Why Will Metamucil Affect Vitamins?

Fiber supplements powder in a bowl next to juice and fruit.
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Metamucil is a fiber supplement derived from psyllium seed husks. The soluble and insoluble fiber from psyllium husks expands when exposed to water to form a thick gel. Taking vitamins or other medications along with a fiber supplement may reduce the amount absorbed into the bloodstream, as a result of medication being detained in the fiber mass in the intestines and excreted.


Uses of Psyllium Husk

Psyllium husk is used to bulk up stool and to treat both diarrhea and constipation. Psyllium is also used to make bowel movements more comfortable in people with irritable bowel syndrome, hemorrhoids and other intestinal problems. Medical studies suggest that supplementation with psyllium husk may improve blood sugar regulation in people with diabetes and may reduce the risk of colon cancer.


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Psyllium Husk and Vitamin Absorption

Because of the large increase in bulk in the intestines caused by psyllium husk, it may reduce the absorption of vitamins or medications. The University of Maryland Medical Center recommends using psyllium husk at least one hour before or two to four hours after taking vitamins or medication.

Increasing Vitamin Absorption

Slower intestinal transport time, better solubility of vitamins and reduced amounts of accompanying fiber and fats improve absorption of vitamins. Take your vitamins with or within 30 minutes of a small meal that contains solid food and no more than 10 g of fats and a low to moderate quantity of fiber.


Factors Decreasing Vitamin Absorption

Avoid taking vitamins with a lot of fat, excessive quantities of water or on an empty stomach. Age decreases the ability of the intestines to process and absorb nutrients. Older individuals should look for vitamins that are more easily soluble, such as those in gel capsules rather than compressed tablets. Consider increasing your daily dosage after discussion with your doctor.



Check with your doctor to determine whether psyllium husk may interfere with the absorption of any medication you may be on. Consume at least 8 oz. of water with psyllium husk and 64 oz. of water per day while supplementing with it to avoid dehydration or constipation. Do not take psyllium husk if you have difficulty swallowing or a disorder affecting the esophagus.




Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.

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