Large international study links blood vitamin D levels to colorectal cancer risk

June 14, 2018, American Cancer Society
Credit: CC0 Public Domain

A new study authored by scientists from the American Cancer Society, the Harvard T.H. Chan School of Public Health, the U.S. National Cancer Institute, and more than 20 other medical centers and organizations finds that higher circulating vitamin D concentrations are significantly associated with lower colorectal cancer risk. This study strengthens the evidence, previously considered inconclusive, for a protective relationship. Optimal vitamin D concentrations for colorectal cancer prevention may be higher than the current National Academy of Medicine recommendations, which are based only on bone health. The study appears online in the Journal of the National Cancer Institute.

Vitamin D, known for its role in maintaining , is hypothesized to lower colorectal risk via several pathways related to cell growth and regulation. Previous prospective studies have reported inconsistent results for whether higher concentrations of circulating 25-hydroxyvitamin D, the accepted measure of vitamin D status, are linked to lower risk of colorectal cancer. The few randomized clinical trials of vitamin D supplementation and colorectal cancer completed thus far have not shown an effect; but study size, supplementation duration, and compliance may have contributed to their null findings.

"To address inconsistencies in prior studies on vitamin D and to investigate associations in population subgroups, we analyzed participant-level data, collected before colorectal cancer diagnosis, from 17 prospective cohorts and used standardized criteria across the studies," said Stephanie Smith-Warner, Ph.D., an epidemiologist at the Harvard T.H. Chan School of Public Health and co-senior author on the article. The analysis included over 5,700 colorectal cancer cases and 7,100 controls from the United States, Europe, and Asia. A single, widely accepted assay and laboratory was used for new vitamin D measurements and calibration of existing vitamin D measurements. "In the past, substantial differences between assays made it difficult to integrate vitamin D data from different studies," explained Regina G. Ziegler, Ph.D., a National Cancer Institute epidemiologist and co-senior author on the article. "This calibration approach enabled us to systematically explore risk over the broad range of vitamin D levels seen internationally."

Compared to participants with circulating vitamin D concentrations considered sufficient for bone , those with deficient concentrations of vitamin D had a 31% higher risk of colorectal cancer during follow-up, which averaged 5.5 years (range: 1—25 years). Similarly, concentrations above bone health sufficiency were associated with a 22% lower risk. However, risk did not continue to decline at the highest concentrations. These associations persisted even after adjusting for known colorectal cancer risk factors. Protective associations were seen in all subgroups examined. However, the association was noticeably stronger in women than men at concentrations above bone health sufficiency. The lifetime risk of colorectal cancer is 4.2% (1 in 24) in women and 4.5% (1 in 22) in men. Colorectal cancer is the third most common cancer and third leading cause of cancer-related deaths in both men and women in the United States, with about 140,250 new cases and 50,630 deaths expected during 2018.

"Currently, health agencies do not recommend vitamin D for the prevention of colorectal cancer," said Marji L. McCullough, ScD, American Cancer Society epidemiologist and co-first author of the study. "This study adds new information that agencies can use when reviewing evidence for vitamin D guidance and suggests that the concentrations recommended for bone health may be lower than would be optimal for prevention."

Vitamin D can be obtained in the diet, particularly from fortified foods, from supplements, and from sun exposure. Experts recommend D be obtained through diet whenever possible because excessive ultraviolet radiation is a major risk factor for skin cancer.

Explore further: Genes involved in vitamin D generation and destruction may influence colorectal cancer risk in African-Americans

More information: Circulating Vitamin D and Colorectal Cancer Risk: An International Pooling Project of 17 Cohorts, Journal Of The National Cancer Institute (2018). DOI: 10.1093/jnci/djy087

Related Stories

Genes involved in vitamin D generation and destruction may influence colorectal cancer risk in African-Americans

October 29, 2012
African-Americans are more likely than non-Hispanic whites to have and die from colorectal cancer. Changes in the DNA sequence of genes that affect how the body makes and destroys vitamin D modify the risk for colorectal ...

Higher Vitamin D levels may be linked to lower risk of cancer

March 7, 2018
High levels of vitamin D may be linked to a lower risk of developing cancer, including liver cancer, concludes a large study of Japanese adults published by The BMJ today.

Proinflammatory diet linked to increased colorectal cancer risk

January 19, 2018
(HealthDay)—Proinflammatory diets are associated with increased colorectal cancer risk for men and women, according to a study published online Jan. 18 in JAMA Oncology.

Vitamin D protects against colorectal cancer by boosting the immune system

January 15, 2015
A new study by Dana-Farber Cancer Institute investigators demonstrates that vitamin D can protect some people with colorectal cancer by perking up the immune system's vigilance against tumor cells.

Recommended for you

Removing sweets from checkouts linked to dramatic fall in unhealthy snack purchases

December 18, 2018
Policies aimed at removing sweets and crisps from checkouts could lead to a dramatic reduction to the amount of unhealthy food purchased to eat 'on the go' and a significant reduction in that purchased to take home, suggests ...

Junk food diet raises depression risk, researchers find

December 18, 2018
A diet of fast food, cakes and processed meat increases your risk of depression, according to researchers at Manchester Metropolitan University.

Children of problem drinkers more likely to marry someone with a drinking problem: study

December 18, 2018
Children of parents who have alcohol use disorder are more likely to get married under the age of 25, less likely to get married later in life, and more likely to marry a person who has alcohol use disorder themselves, according ...

Folate deficiency creates hitherto unknown problems in connection with cell division

December 17, 2018
Folate deficiency creates more problems in connection with DNA replication than researchers had hitherto assumed, researchers from the University of Copenhagen show in a new study. Once a person lacks folate, the damage caused ...

A co-worker's rudeness can affect your sleep—and your partner's, study finds

December 14, 2018
Rudeness. Sarcastic comments. Demeaning language. Interrupting or talking over someone in a meeting. Workplace incivilities such as these are becoming increasingly common, and a new study from Portland State University and ...

Study shows magnesium optimizes vitamin D status

December 14, 2018
A randomized trial by Vanderbilt-Ingram Cancer Center researchers indicates that magnesium optimizes vitamin D status, raising it in people with deficient levels and lowering it in people with high levels.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.