VITAMIN D, THE IMMUNE SYSTEM BOOSTING HORMONE

Dr Vera Martins - Naturopath & Herbalist

Did you know that rather than a vitamin, Vitamin D is actually a hormone? In fact, the final product of Vitamin D conversion in the body is actually considered a hormone. Foods such as oily fish, egg yolks and whole milk are great for obtaining Vitamin D however, 90% of the Vitamin D we get is made by our bodies. Vitamin D is made in the body from direct sunlight (particularly UV-B radiation) in the skin. The synthesis process then continues in the liver and kidneys, until producing the final active form of the hormone. 

The receptor for Vitamin D is contained in several different types of cells in the body, including immune cells. This means the several different types of cells can respond to Vitamin D molecules, triggering different reactions in the body. It's not surprising that vitamin D can affect so many aspects of health including bone health, cardiovascular health, immunity, autoimmune disease, type 1 diabetes, and mental health. 

Can vitamin D help with colds and the flu? 

There is a huge amount of scientific research backing up that a deficiency in Vitamin D increases the chances of infection. 

One study has shown that individuals with low Vitamin D levels are more likely to develop upper respiratory tract infections than those with sufficient levels. It has been seen in several studies that there is an association of lower Vitamin D levels and increased rates of infection, including influenza. In another study, supplementation of Vitamin D for three months during the winter decreased the number of upper respiratory tract infections in children with Vitamin D deficiency. During a study, Japanese children received daily supplementation with Vitamin D for 15 to 17 weeks during the winter significantly, which significantly reduced influenza infections by 42%, compared with a control.  

How does Vitamin D support the immune system? 

For about 35 years the role of Vitamin D in the immune system has been recognized. However, it was only in recent years that the implications of a deficiency of Vitamin D can have an effect on the immune system have become clearer. 

There are two types of immune system that are both equally important in fighting infections. One of the types being the innate system (responsible for quickly fighting infections) and the other being the adaptive system (which produces a slower response but is highly specialised, e.g. responsible for the production of antibodies). Vitamin D seems to modulate both systems which can explain why this hormone has such a vast effect on the immune system. In fact, it is also known that Vitamin D can play a role in autoimmunity. It has been shown that prevalence of Vitamin D deficiency is observed in patients with autoimmune disease, including multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease and lupus erythematosus.

 How can I boost my levels of Vitamin D?

The most natural and desirable way to get enough Vitamin D is regular exposure to sunlight. For a good balance between adequate Vitamin D levels and avoiding the risk of skin cancer in the UK sun, aim for 10-20 minutes of exposure around midday several times a week. During the months of spring and summer, we are more likely to cover our daily needs of Vitamin D from sunlight exposure.

For approximately 2 months Vitamin D is stored in the body. Therefore, the Vitamin D you stocked up during the sunny days back in the summer will start going away as the shorter and colder days of winter get closer. The best way to cover your daily requirements in the winter months is to take a supplement since it is difficult to get enough Vitamin D from food alone.

D3 is the most efficient at raising Vitamin D levels in the body out of the two forms. You can find supplements in tablets but also in sublingual drops or spray, which are a really good choice for people suffering from malabsorption.

How much Vitamin D should I take?

When it comes to how much Vitamin D we should supplement there is a wide range of expert opinion. According to the recommendations from the Department of Health, anyone above the age of four should have 10 micrograms (400 IU) daily. This is particularly important between October and March. People at higher risk (those with little or no exposure to the sun and people with dark skin) are advised to take a supplement all year round. The Department of Health also states 100 micrograms (4000 IU) as the recommended daily limit.

However, it is important to recognize that Vitamin D requirements can vary greatly according to where you live (people living in northern countries are at higher risk of Vitamin D deficiency), age, season, and individual factors (some people may need more than 400 IU daily if levels are very low).  By getting professional advice from a qualified naturopath or nutritionist you will be able to find out what your individual needs are.


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