The present disclosure relates to kits and methods for treating hair. The kits and methods incorporate each of the following components, together, separately, or in any combination thereof, in one or more hair-treatment compositions, provided that each individual component is included in a hair-treatment composition of the kit or method:(a) at least one amino acid or amino sulfonic acid, and/or a salt thereof, which is present in at least one of the one or more hair-treatment compositions in an amount of at least 0.5 wt. %(b) a first non-polymeric mono, di, or tricarboxylic acid, and/or a salt thereof, which is present in at least one of the one or more hair-treatment compositions in an amount of at least 0.5 wt. %(c) a second non-polymeric mono, di, or tricarboxylic acid, and/or a salt thereof, which is present in at least one of the one or more hair-treatment composition in an amount of at least 0.5 wt. % and(d) at least one surfactant, which is present in at least one of the one or more hair-treatment compositions.The kits and methods are particularly useful for strengthening hair and minimizing and/or compensating for damage to hair, for example, damage caused by environmental stress and cosmetic treatments (e.g., repeated washing, drying, heating, chemical processing, etc.). Hair treated with the kits and methods exhibit desirable cosmetic properties such as smoothness, gloss, improved combability, and improved strength and elasticity.
