Updated 25 October 2013

Vitamin D: your key to optimal health

Even in a country with an abundance of sunlight you might have a vitamin D deficiency. Here's why.

Living in a country that offers an abundance of sunlight, you would think that a shortage of vitamin D is one health concern you need not worry about. After all, vitamin D is produced when your skin is exposed to sunlight, right?

Sadly, research suggests that growing numbers of people are not getting enough of the sunshine vitamin.

There are many reasons for this deficiency.

South Africa has the second highest incidence of skin cancer in the world (after Australia) and understandably people are heeding warnings by covering up and staying out of the harsh sun. Our lifestyles have also changed with many of us spending the majority of our work days indoors, only arriving home after sunset.

Furthermore, people with dark skins are much less efficient in producing vitamin D from sunlight (due to the increased melanin pigment which acts as a natural sunscreen).

The elderly also have a decreased ability to make vitamin D due to changes in their ageing skin and their kidneys being less able to convert vitamin D into its active form.

Interestingly, the growing obesity problem has also been linked to an increase in vitamin D deficiency.  In obese people, the body fat binds to some of the vitamin D, preventing it from getting into the blood and being absorbed by the body.

Some digestive disorders such as Crohn’s disease and coeliac disease can also affect the intestine’s ability to absorb vitamin D from food.

Health benefits

Vitamin D is essential for strong bones as it helps with the absorption of calcium and promotes bone growth and repair. Too little vitamin D can result in soft bones in children (rickets) and an increased risk of fractures and brittle bones in older people.

However, vitamin D is also associated with a multitude of other health benefits such as promoting cardiovascular health. According to a number of studies, a deficit in the sunshine vitamin can increase the risk of heart attacks, heart disease, hypertension and stroke.

Low vitamin D-levels have also been found to be a contributing factor in some types of cancer such as colon, breast and prostate cancer, as well as the development of diabetes and multiple sclerosis (a chronic disease of the nervous system).

Research has also confirmed the importance of vitamin D for healthy brain function. A sufficient intake of vitamin D helps to keep the mind sharp, slows mental decline and helps prevent dementia and Alzheimer’s disease.  It can also help to treat mild depression.

Finally, vitamin D plays an important role in boosting the body’s immune system and reducing inflammation – studies have found low vitamin D-levels to increase the risk for respiratory infections such as colds and the flu.

Dietary sources

There are several types of vitamin D, of which vitamins D2 (ergocalciferol) and D3 (cholecalciferol) are the most important. Vitamins D2 and D3 can be ingested from the diet and/or supplements whereas vitamin D3 is also produced by the skin after sun exposure.

Good dietary sources of vitamin D include fatty fish such as salmon, mackerel, tuna and sardines, fish oils, butter, egg yolks, liver, and fortified foods such as breakfast cereals, milk, margarine and orange juice.

The Institute of Medicine recommends a daily intake 600 IU (international units) for children and adults younger than 70, and 800 for those 70 and older. 

Apart from including vitamin-D rich foods in your diet, it is recommended that you get 10 to 15 minutes of sun exposure most days of the week on your face, arms, legs or back (without sunscreen) so your body can produce vitamin D. To safeguard you from the harmful effects of the sun, avoid the direct sun between 10am and 3pm and don’t overdo your exposure –  10 to 15 minutes are enough!

(Sources: National Institutes of Health;;;; Harvard School of Public Health;;

Picture: Woman-enjoying-sun from Shutterstock


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