If you suspect that a calcium supplement is causing you constipation, you may be right. The research on calcium and constipation is mixed, but there are things you can do.

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For stronger bones, a healthier heart, or preventing muscle cramps, you might be taking a calcium supplement. Calcium is a critical mineral your body needs for healthy functioning, and many people don’t get enough from food alone. It’s not surprising, then, that around 22% of men and 32% of women take a supplement that contains calcium.

But some people report that calcium supplements come with an unpleasant side effect: constipation.

Wondering if this mineral is the cause of your digestive troubles? Here’s what research has to say about the calcium-constipation connection and what you can do about it.

Language matters

You’ll notice we use the binary terms “women” and “men” in this article. While we realize this term may not match your gender experience, this is the term used by the researchers whose data was cited. We try to be as specific as possible when reporting on research participants and clinical findings.

Unfortunately, the studies and surveys referenced in this article didn’t report data for or may not have had participants who are transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless.

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Different people may experience different side effects from taking calcium — and constipation can certainly be one of them. But research on calcium’s effects on your bowel habits is mixed.

According to 2018 research, calcium carbonate is often associated with constipation (as well as bloating, diarrhea, and abdominal pain). An older research review of seven randomized controlled trials reported that constipation was one of the most frequently reported side effects of taking calcium supplements.

On the other hand, a study from 2016 found that supplementing with calcium carbonate and calcium phosphate had no effect on stool frequency in healthy women.

The National Institutes of Health concludes that calcium might cause constipation in some (but not all) people.

Calcium isn’t the only supplement that might cause constipation. A variety of other vitamins, minerals, and plant compounds have been linked to slower digestion, including iron, folic acid, and berberine. Taking these along with calcium could lead to even less frequent bowel movements.

Experts believe that calcium’s tendency to stop things up is due to a slowing down of intestinal motility (the ability of the gut to move food along). It may also reduce fluid secretion in your gut, causing hard or dry stool.

If constipation from calcium becomes bothersome, there are some steps you can take. Try consuming plenty of fiber from foods like beans, whole grains, fruits, and vegetables, and be sure to stay hydrated with plenty of fluids. A doctor or other healthcare professional may also recommend a fiber supplement or stool softener.

Worried a calcium supplement might stop you up? Try preventing constipation before it begins. Some possibilities for prevention include:

  • Spread your calcium intake throughout the day. If you take a calcium pill, for example, you might take half in the morning and half in the evening.
  • Take your calcium supplement with food and water.
  • Try a different form. Calcium carbonate has a reputation for being the most constipating. Other forms like calcium citrate, calcium lactate, or calcium phosphate might not affect your bowels as much.
  • Take a calcium-magnesium combo. Magnesium has laxative effects that could counteract calcium-related constipation.

Constipation is considered a chronic ailment when you have three or fewer bowel movements per week or stool that’s hard, lumpy, or difficult to pass, for more than 6 months. It’s time to see a doctor if you meet these criteria.

Does calcium affect bowel movements?

Though some research hasn’t found a link between calcium and bowel habits, other studies indicate that constipation is a common side effect of this supplement.

Only you can tell how calcium affects you. If you notice a clear link between starting a calcium supplement and changes to your digestion, you’re probably onto something.

What kind of calcium does not cause constipation?

Any type of calcium may slow things down in your gastrointestinal tract, but calcium carbonate has a reputation for doing so the most. Other forms, such as calcium citrate, calcium gluconate, calcium lactate, and calcium phosphate, may be less constipating.

Can too much calcium and vitamin D cause constipation?

Taking vitamin D and calcium together could increase your likelihood of constipation. Vitamin D increases your body’s ability to absorb calcium. When this happens, you may end up with even more calcium circulating in your system. The more calcium, the higher your risk of constipation.

Calcium’s effects on bowel health may vary from person to person. If you suspect a calcium supplement is causing constipation, try the strategies above to get things moving smoothly — and don’t hesitate to talk with a doctor or healthcare professional about other solutions.