Calcium citrate: how it keeps bones healthy and strong

Calcium is a little like money in New York City. You need it—probably a lot of it if you want to live there—but you can’t just make it appear. You actually have to get it from somewhere. We also need a decent amount of calcium.

But though it’s the most abundant mineral in the body, we can’t produce it. We rely on dietary intake or calcium supplements to meet our needs. And just like a lot of the money in NYC can be found in a couple of neighborhoods, so too is calcium mostly located in select areas of your body—namely your teeth and bones.

You already know that calcium plays a crucial role in bone health—we’ll get to that in a minute. But what you might not realize is that calcium can’t do what it does best without vitamin D. Your body needs enough vitamin D, whether that’s vitamin D2 or D3, for calcium absorption to happen properly. And the two of them together team up to maintain or even improve your bone health.

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Calcium is important from childhood growth through old age. That’s because our bones go through several phases of development. Unfortunately, we can’t just get enough calcium as kids, build strong bones, and never worry about it again.

Our bones remodel throughout our lives, meaning their composition is broken down and reformed—and not always to the same strength as before. So lifelong bone health, including sufficient bone density, requires hitting your calcium needs consistently.But our calcium needs change several times throughout our lifetimes, so they’re a bit of a moving target. The amounts of calcium boys and girls need rapidly increase during childhood, but when we’re done growing, men’s needs settle down to 1,000 mg of calcium a day from 19–71 before increasing to 1,200 mg of calcium (Office of Dietary Supplements, 2019).

Women’s needs drop down slightly from 19–50 to 1,000 mg a day before increasing again at 51 to 1,200 mg. Though their needs increase again earlier compared to men, their recommended dietary allowance (RDA) stays the same through their 70s and beyond. But there’s a good reason they increase earlier.Bone loss in women starts around the time of menopause. The amount of calcium excreted by the body increases during this time as a direct result of the drop in estrogen.

Estrogen is protective of bone and without it, osteoclasts (cells that break down bones) live longer. As these cells reabsorb more bone, more calcium is released into the blood, which then needs to be excreted through urine. But it’s more nuanced than just that.

Estrogen helps our guts absorb calcium, too. So we not only reabsorb more bone during menopause but also absorb calcium less effectively as our hormone levels change. And if those calcium needs aren’t met, bone loss can accelerate (Nordin, 1997).For men, the bone loss process starts around the age of 55. Although they don’t go through menopause and all the calcium-related hurdles associated with it, they still need more of this mineral as they hit this critical age, and it’s important to meet the increased RDA.

One consequence of weak bones is osteoporosis, which is characterized by a loss of bone mineral density as bones become more porous. This also makes them more fragile, increasing the risk of fractures in older adults.

Osteopenia, on the other hand, is characterized by a loss of bone strength, but not so much that they break easily. It is on the spectrum between having normal bone density and having osteoporosis. While low calcium intake isn’t the only cause of osteoporosis, it does contribute greatly to compromised bone density.

The bone-building benefits of calcium are by far the most well-known. But this mighty mineral does far more for your body—and those tasks aren’t minor either.

Calcium is required for muscle contraction, which not only influences your performance in the gym but also keeps your heartbeat strong and regular. It also facilitates the transmission of nerve signals.

There are more benefits of calcium than we can name here, but here’s a taste of what the vital mineral may help with:

• May help with blood clotting

• May lower blood pressure (and, in turn, risk of heart disease)

• May ease PMS symptoms

• May reduce your risk of colon cancer

For most people, calcium supplements aren’t necessary. It’s easy to work many calcium-rich foods into your daily diet—more than enough to meet your RDA.

Dairy products from cheeses (cheddar, low-fat cottage cheese, or mozzarella, for example) to yogurt—and, yes, even ice cream—are the most well-known way to boost your calcium intake through food sources. 

But dairy foods aren’t the only dietary sources of calcium. Fatty fish like sardines, herring, and mackerel are high in this mineral and are also good ways to boost daily intake since they also have vitamin D.

Vegans can meet their calcium needs through plant sources such as tofu and soy milk, figs, dark leafy greens (such as kale, bok choy, and collard greens), and legumes. Fortified foods, such as orange juice and some breakfast cereals, are also good sources of calcium since they have the mineral added back in. But there are certain groups of people for whom dietary calcium may not be enough. For these people, a supplement may be helpful or even necessary. Like we explained, the amount of calcium adult women need to maintain healthy bones is higher than what men need as they start losing bone earlier than men. A dietary supplement may help meet these changing needs.There are two primary forms of calcium supplements: calcium carbonate and calcium citrate. Carbonate is cheaper and 40% calcium, while citrate tends to be slightly more expensive and less concentrated at 21% calcium.

Calcium citrate is much more readily absorbed and doesn’t need to be taken with a meal, unlike calcium carbonate, which tends to cause more side effects such as gastrointestinal problems. You may also see calcium packaged together with some vitamin D supplements to ensure your body absorbs the mineral properly (Straub, 2007).

True calcium deficiency is uncommon in the United States, which is why most people don’t tend to need supplements. But low levels are complicated and have different types of symptoms.

Acute symptoms come on suddenly when your calcium levels drop too low, but some can take years to progress from chronically low blood levels of calcium. Conditions like osteoporosis are the latter. Sudden, severally low levels of calcium are generally due to another illness. Low calcium may also cause stunted growth in children, the effects of which extend beyond adolescence.

But you can also have too much calcium, called hypercalcemia. This is also often due to some other underlying disorder. Excess calcium can cause side effects in the gastrointestinal system, such as bloating, constipation, and gas. Left unchecked, high levels of calcium may even cause kidney stones and other symptoms.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

December 05, 2021

Written by

Linnea Zielinski

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.