Foods high in calcium may help prevent colon cancer. However, calcium supplements may have adverse health effects, especially in high amounts.
Colon cancer rates are higher in high-income countries, such as North America and most of Europe, and lower in low-income countries, such as much of Africa and South Asia. Moreover, when people migrate from low- to high-income countries, their rates of colorectal cancer increase towards the rates of their new country. This suggests that environmental factors may play a role in cancer development. In particular, researchers found that one in particular—a calcium-rich diet—may lower the risk.
Calcium Could Protect
In the study published in Nature Communications, researchers examined the effect of 97 dietary factors on the risk of colon cancer in more than 500,000 women over an average of 16 years.
Data analysis indicated that dairy products made of milk and yogurt—but not cheese and ice cream—help prevent colon cancer and that calcium is wholly or mostly responsible for the benefit. Based on the findings, eating an extra 300 milligrams (mg)—the content in a large glass of milk—may reduce the likelihood of colon cancer by 14 percent. Calcium intake from non-dairy sources, such as green, leafy vegetables, also showed a protective effect.
The statement added that more studies are needed before concluding that increasing dietary calcium is recommended for everyone.
While the study involved only women, the results should also apply to men, according to Chris Mohr, fitness and nutrition advisor at Garage Gym Reviews.
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“Both genders have the same digestive systems, so they come with similar risk factors for colorectal cancer,” he told The Epoch Times in an email. “Their dietary influences have the same effect, and the mechanisms by which calcium offers some protection are not gender-dependent.”
Why Dietary Calcium May Offer Protection
“We have some idea on why calcium has this effect,” added Papier in the statement. “It’s suggested that calcium might protect against bowel cancer by binding to bile acids and free fatty acids to form a type of a harmless ‘soap,’ which stops them from damaging the lining of our gut.” She explained that this soap has a cleansing effect, removing the accumulation of bile and fatty acids, which decreases their likelihood of causing harm.
In addition to the above indirect effect, calcium may also have a direct protective effect on colon tissue. The researchers cited studies that suggest it may reduce some mutations and other adverse changes in the colon that can lead to cancer.
“Other means of protection from dietary calcium may include improving the composition of gut microbiota through fermented dairy products like yogurt, which may enhance colon health,” Mohr said. “Non-dairy sources of calcium, such as kale and broccoli, also give us antioxidants and fiber, dietary elements that may further reduce cancer risk.”
He said that eating a variety of nutrient-dense foods is key to reducing the risk of colon and other types of cancer, as well as negative health outcomes.
Dietary Calcium Vs. Calcium Supplements
Since calcium-rich foods can help, it raises the question of whether calcium supplements may also help.
Calcium supplements are not advisable for other reasons as well, according to Catherine Gervacio, a registered nutritionist and diet consultant for WOWMD. These include a faster absorption rate of calcium and a propensity of calcium to cause kidney stones.
“Calcium from food is absorbed more gradually than calcium from supplements,” she told The Epoch Times in an email. “With supplements, calcium is released in large amounts into the bloodstream quickly. This sudden increase in calcium levels can possibly strain the kidneys or may contribute to calcium deposits in blood vessels, which increases the risk of kidney stones or heart disease.”
Getting calcium naturally from food is better and provides an adequate daily mineral allowance when added to a healthy diet because it contains antioxidants and other beneficial compounds that help prevent chronic disease, said Gervacio.
“Calcium from non-dairy foods has one limitation,” reported Natalie Reed, assistant professor of nutrition and the program director for California Baptist University’s master of science in integrative nutrition.
“These foods lack vitamin D, which is necessary for the absorption of calcium,” she told The Epoch Times in an email, explaining that vitamin D is derived from sun exposure and from consuming fortified dairy products. This means that a person who relies solely on non-dairy foods for calcium intake should be sure to get enough sunlight exposure.
“Based on experience, people over consume calcium with supplements, especially if they eat calcium-rich foods on a daily basis,” warned Gervacio. “Excessive calcium, especially when done for a long time, may increase the risk of adverse effects. With food, it’s harder to reach such excessive amounts because you’re limited by appetite and the variety of your diet.”
Reed agrees, urging consumers to be aware that excess calcium supplementation may lead to calcium toxicity.
“The recommended dietary allowance for adult men and women is 1,000 mg daily,” she said. “Calcium supplements should be taken in cases of deficiency, but the need should be supported by abnormal laboratory values and directed by your primary medical provider. However, dietary recommendations from a registered dietitian may help increase oral intake of the nutrient in cases of deficiency.” For instance, three large glasses of milk contain 900 mg of calcium, which, when added to a healthy diet, would provide an adequate daily mineral allowance.
Other Health Benefits of Dietary Calcium
Healthy foods rich in calcium have other wellness benefits.
Mohr added that calcium from dairy sources like milk and yogurt may promote weight management. Calcium foods may also help lower blood pressure due to their unique nutrient profiles, which include potassium and magnesium.
“Vegetable based calcium rich foods are high in fiber,” added Reed. “Aside from fiber’s significant importance in decreasing the risk for colorectal cancer, it is most often a non-digestible substance that strengthens the intestinal wall through digestion. Fiber is also a prebiotic that feeds gut microbiota, making it necessary for optimal gut health.”
