Vitamin D and Cancer Prevention

Last updated: August 2022

As knowledge of cancer evolves, so do treatment and prevention methods. Some researchers focus on fighting cancer already in a person's body. Others focus on figuring out things that could help stop or slow cancer before it happens.

One of the prevention methods that researchers have been looking into is vitamin D. Evidence suggests that vitamin D can play an anti-cancer role, especially in bladder cancer. However, there are still gaps in our understanding of how that might work.1,2

What is vitamin D?

Vitamin D is a fat-soluble vitamin that you can get through diet and supplements. You can also get it through sun exposure, which gives vitamin D its nickname "the sunshine vitamin." Many organs and tissues in your body have receptors for vitamin D. All the vitamin D that comes from or through your body passes through the liver and kidneys to become "biologically active." After that happens, you can gain its benefits.2,3

Primary sources and forms of vitamin D

There are two main forms of vitamin D supplements: D2 and D3. Your body naturally produces both from sun rays. Vitamin D2 is also produced in plants and fungi, and vitamin D3 is produced in animals.3

Some sources of vitamin D in food are:3

  • Fatty fish and fish liver oils (best food source)
  • Egg yolks
  • Cheese
  • Mushrooms
  • Foods fortified with vitamin D, like cereal or milk

The sunshine vitamin

Vitamin D produced in the skin from sun rays is your body's main source of vitamin D. However, many people have levels of vitamin D that are too low. This may be because they live in a place without a lot of sunlight or are inside most of the time.3

Also, people with darker skin can have difficulty getting enough vitamin D. This happens because melanin, the pigment that makes skin darker, acts like a cover on their skin. Their vitamin D production from the sun is lower, but so are the damaging effects of sunlight (like skin cancer).1,3

How does vitamin D relate to cancer?

Higher pre-cancer levels of vitamin D have been linked to lower colorectal and bladder cancer risk. Some of vitamin D's effects on the body are great for slowing tumor growth, including:1,2

  1. Reducing inflammation
  2. Slowing the production of new blood vessels
  3. Causing unhealthy cells to die

As of right now, though, there is no specific support from a health institution for vitamin D as cancer prevention. This is because more research needs to be done on its effects and how it works to see if vitamin D is safe and effective for everyone. Future research topics include:1

  • Cancer survival rates
  • The types of tumors vitamin D could help
  • How it interacts with other factors, like genetics
  • How it affects cancer risk in people of color

Consult your doctor first

Before taking vitamin D supplements, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs. Talk to your care team about whether a vitamin D supplement is safe and effective for you.

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