Vitamin DVitamins and Minerals

Vitamin D deficiency: symptoms and treatment

Written by

Lauren Dobischok
5 June, 2022

Medically checked article All HOMED-IQ content is reviewed by medical specialists

Vitamin D plays a crucial role in our health and a deficiency of this essential vitamin can manifest itself through symptoms such as constant fatigue, mood swings or feeling constantly “run down”. An estimated 40% of the European population suffers from a vitamin D deficiency. Do you often feel tired or irritable lately? Then it could be that you are also one of the many people affected by a vitamin D deficiency. Read on if you would like to learn more.

What is vitamin D?

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.


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Felchner, C. & Feichter, M. (2022, May 31). Vitamin D. NetDoctor. Retrieved on June 2, 2022, from (2020, December 17). Vitamin D deficiency: cause, symptoms, treatment. Retrieved on June 2, 2022, from

Warneck, L. (2017, December 14). Why vitamin D is so important! DW.COM. Retrieved June 2, 2022, from

About the author

Lauren Dobischok

Lauren is a health scientist and science communicator currently living in the Netherlands. Originally from Canada, she completed a Research Master’s in Health Sciences at the Netherlands Institute of Health Sciences at Erasmus University Rotterdam (NIHES) with a specialisation in epidemiology. Prior to her master’s degree, she completed a Bachelor’s degree in Health Sciences at Simon Fraser University. With a background in public health, her goal is to create accurate scientific content that is easy to understand and empowers people to make informed decisions. Within Homed-IQ, Lauren works as a Product Developer and Content Lead, working closely with physicians and scientists on medical devices for Homed-IQ’s new products and written communications.