For some time it’s been known that maintaining adequate levels of Vitamin D helps prevent cancer, especially colo-rectal cancer but also of the breast, pancreas and bladder. Now there’s evidence that women who already have breast cancer can benefit from increased Vitamin D.

A major review study reported in the journal Anticancer Research has found that women with high levels of Vitamin D in their blood when diagnosed with breast cancer showed improved survival rates (at average 9 years), compared to women with low Vitamin D levels.

The study involved 4443 patients with breast cancer and according to the statistics there is almost no probability that this difference occurred by chance – though further research is needed to see whether more severe illness can lower Vitamin D levels.

Improved levels of Vitamin D prevent cancer by helping cells to stick together. When cells are loosely packed they start reproducing at a faster rate and may evolve into cancer cells.

The presence of Vitamin D can keep a developing cancer in check by limiting its ability to develop its own blood supply, and/or to invade nearby structures like blood vessels. Dr Cedric Garland of the University of California, San Diego, told Medscape Medical News that up until a fairly late stage of development, cancer cells have intact Vitamin D receptors.

He recommends that women undergoing treatment for breast cancer should check their blood levels of Vitamin D, to keep it in the optimal range. And most women could use more Vitamin D. The average American would be in the “low” group whereas the “high” group had nearly twice as much Vitamin D.

Moreover, current recommendations for daily consumption are conservative: you would have to take a large amount of Vitamin D on a daily basis before signs of toxicity (such as thirst, nausea, stomach upset or muscle weakness) occur. This would be unlikely unless supplements are added to natural sources.

Vitamin D deficiencies by contrast are fairly common, especially in climates where winters are long and cold. Some of the study data came from Canada, but studies in Southern Australia have also found Vitamin D deficiency, so South Africans shouldn’t be complacent about our sunny skies. Here are some ways to keep Vitamin D in good supply:

– Sunlight. Make the most of the sun, especially in winter – it’s 100% free! You don’t need to risk getting burned – 20 minutes will do. After that, avoid the hottest part of the day or use sunblock, keeping the sun off your face if you want to protect your youthful good looks.

– Oily fish, which comes with a bonus of cholesterol-free protein and heart-healthy fatty acids. A generous serving of salmon, trout, mackerel, fresh tuna or eel will provide nearly all your daily requirement of Vitamin D. Canned fish is also good, though not as nice.

– Mushrooms. Not the pale ones grown in the dark – like us, mushrooms make Vitamin D from light. Portobellos or wild mushrooms are perfect. Picking your own is fun, but study them well as some are poisonous.

– Fortified products. It’s not the healthiest way to eat but some dairy products, fruit juices and cereals or porridge are fortified with Vitamin D, as are certain soy and rice milk products. This is an important source of dietary Vitamin D for many people and worth the extra cost.

– Egg yolks. Two egg yolks provide 80 International Units of Vitamin D, 20% of the daily requirement. There is now a consensus that eating eggs is healthy. They contain cholesterol and fat, but are one of very few foods that supply all nine essential amino acids and digestible iron, as well as important vitamins and minerals. The extra cholesterol makes little difference, which is offset by important benefits e.g. preventing age related eye disease. The lutein that helps your eyes actually protects against early heart disease, according to the American Heart Association.

– Calves’ (beef) liver. Also provides Vitamin A, iron and protein. Perhaps not the best choice if you’re watching saturated fat, but a useful meal to boost iron supplies, which are often deficient especially in women.

– Supplementation – Vitamin D from sunlight and healthy food can be supplemented if necessary. Most good quality multivitamins include Vitamin D and Calcium – Magnesium supplements with added Vitamin D are also available. Some people are unable to absorb dietary Vitamin D, and in such cases it might be justified to use UV lamps under medical supervision, to avoid severe loss of bone. But in general, it’s better to eat healthy food – veggies, fruit and whole grains – than to take handfuls of supplements.

Cod liver oil, a traditional remedy and tonic is sometimes recommended. It is high in Vitamin D but also in Vitamin A which isn’t as likely to be deficient and can be hazardous, especially to small children. Recent research has cast doubt on the usefulness of fish oil supplements. Rather eat whole fish for balanced nutrition or use a plant-based source of Omega-3’s (flax seed, pumpkin seed, walnuts, canola).

So the consensus is that Vitamin D helps prevent cancer and assists in cancer treatment. It is often deficient even in sunny climates but with a little planning can be included in a ‘food state’ form without need for supplementation. If you do supplement, take into account how much you get from your diet and/or sunshine, and if you’re undergoing cancer treatment, ask your doctor to check your levels of Vitamin D to ensure that they are optimal.