmood, Dimitrios Papandreou An updated brief review of vitamin D and obesity: adipogenesis and the inflammatory state
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