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Everything you need to know about vitamin D

What is vitamin D, how do we get it, and what are the symptoms of a vitamin D deficiency?

What is vitamin D?

Vitamin D is a fat-soluble vitamin commonly referred to as the ‘sunshine vitamin’. It is important for maintaining healthy teeth, muscles and bones as it helps the body absorb calcium. The vitamin also blocks the release of parathyroid hormone and helps strengthen the immune system. 

Vitamin D

How do we get vitamin D?

Vitamin D is unusual in the fact that the body can produce its own vitamin D whereas it must obtain other vitamins through the diet. Vitamin D is created in the body by the action of sunlight on our skin. Sunlight on the skin produces a substance called cholecalciferol, which the liver converts to calcidiol. The kidneys then convert calcidiol to calcitriol which is the active form of vitamin D. Many factors affect how well the skin can produce vitamin D, including the time of day and year, air pollution, suncream, the age and colour of an individual's skin and the amount of skin exposed to the sun. 

There are certain foods that contain vitamin D including the flesh of fatty fish such as mackerel, tuna and salmon as well as fish liver oils are among the best sources. Small amounts of vitamin D can also be found in egg yolks, beef liver and cheese. It can also be found in some mushrooms (portobello, maitake, morel, button, and shiitake are particularly good), you can improve this by leaving the mushrooms in the sun before cooking them. However, these food types are not enough to provide the body with optimum vitamin D levels and if there is not enough direct sunlight available, supplementing vitamin D is a good way to ensure sufficient vitamin D levels. 

What are the symptoms of vitamin D deficiency?

Many people in the UK are either insufficient (25 - 49 nmol/L) or deficient (<25 nmol/L) in vitamin D. Patients who have had gastric bypass surgery are at a greater risk of a vitamin D deficiency. Having low levels of vitamin D in the body affects the concentration of calcium in the blood for bone growth. Symptoms of vitamin D deficiency include muscle weakness, bone pain, respiratory problems, fatigue and low mood. Low calcium in the body for a prolonged period can cause rickets in children and osteomalacia in adults.

Because vitamin D has a number of different roles in the body, it is believed that a lack of vitamin D in the body may lead to a weakened immune system and an increased risk of diabetes, high blood pressure, certain cancers and heart disease. However, further research is needed before this link between vitamin D, and disease development can be confirmed. 

By making a few easy lifestyle changes such as getting out in the sunshine, increasing the amount of oily fish in your diet and taking a vitamin D supplement, it is possible to change your vitamin D levels for the better.

Learn more about vitamins:

What are vitamins?

Everything you need to know about the B vitamins

Everything you need to know about vitamin C

Everything you need to know about vitamin D

Everything you need to know about vitamin E

Everything you need to know about vitamin K