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Psyllium husks are proof that even shrub-like plants can have big health effects. Psyllium husks are derived from an herb called Plantago ovata, which is most commonly found in India. Each small shrub produces more than 15,000 seeds that can then be used to manufacture psyllium husks, a fiber-rich supplement. While psyllium husks offer benefits in moderation, they can be dangerous when taken in excess. Always check with your doctor before starting to take psyllium husk supplements to ensure they will not interfere with any medical conditions or medications you may have.

How Psyllium Husk Works

Psyllium husk contains soluble fiber, a type of fiber that absorbs water and delays stomach emptying, which helps maintain your blood sugar levels. The fiber also helps your stool pass through your digestive tract more easily. Psyllium can be used as a laxative to reduce constipation or to treat diarrhea by making your stool firmer. Psyllium husk is sold over the counter in a variety of preparations, including powder, capsule, tablet or wafer.

Interferes With Medication Absorption

Taking psyllium husk when you are taking medications is all about timing. If you take it at the same time you take certain medications, the medications may not be absorbed as effectively. For example, do not take psyllium husk with tricyclic antidepressants such as Elavil or Tofranil, according to the University of Maryland Medical Center. Psyllium husk also may interfere with absorption of the seizure-reducing medication carbemazepine, heart-regulating digoxin and cholesterol-lowering medications, such as Questram and Colestid.

Reduce Mineral Absorption

Psyllium husks can also interfere with absorption of vitamins and nutrients. The extra fiber can bind with key minerals and prevent them from being absorbed by the body. Additionally, it's best to get your daily dietary fiber from whole foods such as fruits, vegetables and whole grains instead of supplements, recommends MayoClinic.com. These foods contains more vitamins, minerals and other nutrients than a psyllium supplement.

Mask Chronic Constipation

If you find you need to take psyllium husk supplements on a regular basis to relieve constipation, you could be ignoring the underlying cause. Psyllium husk is meant to be taken on a limited basis, according to Go Ask Alice!, a health and wellness resource from Columbia University. If you experience chronic constipation, see your physician to determine why you are experiencing these symptoms.