Cancer, by definition, is a mutation or abnormal cell growth caused by internal and/or external factors that act together to form carcinogenesis (1). Cancer cells are able to continue to grow, and mutate, spreading in to other tissues which is not a function of normal cells. Cancer cells also have the unique quality of avoiding apoptosis, cell death, which allows for the continuation and growth of the cancer. Cancer will be a diagnosis received by an estimated 1. 5 million people in the United States this year alone. 1500 cancer patients will die each day.
The National Institute of Health estimates the direct medical costs related to a diagnosis of cancer will be near 102. 8 billion dollars (1). Many cancers have been linked to common causes. For example, lung cancer is easily associated with the external factor of smoking. Colon, breast, prostate, and ovarian cancer have an unknown association of a lack of sun exposure, or vitamin D. An inverse relationship has been researched and found that those diagnosed with a deficiency in vitamin D can be at a higher risk for developing these forms of cancer.
According to the American Cancer Society, 209,060 cases of breast cancer, 21,880 cases of ovarian cancer, 217,730 cases of prostate cancer, and 102,900 cases of colon cancer will be diagnosed in 2010 across the United States (1). Adequate intake or supplementation of vitamin D is a factor that can decrease this risk. The common health benefits from vitamin D include improvement in muscle strength, increased immune function, decreased inflammation, promotion of calcium absorption from the small intestine, and helps maintain blood levels of calcium and phosphate needed for bone formation, growth and repair (NIH).
Vitamin D is commonly linked with osteoporosis, bone fractures and bone disease; however it is now being researched due to its link with cancer (Garland, et. al. 2006). Vitamin D comes from exposure to sunlight, dietary intake of fatty fish and fish oils, fortified foods, or supplementation. Examples of the fatty fish include herring, mackerel, salmon, sardines, and tuna. It is very difficult to reach the daily recommended intake from food sources alone.
Research has found that those that live in higher latitude locations (further from the equator) are at an increased risk of vitamin D deficiency which has a direct link to an increased risk of certain cancers (Martinez, et al, 1996). According to a PubMed database search, sunlight or UVB radiation cannot be synthesized in the northern climates 4-5 months out of the year, and sunscreen though protecting against skin cancer, is also blocking the body’s ability to synthesize the vitamin D (Garland, et. al. 2006).
The needed sun exposure to maintain adequate vitamin D stores is fifteen minutes a day in the summer and twenty minutes in early fall or late spring form the hours of 11:00am to 2:00pm (Garland, et. al, 2006). Sun exposure, however, becomes a concern due to the over reddening of the skin, which over time may have the potential to lead to skin cancer. The amount needed to avoid deficiency varies dependent on age, body weight, skin pigmentation, latitude, sun exposure and use of sun block. (Robinson, 2010).
The general recommendation for healthy Americans, according to the National Academy of Sciences, age 1-50 is 200 IU. (International Units). Research studies are finding better success with a daily intake of 500 – 1000 IUs. Vitamin D functions in the regulation of cell growth, fighting infection, and immune function. Vitamin D has the ability to inhibit tumor angiogenesis, reducing the incidence of cancer (Garland, 2006). As previously mentioned, cancer is caused from a mutation in cell growth and formation.
If there is a lack of or deficiency in vitamin D, which is a key component responsible for cell growth, this provides an opportunity for the cell mutation to occur. Epidemiological studies have concluded there is an inverse relationship between vitamin D and incidence of certain forms of cancer; primarily colon, breast, prostate and ovarian (NIH, 2010, Garland, 2006). A research review conducted by WB Grant, was able to conclude that there is a direct relationship between vitamin D levels and risk of colorectal cancer.
At this time, however, it cannot be determined if this relationship is based on supplemental intake or dietary intake (Grant, 2004). A study conducted at the Osteoporosis Research Center in Omaha, Nebraska resulted in a 78% decreased risk of cancer development in women participating in the study with a daily intake of 1000 IUs for four years (Lappe, et al. 2007). In 2004, Garland et. al, conducted a PubMed search with an association of vitamin D as a beneficial effect on the risk of the previously mentioned cancers.
20 of the 30 colon studies found a statistically significant benefit in the incidence of adenomatous polyps, or cancer. 9 of 13 breast cancer studies reported a favorable association, and 13 of the 26 studies in relationship to prostate cancer. 5 of the 7 studies of ovarian cancer actually discussed mortality rate from cancer. These studies found that lower regional sunlight was associated with higher mortality (Garland, 2006). As with any medical or scientific research, not all results are conclusive or supportive of the direct link between vitamin D and cancer development.
It has been determined that observational studies, while do show a decreased risk, are challenging due to the information collected, and bias of individual participant that are responsible for self-reporting of dietary intakes (Sempos, 1999). Controlled variables need to be present and factored in order to determine a direct relationship between vitamin D as a key component of decreased cancer risk. More research is always being done in order to solidify the positive relationship between adequate vitamin D and decreased cancer risk.
Gender, race, genetics, and geographic locations are all limiting factors that play a key role in determining the success of the research currently being conducted (NIH, 2010). There is significant research to prove this relationship in recommending that those at risk of cancer development need to maintain an adequate intake of vitamin D through sun exposure, dietary intake, or supplementation. The majority of studies researched, are finding a protective relationship between vitamin D and cancer, with little to no adverse effects (Garland, 2006). Cancer Facts & Figures 2010. American Cancer Society.
Garland, CF., Garland, FC. , et al. The role of vitamin D in cancer prevention. Am J Public Health. 2006 Grant, WB, and Garland, CF. 2004. Reviews: A critical review of studies on vitamin D in relation to colorectal cancer. Nutrition and Cancer Martinez, ME. , Giovannucci, E. , Coldirz, G. , Stampfer, M. , Hunter, D. , et al. Calcium, vitamin D and the occurrence of colorectal cancer among women. J Natl Cancer Inst 1996;88: 1375-1382. Vitamin D and Cancer Prevention: National Institutes of Health. Robinson, Audrey. Vitamin D Deficiency and Cancer. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial1,2
Joan M Lappe, Dianne Travers-Gustafson, K Michael Davies, Robert R Recker and Robert P Heaney Sempos, CT, Liu K, Ernst, ND. Food and nutrient exposures. What to consider when evaluating epidemiologic evidence. American Journal of Clinical Nutrition 1999; 69(6) 1330S-1338S. Lichtenfeld, Leonard. (2007). Vitamin D and the risk of cancer. http://www. cancer. org/AboutUs/DrLensBlog/post/2007/06/08/Vitamin-D-And-The-Risk-Of-Cancer. aspx.