Increased Calcium Intake May Lower Colorectal Cancer Risk, According to NIH Study
A recent investigation involving 471,000 adults indicates advantages from both dietary and supplemental sources of calcium.
Increasing calcium consumption may lower the risk of colorectal cancer, which is the third leading cause of death in the United States, according to new findings from the National Institutes of Health (NIH).
The study confirmed that the advantages of higher calcium intake were consistent irrespective of the source of calcium or the specific tumor site in the colon or rectum.
Dairy, Supplements, and Diet
Researchers conducted surveys with 3.5 million AARP members aged 50 to 71 in six U.S. states and two metropolitan areas between October 1995 and May 1996. “To our knowledge, this was the largest cohort study” exploring the connection between calcium intake and colorectal cancer risk, the researchers reported.
Following exclusions for factors such as existing cancer, poor health, or unreliable data, the final analysis encompassed over 470,000 individuals who were cancer-free at the beginning of the study.
Participants were divided into two groups: one consuming 400 mg of calcium daily and another consuming approximately 2,000 mg per day. The latter group’s calcium intake exceeded the current NIH recommendation of 1,000 to 1,200 mg daily for individuals aged 19 and older.
This reduction in risk was noted for calcium derived from all sources (8 percent lower risk), dietary sources (16 percent lower risk), and supplements (20 percent lower risk). For every additional 300 mg of calcium consumed daily, the risk also decreased. A large glass of milk—approximately 8 ounces—contains about 300 mg of dietary calcium.
Related Stories
Dairy products contributed approximately 42 percent of overall calcium intake, non-dairy foods made up about 34 percent, and supplements accounted for around 24 percent.
Why Calcium May Show Benefit
The exact reasons behind calcium’s potential benefits remain unclear, although researchers propose several hypotheses.
One theory suggests that dairy calcium can bind to certain bile acids and fatty acids in the colon, which might reduce their cancer-promoting properties. Additionally, the researchers noted that many dairy products are rich in vitamin D, which helps enhance calcium absorption in the digestive tract.
Researchers posit that the lower colon could be where calcium’s protective effects are most pronounced, potentially aiding proper cellular growth and reducing cancer risk.
“This means reducing alcohol intake and minimizing consumption of red and processed meats while increasing fruit, vegetable, and whole grain intake,” Lowes added.
Study Limitations
The authors recognized limitations in the study, noting that dietary data was only collected at the study’s outset, preventing an analysis of calcium intake changes over time.
They also acknowledged the possibility of inaccurate dietary data due to reliance on self-reported questionnaires.
Nevertheless, they underscored that the study’s substantial participant pool and over 20-year follow-up period provide strong evidence for the relationship between calcium intake and colorectal cancer risk, while emphasizing the need for further research among racial and ethnic minority populations.
