June 5, 2022

Vitamin D deficiency: symptoms and treatment

All HOMED-IQ content is reviewed by medical specialists

Have you been feeling drained, suffering from mood swings, or are you tired all day? You may be suffering from a vitamin D deficiency. In countries without high amounts of sunshine, Vitamin D deficiency is very common- in fact, around 40% of the European population suffers from a vitamin D deficiency. Thankfully, a lack of vitamin D is not life-threatening and can be treated relatively quickly. In this article, we will explain exactly what a vitamin D deficiency is and how it can affect our bodies.

Although vitamin D deficiency can be easily treated, you should be careful when taking vitamin D supplements. Taking too many supplements can lead to what is known as vitamin D toxicity. Have you not heard of vitamin D toxicity? Then we recommend you read our article “How much vitamin D is too much?” to learn more!

What is vitamin D?

You’re probably wondering why we need vitamin D for good health. To understand why, we must first clarify what exactly vitamin D is. Contrary to what the name suggests, Vitamin D is not a single vitamin, but rather a collective term for a group of fat-soluble vitamins, which are particularly important for the calcium balance and the mineralization of our bones.

Vitamin D can be obtained by the human body through food or produced with the help of sunlight. This is exactly where vitamin D differs from other vitamins – strictly speaking, vitamin D is not a real vitamin. This is because by definition, vitamins are essential organic compounds that have to be ingested from food because the body cannot produce them or cannot produce adequate quantities.

The main function of vitamin D is the formation and maturation of bone stem cells. Vitamin D is also responsible for calcium absorption in the intestine.

What is a vitamin D deficiency?

Vitamin D deficiency occurs when the body has less vitamin D than it needs. There can be various reasons for this. Since the body’s production of vitamin D with the help of sunlight is responsible for over 80% of the vitamin D in the body, a “sunlight deficiency” is usually the main cause. This usually occurs in people that do not live in a sunny climate, stay indoors often, or have darker skin. However, poor nutrition or illnesses can also cause a vitamin D deficiency.

What is my vitamin D daily requirement?

As with other nutrients, your daily requirement for the vitamin depends on your age. Thus, seniors need twice as much vitamin D as newborns. The recommended daily intake of vitamin D is measured in micrograms (µg).

AgeRecommended amount
Newborns (0 – 12 months)10 µg
Children (1 – 13 years)15 µg
Youth (14 – 18 years)15 µg
Adults (19 – 70 years)15 µg
Seniors (71 years and older)20 µg

Would you like to know your vitamin D level? Then Homed-IQ’s vitamin D test could be of interest to you!

Why is vitamin D so important?

Vitamin D is essential for our daily well-being because it is involved in important processes in the body. Vitamin D strengthens the immune system, supports the muscles, and strengthens the bones. We obtain the majority of our daily vitamin D requirement through our own production when we expose ourselves to the sun’s rays. However, during winter in the northern hemisphere there are few hours of sunlight, which leads to a vitamin D deficiency in many people during the cold season. This deficit cannot be compensated for with a vitamin D-rich diet alone. It is therefore advisable to meet your vitamin D requirements with vitamin D supplements in the months with little sunshine in order to prevent vitamin D deficiency.

What are vitamin D deficiency symptoms?

Vitamin D deficiency manifests itself in a number of ways. Symptoms usually appear when the deficiency has existed for a considerable period of time. If this is the case, the following symptoms usually become noticeable:

  • Muscle weakness
  • Fatigue
  • Bone pain
  • Osteoporosis or broken bones
  • Softening of the back of the head

Note: The symptoms mentioned refer to a long-lasting vitamin D deficiency, and bone damage occurs in only severe cases.

What are the causes of vitamin D deficiency?

As already mentioned at the beginning, there are different reasons for a vitamin D deficiency. Basically, the causes can be divided into three categories – lack of sunlight, poor nutrition, or certain diseases.

People who rarely go out in the sun run a higher risk of vitamin D deficiency than people who spend more time outside. This applies in particular to people who are in institutional care, are older, or people who cover their body, face, or hair outdoors for religious or cultural reasons.

Certain diseases can also be a reason for a vitamin D deficiency. These include rheumatoid arthritis, chronic inflammatory bowel disease, and osteoporosis.

A diet low in vitamin D can also lead to the development of a vitamin D deficiency. Foods rich in vitamin D include products such as fatty fish, organ meats such as kidneys and liver, eggs, porcini mushrooms, and foods fortified with vitamin D such as milk or orange juice.

How can you fix a vitamin D deficiency?

The easiest way to remedy a vitamin D deficiency is to do three things – spend more time outdoors, adopt a balanced and healthy diet and, in certain cases, take vitamin D supplements.

The easiest and most effective way to replenish your vitamin D stores is to take a daily walk outside. How long this walk should be depends on the time of year. As already mentioned, vitamin D supplements are recommended during the winter months. In spring and autumn, on the other hand, 10 – 20 minutes in the sun is enough to meet the daily vitamin D requirement. In summer, 5 – 10 minutes are enough..

Note: Even if a visit to a tanning bed exposes the body to UV radiation, this is not a suitable alternative to going outside for a walk and does not provide adequate vitamin D.

Another way to support vitamin D levels is a balanced diet. While animal products are the highest in vitamin D, people who follow a plant based diet may benefit from drinking plant milks or juices fortified with vitamin D. 

If your vitamin D level is so low that even going for a walk or a balanced diet does not reverse the deficiency, vitamin D supplements are the best and safest way to bring vitamin D levels back to a normal level. However, follow the dosage instructions on the bottle and consider consulting your family doctor beforehand to avoid potential vitamin D toxicity.


Cleveland Professional. (2019, October 16). Vitamin D Deficiency: Symptoms & Treatment. Cleveland Clinic. Retrieved June 2, 2022, from https://my.clevelandclinic.org/health/articles/15050-vitamin-d–vitamin-d-deficiency

Felchner, C. & Feichter, M. (2019, October 3). Vitamin D deficiency. NetDoctor. Retrieved on June 2, 2022, from https://www.netdoktor.de/laborwerte/vitamin-d/lack/

Felchner, C. & Feichter, M. (2022, May 31). Vitamin D. NetDoctor. Retrieved on June 2, 2022, from https://www.netdoktor.de/laborwerte/vitamin-d/

healthy.bund.de. (2020, December 17). Vitamin D deficiency: cause, symptoms, treatment. Retrieved on June 2, 2022, from https://gesund.bund.de/vitamin-d-lack#prevention

Warneck, L. (2017, December 14). Why vitamin D is so important! DW.COM. Retrieved June 2, 2022, from https://www.dw.com/de/warum-vitamin-d-so-important-ist/a-41792161

About the author

Lauren Dobischok

Lauren is a health scientist and science communicator living in the Netherlands. With a background in epidemiology, her goal is to create accurate scientific content that is easy to understand and empowers people to make informed decisions. Her favourite topics to discuss are public health, infectious diseases, and dispelling myths and misconceptions about health topics with research. Coming from Canada, Lauren prefers to spend her free time learning Dutch and exploring the interesting sights this small country has to offer!