Q. I take mild herbal fiber or cleanse pills daily to encourage regularity. Could that be harmful?

A. In the vast majority of cases, constipation results from poor diet choices, namely too little fiber and insufficient fluids. Thus, it's optimal to adjust your dietary fiber and fluid intake before turning to dietary supplements. If you still have problems with regularity after making changes—and women and older people are more likely to suffer chronically from this concern—several herbal products are safe to use on an ongoing basis.

Psyllium, flaxseed, fenugreek, and glucomannan are all herbal bulk-forming laxatives; their high fiber content supplies extra bulk to the stool. They also contain mucilage that expands when it comes in contact with water (which is why these laxatives must be taken with plenty of water). These herbs are fairly mild laxatives and can be taken daily. (Flaxseed is also a good source of nutrients such as magnesium and thiamin.)

Be more careful with herbal stimulant laxatives—such as senna (Cassia acutifolia), Cascara sagrada (Rhamnus purshiana), and aloe vera rind or "latex"—because they tend to be more potent. These stimulant herbs contain anthraquinone glycosides, natural laxatives that induce bowel muscle contractions. After sustained use, your bowels could become dependent, or not move properly without stimulation. Use these herbs for no more than ten consecutive days, for example, as part of a seasonal cleanse program.

This Q&A was written by Victoria Dolby Toews, MPH, a health journalist based in the Pacific Northwest, where she and her family enjoy hiking and cycling.