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The most plentiful mineral in the body, calcium accounts for 1.5 to 2 percent of our overall weight. Our bones and teeth store 99 percent of the body’s calcium. The other 1 percent is dispersed throughout the body, where it has a hand in muscle contraction, blood clotting, hormone release, and nerve transmission.

Because calcium is key to the body’s structure and its function, demand for the mineral is high. “We have a mandatory calcium loss of 500 mg a day, just being alive,” says functional-medicine practitioner Gregory Plotnikoff, MD. “If we don’t have at least that much calcium in our diet, we’ll develop a deficit.”

Our bones and teeth store 99 percent of the body’s calcium.

Calcium is fickle. The body needs vitamin D to absorb it, and vitamins K1 and K2 to accumulate and store calcium in the bones. Vitamin D is the leader here. “Upping your body’s vitamin D levels from 20 to 30 ng/ml [nanograms per milliliter] will increase the amount of calcium you absorb by 65 percent,” Plotnikoff says.

But vitamins K1 and K2 are also necessary for bone health. Due in part to nutrient-poor soil, vitamin K is getting harder to come by in the Western diet, he adds, which is why so many calcium supplements now contain K2 alongside vitamin D.

Calcium can be easily hijacked ­before it reaches the bones. Food components such as oxalates (found in peanuts, sweet potatoes, and spinach) and phytates (in whole grains, cereals, and legumes) may latch onto calcium molecules, preventing the body from absorbing them; an excess of protein or sodium can deplete calcium reserves. (See “All About Antinutrients” for more.)

Plotnikoff notes that all these foods are still part of a healthy diet, but that it’s best to consume them in moderation and to use traditional preparation techniques (such as cooking, sprouting, and fermenting) that maximize the availability of calcium.

How much: The recommended dietary allowance (RDA) for calcium is 1,000 mg a day for adults and 1,200 mg daily for anyone in or past menopause. The body can’t absorb large amounts of calcium at once, so split up your daily dose. If you’re taking 1,000 mg of calcium a day, try 500 mg at breakfast and another 500 mg at dinner. If you experience bloating or constipation, divide the doses into three or four.

Still, there is debate in medical circles about whether the U.S. RDA is too high (the World Health Organization recommends 500 mg). “If your vitamin D is sufficient . . . you don’t need [to take] that much calcium,” Plotnikoff notes, because D ensures you’re metabolizing it.

That’s an important caveat, he says, because the body tucks extra calcium in places no one wants it, like arteries, heart valves, and kidneys.

Best sources of calcium: Dairy milk and yogurt, hard cheeses, canned sardines and salmon with bones, tofu made with calcium sulfate, and cooked kale.

In general, calcium-rich whole foods can keep you out of deficit territory, but if you are postmenopausal or choose not to eat dairy, consider a supplement. Most are either calcium carbonate or calcium citrate, with the latter ­being a little more expensive. Calcium citrate can be taken anytime, while calcium carbonate is best taken with food to aid absorption.

How to know if you’re low: A bone-density test is the gold standard. The U.S. Preventive Services Task Force recommends a baseline screening for women 65 and older and postmenopausal women under 65 who may be at high risk of osteoporosis.

Worth noting: Folks who avoid dairy need to be mindful about their calcium intake, says Plotnikoff, because calcium from plant foods is usually absorbed less efficiently than calcium from dairy. For example, the body retains only 5 percent of the calcium in cooked spinach but 27 percent of the calcium in dairy milk.

This was excerpted from “5 Essential Minerals to Support Your Mind and Body” which was published in Experience Life.

Catherine Guthrie

Catherine Guthrie is an Experience Life contributing editor.

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