Mickie Cathers
Piperine, a major component of black pepper (Piper nigrum), is responsible for black pepper’s distinct flavor, is what makes you sneeze, and gives black pepper its reputation for having antioxidant and anti-inflammatory properties. Piperine supplements are advertised as enhancing nutrient absorption and relieving inflammation (especially when taken with turmeric). Patients taking this supplement may not be aware that piperine interacts with certain drugs.
Background
Black pepper is a climbing perennial plant known worldwide as both a spice and a medicine. Black pepper contains ~2–7% piperine, which gives it pharmacologic effects and health benefits ranging from cancer and diabetes prevention; improved digestion; weight loss; BP control; relief from coughs, colds, and infections; and enhanced brain, hair, and skin health. Black pepper extract is promoted as an antioxidant that maximizes nutrient absorption—especially vitamin C by up to 50% and turmeric as much as 2,000%—and aids in heart health, digestive health, and optimized gut flora.
Many studies have shown that piperine results in antioxidant, antidiabetic, antimicrobial, anti-inflammatory, and gastro- and cardioprotective activities. The alkaloid functionality of piperine assists in cognitive brain functioning and helps stimulate hydrochloric acid in the stomach, which aids in digestion and food absorption, reducing discomfort and gas buildup in the intestines. Studies have also shown that piperine has free-radical scavenging activities and antitumor properties.
Piperine’s dark side
Despite the reported benefits of piperine in the literature, there is evidence of adverse influence on the liver. Piperine may change how quickly the liver breaks down medications such as cytochrome P450 sA4 (CYP3A4) substrates. Piperine may also affect how P-glycoprotein substrates transport medication in and out of cells.
Preliminary data have indicated that piperine inhibited drug-metabolizing enzymes and increased plasma concentrations of several drugs, including phenytoin and rifampin. A 2002 research article published in the Journal of Pharmacology and Experimental Therapeutics investigated the influence of piperine on P-glycoprotein–mediated, polarized transport of digoxin and cyclosporine in monolayers of Caco-2 cells.
Bhardwaj and colleagues showed that piperine inhibited both the drug transporter P-glycoprotein and the major drug-metabolizing enzyme CYP3A4, indicating that dietary piperine could affect plasma concentrations of P-glycoprotein and CYP3A4 substrates, especially if these drugs are administered orally.
A review in Critical Reviews in Food Science and Nutrition in 2007 by Srinivasan backed up the findings of Bhardwaj and colleagues’ article, highlighting piperine’s inhibitory influence on enzymatic drug reactions in the liver.
Dosages and availability
There is no recommended appropriate dose of piperine. Piperine supplements are sold as capsules, gummies, liquid, pills, powder, and tablets and are often marketed in combination with turmeric, ashwagandha, or CoQ10. Most piperine supplements are available commercially as 10 mg capsules to be taken three times per day for a total of 30 mg per day.
What to tell patients
Black pepper sprinkled on food can be enjoyed without concern. However, caution patients that piperine supplements are concentrated forms of black pepper and could change how quickly the liver breaks down medications and increase the chances of adverse effects from some medications. Common adverse effects of piperine include acid reflux, constipation, low potassium levels, and nausea. Contraindications include use with lithium, as piperine may decrease how well the body releases lithium. Piperine may lower blood glucose levels and could cause complications for patients taking diabetes medications. Piperine could also increase levels of atorvastatin in the blood and increase both its therapeutic and adverse effects. ■