Should I be taking vitamin D this winter?

Vitamin D deficiency has overtaken iron as the most common nutritional deficiency in the world. The ‘sunshine vitamin’ is traditionally known best for its essential role in bone health but did you know it also plays a crucial role in our immune function? Here are just some of the amazing things it does for our immune system:

Enhances the innate immune system

This is our body's ‘first line of defence’ against pathogens. Vitamin D helps to regulate our macrophages and monocytes- these immune cells are present in every body tissue and are responsible for engulfing dead cells and unwanted invaders.

Produces antimicrobial peptides

AKA cathelicidins,these are are an essential part of our immune response as they are capable of killing pathogens. Vitamin D supplementation in those who are deficient has been found to improve cathelicidin production and can give added protection against viral infection.

Stabilises the tight junctions found in the digestive tract 

The mucosal membrane of our digestive tract is the barrier of the intestines. When these tight junctions become damaged it leads to intestinal permeability or ‘leaky gut’. Unwanted larger particles including bacteria can then pass through into the blood stream, causing the immune system to mount an excessive immune response. This can lead to allergies, inflammation and autoimmunity.

Controls autoimmunity by modulating our regulatory T-cells

These immune T-reg cells are responsible for deactivating our immune response once it has done it’s job. Vitamin D deficiency is implicated in several autoimmune conditions including:

Psoriasis, type 1 diabetes, multiple sclerosis, inflammatory bowel diseases and rheumatoid arthritis.

Infact many autoimmune conditions have a higher prevalence in northern countries with less UVB radiation, and with children born in the springtime. This links vitamin D levels to autoimmunity, and is one of the first things I check when working with an autoimmune client.

Vitamin D is found in fatty fish such as salmon, mackerel, sardines, high quality cod liver oil and egg yolks. Eating more of these foods particularly in the winter months can really give you a boost, but it is a challenge to obtain good levels from diet alone. Most of our vitamin D is made in the skin in response to sunlight, and in the UK there is simply not enough of this during the winter months to produce sufficient amounts of vitamin D that we need.

Even if the sun does appear on a winters day, when your shadow is longer than you are, this is not enough sunlight to make vitamin D and supplementation may be needed to gain adequate levels.

Signs of a vitamin D deficiency can include:

- osteoporosis

- frequent fractures

- frequent colds and flu

- autoimmune conditions

- unexplained fatigue

- menstrual irregularities

- depression

- muscle weakness and pain

If you aren’t sure of your status or think you may be deficient then it is beneficial to get your levels tested before supplementing to make sure you get the right levels you need for your best health.