Scientists suggest that the calcium found in milk plays a significant role in reducing the risk of colorectal cancer. Recent research also reinforced the link between alcohol consumption and an increased risk of the disease.
Key Highlights:
- Consuming 300 mg of calcium daily—roughly the amount in a single cup of milk—may lower the risk of colorectal cancer by almost 20%, according to a recent study.
- The study further determined that diets high in red and processed meats, as well as alcohol, contribute to a greater risk of developing colorectal cancer. In contrast, calcium, fiber, and essential vitamins provide protective benefits.
- Researchers also found no evidence connecting sugar intake to colorectal cancer, debunking the common belief that sugar directly contributes to cancer development.
The Protective Power of Calcium Against Colorectal Cancer
Recent research suggests that consuming at least 300 milligrams (mg) of calcium daily—equivalent to an 8-ounce glass of milk—may lower the risk of colorectal cancer by nearly 20%. This conclusion comes from one of the most comprehensive studies on diet and colorectal cancer, which analyzed dietary habits and health data from over half a million women and examined nearly 100 different food products and nutrients.
“These results are compelling enough to encourage people to increase calcium intake in their diets, which would probably have other major benefits to bone health,” states Suneel Kamath, MD, a gastrointestinal oncologist at the Cleveland Clinic in Ohio, who was not involved in the study.
Rising Rates of Colorectal Cancer Among Younger Adults
In 2024, over 100,000 new cases of colon cancer and nearly 50,000 new cases of rectal cancer were reported in the United States. While the overall incidence of colorectal cancer has slightly declined in the past 15 years, cases among adults under 55 have been increasing since the mid-1990s. Researchers estimate that more than half of all colorectal cancer cases could be prevented through lifestyle and dietary changes, including increased calcium consumption.
Examining the Link Between Diet and Colorectal Cancer Risk
To understand the impact of diet on colorectal cancer risk, scientists analyzed dietary data from 542,000 women enrolled in the Million Women Study, a large-scale research initiative focused on women’s health. Participants provided detailed information about their food and beverage intake, with a subset completing a 24-hour diet recall assessment. Over an average follow-up period of 16.6 years, more than 12,000 women were diagnosed with colorectal cancer.
Key findings from the study included:
- Calcium-rich foods and beverages, including dairy products like milk and yogurt, were linked to a lower risk of colorectal cancer.
- Both dairy-based and non-dairy sources of calcium, such as leafy green vegetables, appeared to have a similar protective effect, suggesting calcium itself plays a critical role in cancer prevention.
- Regular alcohol consumption was strongly associated with a heightened colorectal cancer risk. Consuming 20 grams of alcohol per day—equivalent to about one and a half glasses of wine—was linked to a 15% increased risk.
- Red and processed meats contributed to an increased risk of colorectal cancer. A daily intake of 30 grams (approximately 1 ounce) above the average consumption was linked to an 8% higher risk.
- Other nutrients, including riboflavin, magnesium, phosphorus, and potassium, also appeared to offer protective benefits against colorectal cancer. Additionally, consuming whole grains, fiber, carbohydrates, breakfast cereals, fruit, and vitamin C was associated with reduced risk.
Understanding Calcium’s Protective Mechanism
Lead author Keren Papier, PhD, a senior nutritional epidemiologist at the University of Oxford, suggests a potential mechanism for calcium’s protective role against colorectal cancer.
“It’s suggested that calcium might protect against bowel cancer by binding to bile acids and free fatty acids to form a type of harmless ‘soap,’ which prevents them from damaging the lining of our gut. This ‘soap’ effect helps these acids to be expelled from the gut, reducing their potential to cause harm,” explains Dr. Papier.
Would These Findings Apply to Men?
Dr. Kamath emphasizes that while this study focused on women, the results likely apply to men as well, as risk factors for colorectal cancer do not significantly differ by gender.
“The study also confirms that alcohol, red meat, and processed meats are carcinogenic for colorectal cancer, which has been observed in other research,” Kamath adds. “Hopefully, this additional information will encourage more people to limit or eliminate alcohol consumption.”
Furthermore, the study reinforces the idea that diets rich in fruits, fiber, whole grains, and essential vitamins can significantly reduce colorectal cancer risk.
The Role of Calcium Supplements and Fortified Foods
The study found that many women consumed well above the recommended daily calcium intake—often by an additional 700 mg. Some of this intake likely came from calcium-fortified foods or dietary supplements.
However, the study authors caution that more research is needed to determine whether calcium supplements or fortified foods provide the same protective effects as naturally occurring dietary calcium.
“I would not recommend calcium supplements based on this study, as it only examined dietary calcium intake,” says Dr. Kamath. “Additionally, we know that excessive calcium intake can increase the risk of cardiovascular disease and heart attack. It is difficult to consume excess calcium from diet alone, but taking supplements makes it easy to exceed safe levels.”
Sugar’s Role in Colorectal Cancer Risk
Another significant finding from the study challenges the common belief that sugar contributes to cancer development.
“Interestingly, people with diets higher in total sugars had lower colorectal cancer risk,” says Dr. Kamath. “Now, I wouldn’t recommend increasing sugar intake, but these data clearly indicate that sugar does not cause cancer—and it’s likely that sugar intake has no direct influence on colorectal cancer risk.”
Practical Steps to Reduce Colorectal Cancer Risk
Dr. Papier suggests that individuals looking to lower their risk should focus on maintaining a healthy weight, quitting smoking, and adopting a diet that reduces alcohol and processed meat intake while incorporating more calcium-rich foods.
“The findings from our study suggest that alongside cutting down on alcohol and red and processed meat intake, calcium could also play a key role in lowering the risk of bowel cancer,” says Dr. Papier.
Dr. Kamath also recommends following a Mediterranean-style diet, which emphasizes vegetables, whole grains, fiber, lean proteins like fish and poultry, and limited red and processed meats.
“The reality is, we figured out the best diet for ourselves hundreds of years ago, and it isn’t going to change,” Kamath states. “The key is consistency—people should focus on sustaining a heart-healthy diet for the long term rather than chasing after the latest superfood or supplement.”
The Bottom Line
This extensive study underscores the importance of dietary choices in preventing colorectal cancer. The findings highlight calcium’s potential protective benefits while reinforcing the risks associated with alcohol and processed meat consumption. While more research is needed to explore the effects of calcium supplements, experts agree that increasing dietary calcium intake through natural sources can contribute to overall health and may reduce cancer risk. By adopting a balanced diet rich in whole foods and essential nutrients, individuals can take proactive steps toward long-term well-being.