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.
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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.
Lady resting on a tropical beach in the shade of a palm tree and wearing hat and sunglasses
The main source of vitamin D is from sunlight. The majority of people can get most of the vitamin D they need from short sun exposure during summer months.
The NHS state that the majority of people should be able to get all the vitamin D the body needs by eating a healthy balanced diet and getting the right amount of sunlight.
But certain groups may be at risk of vitamin D deficiency. These include:
People aged 65 and over
Pregnant and breastfeeding women
Individuals who are not exposed to enough sunlight, such as people who are housebound
People who have darker skin, and
Babies and young children under the age of 5.
According to Harvard Medical School, if the body does not get enough vitamin D, it can only absorb 10-15% of dietary calcium, compared with 30-40% with sufficient vitamin D levels.
This can have negative impacts on bone health. Last year, Medical News Today reported on a study revealing that vitamin D deficiency may speed up the aging of bones.
Low vitamin D levels have also been linked to other negative health effects. A recent study suggested that vitamin D deficiency may cause damage to the brain.
Research has also revealed potential implications for vitamin D deficiency during pregnancy. A study recently suggesting that women who have low vitamin D levels in the first 26 weeks of gestation may have an increased risk of preeclampsia.
According to the Vitamin D Council, symptoms of vitamin D deficiency can include tiredness and general aches and pains, but many people do not have any symptoms.
Potential benefits of vitamin D supplementation
The Vitamin D Council state that the two main ways to get sufficient amounts of vitamin D in the body are to expose bare skin to sunlight and take vitamin D supplements.
But Brant Cebulla, development director of the Vitamin D Council, told Medical News Today that for many people, frequent exposure to sunlight is not possible: