What Dietary Supplements Cause Loose Bowel Movements?

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Loose bowel movements, also called diarrhea, is caused when the fluids in food and drink are not absorbed properly by the body and pass through the digestive system, causing loose, watery stools. According to the National Digestive Diseases Information Clearinghouse, diarrhea can be caused by bacteria, parasites, digestive disease such as irritable bowel syndrome and foods such as milk. Supplements such as fish oil and magnesium may also cause diarrhea.

Fish Oil

Fish oil is available from oily fish such as salmon, mackerel and herring and is also found as a supplement. Fish oil is an important source of omega-3 essential fatty acids, which are called "essential" as the body can’t make them and they must be obtained from the diet or taken as a supplement. According to the University of Maryland Medical Center, fish oil may be helpful for certain health conditions such as heart disease, arthritis, diabetes and depression. According to MedlinePlus, however, fish oil can cause some side effects, including loose bowel movement, heartburn and bad breath.


Magnesium is an essential nutrient needed by every organ in the body, particularly the kidneys, heart and muscles. Magnesium is found in green leafy vegetables, nuts and whole grains. According to the University of Maryland Medical Center, magnesium may be helpful for conditions such as fibromyalgia, diabetes, migraines, high blood pressure and premenstrual complex. According to Drugs.com, magnesium may also cause loose bowel movements.

Amylase, Lipase and Protease

Amylase, lipase and protease are digestive enzymes that help to digest food. Amylase helps to digest carbohydrates such as bread, potatoes and cakes. Amylase helps to break down proteins such as meat and fish. Lipase breaks down the fats in our diet such as olive and sunflower oils. Digestive enzymes are not found in foods and must be produced in the body or taken as supplements. Most people produce enough digestive enzymes, but according to the National Digestive Disease Information Clearinghouse, patients who suffer with certain health conditions such as bloating, wind and stomach pain may find a supplement beneficial. According to Drugs.com, however, amylase, lipase and protease may cause side effects such as diarrhea, nausea and stomach cramps.


Chlorophyll is a naturally occurring green pigment found in plants. It is also available as a supplement. According to the University of California, San Diego, chlorophyllin may be helpful as an internal deodorant to improve bad breath as well as odors from wound infections, urine and bowel movements. According to Drugs.com, chlorophyll may cause loose bowel movements.