Getting 300 milligrams of calcium each day — the amount found in an 8-ounce glass of milk — may reduce the risk of colorectal cancers by nearly one-fifth, according to new research. These findings are part of the largest single study on diet and colorectal cancer, which included over half a million women and examined nearly 100 food products and nutrients.

Colorectal cancer is becoming more prevalent in younger adults. In 2024, there were over 100,000 new cases of colon cancer and almost 50,000 new cases of rectal cancer in the United States. While the overall incidence of colorectal cancer has slightly declined over the past 15 years, rates among adults under 55 have gradually risen since the mid-1990s. Research suggests that more than half of all colon cancer cases are preventable.

Calcium’s Protective Effects

To explore the link between diet and the risk of colorectal cancer, researchers analyzed dietary data from over 542,000 women who participated in a large prospective study on women’s health. The women completed comprehensive surveys about their food and drink consumption, and a smaller subset provided a 24-hour diet assessment. Participants were followed for an average of 16.6 years, during which more than 12,000 women were diagnosed with colorectal cancer.

Key findings included:

• Foods and drinks rich in calcium, such as milk and yogurt, were linked to a lower risk of colorectal cancer.
• Both dairy and nondairy sources of calcium had similar protective effects, suggesting calcium itself may be the main factor.
• There was a clear connection between alcohol consumption and increased colorectal cancer risk, with moderate alcohol intake associated with a significant risk increase.
• Consumption of red and processed meat was linked to higher colorectal cancer risk, with increased intake correlated to an elevated risk.
• Certain nutrients, including riboflavin, magnesium, phosphorus, potassium, and dietary fiber, were associated with a reduced risk.

Research suggests that calcium may protect against bowel cancer by binding to bile acids and free fatty acids, forming a harmless substance that prevents damage to the gut lining.

Implications for Men and Dietary Choices

The study’s findings are likely applicable to men, as the risk factors for developing colorectal cancer are expected to be similar across genders. The study also reaffirms that alcohol, red meat, and processed meats are linked to colorectal cancer risk.

It’s crucial to consider whether calcium supplements or calcium-fortified foods offer the same benefits as dietary calcium. Most women in the study consumed above the recommended calcium levels, which may include added calcium from supplements. However, more research is needed to establish whether supplements provide the same protective effects.

Interestingly, the study found no link between sugar intake and an increased risk of colon cancer, indicating that sugar does not contribute to cancer development.

Reducing Your Risk for Colorectal Cancer

Maintaining a healthy weight and quitting smoking are among the best ways to lower your risk of bowel cancer. The findings suggest that, alongside reducing alcohol and red and processed meat intake, calcium could play an important role in lowering colorectal cancer risk.

The optimal diet for reducing colorectal cancer risk is heart-healthy, such as the Mediterranean diet, which emphasizes vegetables, whole grains, lean meats, fish, beans, and fiber, while limiting red meat and processed foods. The key to long-term health lies in consistently following a nutritious diet rather than chasing after the latest superfoods or supplements.