Labdoor analyzed 30 best-selling melatonin supplements in the United States for melatonin and heavy metal (arsenic, cadmium, lead, mercury) contamination.
Only half of the products tested (15 of 30) measured melatonin levels within 10% of their label claims. 7 products deviated from their claims for melatonin by at least 25%. 3 of those products recorded 40% or more melatonin than their label claims, and 1 product had less than 1% of its label claim for melatonin.
2 products were projected to exceed 0.1 mcgserving of inorganic arsenic. CA Prop 65 proposes a maximum allowable dose level (MADL) of 0.1 mcgday for inorganic arsenic, a developmental and reproductive toxin1. 7 of the 30 tested products contained controversial artificial sweeteners, artificial coloring agents, andor preservatives.
15 of 30 products recorded melatonin content within 10% of their label claims.
Measured melatonin content ranged from being less than 1% of the label claim to being 47.4% more than a product’s label claim, with products deviating off their claim by an average of 16.6%.
More than half of the products (16 of 30) contained less melatonin than what their labels claimed. All but 4 of these products were within 20% of their label claims. Ubervita Ubersleep was the worst performer, measuring only 0.01 mgserving of its 6 mgserving claim.
12 products recorded melatonin content above their label claims, with 10 of these products exceeding their label claims by at least 10%. 5 products exceeded their claims by at least 20%. Natrol Melatonin 5 mg (Time Release), exceeded its label claim most by 47.4%. It measured 7.37 mgserving compared to its claim of 5 mgserving.
2 products, Nature Made Adult Melatonin Gummies and Slumber Fit Advanced Sleep Formula, were found to have the exact amounts of melatonin they claimed on their labels.
2 products recorded arsenic levels that were projected to exceed California’s Prop 65 proposed limit for inorganic arsenic.
All of the tested products passed heavy metal screens for cadmium, lead, and mercury. 2 products, Slumber Fit Advanced Sleep Formula and PacificCoast NutriLabs Melatonin Platinum, were projected to exceed CA Prop 65’s proposed upper limit for inorganic arsenic in a single serving based on the above assumption.
Currently, intake limits for total arsenic have only been established for drinking water. The only available guideline for arsenic in supplement products is a proposed limit from CA Prop 65 on the inorganic component of total arsenic. Generally, inorganic arsenic species (tri- and penta-valent arsenic) are considered more toxic than their organic counterparts. Chemical analysis of this batch of products measured arsenic in total. Since research has shown that the contribution of inorganic arsenic to total arsenic is ~80% (in rice), an 80% assumption was used to project and then compare inorganic arsenic content in these products to the CA Prop 65 proposed limit of 0.1 mcg per day1.
Gummy products recorded calories derived from fractionated coconut oil and added sugars.
Most melatonin supplements in this batch recorded minimal calories, fats, carbohydrates, and added sugars, if any.
The 4 tested gummy melatonin supplements were the only products to record any calories, ranging from 10-15 calories per serving. 3 of these products had added sugars and all 4 had fractionated coconut oil, a separated portion of the fatty acids found in virgin coconut oil used to prevent gummy supplements from solidifying or oxidizing.
7 of 30 products recorded controversial additives like artificial sweeteners and preservatives.
Melatonin does not have an established safe upper limit2. Research has found that acute doses as high as 500 mg were safe in humans. Melatonin in moderate doses is usually recommended for short-term use of up to 2 months3. Research on long-term use is lacking.
Common side effects include daytime sleepiness, headaches, and dizziness. You'll want to avoid activities that require alertness at least for 4-5 hours after taking melatonin3. Melatonin can also interact with common medications. Please consult your doctor on optimal dosing before supplementation.
7 of 30 products recorded flagged inactive ingredients, including the artificial sweetener, sucralose and benzoate-based preservatives that can increase your risk for cancer.
All but one product measured more than 0.3 mgserving of melatonin, the recommended starting dose for adults.
The effects of melatonin on sleep are not dose-dependent; taking more does not necessarily make it work faster or make it more effective for sleep4,5. The "best" amount varies widely from person to person and can depend on the purpose of use. For melatonin's most common use of realigning your own sleep tendencies with nature's normal day and night cycle, research suggests taking melatonin an hour before sleep, starting with 0.3 mg the first night and slowly increasing up to 5 mg in following nights if lower doses don't work. You need enough melatonin to enhance your sleepiness at night, but not too much to impair wakefulness and sleep the next day6,7. In our analysis, 12 of 30 melatonin products exceeded 5 mg. Only 4 products had 1 mg or less.
- 1 CA OEHHA. (2017). Proposition 65.
- 2 Human Performance Research Center. (2017). HPRC Dietary Supplements Classification System: Melatonin.
- 3 Mayo Clinic. (2014). Is melatonin a helpful sleep aid - and what should I know about melatonin side effects?
- 4 Lewy AJ, et al. (2002). Low, but not high, doses of melatonin entrained a free-running blind person with a long circadian rhythm. Chronobiol Int. 19(3):649-58.
- 5 Cassone VM, et al. (1986). Dose-dependent entrainment of rat circadian rhythms by daily injection of melatonin. J Biol Rhythms. 1(3):219-29.
- 6 Examine. (2017). Melatonin.
- 7 Herxheimer A & Petrie KJ. (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. CD001520.