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Labdoor analyzed 21 of the best-selling protein bars in the United States for protein, other macronutrients, vitamins, minerals, and toxic heavy metal (arsenic, cadmium, lead, mercury) contamination.

Overall, products in this batch performed well in label accuracy for protein claims; measured protein content deviated for label claims by an average of 2%. The average product measured 18 g of protein per serving, ranging from 11 g to 32 g. 2 products recorded plant-based proteins; all other products recorded animal-based proteins. Research notes that animal-based proteins are considered higher quality than plant-based proteins due to their amino acid "completeness" and ability to generate greater gains in lean muscle mass11. No evidence of protein spiking was found in any product12.

5 products failed heavy metal screenings for lead. Vega Sport Protein Bar failed screenings for lead, cadmium, and mercury. Additives were also an issue in this testing batch, notably sucralose9 and artificial dyes7, which have been linked to increased cancer risk, and trans fats, which can increase your risk for heart disease and stroke8. Gatorade Recover Whey Protein Bar exceeded the World Health Organization's recommended limit for daily sugar intake in one serving3. Additionally, across the category products tended to underreport total fat content. Most notably, MusclePharm Combat Crunch, which recorded nearly 80% more fat than claimed.



Measured whole protein content deviated an average of 2% from protein label claims.

Products generally performed well in terms of label accuracy for protein claims. Measured whole protein content deviated from label claims by an average of 2%, ranging from -21% to +13% as compared to products' protein claims. No evidence of protein spiking was found in this testing batch.

More than half of the products in this batch underreported total fat content. Measured total fat deviated from label claims by an average of 11%. Some outliers on sugar and sodium label accuracy include Oh Yeah! ONE Bar, which measured about 160% more sugar than claimed, and RXBAR and Vega Sport Protein Bar, each measuring about 30% more sodium than claimed.



5 products exceeded CA Prop 65's MADL (Maximum Allowable Dose Levels) for lead in one serving.

5 of 21 products failed screenings for lead. This means that these products recorded lead levels in one serving that exceeded the established MADL (Maximum Allowable Dose Level) of no more than 0.5 mcg of lead intake per day as published in California Proposition 651.

Vega Sport Protein Bar, failed screenings for cadmium and mercury, in addition to lead. The established MADL for cadmium is 4.1 mcgday. Mercury's "draft MADL" is 0.3 mcgday; the MADL for mercury has not yet been established. All other products passed cadmium and mercury screenings.

All products passed screenings for arsenic. This means that no products in one serving exceeded California Proposition 65's NSRL (No Significant Risk Level) for inorganic arsenic of 10 mcgday.



Overall, products recorded an average of 253 total calories per serving.

Products on average measured 253 total calories per serving, ranging from 156 kcal per serving in the SimplyProtein Bar to 368 kcal per serving in Gatorade Whey Protein Recover Bars.

Products on average measured 10 g of total fat per serving. Rise Bar recorded the highest fat content with 18 g of fat per serving. The Institute of Medicine's Acceptable Macronutrient Distribution Range (AMDR) for total fat intake for men and women over 19 years of age is 20-35% of daily caloric intake2. That's about 44-78 g of fat for a 2,000-calorie-per-day diet 5.

Products on average measured 9 g of total sugars per serving. The World Health Organization recommends limiting sugar intake to 5% of daily caloric intake3. For the average adult, that's about 25 g of sugar per day. Gatorade Recover Whey Protein Bar, with 28 g of sugar per serving, would exceed this limit in one serving.

Products on average measured 200 mg of sodium per serving. MET-Rx Protein Plus and Premier Protein with 468 mg and 426 mg of sodium per serving, respectively, recorded the highest sodium content in this testing batch. The American Heart Association recommends no more than 2,300 mg of sodium per day for the average adult4.



More than one-third of the products recorded sucralose, an artificial sweetener linked to increased cancer risk9.

Additives were an issue in this testing batch. 8 products recorded sucralose, an artificial sweetener. 2 products recorded caramel color, a food coloring agent linked to increased cancer risk6. Artificial dyes, also linked to increased cancer risk, were recorded in Oh Yeah! ONE Bar7. This product also recorded trans fats, which can increase your risk for heart disease, stroke, and diabetes8.

Common allergens in protein bars include milk sources, soy, and nuts. Please consult your doctor to confirm your risk for any allergies.



The average product in this testing batch measured 18 g of whole protein per serving.

Labdoor's Efficacy Score was based on overall grams of protein, both compared to category average and as a proportion of calories from protein in the bar, as well as protein source. Products measured an average of 18 g of protein per serving, ranging from 11 g per serving in Nature Valley Protein Chew Bars to 32 g per serving in Premier Protein. Pure Protein recorded the highest protein concentration in this testing batch, with 44% of total calories coming from protein. The Recommended Daily Allowance (RDA) for protein is defined as 0.8 g of protein per kilogram body weight10. This value may increase depending on physical activity level, health goals, medical problems, and age.

Both Strong & KIND and Vega Sport Protein Bar recorded plant-based protein sources, while all other products recorded animal-based protein sources. According to sports nutrition research, proteins from animal sources provide the highest quality protein due to their "completeness" in terms of essential amino acids. In research, animal-based protein consumption resulted in greater gains in net protein synthesis and lean body mass than plant-based protein consumption. Animal-based proteins, however, have been associated with greater risk for bone loss11.



  • 10 Harvard Health Publications. (2015). How much protein do you need every day?.
  • 11 Hoffman JR & Falvo MJ. (2004). Protein - Which is Best?. J Sports Sci Med. 3(3):118-130.
  • 12 Labdoor. (2016). Industry Secrets: Protein Powders Spiked With Empty Fillers.
  • 1 CA OEHHA. (2016). Proposition 65.
  • 2 Institute of Medicine. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients).
  • 3 World Health Organization. (2015). WHO calls on countries to reduce sugars intake among adults and children.
  • 4 American Heart Association. (2016). Shaking the Salt Habit to Lower High Blood Pressure.
  • 5 Mayo Clinic. (2016). To track how much fat I eat each day, should I focus on grams, calories or percentages?.
  • 6 Johns Hopkins University. (2015). Coloring used in some sodas poses cancer risk to consumers, study suggests.
  • 7 Potera D. (2010). Diet and Nutrition: The Artificial Food Dye Blues. Environ Health Perspect. 118(10):A428.
  • 8 American Heart Association. (2015). Trans Fats.
  • 9 Center for Science in the Public Interest. (2016). CSPI Downgrades Sucralose from "Caution" to "Avoid".