- Department of Health
- All About Calcium Supplements
- Why is calcium important?
- How do I know if I am getting enough calcium in my diet?
- If I am not getting enough calcium, what should I do?
- Is more calcium better?
- How do I choose a calcium supplement?
- What do the symbols on the labels of calcium supplements mean?
- How do I read the label of a calcium supplement?
- Do I need to be concerned about lead in my calcium supplement?
- Do I need vitamin D in combination with my calcium supplement?
- Do I need magnesium in combination with my calcium supplement?
- How do I take my calcium supplement?
- Are there any special considerations if I take an iron supplement?
- Is it a problem to take a calcium supplement with antibiotics?
- Can calcium supplements cause constipation?
- Calcium Supplements: Should You Take Them?
- The Best Calcium Supplement Is None
- A Better Calcium Option
- Exercise to Strengthen Bones
- Vitamin D
- Recommended Daily Intakes of Calcium and Vitamin D
- Sources of Calcium
- Types of Calcium Supplements
- Taking Calcium Supplements
- Calcium-Rich Foods and Drinks
- Additional Resources
Department of Health
All About Calcium Supplements
Why is calcium important?
Calcium is a nutrient that is essential for strong bones. Ninety-nine percent of your body’s calcium is stored in your bones and teeth. The other one percent of your body’s calcium is found in blood. Blood calcium is necessary to support your body’s critical functions such as controlling your blood pressure and maintaining your heartbeat.
The calcium in your bones makes up your bone bank. Throughout your lifetime, the calcium from the foods you eat is “deposited” in and “withdrawn” from your bone bank, depending on your needs. When your calcium intake is too low to keep your blood calcium normal your body will “withdraw” the calcium it needs from your bones. Over time, if more calcium is taken out of your bones than is put in, the result may be thin, weak bones that may break more easily.
How do I know if I am getting enough calcium in my diet?
It is important to know the amount of calcium you need each day. You will find your recommended daily calcium intake on the chart below, listed according to your age and gender.
|If this is your age||Then you need this much calcium
each day(mg = milligrams)
|Birth to 12 months||Supplied by formula or breast milk|
|Men 19 – 70
Women 19 – 50
|*Recommended Dietary Allowances, Institute of Medicine, 2015|
The preferred way to get calcium is from the food you eat. Visit the NYSOPEP website (www.NYSOPEP.org) to help you find out if you are consuming the amount of calcium you need in the foods you eat in a usual day.
If I am not getting enough calcium, what should I do?
- Most people can easily get at least half of the calcium they need from food.
- If your usual calcium intake is too low, first try to eat more calcium-rich foods each day. There are many calcium-rich foods to help you get the recommended calcium from diet alone.
- If you are unable to change your diet to get the recommended amount of calcium each day, speak to your health care provider about taking a calcium supplement.
- If you need a supplement, it is important to select one that contains the proper amount of calcium. Your recommended daily calcium intake minus the estimated daily calcium in your diet will determine how much calcium you need to take from a supplement.
|Recommended Daily Calcium Intake (mg)|
|Minus (-)||Estimated Calcium in your Diet (mg)|
|Equals (=)||Calcium Needed from Supplement (mg)|
Is more calcium better?
Some health care providers may suggest slightly more calcium for people with certain medical conditions that interfere with the body’s ability to use calcium efficiently. It is important to speak to your health care provider about your calcium requirements and not to consume too much calcium on a regular basis. Chronic high calcium intakes, particularly from calcium supplements, may be harmful.
It is also important not to consume too much calcium at one time. For the most ecient calcium absorption, it is best to consume calcium (from food and/or supplements) in amounts of 600mg or less at one time. Your body uses calcium best when it is spread out through the day. Try including a calcium-rich food at each meal or snack.
How do I choose a calcium supplement?
- Calcium supplements may contain different calcium compounds such as calcium acetate, calcium carbonate, calcium citrate, calcium citrate malate, calcium gluconate, calcium lactate, calcium lactogluconate, tricalcium phosphate and others.
- Different calcium compounds have similar bioavailability (the amount of calcium that the body can use) when supplements are taken with food. The presence of food in the stomach causes the release of acid that is necessary to break down most calcium supplements. When calcium is taken with food, it slows down the movement of calcium in the intestines allowing more time for calcium to be absorbed. Therefore, it is best to take calcium supplements with food.
- Calcium citrate is an exception to the rule: it can be taken with or without food. It is the one calcium compound that does not require acid to break it down. If you take acid-blocking medications (H2 blockers or proton pump inhibitors that are sold over-the-counter or by prescription) and cannot get enough calcium in the foods you eat, calcium citrate is the calcium compound of choice.
- In selecting the right supplement for you, it is important to consider how you intend to take the supplement. Calcium supplements are available as liquid, powder, chewable or tablets.
- Taste may also be a consideration; since it may determine if you will regularly take calcium.
What do the symbols on the labels of calcium supplements mean?
There are symbols to look for on the labels of calcium supplements that indicate that an independent laboratory has tested the product The symbols pictured below from left to right include the Consumer Labs International insignia, the Natural Products Association symbol the NSF (NSF International) mark, and the USP (United States Pharmacopeia) verified mark.
When one of the above symbols is found on a calcium supplement, it means the calcium supplement was properly manufactured contains the ingredients listed on the label, breaks down and is released into the body in a specified amount of time, and does not contain harmful levels of lead or specified contaminants. The symbols do not guarantee that a product is safe or eective. It is important to understand that independent laboratory testing is voluntary and costly so many acceptable products may not display a symbol.
Calcium must dissolve in your stomach before it can be absorbed in your intestines and used by your body. If your supplement is not marked with a symbol that indicates that it has been quality tested, you can test it yourself to find out if it will dissolve. Simply put the supplement into a glass of lemon juice. It is very similar to stomach acid. Stir the solution well then occasionally repeat over a 30-minute period. If the calcium supplement breaks down within 30 minutes, it should do so in your stomach, too. If the supplement does not completely dissolve, choose another calcium supplement. Be sure to discard the calcium/lemon juice solution after the test.
How do I read the label of a calcium supplement?
Reading the label of a calcium supplement is as simple as 1, 2, 3:
- Check the serving size (the number of tablets per serving)
- Read the calcium (mg) per serving. The label may refer to calcium as elemental calcium. This distinguishes the weight (mg) of calcium alone from the weight(mg) of the calcium compound on the ingredient list (such as calcium carbonate, calcium citrate, tricalcium phosphate, or others)
- Determine the calcium (mg) per tablet
Do I need to be concerned about lead in my calcium supplement?
One of the above symbols on the label of a calcium supplement means that it does not contain lead or other metals. However, it seems that lead in calcium supplements is less of a concern than some people believe. Calcium supplements, in the dosage prescribed for prevention and treatment of osteoporosis, contain much less than the safe level of lead. A further safeguard is that lead in calcium supplements is usually not absorbed well because calcium blocks lead absorption.
Do I need vitamin D in combination with my calcium supplement?
It is important to get the vitamin D that you need each day. Getting the recommended amount of vitamin D helps your body absorb calcium and helps strengthen muscles, too! There are only a few good natural sources of vitamin D including fatty fish such as catfish eel, mackerel, salmon, sardines, and tuna. Small amounts of vitamin D are added to all milk and to some types of nondairy beverages and other foods. Check the food labels of almond, coconut, rice, and soy beverages as well as juices, yogurt, cheese, and nutrition bars to find out if vitamin D is added. Most people need a vitamin D supplement to get enough vitamin D each day. Vitamin D is available in supplemental form in multivitamins, in combination with calcium in many calcium supplements, and alone in vitamin D supplements Vitamin D is fat-soluble and can be stored by the body. It does not need to be taken in combination with calcium as long as you get the recommended amount of vitamin D each day. It is important to speak to your health care provider about how you can get the vitamin D you need to promotes strong bones.
Do I need magnesium in combination with my calcium supplement?
Most healthy people do not need magnesium supplements. Magnesium is found in many foods but especially in green leafy vegetables potatoes, tomato products, seafood, peas, beans, nuts, seeds, bran and whole-wheat products. However, certain individuals may be at risk for magnesium deficiency. At-risk individuals include those with gastrointestinal diseases that cause poor absorption or increased losses of magnesium, people with diabetes, frail elderly individuals eating poor diets, alcoholics, individuals receiving chemotherapy, and people who take high-dose diuretics (water pills) that cause magnesium loss. Your health care provider will prescribe a magnesium supplement if it is necessary or if you have a condition that causes magnesium deficiency.
Do I need additional vitamins or minerals with my calcium supplement?
For most healthy individuals, additional vitamins or minerals (such as boron, vitamin K, selenium or others) in the form of supplements are not needed for strong bones. The best way to get these nutrients is by following the 2010 Dietary Guidelines for Americans to help you eat a varied, nutrient-rich diet including plenty of fruits and vegetables.
How do I take my calcium supplement?
It is important to read the labels of calcium supplements and follow the directions for use. Chew chewables or swallow tablets as directed along with a full glass of water. For best absorption, most calcium supplements should be taken with food. Calcium citrate is an exception; it may be taken with or without food. It is best to spread out the calcium you consume from food and/or supplements throughout the day In fact, for most ecient absorption, it is recommended to consume 600 mg of calcium or less at one time. If you take more than 600 mg of calcium from supplements each day, the dose should be split to improve calcium absorption.
Are there any special considerations if I take an iron supplement?
For the best absorption of both iron and calcium, it is recommended that you eat foods rich in calcium or take calcium supplements two hours before or after your iron supplement. You should not consume calcium and iron at the same time.
Is it a problem to take a calcium supplement with antibiotics?
Calcium interferes with the body’s ability to use certain antibiotics such as tetracycline or ciprofloxin. If your health care provider prescribes an antibiotic that interacts with calcium, it is important for you to take it properly. You should not take calcium supplements (and not eat calcium-rich foods) at the same time as taking certain antibiotics. Your antibiotic will work best if you take your calcium supplement (or eat calcium-rich foods) at the right time. It is always important to talk to your pharmacist about the proper way to take your medication.
Can calcium supplements cause constipation?
Some people who take calcium supplements complain about constipation but it can usually be prevented. To prevent constipation eat more fiber in your diet (from fruits, vegetables, and whole- grain products), drink six to eight of water each day, and be physically active. If these simple steps are not helpful enough, take a closer look at your diet to try to get more calcium from foods and less from supplements. If you need to take calcium supplements, read the label to find out the amount of calcium in each dose. For example calcium carbonate has the highest amount of calcium per dose. Calcium citrate has less calcium per dose and calcium gluconate is one of the lowest dose options. A low-dose calcium supplement may be better tolerated than a high-dose supplement.
NYSOPEP Resource Center
Helen Hayes Hospital, West Haverstraw, NY
Publication 1980, Version 4/2015
Calcium Supplements: Should You Take Them?
The Best Calcium Supplement Is None
It’s important to protect your bone strength and guard against fractures as you age, but taking a supplement isn’t the best way to do that, says Erin Michos, MD, MHS , associate director of preventive cardiology for the Ciccarone Center for the Prevention of Heart Disease . “A nutrient in pill form is not processed in the body the same way as it is when ingested from a food source. Furthermore, people believe that the proof that calcium supplements fortify bones is more robust than it really is,” she says. “The truth is, the research is inconclusive. But there is a growing body of evidence that suggests no health benefit, or even worse, that calcium supplements may be harmful.”
Multiple studies have found that there’s little to no benefit to taking calcium supplements for the prevention of hip fractures. On the other hand, recent studies have linked calcium supplements with an increased risk of colon polyps (small growths in the large intestine that can become cancerous) and kidney stones, which are hard masses usually formed in the kidneys from an accumulation of calcium and other substances. Additionally, a 2016 study by Michos and her colleagues suggested that calcium supplements may increase the risk of calcium buildup in the heart’s arteries.
“I’m very concerned about the potential for calcium supplements to contribute to heart attacks and heart disease,” says Michos. “The body can’t process more than 500 milligrams of calcium at a time. If you take a supplement with more than that, your body has to do something with the excess. It’s possible that higher calcium levels in the blood could trigger blood clots or that calcium could be deposited along artery walls, which would contribute to the narrowing of blood vessels.”
A Better Calcium Option
While taking calcium supplements may produce unwanted side effects, meeting your calcium needs through your diet is safe. “When you get calcium through your diet, you’re taking it in small amounts spread throughout the day along with other food sources, which helps you absorb the nutrient,” explains Michos. “Most people can get adequate calcium through their diet if they make an effort.”
Women ages 19 to 50 should consume 1,000 milligrams of calcium a day, and the target for women over 50 is 1,200 milligrams per day. Good dietary sources of calcium include:
- Dried figs
- Garbanzo, white and pinto beans
- Low-fat dairy such as milk and yogurt
- Leafy green vegetables such as kale and spinach
Exercise to Strengthen Bones
Being active and exercising on a regular basis protects bone health. Weight-bearing exercises such as walking, jogging and weight training are especially helpful in preventing bone loss.
Simply moving more throughout the day supports bone health, too. Research indicates that women who sit for more than nine hours a day are 50 percent more likely to have a hip fracture than those who are less sedentary. Finding ways to work more walking or standing into your day can add up. For example, park farther away from buildings, take the stairs instead of the elevator and pace while on phone calls.
For most women, skipping calcium supplements in favor of boosting dietary calcium and focusing on weight-bearing exercise is the best way to keep bones strong. But if you’re still concerned about getting enough calcium, talk to your doctor first before taking supplements to see if you really need them.
This information describes calcium supplements and how to take them.
Calcium is a mineral that you need to build and maintain healthy bones. If you don’t get enough calcium from your diet, your body will take it from your bones. This can cause osteoporosis.
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Osteoporosis develops when you lose bone tissue, which makes your bones more likely to fracture (break). Osteoporosis is most common in women who have gone through menopause. But, it can develop in anyone, including men, due to medication or illness. Some risk factors for osteoporosis include:
- Having a thin build
- Being of Northern European or Asian descent
- Having fair skin
- Going through menopause early (before the age of 45)
- Taking certain steroid medications for longer than 3 months
- Not getting enough physical activity
- Not getting enough calcium in your diet (or from dietary supplements)
- Drinking too much alcohol (more than 1 drink per day if you’re a woman and more than 2 drinks per day if you’re a man)
- Taking aromatase inhibitors (medications that stop the production of estrogen and are used to treat breast cancer)
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Vitamin D is a vitamin that helps your body absorb calcium. Your body makes vitamin D after being exposed to the sun. Vitamin D is also found in some foods.
It can be hard to get enough vitamin D from just sunlight and foods. Your doctor or clinical dietitian nutritionist might tell you to take vitamin D supplements. These can be prescription or over-the-counter vitamin D supplement pills or calcium supplements with added vitamin D.
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Recommended Daily Intakes of Calcium and Vitamin D
Getting enough calcium in your diet helps prevent osteoporosis. Calcium is measured in milligrams (mg) that you need per day.
- If you’re between the ages of 19 and 50, you need 1,000 mg of calcium every day.
- If you’re a woman and are age 51 or older, you need 1,200 mg of calcium every day.
- If you’re a man and are between the ages of 51 and 70, you need 1,000 mg of calcium every day.
- If you’re a man and are age 70 or older, you need 1,200 mg of calcium every day.
Vitamin D is measured in international units (IU) that you need per day.
- If you’re between the ages of 19 and 70, you need 600 IU of vitamin D every day.
- If you’re over 70 years of age, you need at least 800 IU of vitamin D every day.
If you have osteoporosis, you might need more calcium, vitamin D, or both. Talk with your doctor or clinical dietitian nutritionist about how much you need per day. Don’t take more than your daily recommended amount of calcium. Taking too much can be harmful to your health.
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Sources of Calcium
The best way to get calcium is through the food you eat. Dairy products are a good source of calcium. If you’re lactose intolerant, try lactose-free dairy products or Lactaid® pills. You can also try calcium-fortified orange juice and other foods. Check food labels to see the amount of calcium in foods.
The table at the end of this resource lists some foods and drinks that are high in calcium.
You may find it hard to get enough calcium from your diet alone. Your doctor or clinical dietitian nutritionist may suggest that you take a calcium supplement. You don’t need a prescription for this. Your doctor or clinical dietitian nutritionist will tell you how much you should take.
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Types of Calcium Supplements
There are several types of over-the-counter calcium supplements, including calcium carbonate and calcium citrate. These supplements are taken orally (swallowed).
Don’t buy calcium tablets that are made from bone or dolomite. These may contain lead or other harmful metals. Certain health-food store preparations have this problem. Most calcium supplements that you buy in a pharmacy have been tested for this.
Calcium carbonate is absorbed best if you take it with meals. OsCal® and Caltrate® are 2 brands of calcium carbonate supplements. Other forms of calcium carbonate include:
- Some antacids, such as Tums®. If you take Tums, you don’t need to take it with a meal.
- Viactiv®, which is a flavored soft chew.
- A liquid form that you can usually get from a pharmacy, but may require a special order.
Calcium citrate is another type of calcium supplement. Some people may absorb calcium citrate better than calcium carbonate. This is true for older people and people with low stomach acid (for example, people who have pernicious anemia).
Calcium citrate absorbs best if you take it 30 minutes before a meal. One brand of calcium citrate is Citracal®, which is available in most pharmacies.
If you have any of the following side effects with calcium carbonate, take calcium citrate instead:
- Abdominal (belly) pain
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Taking Calcium Supplements
- If you’re taking more than 500 mg of calcium supplements per day, take it in divided doses for best absorption. For example, if you take 1,000 mg of calcium each day, take 500 mg in the morning and 500 mg in the evening.
- Talk with your doctor or clinical dietitian nutritionist before taking calcium supplements if you:
- Have a history of hypercalcemia (too much calcium in your blood)
- Take diuretics (water pills) or antacids for indigestion
- Have ever had kidney stones
- Have had problems with your parathyroid glands
- Have a history of heart disease, including heart attack or stroke
- If you’re taking a bisphosphonate medication for osteoporosis (or for other reasons), take your calcium supplement at least 30 minutes after you take it. If you’re not sure if the medication that you’re taking is a bisphosphonate, talk with your doctor.
- Some examples of bisphosphonate medications are alendronate (Fosamax®) and risedronate (Actonel®). Please note that calcium supplements don’t replace other medications for the treatment of osteoporosis.
- Calcium supplements can cause constipation. If you have this side effect, increase the amount of liquids and fiber in your diet. If that doesn’t work, talk with your doctor or nurse about taking a stool softener or laxative, or try to get more calcium from foods instead of taking supplements.
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Calcium-Rich Foods and Drinks
The following tables includes some foods and drinks that are rich in calcium.
|Food||Portion size||Calcium in portion (mg)||Calories in Portion|
|Parmesan cheese||1½ ounces||503||167|
|Cheddar cheese||1½ ounces||307||171|
|Milk, low-fat||1 cup (8 ounces)||305||102|
|Yogurt, plain, nonfat||1 cup (8 ounces)||265||150|
|Soy milk, plain, calcium-fortified||1 cup (8 ounces)||301||80|
|Sardines, canned in oil, with bones, drained||2 sardines||92||50|
|Collards, cooked||½ cup||134||31|
|Bok choy (Chinese cabbage), raw||1 cup||74||9|
|Figs, fresh||2 medium figs||35||74|
|Mineral water (such as San Pellegrino®, Perrier®)||1 cup (8 ounces)||33||0|
If you would like more information on foods that are rich in calcium, please ask to speak with a clinical dietitian nutritionist.
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National Osteoporosis Foundation
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US Pharm. 2015;40(9):HS-28-HS-32.
Calcium is one of the most important nutritional elements for optimal bone and dental health. Several studies suggest that calcium, along with vitamin D, may have benefits beyond bone health, and it is generally accepted that the heart, muscles, and nerves also need calcium to function properly. Millions of women in the United States take calcium supplements in an attempt to boost bone strength, especially after menopause when the risk of fractures increases. Patients with rheumatoid arthritis and other inflammatory forms of the disease also routinely take calcium supplements.
Most people get enough calcium through their diets. However, those who do not may need to take calcium supplements. It is important for individuals to know how much calcium they need and what types of supplements are the most appropriate.1
Calcium supplements are not for everyone. For instance, people who have a health condition that causes excess calcium in their bloodstream (hypercalcemia) should avoid calcium supplements. Too much or too little calcium, whether through diet or supplements, could be problematic for these individuals.1
In this article, we briefly discuss daily human calcium requirements, types of calcium supplements, nutritional considerations of calcium, and problems with too little or too much calcium intake.
The two main forms of calcium supplements are carbonate and citrate.2 Calcium carbonate is the least expensive and, therefore, is a practical option. Calcium supplements contain several different kinds of calcium salts. Each salt contains varying amounts of elemental calcium. The most common calcium supplements are labeled as calcium carbonate (40% elemental calcium); calcium citrate (21% elemental calcium); calcium lactate (13% elemental calcium); and calcium gluconate (9% elemental calcium).
In addition, some calcium supplements are combined with vitamin D or magnesium. Product labels should be read carefully and the supplement ingredients checked to see which form and amount of calcium are present in the product. This information is important if a person has any health or dietary concerns.2
Administration and Dosage
The daily requirement of calcium depends on age and sex. The body’s bone mass peaks between the ages of 18 and 25 years and declines slowly thereafter. The daily calcium recommended dietary allowance (RDA) of calcium for adult males is as follows: aged 19 to 70 years 1,000 mg, and aged >71 years 1,200 mg. The RDA of calcium for females aged 19 to 50 years is 1,000 mg, while for females aged >51 years the RDA rises to 1,200 mg.
People should not take more than 1,200 mg of calcium a day (in supplement form) unless instructed by a doctor or dietitian. On average, the majority of Americans get between 750 mg and 900 mg of calcium daily through diet alone.
It is now known that vitamin D (calciferol) has a big role in calcium absorption. Before 1997, the RDA of vitamin D taken with calcium was 200 IU (international units) for those up to age 50 years, 400 IU for people aged 51 to 70 years, and 600 IU for those >70 years. The requirements increase with age because older skin produces less vitamin D. These recommendations have since increased, as discussed below.2
Conditions associated with calcium deficiency include hypoparathyroidism, achlorhydria, chronic diarrhea, vitamin D deficiency, steatorrhea, sprue, pregnancy and lactation, menopause, pancreatitis, renal failure, alkalosis, and hyperphosphatemia. Administration of certain drugs (e.g., some diuretics, anticonvulsants) may sometimes result in hypocalcemia, which may warrant calcium-replacement therapy.3
People who follow vegan diets, have lactose intolerance and limit dairy products, eat large amounts of protein or sodium, have osteoporosis, have undergone long-term treatment with corticosteroids, or have certain bowel or digestive diseases that decrease their ability to absorb calcium, such as inflammatory bowel disease or celiac disease, are also at risk for low calcium intake. In these situations, calcium supplements may help people meet their calcium requirements.3
Calcium supports the development and preservation of bone mass to prevent fractures associated with osteoporosis and must be taken from natural sources or supplementation. Calcium is found in dairy products and in a variety of nondairy products, including dark green leafy vegetables, grains, figs, fish with soft bones, and calcium-fortified foods. Even with healthy eating and a balanced diet, one may not get enough calcium daily.
Some other natural sources of calcium are coral calcium and oyster shell calcium. Coral calcium is a form of calcium carbonate that comes from fossilized coral sources. The human body undergoes a natural process known as chelating, in which it combines calcium with another material (e.g., an amino acid) that the body can metabolize. Coral calcium is also used in maxillofacial surgery and bone grafting.2,4
Calcium and Vitamin D: A major role of vitamin D is to help the body absorb calcium and maintain bone density. For this reason, some calcium supplements are combined with vitamin D. This vitamin is available in two forms, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). The D2 form of the vitamin has a shorter shelf life compared to the D3 form.5
A few foods are known to have small amounts of vitamin D, such as canned salmon with bones and egg yolks. Vitamin D can also be acquired from fortified foods and produced naturally through sun exposure. The RDA for vitamin D is 600 IU a day for persons aged <70 years and for pregnant or breastfeeding women, and 800 IU for those aged >71 years.
Calcitriol (Rocaltrol) is the biologically active form of vitamin D that is used to treat and prevent low levels of calcium in the blood of patients whose kidneys or parathyroid glands are not functioning normally.
Calcium and Vitamin K2: Vitamin K2 has several isoforms or analogues called MK-4 to MK-10. This vitamin provides major protection from osteoporosis and pathologic calcification of the arteries and soft tissues—a major known consequence of aging. Vitamin K2 is found in animals and bacteria, including beneficial probiotic bacteria from the gastrointestinal tract. Antibiotics interfere with normal growth of healthy bacteria and impact vitamin K2 production.4,5
Although vitamin D3 has been known as the bone vitamin because it puts the osteocalcin gene into action and acts swiftly on bones, the slower-acting vitamin K2 has been recognized as being just as important for bone maintenance. The human skeleton is fully replaced every 8 to 10 years with good, dense bone, and these two vitamins play a large role in the process. The oral osteoporosis treatment dose of vitamin K2 is 45 mg a day.4
The following factors must be considered in selecting a calcium supplement.5,6
Elemental Calcium: Elemental calcium is what the body absorbs for bone growth and other health benefits; therefore, the actual amount of calcium in the supplement is very important. The label on calcium supplements is helpful in determining how much calcium is contained in one serving (number of tablets). For example, 1,250 mg of calcium carbonate contains 500 mg of elemental calcium (40%).
Supplement Choice: Some people cannot tolerate certain calcium supplements owing to side effects such as gas, constipation, and bloating. One may need to try a few different brands or types of calcium supplement to find the one that he or she can tolerate best. In general, calcium carbonate is the most constipating supplement, but it contains the highest amount of calcium and is the least expensive. Calcium phosphate does not cause gas or constipation, but it is more expensive than calcium carbonate. Calcium citrate is the most easily absorbed and does not require stomach acid for absorption, but it is expensive and does not contain much elemental calcium. Women should meet their calcium needs through both their diet and supplements.
Calcium supplements are available in a variety of dosage forms, including chewable tablets, capsules, liquids, and powders. Individuals who have trouble swallowing tablets can use chewable or liquid calcium supplements.
Drug Interactions: Calcium supplements may interact with many different prescription medications, including blood pressure medications (calcium channel blockers), synthetic thyroid hormones, bisphosphonates, and antibiotics. Pharmacists are the best professionals to consult about possible drug interactions and for calcium supplement recommendations.
Bioavailability: The human body must be able to absorb calcium so that it is bioavailable and effective. Calcium supplements should be taken in small doses (500 mg at a time) and preferably at mealtime to increase absorption. Calcium citrate is absorbed equally with or without food and is a form recommended for individuals with inflammatory bowel disease or people who have low stomach acid (individuals aged >50 years or those who are taking antacids or proton pump inhibitors).
Cost and Quality: The Federal Trade Commission holds supplement manufacturers responsible for ensuring that their supplements are safe and their claims are truthful. Many companies may have their products independently tested based on the U.S. Pharmacopeia (USP) standards. Supplements that bear the USP abbreviation meet standards for quality assurance.
Calcium Supplementation and Cardiovascular Effects
Some concerns have been raised about the potential adverse effects of high calcium intake on cardiovascular health among the elderly due to calcification of the arteries and veins. There are several possible pathophysiological mechanisms for these effects, which include effects on vascular calcification, function of vascular cells, and blood coagulation. However, newer studies have found no increased risk of heart attack or stroke among women taking calcium supplements during 24 years of follow-up.7
Some scientists believe that because calcium supplements produce small reductions in fracture risk and a small increase in cardiovascular risk, there may be no net benefits from their use. They claim that since food sources of calcium appear to produce similar benefits on bone density and have not been associated with adverse cardiovascular effects, they may be preferable to supplements. More studies are required to prospectively analyze the effect of calcium or calcium plus vitamin D supplementation beyond bone health. The medical community is still uncertain as to the effects of calcium supplements in women.8
Scoring Coronary Artery Calcium Levels
Calcium deposits can be found in many parts of the body at higher ages. A coronary calcium scan is typically done to check for the buildup of calcium in plaque on the walls of the arteries of the heart. Coronary calcium scan scores range from 0 to more than 400. A calcium score of zero means no identifiable plaque, while a score of above 400 indicates extensive atherosclerotic plaque and significant coronary narrowing.9
Calcification of the artery walls is common at age >65 years. Calcification of the breast is often seen in women above the age of 50 years. Calcium deposits are easily detected by x-ray images because calcification is composed of calcium phosphate, similar to that in bone.
Coronary calcium is part of the development of atherosclerosis; it occurs exclusively in atherosclerotic arteries and is absent in normal vessel walls. The amount of calcium in the walls of the coronary arteries, assessed by a calcium score, appears to be a better cardiovascular disease risk predictor than standard factors.9
Risks of Low Calcium Intake: As mentioned above, calcium is important for healthy bones and teeth, as well as for normal muscle and nerve function. There are health problems associated with low calcium levels: Children may not reach their full potential adult height, and adults may have low bone mass, which is a risk factor for osteoporosis and hip fracture. Normal blood calcium levels are maintained through the actions of parathyroid hormone, the kidneys, and the intestines. The normal adult value for serum calcium is 4.5 to 5.5 mEq/L.10
Approximately 40% of serum calcium is ionized (free), while the other 60% is complexed, primarily to albumin. Only ionized calcium is transported into cells and metabolically active. Decreases in the ionized (free) fraction of calcium cause various symptoms. Hypocalcemia, or low-level calcium, most commonly occurs with low calcium absorption, vitamin D or K2 deficiency, chronic renal failure, and hypoparathyroidism.10
Risks of High Calcium Intake: Many factors can increase blood calcium levels. Although the body has a built-in regulatory process for calcium absorption and maintenance, underlying diseases, medication interactions, or overuse of supplements can cause high calcium levels.
An abnormally high calcium concentration can cause damaging health problems and requires medical treatment. Although dietary calcium is generally safe, excessive calcium does not provide extra bone protection. In fact, if calcium from diet and supplements exceeds the tolerable upper limit, it could cause kidney stones, prostate cancer, constipation, calcium buildup in blood vessels, and impaired absorption of iron and zinc.
Taking calcium supplements and eating calcium-fortified foods may increase calcium above normal levels. As a result, it is very important to stick to the RDA and not exceed the recommended dosage.10
The best way to treat calcium deficiency is to prevent its occurrence. Modification of risk factors is imperative, and pharmacists can play a large role in this area. They can recommend appropriate calcium and vitamin D supplements. Individuals, particularly women, at risk of low calcium should take foods and drinks rich in calcium and vitamin D, quit smoking, and increase weight-bearing and muscle-strengthening exercise. Monitoring one’s body mass index at higher ages is also critical to reducing bone fractures.
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You may be right. Many women seem to have constipation as a reaction to calcium supplements, although there’s no research to explain the connection, says William D. Chey, MD, an associate professor of internal medicine at the University of Michigan Medical School. Here are some strategies you can try:
Take one dose of your calcium supplements in the morning and the rest later in the day—it may reduce the stress on your intestines, Dr. Chey says. Also, if you’re taking a calcium carbonate supplement, you might want to switch to calcium citrate. Although experts aren’t sure why, calcium citrate seems less likely to disrupt your system.
However, the best way to absorb calcium with the least risk of constipation is to get most of it from foods such as low-fat dairy products and fortified orange juice. Between calcium supplements and your diet, you should consume about 1,000 to 1,200 mg of calcium a day. Make sure you’re also getting 21 to 25 g of fiber daily from whole grains and green leafy veggies, or from a supplement. Fiber absorbs water (something else you should be consuming lots of), which helps food pass through your system more easily, so you can be constipation-free.
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