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Calcium: Benefits, Side Effects & Dosage

Calcium: Benefits, Side Effects & Dosage


What is Calcium?

The mineral calcium is common in many living and nonliving things around the world. It’s also the most abundant mineral in the human body. However, the body doesn’t make it by itself, so we have to receive it from food, water or supplements.

Bones and teeth store most of the body’s calcium where it provides strength and structure. However, it’s critical for other operations unrelated to bones. For example, it’s necessary for the proper functioning of blood vessels, muscle contraction, nerve communication and hormone secretion. Calcium is also useful for managing hormone issues, minimizing risk of some cancers, lowering blood pressure and even weight loss.

When the body needs calcium for these other functions, a cascade of physiological processes kick in that release a bit of the mineral from the bones and into the blood. It will usually find the calcium it needs, just at the expense of bone integrity.

Adequate calcium intake is a must. Yet, we often don’t get enough through diet. And those who do make an effort to eat calcium-rich foods may have problems absorbing it. As a result, supplements are very popular. They come in various forms. Even some foods that wouldn’t normally contain calcium are fortified with supplements, like some brands of cereal or orange juice.

There are also multiple chemical forms of calcium available as supplements, such as calcium carbonate and calcium citrate. Consumers may have a hard time understanding the differences between them, but any information you may need can be found below.

Benefits of Calcium

The benefit to consuming dietary and/or supplemental calcium is mainly to avoid problems that accompany low intake. The effects of not getting enough of it are slow to appear and not always readily apparent, such as the development of rickets in children, or osteoporosis in adults. However, calcium intake has other perks unrelated to bones.

Prevents Bone Loss

We know that when our bodies need calcium for vascular function, nerve transmission, muscle contraction and hormonal signaling, it pulls it from the bones. At some point, if the bones aren’t regularly replenished with the minerals they need, including calcium, they will become weak and brittle. This leads to a condition called osteoporosis.

According to the National Osteoporosis Foundation, “Osteoporosis is a bone disease that occurs when the body loses too much bone, makes too little bone, or both. As a result, bones become weak and may break from a fall or, in serious cases, from sneezing or minor bumps.” It effects a whopping 54 million Americans (x).

Certain populations are at a higher risk of bone loss — especially women over the age of 50. When estrogen levels decline during menopause, the body doesn’t absorb calcium as well. In fact, postmenopausal women lose up to 25 percent of their bone mass in the first decade following menopause (x).

Female athletes who engage in certain sports are another group at risk for bone loss. This is due to a combination of calorie restriction and intense exercise, which can reduce levels of circulating estrogen. Even though most of these athletes are not considered menopausal, they may still experience bone loss and increase their risk for bone fractures (x, x).

Weak bones and osteoporosis are more prevalent among women, but people of all genders can be affected. Ideally, adequate calcium intake would prevent weak bones from developing. Once osteoporosis sets in, though, calcium and vitamin D supplements are part of the treatment protocol for managing the condition (x).

Lower Blood Pressure

Many studies now show an inverse relationship in both humans and animals between calcium intake and blood pressure. In other words, those with inadequate calcium intake or problems with absorption are at a higher risk for developing hypertension.

It’s generally acknowledged at this point that by making sure you get the recommended daily amounts of it, you lower your risk of developing high blood pressure and the complications that accompany it (x, x).

Reduces Risk of Colon Cancer

Colorectal cancer is the third most common type of cancer diagnosed in both men and women (x). Studies show that calcium from supplements and dietary sources can help reduce your risk of developing this type of cancer (x). For example, one study found an inverse relationship between dietary calcium and rates of colon cancer in Korean men and women. It’s unclear why calcium may have this protective effect, but researchers think that it could help reduce the irritating effects of fatty acids and free bile in the colon (x).

Promotes a Healthy Pregnancy

While adequate calcium is important for all women during pregnancy, studies show it can be especially critical for those at risk of preeclampsia, a potentially dangerous condition affecting 5-14 percent of pregnancies worldwide. Preeclampsia describes the condition of high blood pressure and excess protein in the urine during pregnancy, which, if severe and untreated, can lead to major complications (x).

Calcium supplements can help improve blood pressure, control insulin levels and reduce inflammation during pregnancy, especially when taken in combination with vitamin D. This effect may be most dramatic in women who are already calcium deficient (x).

Balanced Hormones

Postmenopausal women aren’t the only ones who need an adequate amount of it in their diet. Research suggests that women who don’t get much calcium, vitamin D and magnesium in their diets may be more likely to suffer from PMS (x).

Women with polycystic ovarian syndrome (PCOS) may also experience a reduction in symptoms with calcium supplementation. For example, a study found that a calcium and vitamin D supplement helped reduce inflammation and oxidative stress in women with PCOS (x).

Could Potentially Assist with Weight Loss

Some studies demonstrate that increased intake through diet or supplements can help obese participants lose more weight. This effect is especially evident when combined with supplemental vitamin D. For example, a study of 52 obese women found that those supplementing with vitamin D and calcium lost more weight and had reduced waist circumference after three months compared to control groups (x). Another study involving obese college students yielded similar results (x).

That said, other studies do not show a relationship between it, with or without vitamin D, and weight loss. Evidence is considered to be weak in this area (x). Nevertheless, it certainly can’t hurt to make sure you’re getting enough calcium and vitamin D.

Calcium Benefits

Calcium Side Effects and Dosage

Side Effects

Calcium supplements can cause constipation. They can also reduce the body’s ability to absorb iron and zinc if taken together.

Getting too much from supplements can cause calcification of vascular and soft tissues as well as increase the risk for kidney damage (x).


How much calcium do we actually need? Luckily, the guidelines are very straight forward. According to the National Institutes of Health, the recommended daily allowances (RDA) for calcium through a combination of food and/or supplements are (x):

  • Children ages 4-8: 1,000 mg
  • Older children ages 9-18: 1,300 mg
  • Adults 19-50: 1,000 mg
  • Women ages 51+: 1,200 mg
  • Men ages 51-70: 1,000 mg
  • Men ages 71+: 1,200 mg

Forms of Calcium Supplements

When shopping for a calcium supplement, you’ll most likely find calcium carbonate or calcium citrate. These forms contain different amounts of what’s called “elemental calcium”, or the amount of actual mineral in the supplement (x). Here is a description of the various forms of it you may find:

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Calcium Carbonate

This form is one of the more popular calcium supplements on the market. It consists of 40 percent elemental calcium and should be taken in doses no larger than 500 mg at a time, with food, for best absorption. Calcium carbonate can be hard to absorb for people with low stomach acid or the elderly. It can also cause constipation. On the other hand, it is often present in some antacids and can soothe an upset stomach (x).

Calcium Citrate

This is the second-most common type of calcium supplement. It contains 21 percent elemental calcium and the body absorbs it more easily than calcium carbonate. Those over 50, who take antacids or who have absorption issues may prefer calcium citrate (x).

Calcium Aspartate

Newer to the scene, calcium aspartate is attached to a L-aspartate molecule, which acts as a “mineral transporter”. As a result, it’s touted as a highly absorbable form. This may be true, but currently there is limited quality data backing up these claims (x).

Calcium Lactate

Consisting of 13 percent elemental calcium, calcium lactate is made of, you guessed it, calcium and lactate! This is not to be confused with lactose. Despite similar sounding names, calcium lactate is not derived from dairy products. It’s a dietary supplement but is also approved by the FDA as a food substance to firm, flavor, leaven, stabilize or thicken food (x).

Calcium Gluconate

Calcium gluconate contains 9 percent elemental calcium and can be used like any other calcium supplement. It is classified as a calcium salt, meaning that it is soluble in water (x).

Calcium Ascorbate

Despite the name, calcium ascorbate is actually vitamin C. Sometimes, vitamin C can cause stomach upset. The calcium, however, “buffers” the acidic effects of the vitamin C and makes it gentler on the stomach (x).

Calcium Orotate

Like calcium aspartate, calcium orotate was designed to be readily absorbed. In addition to elemental its benefits, the added orotic acid is used to support athletic performance and endurance (x).

Calcium Pyruvate

Calcium pyruvate isn’t generally used as a calcium supplement. It’s more often a delivery system for pyruvate, which is a substance your body makes during energy metabolism. Lately, this supplement is generating buzz for its potential to increase energy and assist with weight loss (x, x).

How to Take Calcium Supplements

Because there are so many types of calcium supplements, it’s best to follow the label directions.

Calcium needs vitamin D in order to be absorbed. The body stores vitamin D as a result of exposure to sunlight, consumption of some foods like egg yolks, and/or supplements.

The Bottom Line

There is no question that calcium is of utmost importance to our ability to live our best lives. While dairy products are a great source of the mineral, many people cannot or choose not to have them. Some dark leafy greens and other plant-based foods contain smaller amounts, but again, these foods often don’t make their way onto people’s plates often enough.

The great news is that calcium supplements have a strong history of safety and effectiveness if used as directed. Calcium serves many important functions and your body will usually have access to the amount it needs — but at the expense of your bones. To be active, strong and mobile, do yourself a favor and check your calcium intake.

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