Vitamin D, aptly named the sunshine vitamin as it is produced by our skin as a response to sunlight. This vitamin acts like a hormone and each cell in our bodies has a receptor for it – making it very important (1).
You can also consume Vitamin D through foods like fatty fish or fortified foods like cereal, orange juice or milk but it can be difficult to get enough through diet.
The recommended daily intake is between 400-800 IU depending on your lifestyle but many health professionals would recommend even more than that. This is because Vitamin D deficiency is extremely common. In fact it affects about 50% of the world wide population.
A recent study found that 42% of adults in the US do not make or consume enough vitamin D (2).
There are risk factors that make vitamin D deficiency more likely:
- Dark skin.
- A diet low in milk or fish.
- Low exposure to sunlight such as living in darker regions, wearing sunscreen and being indoors too much.
Many people do not realize they have a deficiency so here are some common signs:
Being Sick All The Time
Vitamin D directly affects your immune system’s ability to fight infections and pathogens that cause illness (3). Therefore if you are often sick with colds, seasonal bugs or heal slowly, you could be suffering from low vitamin D
Vitamin D deficiency and fatigue have been linked. One large observational study explored the relationship between tiredness and vitamin D and found that those with blood levels of less than 29 ng/ml complained of consistent tiredness whereas those with blood levels higher than 30 ng/ml did not (8).
Another similar study focusing on female nurses saw a significant link between these low vitamin D levels in the blood and complaints of on-going fatigue. The researchers found that 89% of these nurses were suffering of vitamin D deficient (9).
Low levels of Vitamin D are a contributing factor to pain in the back and bone pain. This is because the vitamin is used for maintaining bone health by improving your absorption of calcium.
One study found that those with vitamin D deficiency were 50% more likely to have bone pain, especially in their joints over those individuals with levels in the healthy range (10).
As mentioned, one of Vitamin D’s roles is calcium absorption and bone metabolism in the body. This means that deficiencies lead to increase bone loss, especially in older women. Those suffering from bone loss have significant increased risks of fractures.
A recent study using 1,100 women either experiencing menopause or postmenopausal, found these at risk women had low vitamin D levels as well as low bone mineral density (14).
Supplementing Vitamin D intake is a good strategy for maintaining bone mass, reducing the risk of bone loss and therefore reducing risk of serious fractures.
Some studies have linked a deficiency in Vitamin D to depression in older adults (15,16). One review study saw that 65% of the studies into this link found correlations between low blood levels of the vitamin and depression
Other controlled studies conclude that supplementing vitamin D in people improves the symptoms of depression – it is the most effective for seasonal depression. This occurs in colder months and could be due to a lack of vitamin D due to low exposure to sunlight (17,18).
Slow Wound Healing
Inadequate levels of Vitamin D have been linked to slow healing and increased risk of infections.
This could be because the vitamin works to increase the production of certain compounds crucial for making new skin cells and is obviously a vital step in the healing process (19).
Another study found that individuals with severe deficiencies were far more likely to experience high inflammation which hampers the bodies healing efforts (20).
There have been studies into vitamin D and controlling inflammation and found that vitamin D does have a positive impact.
However these studies are few and far between and there is not enough research to be definitive about the role of supplementing with Vitamin D and wound healing.
Generally severe hair loss is due to disease or nutrient deficiency.
Alopecia areata is a particular autoimmune disease where the patient experiences severe hair loss all over the body, including the head. This disease is closely associated with rickets – caused by vitamin D deficiency in childhood (22).
A study using people with alopecia areata found that low Vitamin D in the blood was associated with severe hair loss (23).
A topical application of a synthetic supplement of vitamin D successfully treated hair loss in children with issues with their vitamin D receptors (24).
As mentioned earlier, most cells have vitamin D receptors. The nerve cells that sense pain or nociceptors have these receptors as well.
Another study with 120 children who were also deficient in vitamin D found that their reported ‘growing pains’ were reduced significantly by just a single dose of Vitamin D (30).
Correct Your Vitamin D Deficiency
Fixing a deficiency is very easy but will have far reaching benefits for your overall health. You can increase your sun exposure by as little as taking a 15 minute walk in the sunshine each day. You can also eat vitamin D rich foods or even simply take a supplement.
As always if you want to make changes to your lifestyle, consult your doctor and get your blood levels measured.