Study Reveals a Glass of Milk a Day Could Help Lower Women's Risk of Colorectal Cancer Here's why
A new study found that getting a glass of milk's worth of calcium per day, whether or not it comes from dairy, can lower colorectal cancer risk in women
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- New research suggests that drinking a cup of milk a day could lower colorectal cancer risk in women.
- More specifically, the study linked the lower risk to a daily intake of 300 milligrams of calcium from food.
- Experts say maintaining a healthy diet and lifestyle, and getting screened regularly, will also reduce the risk of colorectal cancer.
Getting a glass of milk’s worth of calcium a day could lower colorectal cancer risk in women, a new study published in Nature Communications found.
Colorectal cancer, a malignancy that grows in the colon or rectum, is the fourth leading cause of cancer death for women, and the disease is becoming more common among people under 65.
The new study revealed a link between a daily intake of 300 milligrams of calcium from food—the amount in an 8-ounce glass of milk—and a 17% reduction in women’s colorectal risk.
“Calcium was found to have a similar protective effect in both dairy and non-dairy sources,” Keren Papier, PhD, a senior nutritional epidemiologist at the University of Oxford, who led the study, told Health. However, “we don’t know whether calcium supplements would have the same effect as calcium from food appears to,” she added.
According to Christopher Lieu, MD, co-director of gastrointestinal medical oncology at the University of Colorado School of Medicine, who was not involved with the research, the new study adds to a growing body of research showing that what a person eats plays a big role in their risk for colorectal cancer.
“There are many factors that contribute to a person’s risk of developing colorectal cancer,” Lieu told Health. “We are seeing a trend where healthy diets in general appear to have an impact.”
More Calcium Reduces Cancer Risk
In the largest single study ever conducted on the link between diet and colorectal cancer, Papier and her team examined the diet habits of more than 540,000 women in the U.K. who were part of The Million Women Study, one of the largest-ever prospective studies on women’s health.
The Million Women Study surveyed each woman about her demographics, diet, and lifestyle every three to five years for an average of 16 years. The more than half-million women included in the new study were an average age of 56 when the study started in 1996.
The researchers evaluated whether or not 97 dietary factors—including red meat and dairy consumption—appeared to affect the risk of colorectal cancer. At the end of the study, about 12,000 had developed colorectal cancer.
Epidemiological studies are often limited in that they can show correlation but not causation—that is, that something that appears to affect a person’s risk of disease (like calcium intake) actually does.
However, the new study attempted to get closer to revealing cause and effect by combining the questionnaire data collected from the women with their genetic variants. This method, called Mendelian Randomization, allowed the researchers to zoom in on dairy and then calcium, specifically, offsetting the chances any results could be caused by something else, said Veronika Fedirko, PhD, MPH, a molecular cancer epidemiologist at the University of Texas MD Anderson Cancer Center.
“The study’s findings were especially reassuring,” Fedirko told Health.
The researchers found that every additional 300 milligrams of calcium daily from foods and drinks was associated with a 17% reduction in colorectal cancer risk.
The idea that calcium and dairy may lower colorectal cancer risk isn’t new. Multiple studies worldwide, including a meta-analysis published in 2019 and another in 2020, have linked dairy consumption to a lower risk of colorectal cancer in both males and females. These studies also consistently linked diets high in red or processed meat and alcohol to higher rates of colorectal cancer.
“We think that calcium may protect against colorectal cancer by attaching to bile acids and free fatty acids in the colon, which helps reduce their cancer-causing potential,” Papier said.
Bile acids, produced by the liver and stored in the gallbladder, help digest fats and oils. An excess of these acids has been linked to an increased risk of some cancers.
Calcium also helps regulate molecular processes in the body that are involved with colorectal carcinogenesis, when cells become tumors. Fedirko said it likely plays a role in reducing the risk of colorectal cancer in both biological men and women.
However, the connection between dairy intake and other cancer types "is mixed,” Mary Playdon, PhD, MPH, an assistant professor of nutrition and integrative physiology at the University of Utah, told Health.
Studies have repeatedly found evidence that dairy may lower the risk of breast cancer but have reached differing conclusions about whether dairy promotes or staves off prostate cancer.
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While growing evidence suggests calcium may be protective against colorectal cancer, experts say the key is eating an overall healthy diet.
“It’s not just one factor, but many that drive the risk higher or lower,” Lieu, of the University of Colorado, said.
Fedriko agreed. “While calcium plays a protective role, focusing solely on increasing calcium intake without considering other dietary and lifestyle factors may not be enough to significantly reduce a person’s colorectal cancer risk,” she said.
Mounting research shows that a healthy diet that’s low in alcohol, sugar, red meat, processed food, and calcium and rich in fiber, whole grains, and produce can significantly reduce a person’s risk of colorectal cancer.
Aside from that, “the best thing someone can do to lower their risk of developing cancer is stop smoking, maintain a healthy weight, and attend screening if available,” Papier said.
The American Cancer Society currently recommends people start regular screening for colorectal cancer at age 45 unless they have a personal or family history of the disease. Newer stool-based tests can be used for screening, followed by a colonoscopy if the stool-based test flags any concerns.
Jani Hall
Jani Hall is a news editor for Health with a background in health, science, and investigative reporting. Previously, she wrote full time about parenting issues for the app Parent Lab. Before that, she worked as a reporter for National Geographic covering wildlife crime and exploitation.
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This story originally appeared on: Health News - Author:Kaitlin Sullivan
