‘Sunshine vitamin’ good for young and old
The right amount of vitamin D gives us healthy bones, said Professor Marietjie Herselman of the Faculty of Health Sciences at Stellenbosch University (SU) in her inaugural lecture on Wednesday (2 November).
According to Herselman, vitamin D helps to prevent the softening and weakening of the bones in children. “It has also been linked to conditions such as tuberculosis, cardiovascular disease, diabetes, cancer, arthritis, fractures and muscle weakness.”
However, the potential benefits of vitamin D in these conditions still need to be confirmed by further tests, she said.
Herselman mentioned that light to moderate exposure of the skin to sunlight twice a week is enough to produce sufficient amounts of vitamin D to control calcium and phosphorus levels, and to regulate bone metabolism.
She added that it is important for breastfed infants to be exposed to sunlight because breast milk is a poor source of vitamin D. If this is not feasible, a doctor may prescribe vitamin D supplements.
“Natural food sources of vitamin D are scarce and diet alone is not enough to achieve the optimal levels of vitamin D in the body. The best food sources are fatty fish (salmon, tuna, herring, sardines and mackerel) and fish liver oil (cod liver oil), while small amounts are also found in butter, egg yolk and liver.”
Herselman noted that dietary supplements and foods fortified with vitamin D are important potential sources of dietary intake.
Vitamin D supplements are relatively cheap en widely available in various formulations such as tablets, capsules and liquid drops, she said.
According to Herselman, the benefits of taking more vitamin D than is needed, have, however, not been proven.
“High doses vitamin D should be taken under the supervision of a doctor and blood levels of vitamin D and calcium should be monitored to avoid vitamin D toxicity.”
In most developing countries, the availability of foods fortified with vitamin D is not very reliable, said Herselman.
She pointed out that in South Africa, data on the vitamin D status of the population is almost non-existing, and research should be done, especially on groups at risks of vitamin D deficiency.
Herselman is of the view that such data would be required for the development of policy regarding the need for vitamin D supplementation in at risk groups, including exclusively breastfed infants.