Pick a pink one, though, because pink grapefruit gets its pink-red hue from lycopene, a carotenoid that may help to keep your skin smooth. In a study published in 2008 in the European Journal of Pharmaceutics and Biopharmaceutics, researchers found that of the 20 individuals studied, those who had higher skin concentrations of lycopene had smoother skin. You can also get lycopene from tomatoes, carrots, watermelon, guava and red peppers.