“Have a glass of orange juice!” It’s the cry eternal of well-meaning friends and parents when you’re under the weather. They aren’t totally wrong: vitamin C may help immune systems. A 2014 study in the journal Nutrients found that men who were low in vitamin C caught fewer colds once they increased their vitamin C consumption, but the difference was deemed statistically marginal. Furthermore, another 2014 study published in Clinical Nutrition found that drinking orange juice didn’t lead to a strengthening of the immune system for healthy, well-nourished adults. So getting enough vitamin C is important, but slamming a gallon of orange juice won’t help—it contains too much sugar. Instead, try red peppers, broccoli, or kale, which all have more vitamin C per serving than orange juice. Plus, they have more fiber and other nutrients.