Overview
The authors digested 18 whey and vegan protein powders from China, Japan and India and measured arsenic, cadmium, mercury and lead by ICP-MS, then estimated hazard quotients. Vegan powders had higher readings than whey powders. The plant source of the vegan powders is not stated.
Key numbers
- Vegan powder from China (S_4): arsenic 10.05, cadmium 31.05, lead 9.1 ppb; whey powder from China (S_1): arsenic 0.02, cadmium 1.02, lead 0.04 ppb (Table 3, p. 217).
- Highest mercury: vegan powder from India (S_16) 31.57 ppb (Table 3).
- Stated LOD (µg/L): arsenic 0.7, cadmium 0.9, mercury 0.8, lead 6.9 (Table 4).
Methods (brief)
0.2 g microwave-digested with nitric and hydrochloric acid, diluted to 50 mL, Agilent 7800 ICP-MS in helium mode with rhodium internal standard. Spike recoveries 104 to 115%.
Evidence Fitness
Weak. Table 3 prints “Conc (ppb)” beside instrument counts and it is unclear whether these are digest-solution readings or powder concentrations, so values were not converted. Counts do not match the calibration slopes, many values sit below the stated LOD, one row repeats another’s counts, and the column “sum” equals the “average”. Whey powders measure a non-soy protein source directly, but the numbers should not be used quantitatively until the unit is resolved. The vegan powders are of unstated plant origin and are only a proxy for veggie burgers and meal-replacement drinks.