All in all, garlic is a healthy, natural ingredient that can certainly manage and possibly prevent—but not necessarily treat—cold and flu symptoms. The other compounds help activate immune cells, including macrophages, lymphocytes, natural killer cells, and dendritic cells. “The job of these immune cells is to kill foreign invaders in the body, such as viruses and bacteria,” Gedroic explains. So how does this happen? According to Gedroic, “Given that colds are typically triggered by the rhinovirus and flu, helping to stimulate the immune system can boost the effectiveness of these killer cells in the body.” Ultimately, she says this helps wipe out viruses before they make their way into the system. “Aged garlic3 seems to have the best effects for heart health and lowering blood sugar,” Moday says, “but raw garlic is better for antibacterial, antiviral, and antifungal effects.” That said, raw garlic can be super pungent and kind of hard to stomach (think biting into raw onion). To reap the benefits without the intense flavor, she recommends adding raw garlic to soups or pesto. Oddly enough, chopping garlic is another good way to get more benefits from it. “When garlic is crushed or chopped, an enzyme called alliinase is released and produces allicin,” Gedroic says. The enzymatic process requires about 15 minutes to take effect, though. “Bottom line: Don’t eat or cook with garlic right away,” she says. “You want to let it sit for a while before you do.” Cooking with garlic is perfectly fine (in fact, encouraged) for optimal flavor. But in terms of health benefits, Gedroic says heat can reduce the effectiveness.
