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New Study Shows Vitamin D May Reduce Colon Cancer Risk By 58%
Colon cancer rates are increasing at alarming rates—especially among younger adults. While this cancer is still considered an age-related disease, environmental and lifestyle factors can spur or hasten the progression. Data indicate that around 50% of colon cancer cases1 can be prevented through lifestyle modifications.
One key area to focus on is your vitamin D status. Decades of data indicate that vitamin D may be protective against colorectal cancers, whereas low levels of the vitamin are a risk factor.
In order to get a complete picture of this complex relationship, researchers recently reviewed data from 50 studies and over 1.3 million participants to reveal the role of vitamin D in colorectal cancer prevention2. Here's what you need to know.
Vitamin D status & intake likely reduce colorectal cancer risk
The researchers found that low vitamin D levels are strongly linked to a higher risk of developing colorectal cancer.
Among the 50 studies researchers thoroughly reviewed, these are the general findings from the most notable ones:
- This meta-analysis3 showed that those with higher levels of vitamin D (measured via a blood test) had a 39% lower risk of colorectal cancer compared to those with lower levels. And when vitamin D levels were tracked over time, people with higher vitamin D levels had a 20% reduced risk of cancer.
- A landmark study4 published back in 1996 found that women with the highest vitamin D intake were 58% less likely to develop colorectal cancer than those with the lowest intake.
- In the Danish "Diet, Cancer and Health" study5, vitamin D seemed to have enhanced protective effects against colon cancer risk for those with a genetic risk.
- In the Iowa Women's Health Study, women who took calcium and vitamin D supplements6 had a 15% lower risk of developing colorectal cancer compared to those who didn't take any supplements.
- In this study, increasing vitamin D intake reduced the risk of adenomas (a polyp that may develop into cancer).
- In a Canadian study7, vitamin D supplements reduced the risk of polyps by 33% and high-risk polyps by 43%.
How does vitamin D protect against cancer?
While many studies highlighted in this review showed protective benefits of vitamin D, most were not able to pinpoint the exact mechanisms through which these benefits occurred.
However, lab, animal, and other human studies indicate that the active form of vitamin D in your body (calcitriol) may target colon cancer progression in a variety of ways2:
- Slowing down the growth of cancer cells
- Triggering cell death
- Supporting a balanced gut microbiome
- Keeping intestinal cells healthy
- Reducing gut inflammation
Most people have low vitamin D levels
So yes, vitamin D can be protective against colorectal cancer in addition to aiding everything from immunity to mood and cellular aging.
But most people have very low levels of the vitamin. A 2025 study that looked at the impact of vitamin D levels and muscle mass of over 5,600 U.S. adults found that:
- 42% were vitamin D deficient (blood levels less than 20 ng/mL)
- 37.6% had vitamin D insufficiency (blood levels between 20 and 30 ng/mL)
- ~20% had sufficient vitamin D status (blood levels 30 ng/mL or higher)
That's right: Nearly 80% of folks had low vitamin D levels.
Researchers of this review emphasized the importance of having your vitamin D levels in the 30–40 ng/mL, and many people would benefit from having vitamin D status of 50 ng/mL. So, how do you get there?
Increasing your vitamin D levels
Vitamin D is naturally found in some foods (like cod liver oil, trout, and salmon) or in fortified foods (like milk and eggs). Check out this list of 12 healthy foods that can help you up your vitamin D intake.
However, many people (especially those with low vitamin D levels) would benefit from a high-quality vitamin D supplement.
A good rule of thumb is to look for supplements that provide 2,000-5,000 IU of vitamin D3 (not D2) and take it daily. You should start to see your vitamin D levels start to improve within a few months.
We rounded up our top picks for vitamin D supplements here and the best at-home vitamin D tests so you can check your levels whenever you like.
The takeaway
Vitamin D status is just one lifestyle factor connected to your colorectal cancer risk—and one that's pretty easy to improve with supplementation. You can further reduce your risk by incorporating these six other lifestyle habits into your routine.
And remember, regular screenings (starting at age 45) are essential for early detection and treatment of any concerning findings.
7 Sources
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9836915/
- https://www.mdpi.com/2072-6643/17/8/1351
- https://www.tandfonline.com/doi/full/10.1080/10408398.2021.1939649
- https://academic.oup.com/jnci/article-abstract/88/19/1375/991733
- https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228635
- https://www.tandfonline.com/doi/abs/10.1080/01635581.2018.1539188
- https://www.sciencedirect.com/science/article/abs/pii/S0091743520300967