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Analyses Performed


126 analytical tests on 6 of the best-selling hair vitamins in the United States.
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Must-see Statistic


On average, products measured 46.3% more biotin than what was claimed on their labels.
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Unconventional Wisdom


While biotin deficiency can impair hair growth, research does not show any additional benefit for biotin supplementation above its AI (Adequate Intake).

Testing Summary

Labdoor analyzed 6 of the best-selling hair vitamins in the United States for vitamin and mineral content and heavy metal (arsenic, cadmium, lead, mercury) contamination.

Products were analyzed for 18 different vitamins and minerals, 9 of which are shown in clinical research to have some effect on hair growth and/or quality. These are: biotin, vitamin B3, vitamin B12, vitamin C, vitamin D, vitamin E, zinc, iron, and selenium. All products exceeded the daily Adequate Intake (AI) for biotin in one serving. Label accuracy was an issue for products in this batch analysis. On average, products deviated from their label claims for measured vitamins and minerals by 38%. All tested products passed heavy metal screenings for arsenic, cadmium, lead, and mercury.

Analytical Chemistry Methods: Capillary Electrophoresis (vitamin C, B-vitamins except B12); GC-FID (vitamin E), ICP-OES (zinc); Titration (calcium); LC-MS/MS (vitamin D); Colorimetry (vitamin A); UV-Vis (vitamin B12); ICP-MS (iodine, heavy metals); LC-ELSD (sugars); Combustion (protein); Acid Hydrolysis (fats); Calculated (calories, carbohydrates).


Label Accuracy

Small bottle with magnifying glass Overall, measured vitamins and minerals deviated an average of 38% from their label claims.

Products' measured vitamin and mineral quantities deviated an average of 38% compared to their respective label claims. Zenwise Labs Hair Growth Vitamins performed worst in label accuracy; in 4 of its listed vitamins and minerals, measured content amounted to less than 10% of what was claimed. In terms of individual nutrients, vitamin B1 (thiamine) exhibited the greatest range in label inaccuracy; measured content ranged from -99.7% to +67.4% compared to label claims. All 5 products exceeded their label claims for biotin, recording an average overage of 46%.


Product Purity

Microscope All 6 products passed heavy metal screenings for arsenic, cadmium, lead, and mercury.

All products passed heavy metal screenings, indicating that each product's heavy metal recordings per serving fell below California Proposition 65's proposed and established MADLs (Maximum Allowable Dose Levels) and NSRLs (No Significant Risk Levels): no more than 10 mcg/day of inorganic arsenic, 4.1 mcg/day of cadmium, 0.5 mcg/day of lead, and 0.3 mcg/day of mercury (proposed).

SugarBearHair Hair Vitamins would exceed California Proposition 65's lead MADL in 1.5 servings (3 gummies).


Nutritional Value

Fruits On top of vitamins and minerals linked to healthy hair growth in research, products recorded an average of 6 additional vitamins and minerals.

Hair vitamins in this batch analysis recorded minimal calories, fats, carbohydrates, and sugars. All 6 products contained additional B-vitamins, vitamin A, and other nutrients like collagen, keratin, and choline on top of the 9 vitamins and minerals relevant to hair growth in clinical research: biotin, vitamin B3, vitamin B12, vitamin C, vitamin D, vitamin E, zinc, iron, and selenium.


Ingredient Safety

Caution sign No flagged artificial sweeteners or preservatives were recorded in this batch analysis.

Labdoor's Hair Vitamins Ingredient Safety score takes into account vitamin and mineral content in each product plus average dietary intake of nutrients based on data from the US National Health and Nutrition Examination Surveys (NHANES) from 2001, 2002, 2005 and 2006. These quantities are then held to established Tolerable Upper Intake Levels (ULs) where applicable. ULs are defined by the National Institutes of Health (NIH) as the “maximum daily intake unlikely to cause adverse health effects.” All products measured vitamin and mineral levels within safe limits given the average US diet.

Potentially harmful inactive ingredients in this batch analysis include titanium dioxide, carmine, and FD&C Blue 1.


Projected Efficacy

Line with arrow going up Products on average measured 244 times as much biotin as the established biotin AI.

Based on a thorough review of scientific literature, 9 vitamins and minerals are currently included in Labdoor's Projected Efficacy score for Hair Vitamins: biotin, vitamin B3, vitamin B12, vitamin C, vitamin D, vitamin E, zinc, iron, and selenium. For each of these nutrients, bioavailabilities and pharmacokinetic (PK) profiles of different nutrient forms were taken into account for grading purposes.

Deficiencies in intake for the above nutrients have been shown in clinical research to negatively impact hair growth. For Labdoor's grading purposes, nutrient levels in each product were compared to average deficiencies in the US population. Products were considered effective if their nutrients compensated for respective deficiencies. Average deficiencies were based on data from the US National Health and Nutrition Examination Surveys (NHANES), Recommended Dietary Allowances (RDA), and Adequate Intakes (AI). Beyond fixing nutrient deficiencies, research is inconclusive about whether supplementation on top of a balanced, nutritious diet would benefit hair growth or structure.

Of the 9 vitamins and minerals critical to healthy hair growth, the average US nutrient intake meets RDAs and AIs for 5 of them: vitamin B3, vitamin B12, zinc, iron, and selenium. All 5 products exceeded the AI for biotin in one serving. 4 products measured enough vitamin C to compensate for average US vitamin C deficiencies. 1 of 4 products with vitamin E measured sufficient levels to compensate for average US vitamin E deficiencies. All products claimed vitamin D, but only 2 of them measured enough to compensate for average US vitamin D deficiencies.