International Journal of Pharma Growth Research Review

Oral Supplementation for Brittle Nails: What Does the Evidence Really Support? A Narrative Review

Jozelio Freire De Carvalho¹, MD Elizabeth Hautz², Celso Roberto Cruz Da Colonia Junior³

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Abstract

Background: Brittle nail syndrome is a common condition characterized by increased nail plate fragility, splitting, and breakage. Although oral supplements are widely marketed for nail health, evidence supporting individual substances, optimal doses, and combination regimens remains uncertain. Objective: To critically review the clinical evidence for oral supplementation in brittle nails and onychoschizia, focusing on the substances evaluated, doses, treatment duration, magnitude of nail improvement, and methodological strength of the available studies. Methods: A narrative review with a structured literature search was conducted using PubMed/MEDLINE and Google Scholar from database inception through September 2026. Clinical studies evaluating oral nutritional or nutraceutical interventions for brittle nails, onychoschizia, or nail fragility were considered. Data on intervention, dose, study design, sample size, treatment duration, nail-related outcomes, and methodological limitations were extracted and descriptively synthesized. Results: Biotin was the most extensively investigated individual supplement. Biotin 2.5 mg/day was associated with improvement in nail firmness and hardness in 91% of evaluable patients in an uncontrolled study and with an approximately 25% increase in nail plate thickness in a microscopy-based study. Biotin 10 mg/day combined with topical hydroxypropyl chitosan resulted in ≥50% clinical improvement in 80% versus 53% with topical treatment alone. However, a biotin dose–response relationship has not been established. A recent retrospective study reported >50% improvement in all patients receiving biotin 1 mg plus pyridoxine 100 mg/day, although confirmation in controlled trials is required. Choline-stabilized orthosilicic acid providing approximately 10 mg/day of silicon demonstrated improvement in a randomized placebo-controlled study. Bioactive collagen peptides (2.5 g/day) increased nail growth by 12% and reduced broken nails by 42% in an uncontrolled prospective study. Favorable findings were also reported for MSM, solubilized keratin-containing preparations, and L-cystine-containing multi-ingredient formulations, although attribution to individual components was frequently impossible. Conclusions: Several oral interventions show potential benefit for brittle nails, but the overall evidence remains limited and heterogeneous. Biotin 2.5 mg/day has the largest direct clinical evidence base, while stabilized orthosilicic acid is supported by comparatively stronger controlled methodology. Higher biotin doses have not been demonstrated to provide greater efficacy. Current evidence favors targeted supplementation and correction of documented nutritional deficiencies rather than indiscriminate multi-micronutrient use. Larger randomized, placebo-controlled, dose-ranging, and head-to-head trials are needed.  

Keywords: brittle nailsbrittle nail syndromeonychoschizianail fragilitybiotincollagen peptidessiliconnutraceuticalsdietary supplements

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