Why Your Calcium is Causing Constipation (+ What to Do About it!)

Published: June 7, 2017
Updated: April 1, 2021

calcium and constipation

Unfortunately, most calcium supplements cause constipation and other gastrointestinal issues like bloating, gas, and cramps! Chances are you’re reading this because you’ve had a bad experience with these issues.

Beyond the discomfort, these gastrointestinal issues are a big problem because they can keep you from taking your recommended dosage of calcium every day. Why would you want to feel sick to your stomach, right?

After reading this post, you’ll know how to avoid all these problems and not have to worry about missing your dosing schedule.

Why Do Calcium Supplements Cause Constipation?

Watch the video below or read the transcript here as Lara Pizzorno, Bone Health Expert dives in further to this common question. And don’t forget to continue reading for more insight not in the video.

Most calcium supplements cause constipation because they supply only calcium or just calcium and vitamin D. It takes a variety of nutrients for proper absorption of calcium, especially magnesium. Magnesium is a natural laxative and thus counterbalances the constipating effects of calcium.

If your calcium supplement and/or your diet lack magnesium then constipation can occur. But with enough magnesium, your colon walls will relax helping you pass stool along. Additionally, magnesium attracts water, meaning more water gets to your colon and softens your stool.

On the flip-side, calcium contracts muscles. If you’re getting too much calcium the muscle walls of your colon contract, making it harder to pass stool. The longer your stool sits in the colon, the more water is pulled out of it. This makes the stool dense and hard, making it significantly harder to pass and likely painful.

Magnesium reduces tension on the walls of your colon which allows for a normal peristaltic action. Peristaltic action, also known as peristalsis, means “a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube”. This means the rhythmic movement of your intestinal tract that moves food from one end to the other.

Regularly including magnesium-rich foods in your diet is great for overall health, plus it will keep you regular.

The Top 9 Causes of Constipation

rock calcium

Too Much Supplemental Rock Calcium

The most common type of calcium and the one that causes the most gastrointestinal discomfort is from rock. That’s right – your supplement is most likely calcium derived from limestone or marble (described on your label as ‘calcium from calcium carbonate‘).

Why do we eat rock calcium (and since the 1930s when it was first introduced)?

Because rocks are cheap, rich in calcium (40%) and capable of slowing bone loss.

See, we naturally lose about 1% of our bone per year after age 35. For decades, rocky calcium carbonate has cut that in half so we only lost about 0.5% per year. Given no other calcium (from shell, coral or cattle bone) could boast anything more, slowing bone loss with rock calcium was better than not slowing it at all.

But a very uncomfortable side effect of rock calcium carbonate that we’ve tried to accept is constipation, as well other gastrointestinal issues like bloating, gas, and cramps. These gastro issues happen because rock calcium carbonate essentially turns off the production of stomach acids.

This is why rock is used as the main component in antacids like Tums. It works great if you suffer from acid reflux and heartburn – but your digestive system pays the price! If stomach acids aren’t there to churn and break down your food, then it makes sense that constipation, bloating, gas, and cramps will result.

Plus, taking too much calcium alone at once provides more calcium than the body can absorb, leading to constipation. For this reason, it is recommended to take no more than 500 mg of calcium at a time. After all, calcium is a mineral, and minerals are rocks. So even though it’s an important nutrient your body needs, you’re essentially asking your body to absorb a rock. Be kind and patient with your body by taking amounts that your body can tolerate, absorb and utilize.

Solution: Choose a well-absorbed form of calcium in a dosage of 500 mg or less. Calcium is absorbed most efficiently when it’s taken in amounts of 500 mg or less at one time. However, it’s also important to not supplement with calcium alone, which we’ll get into down at point #9.

iron supplement

Too Much Supplemental Iron

Iron supplements are notorious for causing constipation and that is why many people don’t follow through with their supplementation. While there are some forms of iron that are easier to absorb, they tend to come at a higher cost.

Solution: Speak with your healthcare provider about supplementation options. If you have clinical iron deficiency anemia, your health care provider can write a prescription for an iron supplement that may be easier to digest and is covered by insurance. Additionally, ask to speak with a nutrition professional about how to get your iron from foods.


Too Much Sugar and Unhealthy Fats

Consuming too much sugar and/or unhealthy fats feeds unhealthy bacteria in your gut and causes inflammation. The unhealthy bacteria start to multiply and this reduces the healthy number of bacteria that keep the digestive tract moving properly. Inflammation can then occur and trigger a whole host of problems in the body. This means the intestinal tract can swell with inflammation, making it difficult for food to move through it.

Solution: Reduce or eliminate foods with added sugar and refined carbohydrates. The same goes for unhealthy fats. Avoid fried foods as much as possible, which also tend to contain refined carbohydrates. Also, swap out unhealthy fats for naturally-occurring healthy fats that have a soothing, inflammation-reducing effect. These can be found in plant-based oils, seeds, nuts and fatty fish. AlgaeCal’s Triple Power Omega 3 Fish Oil is perfect for helping you reduce inflammation and transition over to healthy fats.


Lack of Physical Activity

If you ever undergo a medical procedure or end up in the hospital, one of the first things the medical team will do to get you on the mend is help you go for a walk. That’s because we are designed to be on the move and our digestion depends on it. Walking helps move and jostle the food in the digestive tract, using gravity to help move it along. Yoga, jogging, Pilates, and the like will all have the same benefits. They also help strengthen your muscles, including the intestinal tract, giving you greater ability to move things both inside and outside your body.

Solution: Get up and get moving as often as possible. Take a walk after meals and try to take a couple 5-to-10 minute walking breaks during the work day. Prolonged periods of sitting are bad for digestion, mood, and overall health.

Lack of Fiber

Ever eat too many cherries or too much watermelon and find yourself having to make a quick escape to the bathroom? That’s because these fruits are high in flavor and fiber. You get caught up in the delicious flavor, only to find yourself in the bathroom with diarrhea a couple hours later from all the fiber. Take it easy. If you’re not eating a fiber-rich diet, you have the exact opposite problem. Fiber is a key component in the human digestive tract. Fiber binds to water, which softens the stool, making it easier to pass along. Additionally, fiber and the water that it attracts creates “bulk”, which sends a message to the intestinal walls that you’re full and it’s time to get to work passing the food along. In this way, fiber helps with both digestion and weight regulation.

Solution: Slowly increase the amount of fiber you eat each day. Going from next-to-zero grams of fiber to the full recommendation of 20 to 25 grams all at once is going to cause diarrhea. Spread fiber intake out throughout the day to get the benefits without the downside. Strive for 5 grams every meal and snack.

Imbalanced Gut Bacteria

We all get by with a little help from our friends, including the healthy bacteria that make digestion and proper nutrition possible. Healthy bacteria help break down food to extract maximum nutrition and keep it moving along. Certain medications, stress and not eating enough fiber-rich foods can have negative effects on your gastrointestinal bacteria.

Solution: Gut bacteria thrive on foods naturally rich in fiber, such as fruits, vegetables, legumes, nuts and whole grains. Consume probiotic (healthy bacteria) foods and beverages such as kefir, yogurt, kimchi, sauerkraut, kombucha and homemade shrubs. Take a probiotic supplement. If you’re currently taking antibiotic medication, take your probiotic supplement at a different time or you’ll cancel the effects of both.

Certain Medications

A common side effect of several medications is constipation. Always read the information that comes with your medications to see if constipation is a common side effect. The list of medications that can cause constipation is lengthy, but some of the top offenders are opioids, NSAIDs, antihistamines, antacids, blood pressure medications and diuretics.

Solution: Follow your healthcare provider’s instructions relating to your medications, but reach out to get more information and solutions regarding constipation. Discuss the duration you’re expected to be on the medication and ask if there are easier-to-digest alternatives. Eat a healthy, fiber-rich diet full of fruits, vegetables, seeds, nuts, legumes and whole grains. Additionally, exercise regularly, drink plenty of water and get plenty of sleep.

Lack of Water

Water has been mentioned frequently throughout this article and that’s because it’s vital for healthy digestion. Dehydration wreaks havoc on the human body, including the digestive tract. When you’re dehydrated, your body will conserve as much water as possible for cerebral fluid, blood volume, and respiration.

Solution: Drink 8 to 10 glasses of water every day. All fluids count in fluid consumption, but not all beverages are created equal. Avoid sugary drinks and/or those with toxic food additives. Limit caffeine consumption to 2 to 3 cups of caffeinated beverages a day or under the 400 mg mark.

Lack of Magnesium

Magnesium is needed to relax muscles, including those of the gastrointestinal tract. Magnesium is also an electrolyte that affects water balance. Low magnesium intake causes a host of health problems, including constipation. It is also needed to properly absorb and utilize calcium. It is estimated that 80% of Americans are deficient in magnesium.

Solution: Makes sure to eat a variety of magnesium-rich foods such as dark leafy green vegetables, seeds, nuts and beans throughout the day, every day. Keep in mind that calcium and magnesium work together. The proper ratio is 2:1 (2 parts calcium to every part magnesium) so make sure you find a calcium supplement with the same ratio. AlgaeCal Plus naturally contains this 2:1 “golden ratio”.

While all of the above solutions can help ease constipation issues, you’ll still have problems if you take a calcium supplement with calcium alone or with added vitamin D. Consider switching supplementing with a higher quality calcium. Not doing so puts you at risk for constipation and other health-related issues. It’s not worth it to save money by taking what you have on hand.

As you’ve now learned, magnesium is a natural laxative- which will balance the constipating effects of calcium- and also has bone-building properties. Make sure your calcium supplement contains magnesium to prevent constipation, provide bone health benefits, as well as maintain water balance.

Instead of masking the problems from your current calcium supplement, try a natural, plant-based calcium supplement providing you with all the nutrients your bones need. Plus, you won’t have side-effects like constipation, gas or bloating!

AlgaeCal Plus is the only calcium supplement clinically supported to increase bone density in 6 months— at any age! It’s the plant-based solution, meaning it’s more body-friendly, plus it’s more effective at a lower dose than your typical calcium supplement.

How to choose a calcium supplement

How to Choose The Best Calcium (That Doesn’t Cause Constipation)

When looking at calcium supplements, consider these factors:

There are several things to consider when purchasing a calcium supplement. Running out to the store and buying the cheapest one you see can actually do you more harm than good. Not only can that supplement cause painful constipation, it can cause other health issues and end up being one more thing cluttering up your cabinets.

Consider the following points before putting your money towards a calcium supplement: Take a look at why you want to take a calcium supplement; how much you have to spend on the supplement; how frequently you’ll have to purchase more; the dosage; physical size of the supplement (one of the biggest reasons people stop taking supplements is difficulty swallowing them); and product form– liquid, tablet, capsule, powder, etc. Do your research to see what clinical studies, guarantees, certifications and measures for clean, ethical sourcing the company has.

  • True Cost: If your calcium supplement is just calcium alone or calcium and vitamin D it is not enough. Your bones are made up of much more than that! They need magnesium, vitamin K2, D3, C, boron, and trace minerals. Buying all of those separately is expensive and a hassle. Instead, get an all-in-one bone formula.
  • Amount of Calcium: Remember that your body can only absorb 500 mg of calcium at a time, anything beyond that will make you feel sick to your stomach and lead to constipation. In addition to constipation, too much calcium at once or over time has potential health risks like calcium depositing into soft tissues and kidney stones. AlgaeCal Plus is more effective at a lower dose, compared to higher amounts in other calcium supplements. Plus, it contains the mighty mineral called vitamin K2, which directs calcium straight to your bones and keeps it out of your arteries!
  • Supplement Size & Form: Tablets, capsules, chews, oh my! Can you physically swallow the supplement? Interestingly, one of the top reasons people stop taking a pill or supplement is because it’s hard to swallow because of its size. AlgaeCal Plus is placed in veggie capsules that you can pull apart if you find swallowing difficult. There are also calcium “chews” on the market. Those tend to be laden with food dyes, artificial flavors, and added sugars… all things you don’t want, nor need a supplement.
  • Clinically Supported: Do the research to see if the supplement company has done their research. Do they openly share clinical trials supporting the safety and efficacy of their product on their website? Is that information easily accessible to the public?
  • Quality: There are an overwhelming amount of supplements on the market these days and it’s up to the consumer to do their research. While time-consuming, it’s important to know what you are putting in your body. Read up on the supplement company to see what certifications, research and ethical sourcing efforts they have put into their product. Also, check to see if they are certified organic.

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The Bottom Line: All Calcium is NOT Created Equally

Constipation is an unwelcome side-effect. But don’t lose sight of why you started taking a calcium supplement in the first place – bone health. More than likely you started taking calcium to stop bone loss, but did you ever think your calcium supplement could increase your bone density too?

That’s why at AlgaeCal we looked for a way to not only stop bone loss but build bone mineral density too. Plus, we wanted to end the digestion problems from rock-based calcium. Turns out, the answer was floating off pristine South American shorelines this whole time – a bone-friendly, plant-based calcium. In fact, it’s the most mineral-concentrated plant on earth, containing all 73 trace minerals naturally found in your bones right now.

What’s more, the minerals are “predigested” by the plant making them more body-friendly!

That’s why you won’t have any upset stomach or constipation from this rare marine algae. AlgaeCal Plus is the only calcium supplement that has been shown to increase your bone density naturally, without side-effects.

Even better, you can take it with the only mineral known to promote bone building and inhibit bone loss at the same time. This bone-building duo is unmatched by any other supplement or nutrient combination you can find.

Confidently take charge of your bone density today by learning more about these products here.

Article Comments

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  1. gina richards

    June 20, 2013 , 4:00 am

    Thank you for the information. i have been prescribed the powdery chewable tablets that you describe as ‘rock’ for all the years since diagnosis by scan in jan 2006 age 50. i most certainly will try algae cal. also thank you for the dietary info, i will be following a healthier diet from now on. some of your diet plan was already on my weekly agenda, but now i have seen some that i could introduce for variety. much appreciated.

  2. AlgaeCal

    June 25, 2013 , 2:31 pm

    Anytime, Gina.

    We’re here to help. Let us know if you need anything else, OK?

  3. Toni Tobin

    November 19, 2019 , 7:33 pm

    Let me know when you make this in a gummy. I don’t do pills.

  4. Blaire AlgaeCal

    November 20, 2019 , 12:13 pm

    Thanks for reaching out and letting us know, Toni! If you have difficulty swallowing, you can twist or cut open the capsules and sprinkle the powder on cold food and/or beverages like yogurt, smoothies, apple sauce, etc.

    AlgaeCal powder is tasteless but the texture is a little gritty because it is rich in minerals. Some of the minerals are not 100% water soluble and this is the reason why it is best to be mixed with foods or beverages that have a thicker consistency. Hope that helps! 🙂

    – Blaire @ AlgaeCal

  5. Kathy

    August 29, 2014 , 8:34 pm

    Hi there I have been taking calcium citrate and magnesium glycinate and I am having severe constipation. I was wondering if the calcium in the article would work for me. I can’t goon this way with severe constipation.
    Thanks, Kathy

  6. Monica

    September 2, 2014 , 9:38 am

    Hi Kathy,

    AlgaeCal is a plant-based calcium so you should not get any side effects such as constipation.You can try AlgaeCal and if you experience constipation you can call us within 1 month and we offer a full refund on the opened bottle minus the shipping costs.

    – Monica @ AlgaeCal

  7. Jan cutler

    August 29, 2016 , 7:40 am

    I think you have Just solved my problem! Where can I purchase AlgaeCal? Currently I am taking 1 , 60g calcium plus w/ magnesium in the am and one in the pm plus an am vitamin D , 1000iu.

    Thank you

  8. Monica

    August 29, 2016 , 9:33 am

    Hi Jan,

    Wonderful to hear! You can buy AlgaeCal online here: https://www.algaecal.com/products/algaecal-plus/

    Let me know if you have any further questions.

    – Monica @ AlgaeCal

  9. Sarah

    December 14, 2016 , 6:14 am

    Can you by this in the uk?

  10. Monica

    December 14, 2016 , 8:39 am

    Hi Sarah,
    You cannot buy AlgaeCal in stores, but you can buy AlgaeCal online and we ship to the UK. For more information on international shipping go here: https://www.algaecal.com/shipping-returns/

    – Monica @ AlgaeCal

  11. Nikki DeSimio

    March 4, 2017 , 6:33 am

    Hi,I would love to try AlgaeCal but I have a difficult time swallowing pills. Are they large?

  12. Monica

    March 4, 2017 , 8:43 am

    Hi Nikki,
    You can actually pull apart AlgaeCal capsules and sprinkle the powder into foods like yogurt, oatmeal and drinks like juices and smoothies if you find swallowing them difficult.
    – Monica @ AlgaeCal

  13. treva silverman

    July 5, 2017 , 4:05 pm

    Thanks for such helpful information.
    I’d like to know about pulling the capsules apart and sprinkling them on yogurt. Will it have a taste when sprinkling them? In other words, will it change the taste of the yogurt? What other foods will it do well sprinkling on? Thanks so much.

  14. Monica

    July 6, 2017 , 9:21 am

    Hi Treva,

    The taste is neutral so it won’t alter the flavor of your yogurt. Applesauce, smoothies, and oatmeal are also good alternatives. Just remember to mix well so it’s not all clumped together in your food :).

    – Monica

  15. Joyce Loera

    July 15, 2017 , 11:04 am

    I just increased Strontium Plus from one capsule to two and WOW!, I now have great bowel movements. I’m so happy…………

  16. Monica

    July 17, 2017 , 8:19 am

    Hi Joyce,

    Thanks for sharing! That’s great 🙂

    – Monica

  17. Barbara

    October 18, 2017 , 12:43 pm


  18. Sheila

    October 28, 2017 , 1:37 pm

    I started the algaeCal 6 mo trial. Im not sure when but about month 4 or so small bumps slowly appeared along my spine. First I ignored it, but they persisted. y medical professional concluded that ! Had developed an adult onset sensitivity to shellfish. I had to stopped AlgaeCal, the itchy bumps disappeared. At the same time I ceased the Strontium supplement.
    Has anyone else experience the same reaction? After studying AlgaeCal findings I was sorry to stop the program.
    I continue AlgaeCal Omega-3.

  19. Lara Pizzorno

    October 31, 2017 , 11:10 am

    Hi Sheila,

    This seems strange as AlgaeCal does not contain shellfish in any form, and no such side effect has ever been reported in any of the human research studies conducted using AlgaeCal Plus and Strontium Boost. Algas calcareas is a plant, a marine algae. Since it’s possible you had an exposure to shellfish from something else, and because AlgaeCal Plus is so effective in helping healthy bone to rebuild, it might be worth a trial to see if you were actually reacting to AlgaeCal. Hopefully, you still have your AlgaeCal Plus products at home? Try to think about what other exposures you might have had — a new laundry soap? body lotion? shampoo? Do you have a garden? After harvesting the produce from our vegetable garden a few days ago, I developed a contact dermatitis, most likely from the radishes. Definitely NOT from AlgaeCal, which I have now been taking every day for close to 5 years and will continue to take for the next 50 years or so (I just turned 69, so that will make me 120 :-)).

  20. Pat

    July 23, 2018 , 4:51 pm

    Does algaecal cause gas?

  21. Jenna AlgaeCal

    July 31, 2018 , 10:36 am

    Hi Pat,

    Good question! Like this article touches on, many people report discomfort with over the counter calcium and fortified calcium foods/beverages. This can be due to the calcium coming from a single source/rock based calcium such as calcium carbonate, or perhaps a calcium/magnesium imbalance causing digestive discomfort. AlgaeCal is extremely well tolerated across the board, as all of its calcium comes from a whole food, plant source. We get a lot of feedback from people who have switched to AlgaeCal and tell us they find it body-friendly and easy on their system – with no flatulence issues!

    Should there ever be any discomfort, we offer a full, one year product satisfaction guarantee on all of our products, and we stand by this 100%! We want you to be happy in what you are taking and trust that the products will not cause you any digestive issues. There is more information available on this here.

    Feel free to give us a call at 1-800-820-0184 if you have any questions!

    – Jenna @ AlgaeCal

  22. Paula

    May 4, 2019 , 3:16 pm

    I am taking AlgaeCal but I’m also continuing my dairy (4 servings a day — 2 cups of milk and 2 cups of Greek yogurt.) I try not to drink much milk when I take my AlgaeCal, but I do usually end up drinking it within an hour of taking the AlgaeCaL. I was not constipated at all when I just did dairy, but now I’m finding that I tend to be constipated. Should I cut back on my AlgaeCal if I’m going to be consuming that much dairy? I do hate to cut back on my dairy, since my DEXA numbers improved this past year (before the AlgaeCal — I’m hoping for even better this coming year!)

  23. Jenna AlgaeCal

    May 6, 2019 , 3:57 pm

    Hi Paula,

    It sounds like you might not be getting enough magnesium to balance out all of the calcium in your diet! You see, AlgaeCal contains a specific 2:1 calcium to magnesium ratio as this is the balance found in most of our bodies. When you’re consuming a large amount of calcium from dairy, you may require additional magnesium as well — so you could try supplementing with additional magnesium to see how that feels.

    We definitely wouldn’t suggest cutting back on AlgaeCal as it contains all of the other essential nutrients for bone health that dairy products do not! We’ll be super excited to hear how your next DEXA scan goes with the added support of trace minerals, vitamins C, D3, K2, and more.

    If you have any questions don’t hesitate to give us a call at 1-800-820-0184! ❤️

    – Jenna @ AlgaeCal

  24. Rosie Alleva

    June 12, 2019 , 4:28 am

    Can you please show the size or tell the measurement of this pill. When asked, the common response is that it can be pulled apart and sprinkled on food. How does it compare to the large calcium pills most doctors recommend?

  25. Jenna AlgaeCal

    June 12, 2019 , 8:37 am

    Hi Rosie,

    AlgaeCal’s soft veggie capsules are about 0.75 inches long, 0.25 inches wide, and are designed to be easily swallowed! That being said, many members of our community who have difficulty swallowing capsules simply use the powder. As you mentioned, the capsules can easily be twisted open and sprinkled into foods like smoothies, yogurt, and oatmeal. We just don’t recommend hot foods or drinks to avoid denaturing the vitamins. Hope that helps!

    – Jenna @ AlgaeCal

  26. Beverly Raine

    July 7, 2020 , 9:11 am

    My husband takes PPI daily for heartburn, the doctor recommends taking calcium because this medication depletes calcium. I know women need more calcium than men. Is your product too much calcium for a man?

  27. Megan AlgaeCal

    July 7, 2020 , 10:04 am

    Hi Beverly, good question!

    AlgaeCal is suitable for both women and men. A daily dose of AlgaeCal Plus provides 720 mg of calcium. We recommend meeting your daily requirements by adding calcium-rich foods to the diet and have a list your husband may find helpful here!

    Hope this helps and feel free to give us a call at 1-800-820-0184 with any further questions 🙂

    -Megan @ AlgaeCal

  28. Jean

    October 19, 2020 , 3:44 am

    I’ve just recently had a total thyroidectomy and I am on 1800 mg of calcium carbonate 3 x a day until my retransplanted parathyroid glands take. Constipation is a huge issue for me. What would the equivalent does of your product/or the right product from your range be?
    Thank you

  29. Megan AlgaeCal

    October 20, 2020 , 12:48 pm

    Hi Jean, thanks for reaching out!

    For specific medical conditions, we recommend consulting your doctor for their best recommendation. We have an excellent information sheet you can share with them here.

    Hope this helps! If you have any questions before or after you appointment, don’t hesitate to give us a call at 1-800-820-0184 ❤️

    -Megan @ AlgaeCal

This article features advice from our industry experts to give you the best possible info through cutting-edge research.

Prof. Didier Hans
PHD, MBA - Head of Research & Development Center of Bone Diseases, Lausanne University Hospital CHUV, Switzerland,
Lara Pizzorno
MDiv, MA, LMT - Best-selling author of Healthy Bones Healthy You! and Your Bones; Editor of Longevity Medicine Review, and Senior Medical Editor for Integrative Medicine Advisors.,
Dr. Liz Lipski
PhD, CNS, FACN, IFMP, BCHN, LDN - Professor and Director of Academic Development, Nutrition programs in Clinical Nutrition at Maryland University of Integrative Health.,
Dr. Loren Fishman
MD, PhD - Medical Director of Manhattan Physical Medicine & Rehabilitation and Founder of the Yoga Injury Prevention Website.,
Dr. Carole McArthur
MD, PhD - Professor of Immunology, Univ. of Missouri-Kansas City; Director of Residency Research in Pathology, Truman Medical Center.,