Health Benefits of Calcium

Pros and Cons of the Bone Health Supplement

Calcium is the most abundant mineral in the body. 99% of the body’s calcium supply is stored in the bones and teeth, where it supports their structure and function. We ingest calcium from foods such as dairy, green leafy vegetables, and fortified foods (such as non-dairy milk, juice, and cereal).

We can also find calcium in some medications, like antacids, as well as in supplemental form. However, it is best to receive your daily calcium intake through foods that are naturally rich in calcium whenever possible.

Health benefits of calcium
Illustration by Brianna Gilmartin, Verywell.

Health Benefits

Calcium is an important mineral that aids your body by:

  • helping bone and teeth formation
  • helping to maintain strength.
  • playing a role in the movement of muscles.
  • assisting nerves to carry messages between the brain and other body parts.
  • helping blood vessels relax and constrict (which moves blood throughout the body).
  • releasing hormones and enzymes that help with various bodily functions.

Bone density (calcium deposition) increases during the first 25 to 30 years of life and then gradually decreases with age. Adequate calcium intake is required to maximize peak bone mass and limit bone loss later in life (which can lead to fractures and osteoporosis). During times of growth like adolescence, calcium requirements increase.

Particularly in postmenopausal women, bone breakdown exceeds bone formation, resulting in bone loss and increasing the risk of osteoporosis over time. This is another time calcium intake should increase in the body.

Bone Density and Osteoporosis

Consuming adequate amounts of calcium is important for building bone and can prevent or delay bone loss later in life. This is especially important for certain people who are most at risk for bone loss.

Most at Risk for Bone Loss

  • Postmenopausal women
  • The elderly

Osteoporosis, a disorder characterized by porous and fragile bones, is associated with more fractures. Many studies have been conducted on calcium supplementation and osteoporosis. While some studies show supplementation may improve certain fractures, others do not.

Much of the outcome depends on the study population, age, and compliance with supplements. Therefore, it is always important to discuss supplementation with your physician before implementing them.

One thing for certain is that adequate intake of calcium and vitamin D as part of a wholesome, balanced diet, in combination with weight resistance exercise may reduce the risk of osteoporosis later in life.

Colon Cancer

Although it is not conclusive, there is a lot of data that suggests calcium may provide a preventative effect from colon cancer. For example, one review assessed the effect of supplementary calcium on the development of colon cancer and adenomatous polyps (growths that are potential precursors to cancer).

Researchers found that while supplementation may contribute to moderate protection against adenomatous polyps, the data was not sufficient enough to warrant recommendations to prevent colon cancer.

On the other hand, data from one Harvard study suggests a 35 percent reduction in distal colon cancer with increased calcium dosage (1,250 mg per day of calcium). It appears that the amount of calcium, as well as the population that takes it, determines what level of protection calcium can provide with regards to colon health.

Keep in mind that because there are so many other factors that can increase the risk of colon cancer (genetics, weight, diet, smoking), it is highly improbable that calcium supplementation alone is the answer.

If there are no risks for you in taking calcium supplementation, it might be worth discussing with your doctor for its potential preventative effects.

Weight Control

The effect calcium has on weight control is somewhat inconsistent as well. Some studies have shown an association between higher calcium intakes and lower body weight. Some studies even show that diets rich in low-fat calcium (when total calories are restricted) may reduce the risk of obesity and increase weight loss in obese people.

A study in the American Journal of Clinical Nutrition suggests that calcium does not have weight control effects if calories are not restricted. In addition, oral calcium supplementation (as opposed to dietary calcium intake) does not seem to yield such results.

If you are looking to lose weight, the most important thing is to make sure you are creating some sort of calorie deficit, whether by moving more or eating less. In addition, diets should always be well-balanced—rich in non-starchy vegetables, fruit, whole grains, lean protein, and healthy fats.

If you are considering adding more dairy to your diet, keep in mind that whole fat dairy can be rich in calories and saturated fat. Adding more dairy without cutting calories could cause weight gain.

Preeclampsia

Preeclampsia is a condition that occurs in pregnant women and is characterized by high blood pressure, swelling of the hands and feet, and protein in the urine. Potential benefits of calcium in preeclampsia prevention have been investigated in several randomized, placebo-controlled studies.

A recent meta-analysis of 13 trials found that calcium supplementation with at least 1,000 mg per day starting from about 20 weeks of pregnancy was associated with significant reductions in the risk of high blood pressure, preeclampsia, and preterm birth. 

Hypertension

The verdict on whether calcium reduces blood pressure or the risk of hypertension is mixed. Some clinical trials have found a relationship between calcium intake and hypertension risk, while others have found no association. Small changes in systolic blood pressure have been noted, but the type of effect may depend on the population being studied.

The effects vary between people with high blood pressure as opposed to people with normal blood pressure.

Heart Disease

The research on calcium and heart disease is complicated. While there seems to be no direct link between the calcium you consume from your diet and the amount in your arteries (a sign of early heart disease), recent research has observed a link between the use of calcium supplements and cardiovascular disease (CVD).

One theory is that supplemental calcium has a greater effect on circulating calcium levels, which can increase calcification—a marker for cardiovascular disease. Hypercalcemia is associated with increased blood coagulation, vascular calcification, and arterial stiffness, all of which raise CVD risk.

Researchers have found that calcium supplements with or without vitamin D modestly increase the risk of cardiovascular events, especially myocardial infarction. However, once again, one will find mix results based on the variables of the study. Skeptics argue, though, that the strength of the available evidence linking supplemental calcium intake with CVD risk is lacking and not conclusive.

According to the Linus Pauling Institute, "the National Osteoporosis Foundation (NOF) and the American Society for Preventive Cardiology (ASPC) concluded that the use of supplemental calcium for generally healthy individuals was safe from a cardiovascular health standpoint when total calcium intakes did not exceed the Upper Limit." (More on the "Upper Limit" level below.)

Possible Side Effects

The Tolerable Upper Intake Level (UL) of calcium, which is defined as the highest amount a person should take, is 2,500 mg per day for adults ages 19 to 50. For kids ages 9 to 18, this number is 3,000 mg per day. For older adults ages 51 and over, the UL is 2,000 mg per day. Excessive intake above the Upper Limit amount can result in constipation and bloating.

Studies suggest that doses exceeding 4,000 mg have been associated with many health risks.

Risks of Exceeding Calcium Dose

  • Increased blood calcium levels
  • Renal (kidney) damage
  • Milk-alkali syndrome (condition in which there is too much calcium in the body)

Some individuals who take calcium supplements even within the recommended amounts may still experience side effects including gas, bloating, constipation, or a combination of these symptoms. It has been suggested that calcium carbonate is more likely to cause these symptoms over calcium citrate.

Efforts to reduce symptoms include spreading doses of calcium throughout the day and taking calcium with meals.

Additionally, when calcium supplementation is excessive, it can cause high levels of calcium in the blood in a condition known as hypercalcemia. Hypercalcemia can cause renal insufficiency, vascular and soft tissue calcification, hypercalciuria (high levels of calcium in the urine), and kidney stones.

Drug Interactions

If you are taking medications, you should contact your physician before beginning calcium supplements as calcium can interact with certain medications. Calcium may interfere with absorption of the following drugs: salicylates, bisphosphonates, tetracyclines, thyroid hormones (Synthroid, Levothroid), fluoroquinolones (ciprofloxacin), and sotalol.

In addition, certain drugs may interfere with the absorptions of calcium. These include anticonvulsants, cholestyramine, corticosteroids, ciprofloxacin, tetracyclines, mineral oils, and stimulant laxatives. High dosages of calcium increase the risk of milk-alkali syndrome among those who use thiazide diuretics and among individuals with renal dysfunction.

Dosage and Preparation

The amount of calcium a person needs depends on their age. The Recommended Dietary Allowance (RDA) for calcium in the United States is 1,000 mg for adult males and females (women ages 19 to 50 and men ages 19 to 70), and 1,200 mg for elderly individuals (women over age 50 and men over age 70).

To promote the attainment of maximal peak bone mass, children and adolescents ages 9 to 18 should consume a total of 1,300 mg per day of calcium—this can be done in the form of diet plus supplements.

Pregnant and breastfeeding adolescents (ages 17 to 19) should consume a total of 1,300 mg per day of calcium, while pregnant and breastfeeding adults (age 19 or older) should consume a total of 1,000 mg per day of calcium.

If you cannot achieve your calcium needs through diet alone, you can use a calcium supplement. It's best to supplement with 500 mg of calcium at a time for maximum absorption.

It's best not to exceed 500 mg in one single dose. For instance, if you are taking 1,000 mg of calcium per day, you can split up the dosage (500 mg in the morning and 500 mg at night).

What to Look For

Not all calcium types contain the same amount of elemental calcium—the amount of calcium actually absorbed by the body. For example, there is more elemental calcium in calcium carbonate than in calcium gluconate.

Make sure the label of the calcium product you choose lists the amount of elemental calcium as well as the total calcium. If you do not see the words "elemental calcium," you may want to purchase a different type of supplement.

Forms of Calcium

The two main forms of calcium supplements are calcium carbonate (calcite) and calcium citrate (citracal).

Calcium carbonate is more commonly available and must be taken with food, due to its dependence on stomach acid for absorption. It contains 40 percent of elemental calcium, which means it contains the highest concentration of calcium in supplement form for maximum absorption. Most of the time this type of calcium is taken more than once daily and needs to be taken with food.

It is usually affordable and found in some over-the-counter antacid products (such as Tums and Rolaids). On average, each chewable tablet provides 200 to 400 mg of elemental calcium.

On the other hand, calcium citrate can be taken with or without food and is considered a better supplement for people with achlorhydria (insufficient stomach acid), inflammatory bowel disease, or absorption disorders. Fortified fruit juices often contain calcium citrate malate. 

Certain vitamins and minerals, vitamin D, and magnesium are important in calcium absorption. Therefore, you may want to find a calcium supplement that includes one or both of them to make sure you are optimizing your dose.

Dietary Sources

To optimize your dietary calcium intake, aim to eat two to three servings of dairy a day, such as organic milk, yogurt, and cheese.

It's always a good idea to obtain as much of your vitamins and minerals from food as possible.

If you do not eat dairy, you can search for foods fortified in calcium, such as yogurt alternatives, nut-based milk, orange juice, cereals, and tofu.

Fatty fish (such as salmon) also contain calcium. Green leafy vegetables such as collard greens, kale, and cabbage contain calcium as well, but they aren't as bioavailable, meaning they do not immediately absorb for utilization in the body.

Other Questions

How can I get the maximum benefits of calcium supplements?

Avoid taking calcium supplements when eating certain foods such as wheat bran, spinach, and rhubarb. The types of acids found in these foods (phytic acid, oxalic acid, and uronic acid) can interfere with calcium absorption.

Does sodium intake affect calcium absorption?

High sodium diets can increase urinary calcium excretion. Some clinicians advise postmenopausal women whose sodium intake is more than 2,000 to 3,000 mg per day to make sure to increase their calcium intake to around 1,500 mg daily.

A Word From Verywell

Calcium is an essential mineral, however, the health benefits of calcium supplementation are mixed. Some studies suggest that calcium supplementation can improve bone mineral density and reduce fractures, reduce the risk of colon cancer, and improve and prevent hypertension, though this is not conclusive. It's important that you discuss use with your physician before taking calcium supplements. The best way to absorb calcium is through dietary foods.

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