Benefits of Vitamin D in Cancer

Mother and daughter playing in the sun
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The sun, perfectly near and perfectly distant, sustains the delicate balance of life on Earth. The sun gives our planet warmth, heat and the energy needed for photosynthesis. It drives our day-night rhythms and promotes feelings of well being.

Sunlight is also essential for vitamin D synthesis in the skin — that's why vitamin D is sometimes called the sunshine vitamin. And it just so happens that millions of Americans may not be getting enough vitamin D. You can also get vitamin D from your diet, but very few of the most commonly consumed foods in Western diets are naturally good sources of vitamin D.

Risks of UV Exposure

Risks from ultraviolet (UV) exposure have been recognized and discussed for years. UV radiation causes basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. The risk of skin cancers increases when people overexpose themselves to sun, or intentionally expose themselves to artificial sources of UV radiation such as tanning beds. And for those concerned about cosmetic effects, the sun is the source of what’s known as photoaging — the premature aging of the skin due to chronic UV exposure. Effects of photoaging range from wrinkled, discolored skin to precancerous, scaly-crusty growths, or actinic keratoses.

Melanoma Skin Cancer

Though non-melanoma skin cancers are quite common, they are rarely fatal. In contrast, melanoma represents less than 5 percent of all skin cancers but causes the most skin cancer deaths. It is the second most common cancer of women in their 20s and the third most common cancer of men in their 20s. A heightened risk of melanoma has been found for those with increased childhood sun-exposure history.

Sunscreen protects against sunburns, and sunscreen continues to be recommended by the American Academy of Dermatology. Protection against severe burns is a good thing, and it seems to stand that this might also translate to some protection when it comes to malignancy. That said, sunscreen is just one part of the whole picture when it comes to protection from the sun. And no studies have ever demonstrated that sunscreen use, alone, prevents melanomas or basal cell carcinomas, according to an article published March 20011 in the journal, “Pediatrics.” The amount of time spent in the sun and your complexion are also key factors.

Does the Sunshine Vitamin Prevent Cancer?

There’s reason to be hopeful, but there are also many questions that remain unanswered. According to laboratory studies, vitamin D deficiency does seem to help certain malignancies to develop, but experts say more research is needed before routine vitamin D supplementation for cancer prevention could be recommended.

The “Low Cloud Cover” Study and Leukemia

Animal and laboratory studies support the idea that having adequate levels of vitamin D might help prevent leukemia, but no such evidence exists in humans. However, a group of scientists wondered whether they could see evidence of a protective effect from sunlight (and higher levels of vitamin D) based the geography of different nations.

They proposed that people who live in countries further away from the equator, with low UVB exposure, who tend to have lower levels of vitamin D, might show a higher risk of certain cancers, including leukemia.

In contrast to past studies, this group adjusted for the cloud cover in various countries and its affect on UVB exposure of the people living below. They made these adjustments using satellite data from NASA.

In this study, adjusting for cloud cover, leukemia rates were highest in countries relatively closer to the poles, such as Australia, New Zealand, Chile, Ireland, Canada and the United States. They were lowest in countries closer to the equator, such as Bolivia, Samoa, Madagascar and Nigeria.

This kind of study cannot prove vitamin D deficiency leads to leukemia, but it does show an association that can be further dissected and analyzed by scientists.

Vitamin D and Leukemia Treatment

In the case of blood cancers like leukemia and lymphoma, evidence supports the idea that vitamin D actually seems to help certain cancer therapies do their job.

Studies have shown a link between vitamin D deficiency and a worse prognosis in various types of blood cancer, including chronic lymphocytic leukemia (CLL), and diffuse large B cell lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma.

But these studies look backwards, so it can be hard to tell cause from effect. Might vitamin D be used to increase the power of certain cancer therapies? This remains an open question, but data are encouraging.

The traditional role of vitamin D for strong bones is also relevant. Many cancer therapies — and often the cancers themselves — have the tendency to deplete bone mass, increasing the risk of osteoporosis. So maintaining adequate levels of calcium and vitamin D may also be important from the perspective of bone health.

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