Vitamin D and Colon Cancer: What's the Link?

Understanding More About Vitamin D Can Help You Reduce Your Colon Cancer Risk

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poached egg on bread. Jodie Louie/Moment/Getty Images

Do you know your Vitamin D levels? If not, you may want to find out as your results could help inform you of your colon cancer risk. Recent observational studies have found links between 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 if you have less vitamin D in your diet and lower levels of vitamin D in your body.

How Much Vitamin D Do I Need?

Several health experts believe that for optimal colon cancer prevention, you 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. Vitamin D should come from diet, dietary supplements, or from a combination of the two. The medical community is providing further support for increased recommendations for vitamin D. 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.

Vitamin D and Colon Cancer Survival

But before you load up on vitamin D, be sure to talk to your doctor. While you could truly be deficient in vitamin D and need more of the nutrient, you might also not need, or benefit from, extra vitamin D. 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

You would think that a normal part of healthcare would be to check blood levels of vitamin D on a regular basis.

Unfortunately, this is not the case. If you're from the United States, you may not get enough vitamin D and you may not be aware of it. 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). Because the recommended dietary allowance (RDA) for vitamin D is low, you may need a dietary supplement to make sure you get enough vitamin D that exceeds the recommended amount. If your doctor says your vitamin D 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. That is the risk of deficiency is significantly greater than risk of toxicity (getting too much vitamin D).

  • Good food sources of vitamin D include:
    • fatty, cold water fish, such as tuna, salmon, mackerel, and sardines
    • cheese
    • egg yolks
    • 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 and other chronic conditions. Getting more vitamin D also may be a way to increase your chances of survival if you already have colon cancer. But, 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.


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