Some studies connect low levels of vitamin D in the diet and in the body with increased colon cancer risk. As well, the risk of developing adenomas -- a type of colon polyp that can increase colon cancer risk if left untreated -- may be higher for people who have less vitamin D in their diet and lower levels of vitamin D in their body.
Despite these findings, it's important to note that the results come from observational studies. This means they do not prove cause and effect.
How Much Vitamin D Do I Need?
Several health experts believe that for optimal colon cancer prevention, we need between 1,000 and 2,000 IU of vitamin D per day, roughly two and a half to five times the current recommended dietary allowance (RDA) of 400 IU per day. The vitamin D should come from diet, dietary supplements, or from a combination of these two things.
The American Academy of Pediatrics updated its stance on vitamin D in 2008, doubling the amount of the vitamin it recommends for infants, children and adolescents. This provides further support that many in the health community believe Americans need more of this nutrient for best health. Along with calcium, vitamin D is already well-known as an important nutrient in bone health, which is why it's often added to milk.
But before you load up on vitamin D, be sure to talk to your doctor about this. While some people truly may be deficient in vitamin D and need more of the nutrient, others may not need, or benefit from, extra vitamin D.
Vitamin D and Colon Cancer Survival
Colon cancer survivors should take note, too. For people who are diagnosed with colon cancer, having low blood levels of vitamin D may worsen the chances of survival. Also of concern is that among people with colon cancer, receiving chemotherapy increases the risk of vitamin D deficiency. The best way to determine if you could benefit from taking more than the RDA of vitamin D is to ask your doctor for a vitamin D test.
Getting Your Daily Vitamin D Dose
Given all of this, you would think that a normal part of health care would be to check blood levels of vitamin D on a regular basis. Unfortunately, this is not the case. Many people in the United States do not get enough vitamin D and they aren't aware of this.
If you're concerned about your vitamin D levels, keep the following key points in mind:
- Getting enough vitamin D in the diet, or from exposure to sunlight of sufficient strength to allow the body to make vitamin D, is important for health (sunlight helps the body make Vitamin D). Numerous studies have suggested that low levels of vitamin D in the body are associated with greater risk of developing many chronic and life-threatening conditions, including colon cancer, other cancers, heart disease, osteoporosis and autoimmune diseases. Given concern about skin cancer risk with too much sun exposure, getting your vitamin D from food or a dietary supplement is a good option.
- Some health experts believe that the recommended dietary allowance (RDA) for vitamin D is set too low. This means that many people may need a dietary supplement to make sure they get enough vitamin D. Ask your doctor to test your vitamin D level and if it is low, ask how much vitamin D you should take to correct this problem. Do not load up on excess vitamin D without first confirming that you need more of the nutrient.
- Vitamin D insufficiency and deficiency are increasingly considered serious public health issues. Health experts now believe that the risk of deficiency is significantly greater than risk of toxicity (getting too much vitamin D) for many people. Ask your doctor if you should take a dietary vitamin D supplement to improve your health.
- Good food sources of vitamin D include fatty, cold water fish, such as tuna, salmon, mackerel, and sardines; cheese; egg yolks; and vitamin-D fortified foods, including dairy foods, ready-to-eat cereal, and orange and some other juices.
Clearly, vitamin D is not only vital for overall health, but may be important for reducing risk of colon cancer. Getting more vitamin D also may be a way to increase your chances of survival if you already have colon cancer. Be sure to ask your doctor to check your vitamin D level. If you are low, you can work with your health care provider to decide how best to get more vitamin D into your diet and into your body.
Sources
Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. "Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes." The American Journal of Clinical Nutrition 2006 84:18-28.
Fakih MG, Trump DL, Johnson CS, Tian L, Muindi J, Sunga AY. "Chemotherapy is linked to severe vitamin D deficiency in patients with colorectal cancer." International Journal of Colorectal Diseases 2009 24:219-224.
Giovannucci E. "Epidemiological Evidence for Vitamin D and Colorectal Cancer." Journal of Bone and Mineral Research 2007 22:V81-V85.
Gorham ED, Garland CF, Garland FC, Grant WB, Mohr SB, Lipkin M, Newmark HL, Giovannucci E, Wei M, Holick MF. "Optimal Vitamin D Status for Colorectal Cancer Prevention: A Quantitative Meta Analysis." American Journal of Preventive Medicine 2007 32:210-216.
Holick MF, Chen TC. "Vitamin D deficiency: a worldwide problem with health consequences." The American Journal of Clinical Nutrition 2008 87:1080S-1086S.
Vieth R. "Vitamin D and cancer mini-symposium: The risk of additional vitamin D." Annals of Epidemiology 2009 19:441-445.
Wei1 MY, Cedric F. Garland CF, Gorham ED, Mohr SB, Giovannucci E. "Vitamin D and Prevention of Colorectal Adenoma: A Meta-analysis." Cancer Epidemiology, Biomarkers & Prevention 2008 17:2958–2969.
Yetley EA, Brulé D, Cheney MC, Davis CD, Esslinger KA, Fischer PW, et al. "Dietary reference intakes for vitamin D: Justification for a review of the 1997 values." The American Journal of Clinical Nutrition 2009 89:719-727.
