What Is Calcium Citrate?

Maintain strong bones with this easily absorbed form of calcium.

Calcium supplements are typically sold in the form of calcium carbonate or calcium citrate. Calcium citrate is a calcium salt that's easier to absorb but less potent than calcium carbonate. You may need to take more calcium citrate pills in order to achieve your desired dosage.

For anyone who takes heartburn medication or has digestive issues, calcium citrate is often the better choice, since stomach acid isn't required for absorption.

Calcium citrate is safe for most people when not taken in excess of 2,500 milligrams per day. It's available over the counter and typically recommended in multiple doses (of 500 milligrams or less) that add up to 1,200 to 1,500 milligrams a day. Calcium citrate can be taken on a full or empty stomach at any time of the day.

Also Known As

Calcium citrate (sometimes called tricalcium citrate) is found in the following products:

  • Certain brands of calcium-fortified orange juice
  • Citracal
  • GNC Calcimate Plus 800
  • Solgar Calcium Citrate
  • TwinLab Calcium Citrate Caps
Calcium citrate supplements spilling from bottle
apugach / iStock / Getty Images Plus / Getty Images

What Is Calcium Citrate Used For?

Calcium is an essential mineral that supports multiple systems throughout the body. You need to maintain adequate calcium levels in order for your heart, nervous system, and muscles to function properly.

When you don't get enough calcium from outside sources, such as food or supplements, your body dips into the calcium bank stored in your bones to keep blood levels up. Over time, pulling calcium from your bones weakens them and increases the risk of fracture.

Beyond bones, additional possible benefits of calcium supplementation include improvements in blood pressure and weight loss. Here's what the research says.

  • Blood pressure: Although the underlying mechanism is unclear, calcium has been associated with reducing blood pressure in multiple studies. However, there are rising concerns that excessive calcium through supplements may harden arteries and pose cardiovascular risks.
  • Weight loss: When people are placed on low-calorie diets, studies show that adding calcium and vitamin D supplements improves their rate of fat loss while preserving muscle and bone mass.

As with many dietary supplements, taking more calcium than we need probably does more harm than good. Instead of blindly adding calcium citrate, only purchase a supplement if you know you aren't getting enough from food and beverages.

Assessing Calcium Intake

For anyone who has limited dietary intake of calcium-rich foods, or who doesn't absorb calcium well, a calcium citrate supplement can help cover their nutritional bases. Possible reasons for inadequate calcium intake may include:

  • Eating disorders
  • Food allergies or intolerances
  • Irritable bowel syndrome
  • Poor appetite
  • Weight-loss surgery (like gastric bypass)
  • Leaky gut syndrome/intestinal malabsorption

Calcium is important for people of all ages. Children and teens are still in the process of forming their bones and should be mindful of getting sufficient calcium. Sitting down with a healthcare provider to review your dietary habits can help determine whether your intake is adequate.

For women over age 50, a bone density screening is a good way to assess bone status. If you're unsure whether you're meeting your calcium needs, schedule an appointment to speak with a dietitian to discuss if supplementation is necessary.

Additional Factors

You can gain many of the health benefits associated with calcium citrate supplements simply by obtaining adequate calcium through food. Foods that are high in calcium include:

  • Broccoli
  • Calcium-fortified orange juice, soymilk and tofu, or breakfast cereal
  • Cheese
  • Chia seeds
  • Cow's milk
  • Dark leafy greens (like kale, spinach, and turnip greens)
  • Salmon or sardines canned with bones
  • Yogurt

Consuming calcium along with vitamin D enhances calcium absorption and bone health. Smoking, drinking soda, and excessive intake of alcohol can weaken your bones, so remember to look at your health habits holistically.

If you're interested in calcium supplements to prevent osteoporosis, don't underestimate the importance of physical activity for maintaining bone strength. Engaging in regular weight-bearing exercise, like walking and squats, is essential for bones. If your healthcare provider is on board, consider adding resistance training to your routine. Remember, strong muscles support strong bones.

Possible Side Effects

It may be better to take certain types of prescription medications, over-the-counter drugs, and herbal supplements a few hours before or after taking calcium citrate. Specifically, iron or zinc supplements, antibiotics, and levothyroxine (thyroid medication) may interact with calcium supplements. Be sure to ask your pharmacist if you're unsure about possible interactions.

Negative side effects from calcium citrate are rare but may include the following.

  • Allergic reaction: Facial swelling, hives, or difficulty breathing
  • Digestive issues: Upset stomach or constipation
  • Serious side effects: Swelling, nausea, vomiting, bone pain, confusion, increased thirst, increases or decreases in urination

If you have a history of kidney disease or kidney stones, cancer, high calcium blood levels, or parathyroid gland disorder, talk to your healthcare provider before taking calcium citrate supplements. When it comes to dietary supplements, sometimes less is more. It's best to avoid taking higher doses than required to reduce the risk of negative side effects.

Controversy exists over the benefits of calcium supplements. Some researchers suspect that calcium supplements aren't effective at reducing bone fractures and may cause other issues.

Possible dangers of too much supplemental calcium may include colon polyps, kidney stones, or even hardening of the arteries. For this reason, obtaining calcium through food is generally preferable to supplementation.

Recommended Dosage

When it comes to calcium supplements, recognizing the exact dosage can be a bit confusing. That's because pure calcium (also called elemental calcium) is mixed with a filler when manufacturing supplement pills.

For instance, calcium carbonate is made up of 60% carbonate and 40% elemental calcium. Calcium citrate is technically just 21% calcium. Read the label to identify how much pure calcium is provided per pill.

In a 600-milligram pill of calcium citrate, there are about 126 milligrams of elemental calcium.

The Recommended Dietary Allowance for calcium varies by age and sex. Keep in mind that the following values represent the total intake for the day from all sources (including food, beverages, and supplements).

  • 200 milligrams: Birth to 6 months
  • 260 milligrams: 7 to 12 months
  • 700 milligrams: 1 to 3 years old
  • 1,000 milligrams: 4 to 8 years old and 19 to 50 years old, along with men between ages 51 and 70 years old
  • 1,200 milligrams: Women over age 50 and men over age 70
  • 1,300 milligrams: Children between the ages of 9 to 18 years old

What to Look For

Look for supplements that bear the USP label, which stands for United States Pharmacopeia. This ensures that your calcium supplement dissolves well and meets specific quality standards.

Watch out for calcium supplements that contain any of the following ingredients, as they might be contaminated with toxic metals, like lead:

  • Bone meal
  • Coral
  • Dolomite
  • Unrefined oyster shell

A Word From Verywell

Calcium citrate supplements can help you reach the recommended daily value, especially if you have difficulty absorbing calcium. For most people, it's possible to get enough calcium through food alone.

Living a healthy lifestyle that includes regular physical activity goes a long way toward building and maintaining strong bones. If you're concerned about osteoporosis or your calcium intake, ask your healthcare provider whether a calcium citrate supplement is right for you.

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9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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