Cases of colorectal cancer are increasing among younger people. In fact, according to the American Cancer Society, in 2019 fully 20% of diagnosed cases occurred in those younger than 55 — twice the rate of 1995.

What's driving the increase?

Theories include increasingly sedentary lifestyles, an epidemic of excess weight and obesity, heavy alcohol use, and high-fat, low-fiber diets with lots of processed meats.

Researchers have also looked at environmental factors such as microplastics.

But one thing stands out as an easy-to-fix cause of the increased risk: a decreasing amount of calcium in the American diet.

A new study of more than 80,000 people — which appeared in the journal Nutrients — found that a lot of them lacked enough calcium from food or supplements.

And a study in JAMA Network Open shows that higher calcium intake from food reduces the risk of colon cancer significantly among older people. There's no reason to doubt it could do the same for younger adults.

Up to age 50, you're aiming to get 1,000 mg of calcium daily; for women 50 and older and men 70 and older, the target is 1,200 mg.

Food is the best way to get enough calcium; supplements should only be taken with the consent of your doctor. And don't take more than 600 mg daily.

Which foods deliver the most calcium?

Canned salmon, sardines, and herring along with kale, collard greens, bok choy, tofu, nuts, seeds, beans, and fortified nondairy products are good sources. If you eat dairy, opt for low or non-fat products without added sugars.

For more help increasing the calcium in your diet, check out the "What to Eat When Cookbook."