Vitamin D is known as the sunshine vitamin because our bodies should make it from the sun.
Unlike certain vitamins or nutrients that the body cannot create, vitamin D can be produced by the body. When your skin is exposed to sunlight, it makes vitamin D from cholesterol. The sun’s ultraviolet B (UVB) rays make contact with the cholesterol in the skin cells, providing the energy for vitamin D synthesis to occur. Vitamin D has many roles in the body and is essential for optimal health
Despite its name, vitamin D is not really a vitamin, but rather a prohormone, or precursor of a hormone.
Vitamin D has multiple roles in the body. It assists in:
- promoting healthy bones and teeth. It increases the absorption of calcium, along with magnesium and Vitamin K so is vital for healthy bone density
- supporting immune, brain, and nervous system health
- regulating insulin and is supportive in the management of diabetes.
- supporting lung function and cardiovascular health
- influencing the expression of genes. Certain individuals are genetically predisposed to have lower absorption of vitamin D due to a Vit D receptor irregularity.
A severe deficiency in children causes rickets, but in adults it causes the bones to soften and can cause a reduction in bone density which can result in osteoporosis.
Other symptoms of Vitamin D deficiency may include:
- regular infections (poor immunity)
- fatigue
- bone and back pain
- low mood (or winter blues – Seasonal Affective Disorder (SAD))
- impaired wound healing
- hair loss
- muscle pain
During winter we tend to spend more time indoors and have much less exposure to sunlight. Because the daylight hours are shorter, we are not exposed to as much sunlight which reduces the amount we can absorb from the sun and so our requirement for Vitamin D can be higher. Wearing sunglasses and sunscreen also reduces our ability to absorb vitamin D from the sun. Despite living in a sunny climate, we can still be at risk of a Vitamin D deficiency if our bodies don’t absorb it well from the sun. It is important to test our Vitamin D levels because many of us can be deficient without even knowing it.
Spending time outdoors and with as much skin exposed as possible, but avoiding the hottest part of the day, is the best way to increase our levels of vitamin D naturally, but we can also eat foods containing vitamin D, which include the following:
- Fatty fish, like tuna, mackerel, and salmon
- Foods fortified with vitamin D, like some dairy products, orange juice, soya milk, and cereals
- Beef liver
- Cheese
- Egg yolks
Listen to my interviews with Brad Kirsten from Radio Cape Pulpit on 20 and 27 November 2025 to learn more. Listen to my next interview on Thursday at 7.45am.