What you should know about taking calcium to boost your nutrients
Experts agree that the ideal way to get the nutrients you need to stay healthy is from food. But when it comes to taking calcium, some people may not find it practical or possible to meet the recommended daily intake (RDI) from diet alone. For adults, the RDI is 1,000 milligrams (mg) daily, which rises to 1,200 mg per day for women over age 50 and men over age 70.
If your doctor advises you to take a calcium supplement, how do you choose among the dizzying array of available choices, which include pills, chewable tablets, flavored chews, and liquids? The following information may help you decide.
What form of calcium?
The calcium in supplements is found in combination with another substance, typically carbonate or citrate. Each has benefits and downsides. Calcium carbonate supplements tends to be the best value, because they contain the highest amount of elemental calcium (about 40% by weight). Because calcium carbonate requires stomach acid for absorption, it's best to take this product with food. Most people tolerate calcium carbonate well, but some people complain of mild constipation or feeling bloated. Some well-known calcium carbonate products include Caltrate, Viactiv Calcium Chews, Os-Cal, and Tums.
Calcium citrate supplements are absorbed more easily than calcium carbonate. They can be taken on an empty stomach and are more readily absorbed by people who take acid-reducing heartburn medications. But because calcium citrate is only 21% calcium, you may need to take more tablets to get your daily requirement. Calcium citrate products include Citracal and GNC Calcimate Plus 800.
How much calcium per serving?
Reading the labels with an eye toward cost and convenience may help you sift through your options. Check the serving size and the "% Daily Value" for calcium and multiply the percentage by 10 to find out how much elemental calcium the product contains. For example, if the label says a serving of the product contains 40% of the Daily Value, it has 400 mg of elemental calcium.
While products that yield a high amount of calcium may seem to be the best bet at first blush, they may not serve you best. Because your body has difficulty absorbing more than 500 mg of calcium at a time, more of the mineral may go to waste. So, while you may think that you've met your daily requirements by taking that 1,000-mg calcium pill, you may actually be only halfway to your target. Calculate your cost per serving based on how many tablets or chews the package contains, and consider whether you might find it inconvenient to take several tablets a day.
Here are some final tips for choosing and taking calcium supplements as found in the Harvard Special Health Report Osteoporosis: A guide to prevention and treatment:
- Avoid products made from unrefined oyster shell, bone meal, dolomite, or coral, as they may contain lead or other toxic metals.
- Don't exceed the daily dose recommended by the manufacturer—doing so increases the risk for side effects.
- If you take iron or zinc supplements, tetracycline antibiotics, or levothyroxine (used to treat hypothyroidism), take them several hours before or after takingcalcium to avoid potential negative interactions.
- Make sure you're also getting enough vitamin D, which helps your body absorb calcium. If you aren't getting enough from sunlight, your diet, or your multivitamin, you may want to choose a calcium supplement that contains vitamin D.
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By Julie Corliss
Executive Editor, Harvard Heart Letter
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Calcium is an essential nutrient for strong, healthy bones and teeth. Although a person may be able to get the calcium they need from their diet, some people need extra support from a calcium supplement.
Factors such as age, diet, and underlying medical conditions can affect how much calcium a person’s body absorbs.
This article will look at who might benefit from a calcium supplement, how much calcium a person needs, some of the products available, and when to speak to a doctor.
Many people can get enough calcium from a balanced diet.
However, the Office of Dietary Supplements (ODS) note that certain groups may be more at risk of calcium deficiency, including:
- Postmenopausal females: Decreases in estrogen can reduce calcium absorption and increase the risk of osteoporosis. Taking calcium supplements may slow the rate of bone density loss in postmenopausal females.
- People with infrequent or no periods: People who do not have a regular menstrual cycle may also have lower estrogen levels. Athletes or people with eating disorders can sometimes have irregular cycles.
- People with lactose intolerance or a dairy allergy: Avoiding dairy products can make it harder to get enough calcium. Taking a supplement can help boost levels.
- Vegans and some vegetarians: Vegans and ovovegetarians, who eat eggs but no dairy products, may not get enough calcium from their everyday diet.
If a person is concerned that they have a calcium deficiency, it is important to speak to a healthcare provider. They can perform certain tests and analyze the person’s overall health and diet to confirm whether or not a calcium supplement is necessary.
The best calcium supplement will depend on the person’s unique circumstances. The type and quantity of calcium a person needs will vary depending on:
- their age
- whether or not they take any medications
- whether or not they have any health conditions
A doctor can advise on the best way for someone to get more calcium based on these factors.
When looking for a product, it is important to consider the following factors.
Dosage
It is important to choose a supplement that contains the right amount of calcium for a person’s age. The ODS suggest that people get the following amounts of calcium in their diet each day:
People below the age of 18 who are pregnant or breastfeeding need 1,300 mg of calcium per day.
Ingredients
In addition to finding a product with the right dosage, it is also a good idea to consider which form of calcium will be most suitable.
There are two main forms of calcium in supplements: calcium carbonate and calcium citrate.
Calcium carbonate is:
- widely available
- inexpensive
- higher in calcium
However, calcium carbonate relies on stomach acid for absorption, so people should take it with food. Some people may also find that calcium carbonate causes side effects, such as gas and bloating.
Calcium citrate does not depend on stomach acid for absorption. As a result, it can be more suitable for people with:
- lower levels of stomach acid
- inflammatory bowel disease
- malabsorption
- a sensitivity to calcium carbonate
However, calcium citrate is more expensive than calcium carbonate, and it contains less calcium overall. This means that a person may need to take it more frequently.
The following products contain safe dosages of calcium for adults and have undergone quality testing by a third party.
Some also contain other nutrients that can help with calcium absorption, such as vitamin D.
Please note that the statements below are research-based. No one at Medical News Today, including the writer, has tried these products.
NOW Supplements Calcium Carbonate Powder
This product contains pure calcium carbonate powder. Half a level teaspoon (tsp) provides 600 mg of calcium. Because this calcium supplement comes in powder form, a person can customize the dosage according to their needs.
The manufacturers recommend mixing the powder into juices, such as orange or tomato juice, and taking it with a meal. Each bottle contains 200 servings.
This product is suitable for Kosher and vegan diets, and it is Good Manufacturing Practice-assured. This means that every aspect of the company’s manufacturing process adheres to strict quality standards.
NOW Supplements Calcium Carbonate Powder is available for purchase online.
NOW Supplements Calcium Citrate Powder
This supplement may be a better choice for people whose bodies do not tolerate calcium carbonate. It contains 600 mg of calcium per 1.5 tsp serving.
A person can use this powder in the same way as the calcium carbonate powder, adding it to juices to take with a meal. It also meets the same quality and manufacturing standards as their Calcium Carbonate Powder.
NOW Supplements Calcium Citrate Powder is available for purchase online.
Thorne Research Basic Bone Nutrients
This product contains several nutrients that work together to support bone health, including:
- calcium
- vitamin D3
- vitamin K2
- magnesium
According to a 2017 review, there is evidence to suggest that taking vitamin K and D together is more effective than taking vitamin D alone. Additionally, vitamin D helps the body absorb more calcium.
The manufacturers suggest taking one to four capsules daily or however many a healthcare provider recommends.
It is important to note that this product does not provide specific dosage recommendations, since calcium needs vary significantly from person to person.
Therefore, it may be best to talk to a healthcare provider to find out how many capsules are necessary to take per day. Each capsule contains 200 mg of calcium in the form of dicalcium malate.
Thorne Research Basic Bone Nutrients is available for purchase online.
Designs for Health Calcium Malate Capsules
This supplement contains dicalcium malate, which is a compound of calcium and malic acid. According to the manufacturers, this form of calcium is easier to absorb than calcium alone.
The product also contains a small amount of vitamin D to aid absorption. Two capsules provide 500 mg of calcium and 100 international units of vitamin D.
This product is dairy- and soy-free and suitable for vegetarians.
The manufacturers make their products in facilities that have one or more certifications to demonstrate their safety and quality. They also ensure Food and Drug Administration (FDA) compliance.
Designs for Health Calcium Malate Capsules are available for purchase online.
Calcium supplements may cause adverse effects — such as gas, bloating, or constipation — for some people. Taking too much calcium may also lead to:
- kidney stones
- soft tissue calcification
- renal insufficiency
According to the ODS, there is also some evidence to suggest that high calcium intakes may contribute to prostate cancer and cardiovascular disease. However, studies looking at these risks have had mixed results.
Calcium supplements can interact with other medications, such as:
- osteoporosis medications, such as bisphosphonates
- certain antibiotics, such as tetracycline or fluoroquinolone
- anticonvulsant medications, such as phenytoin
- thyroid medications, such as levothyroxine
- medications for Paget’s disease, such as tiludronate disodium
People who take any medications or who have any underlying conditions should talk to their healthcare provider before trying a calcium supplement.
A person may be able to get enough calcium from food alone. Dairy products such as yogurt, milk, and cheese contain the highest levels of calcium.
Some dairy- and lactose-free sources of calcium include:
- nuts and seeds
- dark, leafy greens, such as spinach and kale
- beans and lentils
- tofu made with calcium sulfate
- canned fish, such as sardines or salmon
- fortified breakfast cereals
- fortified milk alternatives
- fortified fruit juice
Some substances can also reduce the amount of calcium the body absorbs. These include:
- caffeine
- alcohol
- high amounts of salt
- high amounts of protein
If a person’s body has difficulty absorbing calcium, they may benefit from reducing their intake of foods and beverages that contain these substances.
Learn about other non-dairy sources of calcium here.
People who suspect that they have a calcium deficiency should speak to a healthcare provider, if possible. They can determine if this is the case and, if so, recommend some ways to get more calcium.
If a person experiences new or worsening symptoms while taking calcium, they should stop taking the supplement and talk to a healthcare provider.
Calcium is an essential nutrient for bone health. Some people may not be able to get enough calcium from their diet, in which case they may benefit from taking a supplement.
A healthcare provider can help someone choose the form and dosage they need. They can also advise on any other nutrients that might help with absorption.