What Is Vitamin D and What Does It Do for Your Body?

Vitamin D is most famous for its impact on bone health, although it has many more functions and a fairly complex relationship with the immune system. Here's all you need to know about Vitamin D to improve your health.

getting vitamin D from the sun
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What is Vitamin D?

A vitamin is an organic molecule that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism and can not be made by the body. The molecule known as calciferol is considered to be a vitamin and is more commonly known as vitamin D, which is made in the skin upon exposure to sunlight. The UVB spectrum of sunlight converts a form of cholesterol into vitamin D. As the body makes vitamin D, it is not truly a vitamin despite, as mentioned above, it is widely considered so and named so.

The difference between Vitamin D, Vitamin D2 and Vitamin D3

Vitamin D is also two different molecules commonly known as Vitamin D2 (ergocalciferol), mainly found in plant sources, and Vitamin D3 (calciferol), which is only found in animal sources. Multiple metabolic steps are essential in vitamin D metabolism called activation steps that occur after synthesis or ingestion to allow for proper use. The organs that are vital in these processes are the liver and the kidney. Once cholesterol has been converted to the vitamin D precursor, it firsts travels to the liver to become hydroxy vitamin D or 25(OH)D, the form of vitamin D usually measured to assess levels within the body. This form is inactive and travels to the kidney to be activated into 1,25 hydroxyvitamin D or 1,25(OH)D, also known as calcitriol.

What does Vitamin D do for your body?

Vitamin D is most famous for its impact on bone health. However, it has many more functions and a fairly complex relationship with the immune system. Some basic examples of what vitamin D can do for your body are listed below:

  • Calcium absorption in the intestines
  • Bone formation
  • Regulation of calcium and phosphate transport
  • Parathyroid regulation
  • Insulin secretion
  • Fibroblast growth factor regulation
  • Enhances/facilitates the innate immune reaction
  • Inhibits/modulates the adaptive immune response
  • Modulates inflammatory molecules (cytokines)
  • Cardiac regulation
  • Thyroid function

The two examples above relating to the innate and adaptive immune system are where vitamin D's relationship to the immune system gets a little complex. The innate immune system can not initiate defensive capabilities without sufficient vitamin D. Oppositely, the adaptive immune system needs vitamin D to control the severity of its function. When the adaptive immune system is allowed to run free with little vitamin D to rain, it in can cause what is now famously known as a cytokine storm thanks to the COVID-19 pandemic.

What might affect Vitamin D levels?

As vitamin D is made in the presence of UVB light, which depending on where you are on the planet, it only hits the ground at certain points of the year, your exposure to this light is a major factor. Even when exposed to that form of light, due to its wavelength being fairly short, it will not penetrate thick clothing or any form of glass. Meaning that your exposure can often need to be purposeful and planned in the average modern lifestyle.

As certain inflammatory molecules cause the activation of vitamin D from its 25(OH) form into its 1,25(OH) form, we can also see acute inflammation will directly reduce circulating levels. This will be especially true if more of the 25(OH) form is not being produced or ingested at sufficient levels to replenish the non-active stores. There are also a number of things that might affect your ability to make or absorb 25(OH) D3, such as inflammation of the mucus membranes in the intestines may prevent uptake of any supplementation. The skin cells may be negatively affected by heat or dehydration to the point of cellular damage (sunburn), resulting in cell death and failure to produce vitamin D. Hence it is important to understand how to make the most of your vitamin D status.

How to improve Vitamin D levels?

Outside of the obvious, get more sun, certain strategies may help optimise this precious time and help improve your vitamin D levels:

  1. Stay hydrated, dehydration will drive poor cellular function and, therefore, inflammation, and that is before we consider how water is needed to regulate temperature, which is vital in protecting yourself from sunburn.
  2. Get out in the sun with as much skin exposed as possible but be sure to cover up and or get in the shade once your skin has had enough. Know your limits! This can be a difficult thing for some to gauge at first, so air on the side of caution, but as your skin acclimatises to the sun, you will be able to last longer and get a better intuitive feeling of when enough is enough.
  3. Consume plenty of Vitamin E with EPA & DHA omega-3 fatty acids and retinol (Vitamin A). Omega-3s are well known anti-inflammatory and help replace any of the omega-3s damaged in the skin cells when out in the sun. Vitamin E will help slow down any oxidation of fatty acids in the cell membranes that might occur in response to sun exposure and improve the absorption of the omega-3s. Vitamin A is a significant co-factor that works in tandem with vitamin D in the immune pathways, enhancing the efficacy of vitamin D and helping spare it.
  4. Ensuring your digestion is optimal will go a long way to aiding overall vitamin D levels. Not only due to improved absorption of any supplements taken, but also over 50% of the body's immune cells sit in the gastrointestinal tract and meaning that dysregulation can cause a major inflammatory drain on your vitamin D reserves.

Note: Do not forget that thick clothing and any form of glass will block UVB's effects on the skin and therefore reduce vitamin D production.

What about sunscreen and cancer?

Firstly sunscreen is a functional tool that should be used in certain circumstances, but many contain chemicals that are not only toxic to the environment but also have shown to be carcinogenic themselves. There are now many more non-toxic options, but you can choose the route of respecting the sun and not look for artificial protection that will reduce the health benefits you get from being outdoors.

Does exposure to UVB light cause cancer? Yes. Will it if you have reasonable exposure? No. It's important to understand that the dose makes the toxin and that vitamin D also has anti-cancerous effects. To this end, why would the same thing that is shown to have positive impacts on cancer prevention also cause cancer through its natural production? Context is the answer. Excessive exposure can cause damage and lead to DNA damage and then potentially cancer; exposure that is within your personal limits increase Vitamin D and, therefore, protects against cancer. In 2014, P. G. Lindqvist et al. published a study showing women with less sun exposure had an increased mortality rate, the study did have a few floors in its design if we were to assume a full connection to vitamin D here as it was not measured and other confounding variables could have been at play, but it is another good piece of evidence to show that a lack of sun can be just as bad as too much sun for human health.

Key takeaways about Vitamin D

  • The sun is good for you in moderation
  • Vitamin D is a complex molecule needed for optimal health
  • Supplementation or sunlight without consideration to affecting factors may result in surprisingly low levels when you run a blood test.

Visit the Omnos shop to checkout the tests mentioned in the article.

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