To strengthen hair from the inside, Dr. Fusco encourages all her patients to consider taking three to five grams of a daily fish-oil supplement with omega-3 fatty acids. "They are the building blocks of healthy cells and can help your body hold on to moisture," she says. "A deficiency in omega-3 fatty acids can lead to a drier scalp and dull hair."
(Whole Foods Omega-3, $9/60 soft gels; wholefoodsmarket.com.)Read MoreLess