The #1 Best Food to Eat for Calcium, Says Science

What food comes immediately to mind when you think of building strong bones? Milk, of course. Mom probably poured you a glass at every meal when you were a kid to help you grow. But you may feel that milk isn't doing your body as many favors in your older age if you're one of the 36 percent of Americans who has lactose malabsorption and may experience diarrhea, gas, and bloating after sipping dairy. While there are obvious ways around these common side effects—like lactose-free dairy products—let's spill the milk and look to a lesser-known source of calcium that'll give you even more of this bone-building mineral than cow's milk: Sardines.

A 3-ounce serving of sardines contains about 325 milligrams (mg) of calcium compared to about 276 mg and 299 mg for whole milk and non-fat milk, respectively, according to the National Osteoporosis Foundation and the National Institutes of Health. That's about a third of the Recommended Daily Intake (RDI) of 1,000 mg for most adults. The RDI for women over 50 and men over 70 is 1,200 mg.

Breaking Down Bones

Calcium is a critical mineral for your body. It plays a role in proper muscle function, blood clotting, hormone secretion, and blood vessel contraction and dilation and, most notably, calcium makes up much of the structure of your bones, according to The Journal of Clinical Endocrinology and Metabolism.

Your bones aren't set in stone, so to speak; they are constantly breaking down and being rebuilt, unbeknownst to you.

Unless you keep supplying your body with calcium from the foods you eat and stressing your bones with exercise, your body may make less bone or lose bone and weaken with age. That's known as the bone disease osteoporosis, a reduction in bone density that often leads to fractures. To learn more about this debilitating disease, read The #1 Cause of Osteoporosis, According to Science.

Building Up Bones

Eating sardines builds bone strength because you eat the whole fish, including the soft bones, the source of the all-important calcium. Some researchers have noted that Japan has less incidence of osteoporosis than the United States even though the Japanese consume far less dairy than Americans do because of the high fish consumption in Japan and other Asian countries.

Other nutrients in fish, such as vitamin D and protein, play a role in bone building, as well. Vitamin D is essential for calcium absorption and bone mineralization, which is what builds denser, stronger bones. Oily fish like sardines are among the best dietary sources of vitamin D3, which is believed to be the most effective of the two types of vitamin D for bone health, according to a 2010 report in the journal Nutrients. (Read more: The #1 Best Vitamin D Supplement to Take, Says Dietitian.) A can of sardines provides a bit more than 40% of your daily vitamin D needs, according to the USDA.

Protein, a Plus

Sardines, like bone-building milk, deliver a healthy dose of muscle-growing protein, too, 25 grams per 3-ounce serving of fish. That's nearly half of the amount of protein a 50 year-old sedentary woman weighing 140 pounds needs in a day, according to the Harvard Health Blog.

Clinical studies have demonstrated the importance of protein in protecting against osteoporosis. Proteins, after all, make up about a third of your bone mass.

One large investigation based on Women's Health Initiative clinical trials and observational studies monitored more than 144,000 postmenopausal women over a six-year period. The researchers, reporting in the American Journal of Clinical Nutrition discovered that higher protein consumption was linked to significantly higher bone density in the hip, spine, and total body and also lower risk of forearm fractures in the women.

Other Benefits

There are other good reasons to get some of your calcium from sardines. For one, in addition to calcium, vitamin D, and protein, you'll be consuming more heart-healthy omega-3 fatty acids, which are found in abundance in oily fish like sardines.

A 2021 study in Clinical Nutrition highlights another plus: diabetes prevention. In a study of elderly people with prediabetes, researchers found that just two servings of sardines per week for 12 months provided enough calcium, vitamin D, and omega-3s to significantly reduce risk of type 2 diabetes. Of the group of people that included sardines in their diet, 37% were at high risk of progressing to diabetes at the start of the study. By the end of the trial, only 8% remained at very high risk.

Tip: While you're at the grocery store stocking up on canned sardines, fill your cart with these 20 Best Calcium-Rich Foods That Aren't Dairy.

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