Your bones need it—and so does your heart, immune system and more… 

It has been drilled into us for decades that calcium is crucial for the health of our bones and teeth. When we hit age 50, we hear the refrain even more loudly—don’t slight your calcium intake, since bone-thinning osteoporosis affects one in four women and about one in 20 men in later life. Calcium even helps us keep our teeth as we grow older. 

So you might have missed the rest of the story on calcium—that your muscles, heart, immune system…indeed, your very well-being…are linked to this mineral, which comes from what we eat and drink rather than occurring naturally in our bodies. 

And even though calcium is often ­pigeon-holed as something mainly older women need to worry about, ­virtually every cell in every person’s body, throughout one’s lifespan, depends on this nutrient to work properly. What you need to know about calcium—and the levels you need to stay healthy…

Too little can be too late 

At a fundamental level, calcium serves as a link between cells throughout the body. Among the key body functions that involve calcium…

Muscle contraction. All the muscles in your body rely on calcium to trigger contraction by reacting with certain proteins in muscles that regulate movement. Without enough calcium, muscle contraction can be impaired, leading to muscle spasms. 

Heart rate. The heart is a muscle, of course, and its ability to pump relies heavily on calcium. Without it, a ­dangerously irregular heartbeat (arrhythmia) can develop. 

Brain health. For communication between our neurons to occur, we need calcium. Calcium is known as an intracellular messenger and plays many roles in the brain’s ability to function properly. 

Blood clotting. Calcium contributes to the essential ability of blood to clot—for example, to stop the bleeding if you cut yourself. (This is different from life-threatening blood clots such as occur with atrial fibrillation, when the heart beats irregularly and/or ­quivers, causing blood to pool and form clots in the heart’s chambers.) 

Immune response. Calcium is vital to the cell communication that helps regulate how well our immune system fights off germs and other invaders. Low levels of the mineral can lead to disruptions in the production of ­infection-fighting white blood cells.

Skin and other connective tissue. Since our bodies are constantly creating new cells—a process that’s key to the skin’s elasticity—low calcium levels can contribute to sagging skin. The nutrient also helps support ligaments, tendons and other connective tissues. 

The testing conundrum

Unfortunately, there is no good way to determine whether someone is running low on calcium. Technically, a simple blood test can measure your levelof calcium. But because the body pulls calcium from the bones and teeth to make sure there is enough in the blood for critical body functions, the blood test isn’t a reliable gauge. 

Even if the blood level were consistent, this alone cannot reveal how well your body absorbs calcium. You may be consuming “enough,” but what’s most important is how well your body is using the mineral. Certain dietary habits, such as consuming a lot of salt, can interfere with calcium absorption.

Bone-density testing presents a catch-22. This type of test is able to deduce whether you’re low on calcium by revealing problems such as osteopenia or osteoporosis after it’s already developed…or worsened. 

By then, the body has leached too much calcium from the bones—its calcium “bank”—and the only option is damage control to help prevent further bone loss since it’s too late to completely shore up a weakened skeletal system. 

Osteoporosis drugs can help slow further bone breakdown, but they can’t reverse it. Some studies suggest that strength training can help to rebuild muscle strength and bone, which are related, but the mechanisms through which this occurs aren’t well understood. 

Nutritional teamwork

Since our bodies don’t produce calcium, our stores depend on what we consume in our diets. But the process is more complicated than simply downing calcium-rich foods. 

Notice how a carton of milk might say, “Fortified with calcium and vitamin D”? Certain other nutrients (known as synergists) interact with calcium, boosting the mineral’s ability to be more fully absorbed. This is why so many foods, such as dairy products, ­orange juice and cereals, are fortified with calcium and vitamin D. Another significant synergist is vitamin K, which is rich in vegetables such as cabbage, watercress, broccoli and asparagus. 

Magnesium is also important to calcium functioning. It converts vitamin D into its active form so that it can help with calcium absorption. Other minerals, such as potassium, also play a role in calcium absorption.

It’s not that difficult to fulfill your daily calcium requirements with a healthful diet. Ideally, look for fortified versions of dairy products such as ­yogurt, milk and cheese…and eat plenty of dark-green, leafy vegetables such as kale, collard greens and broccoli, which are also rich in vitamin K. Fish with edible, soft bones, such as sardines and canned salmon, are also calcium-rich and good sources of vitamin D. 

The task gets more challenging for people who forgo dairy products. Fortunately, Lactaid, a lactose-free milk, and almond and other nondairy milk alternatives come in calcium-­fortified versions. You can also double up on dark-green, leafy veggies and add other calcium-rich foods to your diet, including beans (such as kidney, navy and Garbanzo) and fruit (such as oranges, figs, apricots, kiwi and papayas). 

To make sure you’re getting enough calcium, aim for these daily levels through your diet and/or supplements (see below): For women age 19 to 50, the recommended dietary allowance (RDA) is 1,000 mg per day…and 1,200 mg daily after age 50. For men age 19 to 70, the RDA is 1,000 mg daily…and 1,200 mg thereafter. 

Helpful: To make sure you are consuming enough calcium each day, you can use an app to log your food intake, which will show how much calcium you are getting. 

Since excess caffeine intake, certain medications, renal disorders or diets rich in foods that contain phytic acid or oxalic acid (such as whole grains, rhubarb and spinach) may cause a decrease in calcium absorption, ask your doctor whether it’s wise to consume a bit more, considering your age and any health conditions. This may be especially important if you have pancreatitis, celiac disease or inflammatory bowel disease.

How to use supplements safely

Even though the foods described above—which offer multiple ­nutrients—are the preferred source of ­calcium, supplements can be used to ensure that you’re getting enough of this vital mineral. While calcium supplements are available in many forms, calcium citrate is typically best absorbed. Look for a sublingual (under-the-tongue) version, which dissolves faster…and without sugar. 

Proceed with caution

Of course, too much of anything is bad, and that’s true for calcium as well. People who are predisposed to kidney stones face a greater risk for these nasty visitors if they consume more than the RDA of calcium, since the kidneys can’t reliably filter out calcium that’s not readily used by the body. 

Some research also has linked the use of calcium supplements (without adequate levels of vitamin D) to cardiovascular disease. And calcium supplements may be associated with increased risk for dementia in older women who have had a stroke, ­according to research. 

To help with bone health, research shows that it may require taking a vitamin D supplement (800 IU daily). Also, certain medications, such as H2 blockers and proton pump inhibitors for reflux or tetracycline ­antibiotics, can affect the efficacy of some calcium supplements. If you use one of these drugs, talk to your doctor before taking a calcium supplement.