Everyone needs calcium, right? It seems many people are concerned about avoiding osteoporosis. No one wants to break a bone or develop stooped posture. So should we all load up on calcium supplements? Not so fast. Too much calcium can crowd out other nutrients and cause kidney stones, constipation, and other significant problems. Interactions with meds can be serious, and there’s a hint that calcium supplements may boost the risk for heart disease.
Though calcium is needed for various bodily functions to work well, it mainly helps to keep bones and teeth strong. “Calcium is crucial for optimal bone health throughout your life,” says Taz Bhatia, MD, an integrative health expert and founder of CentreSpring MD, an Atlanta medical practice. Without enough of the mineral, you may have a higher risk of osteoporosis and bone fractures, which become more common with age as bones become thinner. Calcium is helpful for increasing bone density in people with and without osteoporosis.
Who Needs Supplements
Before you start taking calcium supplements, your doctor should test your blood to gauge your nutrient levels. It’s important to check that all your minerals are in balance because some “might get crowded out by calcium in the gut, such as zinc and iron, which are important minerals involved in many reactions in the body,” says Fraser Smith, ND, a naturopathic doctor, chief academic officer and assistant dean for naturopathic medicine at National University of Health Sciences in Lombard, Ill.
So who is at an elevated risk of having low calcium levels? Vegans and people with lactose intolerance for starters, since they avoid many foods and beverages that are rich in the nutrient.
Both protein and sodium work to remove calcium in your body. If you are on a high-protein diet or tend to be attracted to salty foods, it could affect your calcium levels.
“I’ve also had patients with serious digestive issues like irritable bowel syndrome (IBS) or celiac disease that have affected their ability to absorb calcium, and therefore they need an extra source of calcium,” says Dr. Bhatia. Also, research has shown that people with IBS may avoid high-calcium foods, such as dairy products, in an effort to prevent painful symptoms.
Drug Interactions With Calcium
Despite the bone-building boost that these supplements may provide, there can be disadvantages in certain cases. “One downside is that calcium supplements may interact with certain medications and may make it harder for them to work,” according to Mohamed A. Jalloh, PharmD, assistant professor at Touro University California College of Pharmacy and spokesman for the American Pharmacists Association. “An example is an HIV drug named Tivicay [dolutegravir],” he says. “Calcium makes it harder for this medication to work and requires patients to separate the doses by a few hours.” Alternatively, Tivicay and calcium can be taken together with food to prevent the interaction.
It might seem logical to take calcium supplements if you have osteoporosis, but check with your healthcare provider if you are taking a bisphosphonate, a medication typically used for the condition, such as Fosamax (alendronate), Actonel (risedronate) or Boniva (ibandronate). A calcium supplement may interfere with absorption of these drugs.
However, patients with osteoporosis often don’t have enough calcium in their diet and will need a supplement. To prevent supplemental calcium from interfering with the bisphosphonate’s absorption, dosages should be separated by at least an hour.
Taking a calcium supplement can also boost the risk of a toxic reaction with the irregular heartbeat medication Lanoxin (digoxin).
There are many other drugs and over-the-counter products that calcium supplements may interfere with. Following are a few that commonly interact with calcium:
- antacids that contain aluminum
- certain diuretics (hydrochlorothiazide, furosemide and bumetanide), which are used to treat fluid retention
- antibiotics known as fluoroquinolones, including Levaquin (levofloxacin) and Cipro (ciprofloxacin)
- antibiotics known as tetracyclines, including doxycycline and minocycline
- levothyroxine, a drug for hypothyroidism
- phenytoin, a seizure med
Your Body Doesn’t Want Too Much
Adverse effects can occur if you overdo your intake. “Most of us only need 1,000 mg to1,200 mg of calcium each day, and taking any more than you need can lead to constipation and may even increase the risk of kidney stones,” Dr. Taz cautions.
And overdoing supplements can seriously damage the heart and kidneys due to hypercalcemia, or elevated calcium levels in the blood, adds Dr. Smith. A condition called milk-alkali syndrome, hypercalcemia almost always caused by excessive use of calcium supplements, can lead to kidney failure that requires dialysis.
Also, some research suggests taking too much calcium may be associated with death from cancer. In a study published in the Annals of Internal Medicine researchers looked at responses from almost 31,000 adults who answered questions on dietary supplement use from the National Health and Nutrition Examination Survey. The adults were also followed for an average of 6.1 years. The researchers found that excess calcium intake was associated with a higher risk of cancer death.
Where You Get Calcium From Counts
It’s important to note that you should get as much calcium daily as possible from foods, rather than rely on supplements, in part because it’s much easier to overdo calcium if you’re taking supplements. Experts say excess intake of calcium is almost never due to calcium from foods. Also, the body typically absorbs more calcium if it’s combined with certain other nutrients, such as vitamin D. And eating stimulates the production of stomach acid, which also boosts absorption.
Your body can absorb about 30% of the calcium present in dairy products, such as milk, and fortified foods but 50% in certain vegetables (Brussels sprouts, kale, mustard greens, broccoli, bok choy, cauliflower).
The body can absorb 20% to 40% of the calcium present in a supplement, but the body is limited as to how much it can absorb at one time. In addition, some people can experience gastrointestinal side effects from the supplements. And as mentioned before, calcium supplements can interfere with the body’s ability to absorb zinc and iron, as well as other medications you may be taking.
There are plenty of foods to choose from to meet your calcium needs, and you’ll be getting all the benefits of the other nutrients and fiber available in whole foods and which are absent from supplements. Aside from the well-known sources like milk, cheese and yogurt, you can get significant amounts from vegetables like kale, broccoli and collard greens, as well as some fish, like sardines and salmon. Many cereals and fruit juices are also fortified with calcium.
So just how much calcium do you need per day? Well, that depends mostly on sex, age and other health factors. The Food and Nutrition Board of the National Academies provides intake recommendations, including recommended dietary allowance (RDA) and the tolerable upper intake level (UL). The RDA is the average daily amount estimated to meet the needs of nearly all healthy people, and the UL is the maximum daily amount unlikely to be harmful. Here are helpful guidelines from the National Institutes of Health Office of Dietary Supplements:
CCalcium: Daily recommended amounts for adults
|19-50 years||1,000 mg||2,500 mg|
|51-70 years||1,000 mg||2,000 mg|
|71 and older||1,200 mg||2,000 mg|
|19-50 years||1,000 mg||2,500 mg|
|51 and older||1,200 mg||2,000 mg|
Men up to age 50 shouldn’t take more than 2,500 mg daily and those 51 to 70 should avoid taking more than 2,000 mg daily.
Women up to age 50 should take no more than 2,500 mg daily. Women 51 and over should take no more than 2,000 mg daily, max. Exceeding the upper limits can lead to side effects and potential health problems.
Because calcium comes in different forms in supplements, it’s important to take ones that have the most active amount of the mineral, known as elemental calcium. Calcium carbonate supplements contain the most elemental calcium — 40% — followed by calcium citrate, with 21%. Some common name brands with calcium carbonate are Os-Cal and Caltrate, while calcium citrate is found in Citracal and products made by Solgar and Nature’s Way.
A Link to Heart Disease?
There have been concerns that calcium supplements may increase the risk of heart disease. Some doctors and researchers believe that excessive amounts of calcium can make their way into fatty plaque in arteries and cause atherosclerosis, or hardening of the arteries, which boosts the risk for heart disease. For example, a study published in the Journal of the American Heart Association involving more than 2,700 people found that there was an association between those taking calcium supplements and coronary artery calcification, a measure of atherosclerosis. But those who achieved their calcium goals through diet alone didn’t share that risk.
A 2019 analysis of 42 studies including over 1 million people determined that taking more than 1,000 mg per day of calcium supplements can increase the risk of heart attack, but less than 1,000 mg had no association with heart disease risk. And when taken with vitamin D, calcium supplements did not increase the risk of heart disease. Those who got their calcium from dietary sources did not share the same risk of heart disease as those taking high amounts of calcium in supplements.
In a study of more than 61,000 women published in The BMJ, researchers investigated the association between dietary and supplemental calcium intake and death from cardiovascular disease as well as all causes. The highest death rates from all causes, cardiovascular disease and ischemic heart disease, but not stroke, were seen in women whose dietary calcium intake exceeded 1,400 mg per day compared to those whose intake was 600 mg to 1,000 mg. Death rates were even higher in those with intakes over 1,400 mg who took calcium supplements. But those who took only 500 mg of supplemental calcium per day and stayed within the 600 mg to 1,000 mg daily range did not experience an increased risk of death.
Jalloh says the talk about calcium supplements and heart disease is inconclusive, noting that most research has confirmed that they are generally safe when taken at recommended doses. “After reviewing all of the important studies, the consensus actually showed that calcium intake from supplements and food that doesn’t exceed the UL is not linked with heart disease,” he says. “In multiple studies, calcium and vitamin D supplementation actually helped people live longer.”
To choose and use calcium supplements wisely, heed these additional expert tips:
1. Try Food First
Dr. Taz suggests incorporating high-calcium foods into your diet before turning to supplements, and emphasizes the importance of discussing the topic with your healthcare provider first.
2. Don’t Overdo It
Remember that the recommended daily allowance for calcium is 1,000 mg to 1,200 mg, and you are likely already getting a good portion of this from your diet. To avoid overdoing it, read food and beverage labels to check the amount of calcium they provide toward the recommended amount. “If a label lists ‘Calcium 25%,’ that means that you will be consuming 250 mg of calcium per serving,” Jalloh notes. If you find that you are meeting the recommended amount through your diet, you may not need to take supplements unless advised by your doctor.
3. Vitamin D Helps Calcium Be Absorbed
Calcium is absorbed best when taken with food, and low levels of vitamin D affect absorption as well. “Without enough vitamin D, we do not absorb calcium well and we excrete it from the kidney too readily,” Dr. Smith explains. Calcium supplements that contain vitamin D can be helpful, and natural sources of vitamin D include dairy, fish, and limited sun exposure. Experts suggest avoiding sun exposure as a primary vitamin D source because it increases the risk of skin cancer. But for some people as little as 5 minutes in the sun twice a week can lead to significant vitamin D synthesis.
4. Check With a Pharmacist
Though this advice applies to many types of drugs and supplements, patients “should always ask their pharmacist to double-check their medications to ensure that none of them interact with calcium,” Jalloh recommends.