Overview
Ring and colleagues validated an ICP-SFMS method and used it to measure 21 elements in 36 protein powders bought in Ireland in 2016 and 2017, then estimated hazard indices and cancer risk at one and three servings a day. Table 6 prints one value per product for 20 elements (magnesium was above the calibration range in all samples). Cadmium, mercury and lead were low in all products; arsenic was not measured.
Key numbers
- Lead: 0.8 (P31, whey) to 88.4 µg/kg (P28, whey); casein product P19 22.3 µg/kg (Table 6; Section 3.4.6).
- Cadmium: up to 58.1 µg/kg (P1, mixed plant); pea powders 40.6 and 15.4 µg/kg; casein P19 17.0 µg/kg (Table 6).
- Mercury: <0.2 to 18.4 µg/kg (P1, mixed plant) (Section 3.4.4).
- Aluminum, where within calibration: 1197.0 to 6356.1 µg/kg; many samples were above range and not reported (Section 3.4.7).
Methods (brief)
About 0.5 g of each powder was microwave-digested with nitric and hydrochloric acid and measured on an ELEMENT2 sector-field ICP-MS with internal standards. Accuracy was checked with a urine trace-element reference material (85 to 115 percent recovery) and matrix-spiked controls on one whey sample. Results are per kilogram of powder as sold.
Evidence Fitness
Each product is a single analysis, and cells above the calibration range (NR) leave gaps for aluminum, manganese, iron and copper. Arsenic is absent. Only one casein product and two pea, two soy and two mixed plant powders were tested, so plant and casein estimates are thin. The soy powders are not described as isolates, so they are a proxy for soy-protein-isolate, not a direct measurement. The study is also only a proxy for meal-replacement drinks.