Clif Bar, manufacturer of the Luna nutrition bar—marketed “for women”—is asked this question all the time. The concern is baseless, however. Luna bars, which come in flavors including Lemon Zest, S’mores, and Dulce de Leche, contain no estrogen or other hormones that might cause men to grow mammary glands. They’re for women because they’re fortified with nutrients females typically need more of, or sometimes have a hard time getting in their diets. These include folic acid, calcium, iron, B vitamins, and fiber.
For example, women (and men) between the ages of 19 and 50 need 1,000 to 1,200 milligrams of calcium per day: the equivalent of three glasses of milk. Luna bars contain as much calcium as one glass of milk. But women tend to diet more than men, says Tara DelloIacono Thies, nutrition strategist for Clif Bar, and “calcium seems to go first, because they’re drinking less milk and eating fewer dairy products.” Folic acid is a form of vitamin B found in fruits and vegetables that’s also necessary to both sexes. But it’s particularly crucial for women trying to get pregnant, because a folic acid deficiency can cause birth defects. Men won’t suddenly find themselves expecting a child after consuming a Luna bar, either, just in case you’re wondering.