Vitamin D and Skin Cancer
The relationship between vitamin D and skin cancer is one that has sparked great controversy in the medical community. While some advocates maintain that exposure to the sun the main source of vitamin D for humans is harmful and increases the risk of skin cancers including melanoma, others believe that some exposure to sunlight without sunscreen is important in order to avoid vitamin D deficiency, which studies have found are linked to other types of cancer, including breast cancer. So is living in the sunlight really a safe way to avoid vitamin D deficiency or should we keep reaching for the sunscreen in order to reduce the risk of skin cancer?
Sun Exposure and Vitamin D Deficiency
The relationship between sun exposure and vitamin D deficiency is one that has recently been put under the microscope, and studies seem to be suggesting that the sun is our best bet when it comes to maintaining healthy levels of this vitamin, which is imperative to maintaining healthy bones and teeth, as well as a healthy immune system and cell growth.
It is believed that up to 25% of Australians are vitamin D deficient, a fact attributed to a lack of sunshine. In addition, research points to a link between breast cancer, colon cancer and prostate cancer and insufficient levels of vitamin D.
Some scientists have even estimated that 25% of breast cancer deaths in Europe can be prevented if women maintain lifelong healthy levels of vitamin D. Studies have also indicated that healthy vitamin D levels reduce the risk of hip fractures due to osteoporosis by 25 to 40%.
Lack of proper vitamin D intake has also been linked to multiple sclerosis (MS), hypertension, colon cancer, ovarian cancer, influenza and type II diabetes. People at the greatest risk for vitamin D deficiency are people with dark skin (because their pigmentation levels filter out more sunshine compared to those with fair skin) and those who wear modest clothing and who have very limited exposure to sunlight (i.e. those who work indoors).
Vitamin D is manufactured in the skin upon exposure to sunlight. While sunscreens with an SPF of 8 and higher block harmful UVA and UVB rays from penetrating our skin, they also block the body's natural ability to produce vitamin D. Dietary sources of vitamin D include milk, salmon, mackerel, tuna and fortified breads and cereals; however these sources of vitamin D are considered to be minor in comparison to sunlight exposure.
There is also debate as to what constitutes a healthy intake of vitamin D. For example, some health boards believe that women between the ages of 19 and 50 should consume 200 International Units (IUs) daily in order to maintain proper health, a figure that they state should be the same for men of the same age group as well as pregnant and lactating women the latter of whom can pass on a vitamin D deficiency to their infants through breastfeeding. However, many vitamin D researchers feel that these recommended intakes of vitamin D are too low and recommend a daily vitamin D intake of approximately 2 000 IU. Others urge that this level should be higher in the winter months (4 000 IU) when sun exposure is lower.
Symptoms of vitamin D deficiency include rickets (a condition that causes bone deformities and delayed growth), bone pain and/or osteomalacia (soft bone). A blood test can assess vitamin D levels.
Alternatively, symptoms of excessive vitamin D intake include nausea, vomiting, weakness, weight loss, decreased appetite and heart beat irregularities.
But What About Skin Cancer?
While minimizing sun exposure and wearing protective clothing in addition to wearing sunscreen has long been touted as the best way to stay safe in the sun, Australian researchers have found that vitamin D destroys cancerous cells while helping to protect healthy cells from sun damage, suggesting that sun exposure can in fact prevent cancer.
But how much sun exposure is safe if any is still not clear. Some medical experts believe that 10 to 15 minutes of sun exposure daily without sunscreen is safe and is sufficient for maintaining healthy levels of vitamin D, while others believe that most individuals get adequate vitamin D from their daily, routine exposure to the sun. Still others believe that 10 to 15 minutes of sun exposure at least two times a week is best.
There are also many factors that affect an individual's level of exposure to the sun. This includes factors such as season, time of day, smog, cloud cover and geography (latitude). In fact, women who live in higher-latitude countries, including Canada and the United Kingdom, have higher rates of breast cancer and other cancer mortality rates in comparison to more southerly countries, such as Greece and Mexico.
Other factors that affect an individual's absorption of vitamin D include obesity as well conditions that interfere with the body's ability to absorb dietary fat such as cystic fibrosis, liver disease and gall bladder disease.
Chat with other women about the risks of skin cancer in our forum.