1095 analytical chemistry and molecular biology assays on 73 best-selling protein supplements.
38 of 73 protein supplements recorded measurable amounts of free amino acids, with one product recording nearly 64% of its claimed protein content in the form of unbound protein.
Actual sodium content was found to be 70.4% higher on average vs. the 73 products' Supplement Facts label claims. This may cause water retention and fake the look of quick muscle gains.
Labdoor analyzed 73 best-selling protein supplements in the United States. Our analysis quantified protein, fat, sugar, cholesterol, calcium, sodium, lead, cadmium, arsenic, and mercury content and recorded presence/absence data for 63 inactive ingredients.
Our scientists recorded 17 variations of protein sources, featuring the fast-digesting whey varieties (indicated for exercise recovery), protein blends (indicated for meal replacement), soy and casein sources (indicated for sustained protein supplementation), and several forms of plant-based proteins, including hemp seed, pea, and brown rice (typically appropriate for those sensitive to dairy/soy or for those observing a vegan/vegetarian diet).
In a surprising find, over 52% of products recorded measurable amounts of free-form amino acids, which spike protein content in standard laboratory tests but add little nutritional benefit (beyond physiologically appropriate proportions). Asparagine was the most commonly spiked amino acid (15/73 products), followed by alanine (11/73), glycine (8/73), taurine (8/73), and leucine (7/73). Histidine, glutamine, alanine, cysteine, and taurine were the highest-risk amino acids, recording the most severe spikes in our batch analysis, respectively.
All protein powders tested in this batch passed our heavy metals screens for arsenic, lead, cadmium, bismuth, antimony, and silver (below 1 part per million). However, controversial artificial sweeteners, including Aspartame and Acesulfame Potassium, preservatives (Benzoic Acid), and artificial colors (FD&C Yellow 5, FD&C Blue 1, and FD&C Red 40) were commonly found in tested protein supplements.
38 of 73 products recorded measurable amounts of free amino acids, with 10 products recording more than 3% of their claimed protein content by way of spiked amino acids.
All sixty protein products tested in this batch passed heavy metals screens for arsenic, lead, cadmium, bismuth, antimony, and silver (below 1 part per million).
RTD (Ready-To-Drink) products ranked significantly worse than their powdered forms due to increased fat, sodium, and preservative content.
63 inactive ingredients and 147 active ingredients were identified in at least one protein supplement analyzed.
17 forms of protein were utilized in these 73 products, lead by whey protein isolate (52/73) and whey protein concentrate (40/73).