Vitamin D supplements: are they really good for our health?

There is no doubt that our bodies need vitamin D. It helps regulate the absorption of calcium and phosphorus in our bones, helps our cells to communicate with each other, and helps strengthen our immune system. But can vitamin D supplementation really offer additional health benefits?

Previous research suggests it can. But other studies indicate that vitamin D supplementation does not do any more than promote bone and immune system health and is only useful for people who have a vitamin D deficiency.

We look at both sides of the argument in an attempt to determine whether vitamin D supplementation really is good for us.

How vitamin D works

Vitamin D is a fat-soluble vitamin. There are five forms of the vitamin - D₁, D₂, D₃, D₄ and D₅.

However, vitamins D₂ and D₃ appear to be the most important in the human body.

Sunlight is the the body's main source of vitamin D. There is no set amount of time a person should spend in the sunlight to get a good amount of this vitamin. However, the Vitamin D Council state that "you don't need to tan or burn your skin to get vitamin D."

The UK's National Health Service (NHS) states that short bursts of sun exposure during summer months should be enough.

The energy from the sun changes a chemical in the skin to vitamin D₃, which is then carried to the liver and the kidneys where it is made into active vitamin D.

Some foods, such as oily fish, eggs and fortified fat spreads, also contain the vitamin, although these are in very small amounts. Once consumed, it is sent to the liver and processed in the same way.

The main function of vitamin D is to increase the intestinal absorption of calcium - a process that is crucial for good bone health.

Vitamin D also helps strengthen the immune system and aids cell to cell communication in the body.

The Vitamin D Council also state that the vitamin is important for muscle function, the respiratory system, cardiovascular function, brain development, and it even has anti-cancer properties.

Vitamin D deficiency

Vitamin D deficiency occurs when a person does not have the sufficient amount of the vitamin in their body.

According to the Food and Nutrition Board at the Institute of Medicine of The National Academies, the recommended dietary allowance of vitamin D for people aged 1-70 is 600 IU each day and 800 IU for those aged over 70 years.

Infants between 0-12 months should have an intake of 400 IU of vitamin D each day.