During the winter months around 90% of people in Belgium are deficient in vitamin D due to a lack of exposure to sunlight. Nevertheless, experts say that it is not necessary for us all to start taking vitamin D supplements en masse. What can you best do if you are found to be deficient in vitamin D and is vitamin D deficiency really such a problem anyway?
Most people in Belgium are deficient in vitamin D, but is it worthwhile taking supplements?
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The winter has been generally dull with relatively few hours of sunshine. The lack of sunlight during the winter months serves to greatly increase the percentage of people in Belgium that are deficient in vitamin D.
But can going outside and taking a long walk help keep your vitamin D levels up during the winter months? It is certainly beneficial for a person’s state of mind if they get a few hours of daylight out of doors during the winter. It also helps them get a good night’s sleep. However, long winter walks do little if anything to address vitamin D deficiency. Each year from around October until March the ultra-violet rays from the sun in Belgium are not the correct type to allow our bodies to produce vitamin D. Even though there is also some vitamin D in our food (for example in oily fish) we don’t absorb enough to keep our Vitamin D levels up.
The vitamin D reserves built up during the summer that we have stored in our liver and body fat are insufficient to see up through the winter months. Consequently, 90% of us suffer from vitamin D deficiency during the winter and the early spring. But is this really a problem? Should we take vitamin D supplements or not and if we do how many should we take?
Vitamin D
The Leuven University professor and Leuven University Hospital endocrinologist Dr Chantal Mathieu told VRT News that 80% of our vitamin D is produced through exposure to sunlight during the summer months. In this sense vitamin D is also a hormone.
Daily exposure of the hands and face for between quarter of an hour and half an hour during the summer is enough for a person’s body to produce enough vitamin D. If we remain in the sun for longer than half an hour, we will not produce too much vitamin D as our bodies will regulate the amount we take in.
However, from the late autumn to the early spring the sun is lower in the sky and also shines less often. "The ultraviolet rays that we need to produce vitamin D are the same as those we need to make us tan”, Dr Mathieu said.
There is also vitamin D contained in some of our food. Foodstuffs such as oily fish contain vitamin D. Vitamin D is also sometimes added to other foodstuffs such as margarine, yoghurt, some types of breakfast cereal and soja products. This is also sometimes the case with milk and fruit juice.
The two most important types of vitamin D are vitamin D3 that comes from animals (and fish) and D2 that is to be found in some plants.
Is vitamin D deficiency really such a problem?
The symptoms encountered by those suffering from vitamin D deficiency include tiredness and despite being tired an inability to get a good night’s sleep.
One otherwise fit and healthy person in their 30s interviewed by VRT News said that when they went to their GP a blood test revealed that their vitamin D levels were just half of what they should be.
In most cases vitamin D deficiency has little or no impact on a person’s health. However, it can leave a person feeling tired and lacking energy. But what is vitamin D good for? Vitamin D is good for our bones as it stimulates calcium intake from our food. Calcium is important for strong bones and teeth. Vitamin D and calcium deficiency in children can cause rickets. Among older people too it is advisable to monitor vitamin D levels.
During the winter months we should ideally ingest 10 microgrammes of vitamin D. The advocates of vitamin D supplements say that it is impossible to achieve this through diet alone. They say that supplements are essential as vitamin D helps prevent some forms of cancer, depression and cardio-vascular diseases. Furthermore, it strengthens a person’s immune system.
Is it best to take vitamin D supplements?
The Flemish government's science forum ‘Gezondheid en Wetenschap’ (Health and Science) that focuses on Evidence-Based Medicine (EBM) says that while vitamin D supplements can be useful for certain at-risk groups this is not the case for everyone. “As yet no health benefits have been proven for healthy adults. It is not because a person’s vitamin D levels are low during the winter that extra vitamin D will improve their health. Moreover, a lot of foodstuffs contain the vitamin”.
Gezondheid en Wetenschap’s experts even go so far as to say that healthy adults taking vitamin D supplements is “useless”. There are no benefits when it comes to preventing certain types of illness or cancers. "Studies also show no demonstrable advantage when it comes to cardiovascular diseases, obesity, diabetes, depression, muscular disease, TB, cancer and pregnancy”, Gezondheid en Wetenschap writes in its report.
This view is echoed by Dr Chantal Mathieu who says that taking extra vitamin D will not make a healthy person healthier.
Gezondheid en Wetenschap says that there is no causal link between taking vitamin D supplements and health among people without specific health issues.
However, this is the case among pregnant women, elderly people in care homes, people with osteoporosis, children under the age of 1 and adults that have had a gastric bypass operation.
Conclusion and warning
If you aren’t in an at-risk group and get enough sunlight vitamin D supplements are not necessary, except perhaps during the winter. Those with any doubts can take a blood test to check their vitamin D levls.
Too much vitamin D can also cause health issues such as kidney stones. Dr Mathieu advises to be prudent when taking supplements and not to take them without seeking the advice of your GP first.
Some people are at risk from vitamin D deficiency throughout the year. These include teenagers that spend too much time indoors, people with a dark skin colour as this filters the sun’s rays more, woman that for religious reasons are covered from head to toe, people that live in care homes and hardly go out and young babies that are being breast fed.