Vitamin D Function: Measure and Treatment
This article was last reviewed on 12 March 2020. This article was last modified on 10 February 2020.
Modern books on wellness management often mention Vitamin D. It is commonly called overall health hormone1. And it makes sense! Vitamin d function is to help prevent chronic diseases and affect people’s longevity in general. Meanwhile, vitamin D insufficiency affects almost 50% of the population worldwide. An estimated 1 billion people worldwide, across all ethnicities and age groups, have its deficiency. That is and why sustaining its optimum level is critically important for your health.
What is unique about vitamin D is that we don’t only get with food but can also produce it in our body by being exposed to sunlight. It plays a major role in keeping bones healthy, therefore it insufficiency can lead to child rickets, and adult malacosteon (bone softening) and osteoporosis (bone loss). But this vitamin’s role is not limited to this function.
Role of Vitamin D
Besides, it is vital for a healthy immune system4. Without sufficient its amount our immune cells cannot properly react to threats, making our body more vulnerable to infections. In addition, vitamin D affects both inborn and acquired immunity.
It’s worth mentioning that vitamin D has anti-cancer effect for various types of cancer5. Emerging research supports the possible role of it against cancer, fractures and falls, autoimmune diseases, influenza, type-2 diabetes, and depression. Many health care providers have increased their recommendations for vitamin D supplementation to at least 1000 IU6. A meta-analysis published in 2007 showed that this supplementation was associated with significantly reduced mortality.
By now we have received the evidence of an increased risk of prostate and endometrium cancer, esophageal, stomach and pancreatic cancer, bladder and renal cancer, Hodgkin’s disease and non-Hodgkins lymphoma caused by vitamin D deficit. It is remarkable that randomized double-blind examination shows significant 60% decrease in general oncological risk among postmenopausal women who were treated with vitamin D and calcium, as opposed to those who received placebo treatment during 4 years of observation7. The studies show the optimum 25 (OH)D in blood serum for cancer prevention to be 40-60 ng/mL (100-150 nmoles/L).
Chronic fatigue, low spirits may also be caused by vitamin D insufficiency. Besides, muscle weakness is considered a clear indicator of its clinical deficiency. Clinical symptoms of myopathy deficiency include proximal muscle weakness, diffusive muscle pains, and balance disorder. It also reduces age-related and general inflammations, which is critically important for cognitive function retention.
How to Measure Vitamin D Levels
Your vitamin D can be tested in a blood test which measures its content (25-OH vitamin D). 25(OH)D is the main metabolite of it in the blood. Two main forms of 25(OH)D are cholecalciferol (D3) and ergocalciferol (D2). D3 is mainly formed in our skin under ultra-violet rays, while the source of D2 is food. Significantly, 25(OH)D concentration is made up of these two components, both forms are measured equimolarly. 25(OH)D is considered the best indicator of vitamin D in the body.
Vitamin D, 25-Hydroxy, Total, Immunoassay
Test Code: 17306
Specimen Type: Blood
What if the level turns to below?
Sun Exposure as a Source of Vitamin D
Sun exposure is a good source of vitamin D. So, most people can receive enough vitamin D through daily sun exposure. It happens because sunlight enables our body to synthesize it from cholesterol. According to this recommendation, wearing a tank top and shorts for 10–30 minutes three times per week during the summer should be sufficient8. People with darker skin may need a bit longer than this.
At the same time, a Korean study did not confirm the effectiveness of this recommendation. For their experiment, they invited Korean adults aged 20–49 years with serum 25-hydroxyvitamin D (25[OH]D) levels of < 20 ng/mL9.
The results showed that the sunlight exposure group showed a slight increase in serum 25(OH)D level. The sunlight exposure group had sunlight exposure on 20% to 30% of their body surface areas for 30–60 minutes per day, 3 times a week during the summer season.
Let’s see how much vitamin D can be obtained through sunbathing? A Norway study found that 30 minutes of midday summer sun exposure to the whole skin is equivalent to taking 10,000-20,000 IU vitamin D orally10. At the same time, the winter levels of vitamin D are 10 to 100% lower than the summer levels. That means people in Norway cannot make vitamin D from sunlight between October and March.
There are a lot of factors that can affect your ability to make vitamin D from sunlight. Firstly, how sensitive your skin is to sunlight. Other factors include the time of day, your skin color, and how far you live from the equator. Secondly, how much skin you expose to sunlight and whether you’re wearing sunscreen.
And finally, a few words about sunscreen. Some studies estimate that sunscreen of SPF 30 or more reduces vitamin D production in the body by about 95–98%11. However, several studies have shown that wearing sunscreen only has a small impact on your blood levels during the summer121314. Perhaps the different results are related to different factors and the duration of the experiments. Another possible explanation is that even though you are wearing sunscreen, staying in the sun for a longer period may cause enough vitamin D to be made. Anyway, the effect of sunscreens on circulating vitamin D levels remains debated.
In conclusion, in order to resolve the dilemma of sunscreens, you may try going without sunscreen for just the first 10–30 minutes. This period should depend on how sensitive your skin is to sunlight. And then you need to apply sunscreen before you start burning.
Vitamin D Deficiency Treatment Guidelines
Apart from sunbaths, another way to increase your level is food products. In spite of the fact that they will not give you as much as the sunlight, combined with sun exposure they will work quite well. So make sure that your winter and summer diet includes oily fish (salmon, mackerel, tuna), egg yolks, cheese, liver, as well as enriched dairy and cereal-grain products.
In case of insufficiency (especially when the numbers are critically low, 25(OH)D less than 30ng/mL) it is advisable to take it individually as a supplement. An increase of 25(OH)D levels at dietary intake is quite individual, but dose-response data suggests that taking 100 ME amounts of vitamin D by non-overweight people. This amounts of vitamin lead to increase levels by less than 1 ng/mL – 0.4 ng/mL/mkg/day. This is not much, so if the result is less than 30 ng/mL, it is advisable to take a treatment dose of the medication with later switch to maintaining doses. You need to discuss the treatment deficiency with your doctor, as it is important to consider the presence of a health problem, which may require an individual approach to its dosage.
General vitamin D deficiency treatment guidelines suggest that sustaining the optimum vitamin D levels of more than 30 ng/mL. To reach these numbers, it may require a daily intake of >1500-2000 ME a day. And in case of overweight or metabolic imbalance, a dose should be more than 6000-8000 ME a day.
Don’t be surprised if it will take you half a year or more to achieve the optimum levels of this vitamin in your blood. Furthermore, when the desired level of vitamin D is achieved, to sustain it you will need to take 1000-2000 ME a day and regularly control its level to prevent its overaccumulation in your body. Vitamin D3 (cholecalciferol) is considered to be more effective than vitamin D2 (ergocalciferol), although some recent studies have proven them equally effective.
Maintenance Dose of Vitamin D
The recommended concentrations of 25(OH)D vary from 30 to 60 ng/mL since the tendency to achieve 61-100 ng/mL has no proven advantages. Along with taking preventing and maintaining doses, it is advisable to test your 25(OH)D in blood every 6-12 months. First of all, this recommendation is associated with a risk of falling below the levels of vitamin D.
It’s worth noting that in order to prevent vitamin D deficiency people aged 18-50 should receive 600-800 ME a day, those older than 50 – as much as 800-1000 ME a day. It is not recommended to prescribe more than 10,000 ME a day for a long period (more than 6 months) without medical supervision and control. Due to the lipophilicity, its accumulation in fat tissue may result in vitamin D becoming toxic.
- Vitamin D and Chronic Diseases
- Vitamin D in Cardiovascular Disease
- Vitamin D deficiency and the risk of tuberculosis: a meta-analysis
- Vitamin D and the Immune System
- The Role of Vitamin D in Cancer Prevention
- Vitamin D: The “sunshine” vitamin
- Vitamin D and Calcium Insufficiency-Related Chronic Diseases: an Emerging World-Wide Public Health Problem
Recommended summer sunlight exposure levels can produce sufficient (> or =20 ng ml(-1)) but not the proposed optimal (> or =32 ng ml(-1)) 25(OH)D levels at UK latitudes
- Can Current Recommendations on Sun Exposure Sufficiently Increase Serum Vitamin D Level?: One-Month Randomized Clinical Trial
- Sun and sun beds: inducers of vitamin D and skin cancer
- Sun and sun beds: inducers of vitamin D and skin cancer
- The effect of regular sunscreen use on vitamin D levels in an Australian population. Results of a randomized controlled trial
- Clinically prescribed sunscreen (sun protection factor 15) does not decrease serum vitamin D concentration sufficiently either to induce changes in parathyroid function or in metabolic markers
- Sunscreens block cutaneous vitamin D production with only a minimal effect on circulating 25-hydroxyvitamin D