brittle hair

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1. Dry, Brittle Hair

THE EXPERT: Malia Manuel
Professional surfer, 24, Kauai, Hawaii

The ocean—good for the soul, not so great for your hair. Briny seawater can dehydrate strands, leaving them strawlike, so Manuel saturates hers with quenching oils regularly. "After every surf, I use a treatment with marula oil to bring back shine and help detangle," she says. She likes MarulaOil Rare Oil Treatment ($41; And a friend turned Manuel on to essential oils like cedarwood, which helps soothe a dry, flaky scalp: "I add a few drops to my shampoo."