Vitamin D
Did you know vitamin D is the only vitamin which is synthesised mainly by the human body, rather than through the food we eat? You might know it as “the vitamin that helps tanning”, but what else do you know about it? This post will describe the compound, its functions, how it’s produced and where we can get it.
How is vitamin D produced?
Vitamin D is produced as a result of the sun’s effect on our skin.
Solar radiation is needed to convert the precursors of vitamin D into their active, functional form. This is why it’s so important for us to receive the sun’s rays without sunscreen for 10–15 minutes a day, as a rule of thumb. However, we should be careful not to misunderstand this idea: continuous, unprotected exposure to the sun oxidises and damages the skin; this damage can be serious and irreversible. Even so, the ideal dose of sunlight at the right time of days promotes vitamin D synthesis.
It is important to keep your skin’s phototype in mind, as paler skin synthesises vitamin D more efficiently than skin with more pigmentation.
What are the functions of vitamin D in the body?
Fixing calcium molecules
Vitamin D’s essential function is its direct role in phospho-calcium metabolism. Vitamin D has a role in bone mineralisation and absorption. It also prevents bones from being broken down to obtain endogenic calcium. People with vitamin D deficiency can be affected by conditions such as osteoporosis or rickets.
Improving muscle function
Vitamin D deficiency can cause muscular weakness and atrophy (type II muscle fibre), so it’s a good idea to eat foods containing vitamins D.
Protection from cardiovascular disease
Vitamin D helps reduce blood pressure and improves the elasticity of your blood vessels.
On the one hand, it decreases the risk of type 2 diabetes, as it improves beta cells (involved in insulin production and storage) and prevents deficiency.
On the other hand, it strengthens the immune system. Vitamin D is thought to reduce the risk of 17 different types of cancer, including colon, breast, ovarian and prostate cancer.
It also inhibits the growth of cancer cells, boosts calcium absorption, promotes cell differentiation, and reduces metastasis.
Does vitamin D really help promote tanning?
Vitamin D is essential in multiple essential functions of the human body, but it has no role in the direct synthesis of melanin, our skin’s natural pigment.
However, it does promote regeneration in the skin’s basal layer, and causes the proliferation of keratinocytes, making it an important part of skincare.
Therefore, although it is known as the “sunshine vitamin”, it doesn’t cause an increase in skin pigmentation. If we don’t expose ourselves to the sun, however, vitamin D synthesis will be deficient.
Where do we obtain vitamin D?
- From the sun: the sun is the main healthy, natural source that converts the precursors we get from our diets into vitamin D.
- Dietary sources:
- Oily fish (tuna, salmon and mackerel) are some of the best sources of vitamin D.
- Beef liver, cheese and egg yolks provide small amounts.
- Mushrooms also contain some vitamin D.
- Dietary supplements: many foods, such as cereals, include artificially-synthesised vitamin D. In environments with limited sunshine (the Nordic countries, for example), it is essential to add vitamins D to the diet as an oral supplement to avoid deficiency.
