Vitamin D May Lower The Risk Of Developing Cancer
As the days lengthen and we think about spending more time outdoors, let’s take a closer look at the “sunshine vitamin”, vitamin D. This important vitamin is produced by the body through exposure to sunlight. Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorus, and facilitating normal immune system function. Getting a sufficient amount of the vitamin is important for normal growth and development of bones and teeth, as well as improved resistance against certain diseases.
The health benefits of Vitamin D
Vitamin D has multiple roles in the body including:
- Maintaining the health of bones and teeth
- Supporting the health of the immune system, brain and nervous system
- Regulating insulin levels and helping the management of diabetes
- Supporting lung function and cardiovascular health
- Influencing the genes involved in cancer development
The link between vitamin D and lowering the risk of cancer
Scientists have been conducting research into vitamin D for decades. In the 1980s Professor Cedric Garland and his late brother Frank from the University of California-San Diego School of Medicine, linked low levels of vitamin D with cancer. They found that people who lived at higher latitudes where there was less sunshine, had lower levels of vitamin D and were more likely to develop bowel cancer. Further studies have found links between low levels of vitamin D and other cancers including cancers of the breast, lung and bladder.
In a new study, led again by Professor Garland, the aim was to determine what level of the vitamin was required to effectively reduce cancer risk. There has been much debate in recent years about what the recommended blood levels of vitamin D should be. The study included all invasive cancers, excluding skin cancer and looked at two groups of women, totalling over 2,300 participants. The researchers found that cancer rates went down as vitamin D levels rose. They did not say what the optimum intake level should be or whether it should come from increased exposure to sunlight, dietary changes or supplements.
Professor Garland says their findings simply show that it is possible to see reduced cancer risk when blood levels of vitamin D reach 40ng/ml. At this level or higher, women had a 67% lower risk of developing cancer than women whose level was 20ng/ml or lower.
How to obtain vitamin D
We get most of our vitamin D from our body’s exposure to sunlight on our skin. A little goes a long way and 10 minutes a day of summer sunlight is sufficient, especially if you are fair-skinned. But many lifestyle and environmental factors can affect your ability to get sufficient amounts from the sun alone. Factors such as pollution, use of sunscreen, spending time indoors, working longer hours in offices and living in cities where buildings block sunlight, can contribute to vitamin D deficiency. Therefore it is important to get some of your vitamin D from other sources.
Vitamin D is also found in a small number of foods and many foods are fortified with it. Good food sources include:
- Oily fish such as salmon, sardines and mackerel
- Fortified fat spreads
- Fortified breakfast cereals
- Some powdered milks
In the UK, cow’s milk is generally not a good source of vitamin D as it is not fortified as it is in other countries.
If you find it hard to get enough of the vitamin through sun exposure and food alone, taking supplements can help. It is important to stick to the recommended daily doses as too high a dose can cause more calcium to be absorbed than can be excreted. This can then be deposited in the kidneys thus causing damage. Excessive intake of vitamin D can also encourage calcium to be removed from bones which can soften and weaken them.
Professor Garland and his team concluded:
” Primary prevention of cancer, rather than expanding early detection or improving treatment, will be essential to reversing the current upward trend of cancer incidence worldwide. This analysis suggests that improving vitamin D status is a key prevention tool.”
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