Labdoor analyzed 15 of the best-selling electrolytes supplements in the United States. Tests were performed on electrolyte content (sodium, potassium, calcium, magnesium, chloride), sugars, and heavy metal contamination (arsenic, cadmium, lead, mercury).
Research supports supplementing with sodium, and in extreme cases, potassium, for exercise lasting longer than 90 minutes and/or exercise in extreme heat if you're not used to those conditions7,8,9. In these situations, they've been shown to help with signs of dehydration and electrolyte imbalance like dizziness, nausea, and muscle spasms10,11.
In our testing, we found that label accuracy was an issue. A quarter of the products had more than double their claims for sodium and/or potassium. Fortunately, 5 products still met concentration recommendations for these electrolytes based on their dosing instructions. Research suggests that carbohydrate concentrations higher than 8% by weight can hinder electrolyte delivery to your body17. All products claiming sugar content measured less than 8% carbohydrates. All but 1 product passed heavy metal screenings.
Scoring: Label Accuracy scores reflect the accuracy of label claims for sodium, potassium, magnesium, chloride, and sugar where applicable. We measured each ingredient, rounded their values according to FDA labeling rules, and then assigned a range for each ingredient based on the amount that the FDA considers to be "insignificant"1. If a claim fell within this range, it received full points. If not, a penalty was given based on the difference between measured and claimed values.
Results: 4 of the 15 products we tested had more than double their claims for sodium and/or potassium. Toniiq Hydration Vitamin performed worst in label accuracy with around 3 times the sodium, potassium, and magnesium it claimed and almost 4 times the chloride it claimed. All sugar claims were accurate as far as FDA nutrition labeling rules go.
Scoring: Product Purity scores reflect whether measured heavy metal contaminants surpass the following California Prop 65 proposed and established safe harbor levels in 1 serving: arsenic - 10 mcg/day, cadmium - 4.1 mcg/day, lead - 0.5 mcg/day, mercury - 0.3 mcg/day2.
Results: Almost all products passed their heavy metal screenings. The exception was Celtic Sea Salt, which was found to exceed the lead threshold in 1 serving. Notably, Toniiq Hydration Vitamin recommends up to 12 servings per day and would exceed the limit for arsenic in 2 servings.
Scoring: Nutritional Value scores for this category are based on a comparison of each products' macronutrients with recommended daily intakes and limits published by the NIH3.
Results: All products recorded macronutrients like sugars within their daily upper limit recommendations.
Scoring: Ingredient Safety scores reflect the safety of each product's active and inactive ingredients. For active ingredients, we compared active ingredient levels to upper limits as published by the NIH, HHS, and USDA3,4. For inactive ingredients, we used the FDA's "Generally Recognized As Safe" (GRAS) database, CSPI classifications, and primary research literature to assign scoring penalties5,6.
Results: None of the products in this batch exceeded safety limits for their vitamin or mineral (electrolyte) ingredients. 4 products recorded artificial sweeteners like sucralose and acesulfame potassium. 5 products recorded malic acid, which can be an allergen or intolerant for some people in rare cases.
Generally, research only supports the use of electrolyte supplements for exercise lasting more than 90 minutes or if you're working out in extreme heat and you're not already used to those conditions7,8,9. In these cases, sodium (and sometimes, potassium) might help with signs of dehydration and electrolyte imbalance like headache, dizziness, and muscle spasms10,11.
Scoring: Sodium accounted for 80% of the score, and potassium, 20%. While sodium is the primary electrolyte lost in sweat, potassium might need to be replaced during extended exercise as well12,13. The National Athletic Trainers' Association recommends that sodium supplementation be in the range of 0.3 - 0.7 g/L10. This is supported by the American College of Sports Medicine and other academic research publications14,15. For potassium, the Institute of Medicine recommends a range of 78 - 195 mg/L16.
For scoring purposes, we added a 20% cushion to both ends of these ranges to account for individual sweat variation and gradually applied penalties to sodium and potassium measurements that fell outside of those ranges. Concentrations were calculated based on what labels listed as the lowest amount of fluid to use for preparation.
A carbohydrate concentration above 8% by weight can delay fluids from reaching and being absorbed by your intestines, which ultimately limits electrolyte delivery to your body17. For this reason, products with more than 8% carbohydrates received a 30% penalty on top of their overall score.
Results: 10 of the 15 products we tested had sodium concentrations within what we considered to be an effective range. 5 products had both sodium and potassium concentrations within effective range. All 4 products claiming sugar had less than an 8% concentration by weight of carbohydrates.