Though it gets a bad rap for delivering bad breath, garlic is America’s top-selling—and most studied—natural remedy. Not only can the funk- fragranced herb help prevent colds, flu and other infectious diseases, publications from the Journal of the American Medical Association to Preventive Medicine have documented its safety and ability to kill bacteria and fungi; shrink tumors; fight cancer by helping cells eliminate carcinogens; and lower cholesterol, blood pressure and glucose levels. A 1989 German study found that garlic helps the body’s natural killer white blood cells fight some viruses. Though the study is almost 20 years old, it has not been refuted.

There are many ways to take garlic. Some people prefer to eat it raw; others ingest fresh extract, aged garlic or garlic oil. Unfortunately, these forms all contain the herb’s unpleasant smell. There are also odorless tablets that are enteric-coated, allowing the pills to pass through the stomach intact to the small intestine, where they are absorbed. Some researchers believe that the cured herb, known as aged garlic extract, works best. Whatever form you favor, experts recommend taking 600 mg to 900 mg per day.

As with any nutritional supplement, follow the dosing instructions on the label carefully and consult your doctor. If you’re HIV positive and your combo includes a protease inhibitor (PI), be extra cautious: Garlic pills decrease blood levels of saquinavir and possibly other PIs. When used at therapeutic levels over time, garlic can cause bleeding, particularly after surgery or dental work. You can raise any questions or concerns about garlic’s safety or side effects with the retailer or manufacturer or your doctor.    

Glenn Ellis is a homeopath and herbalist.