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5 ways calcium can benefit bone strength

Written by John Davis

Last updated: December 21, 2022

Calcium is a mineral nutrient that plays an essential role in bone health. It’s critical for building and maintaining bone strength throughout your life.

However, calcium can’t do its job alone: it works best in conjunction with other nutrients to promote bone strength. Want to optimize your calcium intake? Read on to find out how.

Calcium benefits

1. Calcium supplements help ensure your bones stay as strong as possible

Calcium salts are one of the primary constituents of skeletal bones, and without sufficient calcium intake, you risk having low bone density and osteoporosis.

This is not just a concern for older people; much of your ultimate lifetime bone density is determined in adolescence, and insufficient calcium intake in middle age can cause bone density loss to accelerate sooner and more rapidly (1).

2. Calcium can help prevent osteoporosis

Over ten percent of all adults age 50 or older in the United States have osteoporosis (2).  On top of this, an even larger fraction (some 44% of all adults over 50) of the population has low bone density—these people are at risk for developing osteoporosis in the future.

The good news is that there are some well-known ways to help prevent osteoporosis, and calcium supplementation is one of them.

3. Calcium supplements combine well with vitamin D and exercise

Calcium supplementation seems particularly effective when combined with vitamin D, which boosts calcium absorption (3), and exercise, which stimulates bones to increase their strength.

In fact, one 1991 study found that calcium supplementation alone was significantly less effective at preventing bone loss than calcium supplementation combined with exercise (4).

4. Calcium can prevent osteoporosis-related fractures in both men and women.

A study published in the New England Journal of Medicine showed significant decreases in fractures among men and women taking a calcium + vitamin D supplement (5).

The results of this study mean that calcium supplementation reduces the risk of serious injuries linked to low bone density, meaning that the increase in bone density from calcium supplements is sufficiently large enough to prevent bone fractures.

5. Calcium can help female athletes prevent stress fractures

Osteoporosis-related bone fractures aren’t the only consequences of inadequate calcium intake.

Athletes in training might be at a greater risk for stress fractures in their legs if they aren’t getting enough calcium.

A study on female Navy recruits, who experience a high rate of stress fractures because of the demands of basic training, showed a 20% reduction in stress fracture incidence when they were given calcium supplements (6).

Calcium dosage 

When it comes to what kind of calcium supplement to take and what dosage you should aim for, there are some pretty solid guidelines that can be found in the scientific research.

Target at least 1200 mg of calcium and 800 IUs of vitamin D for optimal results. According to one meta-analysis, clinical trials that used dosages of more than 1200 mg of calcium and more than 800 IU of vitamin D per day were more successful than those that used less (7).

Older adults might have to take more than the RDUs for calcium and vitamin D. The recommended daily intake for calcium is only 1000 mg and the recommended daily intake for vitamin D is only 400 mg—the evidence from the research indicates that these values might need to be revised upwards, at least for adults over age 50.

Calcium side effects

Calcium supplementation might or might not increase heart disease risk. There is some conflicting evidence on whether high levels of calcium supplementation may be associated with an increased risk of heart disease.

On one hand, a 2007 study conducted in New Zealand found that calcium supplementation increased risk of heart disease and stroke among postmenopausal women (8).

On the other, a 1998 study by researchers in South Carolina, Minnesota, and Pennsylvania found that high levels of calcium intake reduced the rate of heart disease in postmenopausal women (9).

The jury is still out on this, so you should talk to your doctor if you’re concerned about the effects of supplementation on your dietary risk.

Calcium can inhibit iron absorption. Supplemental calcium can out-compete iron for absorption, so if you are also trying to increase iron levels in your body, don’t take your calcium supplement at the same time as an iron supplement or a high-iron meal.

The effect is high enough that iron absorbed from a cheeseburger is significantly less than a hamburger without cheese, so you definitely don’t want to discount the interactions between calcium and iron.

Calcium benefits FAQ

Q: What foods are rich in calcium?

A: Dairy is the most obvious type of food that’s rich in calcium; milk, yogurt, and cheese are all excellent sources of calcium.

Beyond dairy, though, other foods like almonds, kale, broccoli, beans, and even salmon are rich sources of calcium.

Some fortified foods, like breakfast cereals, also contain calcium, but it’s added in a low-cost supplemental form, not a naturally-occurring form.

Q: Who is at risk for calcium deficiency?

A: Women are at a particularly high risk for calcium deficiency during and after menopause, because their hormone levels change in a way that is not favorable for calcium metabolism. These hormonal changes can also start to induce bone loss, so the need for calcium in these women is particularly acute.

Vegans, vegetarians, and people with milk allergies or lactose intolerance are also at a high risk for calcium deficiency because one of the major categories of calcium sources (dairy) is off-limits to them.

Q: How much calcium is in almond milk?

A: While almonds themselves have quite a lot of calcium, this calcium doesn’t make it into almond milk. As a result unfortified almond milk has very little calcium.

Fortunately, the best almond milk brands fortify their almond milk with both calcium and vitamin D.

Q: Are calcium supplements bad?

A: For most people, calcium supplements are good, not bad. Calcium supplements have a well-demonstrated record of increasing bone density and decreasing fracture risk in older adults.

Still, there are some people who should exercise caution with calcium supplements. While the evidence is inconclusive, some research has suggested that people who have very high calcium intake might have an increased risk of heart disease.

At the same time, while high dietary intake of calcium is associated with a decreased risk of kidney stones, some research suggests that high supplemental intake could increase the risk of kidney stones.

These findings, while tenuous, suggest that you might want to talk to your doctor if you know you are at a high risk for heart disease, or a high risk for kidney stones, before taking a calcium supplement. For these people, the potential risks need to be weighed against the potential benefits for bone health.

Related: Our top calcium picks


Calcium, alongside key co-nutrients like vitamin D and vitamin K, plays a fundamental role in building and supporting bone health.

At the right dosage, calcium and its supporting nutrients can play a big part in supporting bone health.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.