NEW You can now listen to Fox News articles! If you're looking to extend the caffeine buzz from your daily coffee , a taste of grapefruit might do the trick. Grapefruit contains a chemical that interacts with other substances, which is why doctors caution against pairing it with dozens of medications . The chemical works by blocking an enzyme in the digestive system that helps break down certain substances, allowing more of the drug to enter the bloodstream. Drug concentrations in the blood can rise too fast and to dangerously high levels, Harvard Medical School reported. SCIENTISTS USED ELECTRICITY ON COFFEE AND DISCOVERED WHAT MAKES IT TASTE GOOD It's this same chemical in grapefruit that some theorize could slow down the metabolizing process of caffeine and make its energizing effects last longer.…