5 Supplements that might be the cause of your constipation

This blog post is from the article “5 Supplements That Could Actually Make Constipation Worse, According to Experts” in EatingWell magazine by Victoria Whittington, RDN.

Did you know that some of the supplements you take might be one of the causes of your constipation or be making it worse? Typically constipation is related to what you eat and lifestyle, but it may also be caused or exacerbated by some supplements and medications. Sometimes pharmaceuticals, vitamins, minerals, and herbal supplements can be disruptive for health bowel movements. 

Here are 5 supplements that might be the cause of your constipation:

1. Calcium Supplements

Calcium supplements may worsen constipation because they slow down intestinal motility, the movement of food moving through your digestive tract. Calcium may also interfere with how much fluid is secreted in the gut, causing stools to become hard, dry and more difficult to pass. (2,3)

If you’re supplementing with high doses of calcium and not drinking enough water or eating enough fiber, you’re more likely to experience constipation. Sometimes the supplementation may be necessary, so speak with your healthcare providers for options.

2. Iron Supplements

Iron supplements commonly cause constipation, so if you’re iron-deficient, you may want to consider a food-first approach, depending on the severity.⁴ 

“While it’s true that around 40% of women of reproductive age are iron-deficient, I’d use caution before diving into an iron supplement. Iron is one of the top supplements that can cause constipation,” says Ashley Dwyer, Pharm.D., founder of BDN Coaching. Instead, Dwyer recommends increasing your intake of foods rich in iron (such as legumes, leafy greens, fish and red meat) and vitamin C (like citrus, fruit, leafy greens and peppers) first. 

3. Fiber Supplements

Fiber supplements may worsen constipation in some people, depending on the circumstances.⁵

“Based on current research, fiber appears to benefit constipation for most generally healthy adults, and it’s one of the main treatments for constipation,” says Kelsey Costa, M.S., RDN, a registered dietitian and science communications officer at Examine.⁶ 

“However, simply increasing fiber intake or using supplements may not always help with bowel movements, depending on the root cause of constipation,” according to Costa

“Fiber supplements can bulk up the stool too much and cause constipation, especially a supplement high in insoluble fiber,” says Rhyan Geiger, RDN, a Phoenix-based dietitian.

“Increasing fiber intake too quickly may also worsen constipation. “Fiber absorbs water in the digestive system, so if you consume a lot of fiber without increasing your water intake, stools can become harder to pass, making constipation worse,” says Costa.

4. Vitamin D Supplements

When consistently taken in higher doses, vitamin D supplements may lead to digestive issues such as constipation. Too much vitamin D can increase the amount of calcium circulating in your blood, and as we mentioned above, too much calcium in the body may also worsen constipation.^7,2

If you’re taking a vitamin D supplement, talk with your doctor or dietitian to make sure your dose is right for you. Be sure to drink plenty of water and eat a variety of whole, nutrient-dense foods to support a healthy gut. 

5. Senna

Senna is an herbal supplement used for treating constipation due to its strong laxative effect. However, it may cause digestive issues and worsen constipation when used too frequently.⁸ 

“Like many other laxatives, long-term or excessive use of senna may lead to serious reactions and side effects, including dependence on laxatives, chronic constipation and loss of normal bowel function,” says Costa. “This appears to occur because the intestines become used to the laxative stimulation and lose their ability to contract normally without it,” she adds.  

Relying on senna too frequently may also cause fluid loss and electrolyte imbalance, “which can lead to dehydration and may contribute to constipation when not in use,” says Costa.

Other Ways to Help Relieve Constipation 

Instead of relying on supplements, habits like eating more insoluble fiber, drinking more water, and finding ways to be active may all help relieve constipation. 

Eat a variety of whole, nutrient-dense foods including fruits, vegetables, whole grains and fermented foods that contain probiotics such as miso, kefir, kimchi and sauerkraut. “Fruits, vegetables and whole grains contain fiber that support digestion,” says says Kerry Conlon, M.S., RD, a digestive-disease dietitian. These foods also offer a range of other essential nutrients and bioactive compounds, including essential vitamins, minerals, phytochemicals and antioxidants, that support our overall health.

Research suggests that regular physical movement should be part of the treatment for constipation. Try to incorporate more daily movement in whatever way possible, whether it’s walking, yoga, biking or something else that you enjoy and you can do on a regular basis.

The Bottom Line

Constipation is often affected by diet, lifestyle and some supplements and medications. Experts recommend a food-first approach before turning to supplements. In fact, some supplements like calcium, iron, vitamin D and senna may actually worsen constipation symptoms. While fiber is usually helpful for improving it, fiber supplements may worsen constipation if you increase your intake quickly and are not drinking enough water. To help relieve constipation, try to eat more whole foods, drink more water and stay active.

2. Matikainen N, Pekkarinen T, Ryhänen EM, Schalin-Jäntti C. Physiology of Calcium Homeostasis: An Overview. Endocrinol Metab Clin North Am. 2021 Dec;50(4):575-590. doi: 10.1016/j.ecl.2021.07.005.

3. Singh, P., & Goyal, J. (2022). Calcium supplementation. In StatPearls. StatPearls Publishing.

4. Parvataneni, S., & Maw, M. (2020). Ileus Due to Iron Pills: A Case Report and Literature Report on the Importance of Stool Softeners. Cureus, 12(6), e8392. https://doi.org/10.7759/cureus.8392

5. Goyal, H., & Singla, U. (2022). Constipation. In StatPearls. StatPearls Publishing.

6. Ioniță-Mîndrican, C. B., Ziani, K., Mititelu, M., Oprea, E., Neacșu, S. M., Moroșan, E., Dumitrescu, D. E., Roșca, A. C., Drăgănescu, D., & Negrei, C. (2022). Therapeutic Benefits and Dietary Restrictions of Fiber Intake: A State of the Art Review. Nutrients, 14(13), 2641. https://doi.org/10.3390/nu14132641

7. Tebben, P. J., Singh, R. J., & Kumar, R. (2016). Vitamin D-Mediated Hypercalcemia: Mechanisms, Diagnosis, and Treatment. Endocrine reviews, 37(5), 521–547. https://doi.org/10.1210/er.2016-1070

8. ScienceDirect. Senna. In Topics in biochemistry, genetics and molecular biology.