Vitamin D and Your Immune System

Coughs and sneezes spread diseases but vitamin D might help protect you this winter.

Beckie Port | Tuesday 5 November 2013

It is well known that vitamin D plays an important role in keeping your bones strong and health but did you know it may also be essential for maintaining your immune system? Scientists have discovered that deficiency is associated with autoimmune diseases and can make you more vulnerable to infections. And research has even shown that the number of cases of influenza rise in the winter when vitamin D levels are at their lowest 1. So, could more vitamin D help prevent a runny nose this season?

Vitamin D has been described as a "prohormone" and is unique as it can be both ingested, from foods such as oily fish and eggs, and synthesised by our body. Our recent blog post (The UK's Vitamin D 'Epidemic')  talked about vitamin D2 synthesis when the skin is exposed to sunlight, and the lifestyle changes that have lead to the UK, as a nation, becoming vitamin D deficient. However, as winter closes in - and the warm coats make their annual decent from boxes hidden in attics and appear from the back of wardrobes - the chance to synthesise vitamin D this year, in the UK at least, has passed. Between the months of October and March the sun's rays are too weak at our latitude to allow the skin to produce this vitamin and we must rely on the vitamin D that occurs naturally in foods, that is added to fortified milk, cheese and yoghurt or that comes in the form of supplements to maintain sufficient levels. But how exactly might vitamin D help you fight off those winter sniffles?  We investigate why this vitamin is important for our immune system and look at what you can do to help keep your levels up until the sun comes back next year.

Research has suggested that Vitamin D plays an important role in our immune system. The vitamin D receptor molecule - that captures and binds to vitamin D - is found on a number of immune cells including B-cells and T-cells 2. These specialised immune cells are are found in your blood and help fight foreign and invading organisms in our bodies. Studies looking at how this vitamin helps regulate the immune system have discovered that T-cells may use vitamin D to communicate with "phagocytes" - the cells which engulf and destroy harmful particles and bacterial 3. This prohormone also helps maintain parts of the immune system that, when left unchecked cause autoimmune disease - where the body starts attacking healthy cells by mistaking them as harmful foreign invaders 4. 

The research all suggests that having adequate levels of vitamin D is important to keep you fit and healthy this winter, and whilst using vitamins to fight infection may sound a little "new age" vitamin D has been used to treat infections since before antibiotics were invented - a report from 1849 described the use of cod liver oil, which is a good source of this vitamin, to treat patients with tuberculosis 5. So this winter when you wrap up to protect your self from the cold outside, consider taking vitamin D supplements to help boost your immune system and help it protect you form the inside.

1. Cannell JJ, 2004
2. Aranow C, 2011
3. Chandra G, 2004
4. Adorini L, 2005
5. Williams C, 1849


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