Whether they are pinworms, tapeworms, or microscopic protozoa like Giardia lamblia or amoebas, intestinal parasites are never beneficial. They attach to the lining of your bowels, typically living off the food you eat and damaging your intestinal cells. They may go unnoticed or cause nutritional deficiencies, diarrhea and other symptoms. Prescription medications that kill the organisms are the mainstay of treatment for all intestinal parasites. Although many cultures have a long tradition of using foods to treat these infections, very few studies have been conducted in humans to confirm their effectiveness. Nevertheless, current research suggests that pumpkin and papaya seeds, some berries and some probiotics have antiparasitic effects in humans -- destroying or inhibiting growth or reproduction of these unwanted visitors.
Pumpkin seeds indirectly kill tapeworms. Their antiparastic effects have been attributed to curcubitine, a substance that paralyzes tapeworms so they can no longer hold onto intestinal cells. A study published in the November 2012 issue of “Acta Tropica” found that a single dose of peeled raw pumpkin seeds caused tapeworms to be released into the stool in 75 percent of people with these parasites. This increased to 89 percent when the seeds were combined with areca nut extract, a traditional Chinese medicine that also paralyzes tapeworms. Pumpkin seeds are often followed by a laxative to help expel the worms from the intestines. Once released, the tapeworms will eventually die.
Papaya seeds may also have antiparasitic qualities. Their effectiveness has been attributed to the breakdown of parasites by papain, an enzyme in papaya seeds. In a study of 60 children published in the March 2007 issue of “Journal of Medicinal Food,” parasites were eliminated from the stools in 77 percent of those given a single dose of a combination of dried papaya seeds plus honey and only 17 percent of children given honey alone. No subsequent studies of papaya seeds for intestinal parasites have been conducted in humans. Honey is useful to mask the bitter taste of papaya seeds.
Various berries have been used as traditional remedies for intestinal parasites. Their effectiveness has been attributed to chemicals called polyphenols, which are found in all plants. A laboratory study published in “Parasitology” in August 2011 reported that polyphenol-rich extracts from a number of berries killed G. lamblia. The most effective were strawberry, Arctic bramble, blackberry and cloudberry extracts, which were as effective as metronidazole, the standard medication for Giardia infections. Although studies in humans have not yet been conducted, the “Parasitology” study researchers noted that the concentration of extracts with the most potent antiparasitic effects would be easily achieved within the intestines of people eating these berries.
Probiotics are live bacteria or yeasts with health benefits. They are found in foods such as yogurt, kefir and sauerkraut. Laboratory and animal studies have reported that some probiotics kill certain intestinal parasites, although these effects are limited and poorly understood. Very few human studies have evaluated the use of probiotics for this purpose. A study published in the July 2006 issue of the “Scandinavian Journal of Infectious Diseases” reported that a combination of the yeast Saccharomyces boulardii plus metronidazole was more effective than metronidazole alone in treating the parasite G. lamblia. Likewise, a study of 50 children in the June 2009 issue of “The American Journal of Tropical Medicine and Hygiene” found that the same combination was more effective than metronidazole alone in clearing the amoeba Entamoeba histolytica from the intestines. While dietary supplements are the most common way to obtain the probiotic Saccharomyces boulardii, it may also be found in certain types of kombucha, a fermented drink.
Considerations and Warnings
Although numerous other foods have been touted to kill intestinal parasites, no quality human research has confirmed this. Garlic, onions, coconuts, figs, dates, chicory, avocado seeds, ginger, black pepper and pomegranates are examples of foods shown to promote antiparasitic activity in laboratory or animal studies, but the effectiveness of these foods not yet been properly evaluated in humans. More research is clearly necessary, but it is questionable whether any food will ultimately be determined to be more effective than medications. It is more likely that certain foods may be useful additions to, but not replacements for, drug therapy. If you suspect that you have intestinal parasites, see your doctor. Do not treat this condition on your own. Also talk with your doctor before making any significant dietary changes, as excessive intake of almost any food may cause problems.
Reviewed by: Kay Peck, MPH, RD