By Dr Jamal Karwan
The importance of vitamin D
Vitamin D plays an important role throughout the body. It helps the absorption of calcium and phosphorus in our diet by the gut, both of which are essential for the structure and strength of our bones. In addition, vitamin D is important for our muscles and general health.
Scientists have found that vitamin D may help to prevent other diseases such as cancer, diabetes and heart disease. Research also suggests that vitamin D may provide protection from osteoporosis, hypertension (high blood pressure), and several autoimmune diseases.
Vitamin D production needs sunlight
Our main source of vitamin D is that made by our own bodies. Ninety percent of our vitamin D is made in the skin with the help of sunlight. Ultraviolet B (UVB) sunlight rays convert cholesterol in the skin into vitamin D. The sunlight needed has to fall directly on to bare skin (through a window is not enough). This is not the same as sun tanning; the skin simply needs to be exposed to sunlight.
The amount of sunlight needed to synthesize adequate amounts of vitamin D varies, depending upon the person's age, skin colour, sun exposure, and any underlying medical conditions. The production of vitamin D from the skin decreases with age. In addition, people who have darker skin need more sun exposure to produce adequate amounts of vitamin D, particularly during the winter months.
The sun's rays can be damaging and sunburn should be avoided as it can increase the risk of skin cancer. Children especially should always be protected from the harmful effect of the sun's rays. Most foods contain very little vitamin D naturally, but you can get a healthy dose from oily fish (such as sardines, pilchards, herring, trout, tuna, salmon and mackerel), egg yolk and fortified foods (this means they have vitamin D added to them) such as margarine, some cereals and infant formula milk.
People at risk for vitamin D deficiency
Those most at risk for developing vitamin D deficiency are:
all pregnant and breastfeeding women
young children, specifically under 5 years of age
all people aged 65 years and over
people who are not exposed to much sun, for example those who cover their skin for cultural reasons, who are housebound or confined indoors for long periods
people from ethnic minorities who have darker skin, because their bodies are not able to produce as much vitamin D.
Symptoms of vitamin D deficiency
Many people have no or only vague symptoms such as tiredness or general aches. In the more severely deficient, there may be more pain and weakness. This may lead to difficulty standing up or climbing stairs, or can lead to walking with a 'waddling' pattern. This is known as osteomalacia. Bone pain may develop and are typically felt in the ribs, hips, pelvis, thighs and feet.
Babies with severe vitamin D deficiency can experience muscle spasms (cramps) and breathing difficulties. Children with a severe deficiency may have a soft skull or leg bones and their legs may look curved (bow-legged) – a condition known as rickets. They may also display poor growth, tooth decay and irritability. Children with vitamin D deficiency are more prone to infections.
Diagnosing and treating a lack of vitamin D
A lack of vitamin D may be indicated by the medical history, symptoms, or lifestyle whilst a simple blood test can make the diagnosis. Identifying and treating vitamin D deficiency is important to maintain bone strength. Treatment may even improve the health of other body function, such as the immune, muscular, and cardiovascular systems, although more research is needed in these areas.
There are many types of vitamin D preparations available for the treatment of vitamin D deficiency or insufficiency. Vitamin D can be given as an injection or as a medicine (in liquid or tablet form). The dose and best treatment schedule depends on the patient’s situation, age and the severity of the deficiency.
After vitamin D deficiency has been treated and the body's store of vitamin D replenished, long-term maintenance treatment is often needed to prevent further deficiency. The outlook for those with a vitamin D deficiency is usually excellent as both the vitamin levels and the symptoms generally respond well to treatment. However, it can take time (months) for bones to recover and symptoms to get better.