Happy #moleculemonday! There's a new compound popping up in a lot of preworkouts, but it's not some new crazy stimulant. Bioperine, or black pepper extract is a potent inhibitor of the enzymes CYP3A4 and P-glycoprotein. These enzymes are responsible for breaking down many important fat burning molecules such as caffeine and catecholamines(norepinephrine), as well as cortisol and androgens. Essentially, by adding Bioperine to a preworkout, not only does it vastly increase the bioavailability of these molecules, it also prolongs their half-life, making them more active for longer periods of time. This means you can effectively take less caffeine and other stimulants, while having the effects of taking a higher dose. Worth noting-a 2006 study showed subjects taking Bioperine while fed a high fat diet showed significantly reduced plasma lipid and LDL(bad cholesterol) levels. Subjects also had significantly elevated levels of HDL(good cholesterol), as well as T3, T4 and testosterone. Most products contain 5mg of a 95% black pepper extract. If your preworkout contains high levels of caffeine or catecholamines and doesn't have Bioperine, I highly suggest adding it.