Vitamin D Deficiency: Risks, Symptoms, and Effective Supplementation Strategies

We all know that vitamin D deficiency in children leads to malformations known as rickets, while in adults, it disrupts bone composition (causing osteoporosis, osteopenia) and increases the risk of fractures. However, vitamin D deficiency is also associated with autoimmune diseases (such as multiple sclerosis), osteoporosis, heart disease, infertility, miscarriages, mental health issues (particularly depression), obesity, diabetes, reduced mental performance, weakened immune system, and various types of cancer. Currently, it is most talked about in relation to the COVID-19 virus. Some scientific studies suggest that adequate vitamin D levels could reduce the risk of infection and severity of COVID-19.



What is Vitamin D and Why Do We Need It?

Vitamins are small organic molecules that are essential for proper metabolism and the production of substances necessary for life. Vitamin D, in fact, refers to five substances with similar structure and effects. The most well-known representatives are vitamins D2 (ergocalciferol) and D3 (cholecalciferol). Studies suggest that vitamin D3 is slightly more potent than D2.

In the human body, "D" is synthesized through the action of UVB rays from sunlight on the skin. To function properly, it must be converted by the kidneys and liver (with the help of the immune system) into its active form, called calcitriol. Vitamin D plays a role in regulating various bodily processes, primarily the absorption of calcium and other minerals in the small intestine and kidneys. In this way, vitamin D helps maintain the strength of bones and teeth.

It is also important for the proper functioning of:

  • Muscles and nerves
  • Thyroid gland
  • Immune system (reduces inflammation)
  • Cellular division

Tip: In another article, you can learn about 5 tips to boost your immune system.

Symptoms of Vitamin D Deficiency

Up to 40% of Europeans suffer from a deficiency of vitamin D, mainly due to inadequate sunlight exposure and imbalanced diet. People with inflammatory bowel diseases such as Crohn's disease or ulcerative colitis also struggle with low levels of vitamin D due to poor absorption in the inflamed intestines. Obese individuals (for unclear reasons) are also a high-risk group. The most common symptoms of deficiency include:

  • Hair loss
  • Breathing difficulties
  • Depression
  • High blood pressure
  • Slow wound healing
  • Muscle and bone pain
  • Increased tooth decay
  • Increased risk of osteomalacia, osteoporosis, and bone fractures (due to lack of bone-building components)
  • Development of rickets in children

Vitamin D Deficiency in Infants and Children

Vitamin D deficiency poses a significant danger, especially for infants, toddlers, and young children. It leads to rickets, which is characterized by bone softening, bending, and deformation.

Rickets due to vitamin D deficiency most commonly manifests between the ages of 3 and 18 months. Symptoms of the disease include a flattened forehead, bending of the long bones of the lower extremities, and deformation of the spine and pelvis. Children with rickets also suffer from frequent muscle cramps and are more susceptible to fractures.

Vitamin D is also essential for proper development of the nervous system in childhood. Deficiency of vitamin D in pregnant women is associated with an increased incidence of hyperactivity and autism in their offspring. Infants can also experience a deficiency of vitamin D during breastfeeding. Therefore, many pregnant and lactating women take preventive vitamin D supplements.

Tip: Read an article about vitamin C and its proven effects on the skin.


Recommended Daily Intake of Vitamin D

The recommended daily dose of vitamin D is typically indicated in micrograms (μg) and international units (IU), where 1 μg is equivalent to 40 IU. The ideal daily amount for a healthy individual varies not only by age and health status but also by the organization providing the recommendations.

According to the European Food Safety Authority (EFSA), the recommended daily doses of vitamin D are as follows:

  • Infants (up to 12 months) - 10 μg (400 IU)
  • Children (1 to 10 years) - 15 μg (600 IU)
  • Adolescents (11 to 17 years) - 15 μg (600 IU)
  • Adults (18 to 75 years, including pregnant and lactating women) - 15 μg (600 IU)
  • Seniors (over 75 years) - 15 μg (600 IU), although other organizations recommend 20 μg (800 IU).

Several studies suggest that obese individuals and postmenopausal women should receive an increased amount of vitamin D. The necessary dosage should always be determined by a physician - never increase it on your own! The maximum safe dose for infants and children is 25-75 μg (1,000-3,000 IU), and for adults, it is 100 μg (4,000 IU).

Tip: Overdosing on vitamin D (hypervitaminosis) leads to increased calcium intake and deposition in internal organs. This can result in nausea, vomiting, weight loss, and kidney stones. In extreme cases, it can cause kidney damage.

Tip: Read about solar eczema in another article.

How to Supplement Vitamin D: Best Dietary Supplements

Vitamin D is available in the form of dietary supplements, such as fast-dissolving tablets. Their use is particularly suitable during the winter months when we spend the majority of our time indoors.

Preventively, vitamin D can also be taken by pregnant and lactating mothers, as well as by overweight individuals and seniors. A 2014 study even found a connection between vitamin D supplementation and reduced mortality among older people. However, these findings should be taken with caution.

In addition to standalone vitamin D preparations, you can find complex products on the market, such as Immunity Complex, which contains vitamin D, vitamin C, and zinc.

Natural Sources of Vitamin D

Considering the information above, longer exposure to sunlight may seem like a logical step, but experts issue a warning. The Skin Care Organization recommends targeted sun exposure no more than three times a week for about 15 minutes. Prolonged sunbathing does not lead to further vitamin D production; on the contrary, it increases the risk of skin cancer. Therefore, it is essential to protect your skin with sunscreen.

Naturally, vitamin D is found in high quantities in cod liver oil (1 teaspoon contains 450 IU of vitamin D) and in the flesh of salmon (5.2 IU/g) and cod (4.6 IU/g). To increase vitamin D content in the human body, it is artificially added to milk and dairy products, cereals, flour, and infant formula.


Key Takeaways from the Article

Vitamin D plays a role in calcium and mineral absorption, ensuring the strength of bones and teeth. It is also important for the proper functioning of muscles, the nervous system, the immune system, and thyroid hormones.

About 40% of the European population suffers from vitamin D deficiency. High-risk groups include breastfeeding and pregnant women.


What is Vitamin D?

Vitamin D is a fat-soluble vitamin that is naturally present in a few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis.

Why is Vitamin D important?

Vitamin D is important for maintaining healthy bones and teeth, and it may also protect against a range of conditions such as cancer, type 1 diabetes, and multiple sclerosis. It plays a significant role in the regulation of calcium and maintenance of phosphorus levels in the blood, two factors that are extremely important for maintaining healthy bones.

What are the sources of Vitamin D?

Vitamin D can be obtained from sunlight exposure, foods, and supplements. Food sources include fatty fish like salmon and mackerel, fish liver oils, and egg yolks. In the U.S., it's also commonly fortified in foods like milk and cereal.

What are the symptoms of Vitamin D deficiency?

Vitamin D deficiency may not always cause symptoms, but when they do occur, they can include fatigue, bone pain, muscle weakness, mood changes like depression, and impaired wound healing.

How is Vitamin D deficiency diagnosed?

Vitamin D deficiency is typically diagnosed with a blood test. If your doctor suspects a deficiency, they will likely order a 25-hydroxy vitamin D blood test to measure the amount of the vitamin in your blood.

How is Vitamin D deficiency treated?

Vitamin D deficiency is usually treated with oral vitamin D supplements. In addition, it's often recommended to increase exposure to sunlight and consumption of foods rich in vitamin D. However, the exact dose depends on the person's age, overall health, diet, and amount of sun exposure, and should be determined by a healthcare provider.

Can you have too much Vitamin D?

Yes, it is possible to have too much vitamin D, a condition known as hypervitaminosis D. This usually happens from taking too many supplements. Symptoms of hypervitaminosis D include nausea, vomiting, weakness, and frequent urination. It can also lead to dangerous conditions like kidney stones or damage, irregular heartbeat, and bone loss.

Does Vitamin D affect immunity?

Yes, vitamin D is known to enhance the function of immune cells, including T-cells and macrophages, that are important for the defense against pathogens. Low levels of vitamin D have been associated with increased susceptibility to infection, disease, and immune-related disorders.

What is the recommended daily intake of Vitamin D?

The recommended daily intake of vitamin D varies depending on age, sex, and overall health. Generally, for adults ages# The assistant is missing the specific values of daily recommended intake of Vitamin D. # These values are updated by health organizations, therefore, it needs to be checked from the reliable sources. search("recommended daily intake of Vitamin D")18 to 70 years, it's generally 600 IU, and for those above 70 years, it's 800 IU. However, different health organizations might have slightly different recommendations.

Can Vitamin D help with COVID-19?

Recent research suggests that vitamin D may be beneficial in treating severe COVID-19. Studies have found an impaired vitamin D gene signature in CD4+ T cells of patients with severe COVID-19. Vitamin D alters the epigenetic landscape of CD4+ T cells, leading to the production of pro-resolving T_H1 cells that can help resolve severe COVID-19. However, further research is needed to fully understand the relationship between vitamin D and COVID-19.


About author Lukas Konecny

  • Since May 2020, Lukáš has played a pivotal role in nanoSPACE, driving the company's strategy and spearheading its development initiatives. His deep understanding of the industry, combined with his passion for innovation, makes him an indispensable asset in the world of dietary supplements.
Lukáš Konečný, Strategy and business development, nanoSPACE
Lukáš Konečný has been active in the nano field since 2015. He graduated from the University of Economics and Business and has long been involved in digital marketing, digitisation and automation of advertising for technology companies and online projects. At nanoSPACE, Lukáš has been in charge of strategy and business development since May 2020.