Can Vitamins Change the Color of Your Bowel Movements?
Updated on August 6, 2025
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It can be alarming when you go to the toilet for your daily business and notice that the color of your stool has changed. If you’ve introduced a new vitamin, mineral, or other type of supplement into your daily regimen, that might be the cause. Taking a new supplement is one of the most common reasons for a change in the appearance of your stool.
However, changes in stool color may also indicate a serious health problem, so if things don’t go back to normal a few days after stopping the supplement, be sure to tell your doctor.
Iron
Iron supplements are taken to build red blood cell counts in people who have anemia. They’re also often recommended to women to compensate for blood loss experienced during menstrual periods.
Whether taken as a tablet or in liquid form, iron supplements can cause someone to have darker than normal, dark green, or even black stool. If you take an iron supplement or a multivitamin that contains iron, you should know that darkened stool is a common side effect.
If the dark stool also has a foul smell and is accompanied by other symptoms like abdominal pain, lightheadedness, or vomiting, it’s important to let your doctor know, as these may be signs of a more serious issue.
Chlorophyll
Chlorophyll is believed to have numerous health benefits, from fighting acne to aiding wound healing to helping prevent cancer. While there’s little research to support these claims, chlorophyll is safe for human consumption.
You can get your chlorophyll in a shot of wheatgrass juice, which has a medicinal, organic taste. But don’t be surprised if your stool appears green afterward.
Carotenoids
Vegetables such as bell peppers, carrots, tomatoes, and pumpkins get their vibrant colors from a group of pigments called carotenoids. Taking multivitamins or supplements with high levels of carotenoids — beta-carotene is a common one — may cause your poo to turn yellow, orange, or other colors of the rainbow.
Other Whole-Food Supplements
There are many nutritional whole-food supplements made from plant matter. Turmeric (and its active ingredient curcumin), licorice root, and antioxidants in the form of red wine flavonoids are just a few of the various types of ground-up plant matter that you can swallow in pill form.
But if you’re ingesting large quantities of these products, it’s quite possible that you could wind up changing the color of your stool.
Antacids
Bismuth subsalicylate is an ingredient used in certain medications for acid indigestion or diarrhea. Found in Pepto-Bismol, Kaopectate, and similar over-the-counter products, it can cause dark or black stool, just as iron supplements do.
The Takeaway
- Introducing certain vitamins and supplements — such as iron, chlorophyll, and carotenoids — into your diet can lead to changes in stool color.
- This change in stool color is harmless, and your bowel movements should return to normal once the supplement is reduced or removed from your diet.
- Changes in stool color that persist after stopping the supplement may require medical evaluation, so be sure to tell your doctor if that’s the case. And it’s always a good idea to check in with your medical provider before starting a new supplement.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Can Food Change the Color of Your Poop? Cleveland Clinic. February 26, 2025.
- Iron Deficiency Is a Huge Problem for Girls. Columbia University Irving Medical Center. January 24, 2024.
- Taking Iron Supplements. MedlinePlus. July 8, 2023.
- Bloody or Tarry Stools. Mount Sinai.
- Higdon J et al. Chlorophyll and Metallo-Chlorophyll Derivatives. Oregon State University. March 2022.
- Alexander H. 6 Things to Know About Chlorophyll. MD Anderson Cancer Center. April 21, 2021.
- Why Is Your Poop Green? Cleveland Clinic. January 9, 2025.
- Eat the Rainbow: The Health Benefits of Carotenoids. Cleveland Clinic. July 12, 2023.
- 4 Things That Cause Yellow Diarrhea. Cleveland Clinic. March 5, 2025.
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Martin Booe is a health, fitness, and wellness writer who lives in Los Angeles.