How much vitamin D do you need and what affects its level in the body?

Do you know what the right dose of vitamin D is for you? Recommendations for use may vary depending on several factors, including genetics, age, skin color, general health, medications used, but also the area where you live.  In this article, we will take a closer look at some of the variables that affect the resulting concentration of vitamin D in the body, making it easier for you to imagine how much vitamin D you need.

What will you learn in this article?:

1. The vitamin D deficiency pandemic
2. “Sunshine vitamin” and its effect on our health
3. What all affects the value of vitamin D?
4. How to find out if you have a vitamin D deficiency?
5. What is the ideal vitamin D status?
6. How much vitamin D to supplement?
7. Conclusion

The vitamin D deficiency pandemic

Vitamin D deficiency is very widespread worldwide, and also in the European population, the deficiency manifests itself to an alarming degree. A large-scale analysis of 14 European population-based studies from 2016 revealed that more than 40% of Europeans are vitamin D deficient (serum 25(OH) vitamin D values ​​below 50 nmol/l) and 13% of Europeans are severely deficient (values 25(OH) of vitamin D are lower than 30 nmol/l) [1]

In 2018, the State Institute of Health (SZÚ) published an analysis including 398 blood serum samples, which examined not only the body’s supply of vitamin D (by measuring the metabolite 25(OH)D in blood serum). The results of this analysis revealed that 68% of the population had insufficient values ​​(25(OH)D level below 75 nmol/l), while only 32% of people had a normal supply of vitamin D (values ​​above 75 nmol/l). The lowest levels were logically measured in the winter months, specifically in March. [2]

“Sunshine vitamin” and its effect on our health

Vitamin D plays a key role in maintaining our health . This so-called ” sunshine vitamin ” affects cell proliferation and differentiation, thereby supporting optimal cell function throughout the body, supporting the immune system and, last but not least, maintaining healthy bones and teeth through the regulation of calcium metabolism.

On the contrary, its deficiency is associated with an increased risk of developing a number of diseases , including respiratory infections, cardiovascular diseases, osteoporosis, neuro-psychiatric disorders or autoimmune diseases (such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, psoriasis and others). . [3] [4]

What all affects the value of vitamin D?

As already mentioned, many factors affect the level of vitamin D in the body. Recommendations for use may thus vary depending on these variables.

• Genetics

Genes affecting vitamin D metabolism also affect the resulting serum vitamin D levels. Genetic variants affect how much vitamin D we need . The same dose of vitamin D will thus lead to a different response in each individual.

• Age 

Elderly people have a reduced capacity of the skin to synthesize vitamin D. A recent study from 2020 [5] calculated that vitamin D production in the skin decreases by 13% for each decade of life from age 25 . Older people also spend more time indoors and less exposure to sunlight, which is the most important source of vitamin D.

• Skin color

People with darker skin are more prone to vitamin D deficiency , which is due to the greater amount of melanin in their skin. Melanin is the pigment that determines the color of the skin and protects the skin from the sun’s UV radiation. For these individuals, a longer period of exposure to sunlight is needed for sufficient synthesis of vitamin D.

• Weight

Body weight is another variable affecting the need for vitamin D. In general, a higher proportion of body fat is associated with lower vitamin D values . Thus, obese people may need a higher intake of vitamin D to achieve similar levels of 25(OH)D as people of normal weight. [6]

Overweight and obese people are generally more at risk of common diseases, so vitamin D dosage should also depend on BMI, so that these individuals achieve the necessary amount of vitamin D to support health. [7] The Endocrine Society recommends that the dose of vitamin D be increased 2-3x in obese patients.

• Latitude of residence

Countries near the equator have enough sunlight all year round. On the contrary, people living further from the equator have less sunlight, which also contributes to lower levels of vitamin D in the body. In our geographical conditions, it is important to take care of sufficient intake of vitamin D through quality supplementation, especially during the winter months .

• Certain health problems

Vitamin D is a fat-soluble vitamin, and the ability of the intestines to absorb fats from the diet is important for its absorption . Fat malabsorption is associated with health problems, including some forms of liver disease, cystic fibrosis, celiac disease, Crohn’s disease or ulcerative colitis. Inflammatory bowel disease also contributes to vitamin D deficiency.

• Pregnancy, Lactating Women & Infants

The content of vitamin D in breast milk is closely related to the mother’s vitamin D status . Thus, the consumption of breast milk alone may not be sufficient to cover the need for vitamin D in breastfed children.  A study investigating maternal vitamin D status and its effect on the vitamin D content of breast milk concluded that vitamin D deficiency is widespread during pregnancy and lactation and may increase the likelihood of vitamin D deficiency in breastfed infants who do not receive sufficient sunlight exposure and vitamin D in the form of supplements. [8]  Studies also suggest that the breast milk of mothers who take supplements containing at least 2,000 IU of vitamin D3 daily has higher levels of this vitamin.

It is proven that vitamin D supplementation during pregnancy helps reduce the risk of preeclampsia by 60%, the occurrence of gestational diabetes by 50% and premature birth by 40% . Prenatal screening of 25(OH)D levels to detect women suffering from vitamin D deficiency and follow-up measures may thus represent an effective way to reduce these pregnancy risks. [9]

• Magnesium

It should also be mentioned that various steps in the metabolism of vitamin D depend, for example, on magnesium as a cofactor. In the case of magnesium deficiency, the activation of vitamin D is reduced . The combined effects of magnesium and vitamin D deficiency can lead to higher health risks, such as bone fractures.

In conclusion, we can say that there are certain groups of people who need more vitamin D than others . These include, for example, the elderly, people with dark skin, obese individuals, people who avoid the sun in summer, people living further from the equator and, last but not least, those who suffer from certain health problems such as liver or kidney disease, malabsorption syndromes and inflammatory bowel disease.

How to find out if you have a vitamin D deficiency?

Blood testing for 25-hydroxyvitamin D, or 25(OH)D, is generally considered the best indicator of vitamin D status in the body. In domestic laboratories, the normal range for 25(OH)D ranges from 75 nmol/l – 250 nmol/l. Levels below 75 nmol/L are considered insufficient and levels below 50 nmol/L indicate severe vitamin D deficiency.

At Trim, we now offer the opportunity to try a simple quiz , which, by answering a few questions, will help you detect a possible vitamin D deficiency.

What is the ideal vitamin D status?

International guidelines differ in their recommendations for adequate vitamin D status, and unfortunately there is currently no consensus on what concentrations of circulating 25(OH)D are optimal for health.  In an extensive study focusing on the immunological effects of vitamin D, the authors concluded that although the optimal level of vitamin D remains unclear, maintaining a serum 25(OH)D level between 100 and 150 nmol/L is healthy . [10]

Jakub Přibyl, author of Trime recipes and long-time consultant for personalized nutrition, agrees with this.  “The reference limits for 25-hydroxyvitamin D differ between individual laboratories, so a number of people with a mild 25(OH)D deficiency can be classified by a doctor as satisfactory, yet according to the latest criteria, it is already a deficiency state. Similarly, there are recommendations from various professional societies and health organizations regarding vitamin D supplementation. The range for the reference intake of vitamin D from diet or supplementation is between 400-5,000 IU/day. From my own practice, I consider the optimal values ​​of 25(OH)D measured in the serum to be between 100 nmol/l – 150 nmol/l, which few people achieve in domestic conditions without supplementation. That’s why I find it useful to know your 25(OH)D level measured at least twice a year. E.g. at the beginning of the “sunny” season at the turn of April/May, and then sometime during November, when the “summer” vitamin D supply will be depleted. In this way, everyone can get a better idea of ​​how the metabolism of vitamin D is in reality and whether or not the intake from food and the sun is enough for them,”   says Jakub Přibyl.

How much vitamin D to supplement?

The current recommendations of the European Food Safety Authority (EFSA) state that the preventive daily dose of vitamin D for adults is 600 IU per day. [11] This recommended dose may be sufficient to prevent rickets. However, vitamin D is also important in other areas of health and immunity, so many experts agree that this dose is insufficient and it would be appropriate to reconsider the current recommendation .

Even in the area of ​​a safe upper limit for vitamin D supplementation , there is no consensus between individual organizations. While the Endocrine Society states an upper daily limit for adults of 10,000 IU, EFSA recommends not exceeding 4,000 IU/day. [12] [13]

The table below shows the recommended daily values ​​and upper limit of intake for vitamin D depending on age (as recommended by the Endocrine Society). [4]  These recommendations apply to individuals at risk of vitamin D deficiency.

Conclusion

Getting enough vitamin D is key to maintaining our overall health, yet most of our population is deficient . Appropriate recommendations for vitamin D intake depend on individual health status, body weight, geographical latitude of our residence, or dietary and cultural habits . In our geographical conditions, exposure to sunlight and intake of vitamin D from food alone are insufficient to maintain the desired concentration of vitamin D throughout the year. For this reason, supplementation is often necessary to achieve an optimal vitamin D status . Side effects related to vitamin D use, such as hypercalcemia, are rare and usually result from long-term use of extremely high doses, exceeding tens of thousands of IU per day.