Brzezinska-Rojek et al. 2023 — Elemental composition and safety of beetroot dietary supplements, Poland
Brzezinska-Rojek et al. measured 19 elements in 37 beetroot-based dietary supplements (tablets, capsules, and powders) available in Poland, using microwave plasma atomic emission spectrometry (MP-AES; Agilent 4210). Products were homogenized and microwave-digested (Anton Paar Multiwave Go); recoveries 80–120%; LOQ values ranged by element (Pb LOQ 0.035 mg/kg, Cd LOQ 0.066 mg/kg, Al LOQ 0.26 mg/kg). The safety-critical finding is that five products exceeded 4–134% of the PTMI for cadmium, two products delivered 11–12% of the PTWI for aluminum per daily dose, and three products provided Ba at 1.085–1.331 µg/daily dose. Lead was below LOQ in all 37 samples (LOQ = 0.035 mg/kg). Powders generally contained the highest element concentrations per daily dose, substantially exceeding tablets and capsules, because powder daily portions (3–15 g/day) are far larger by mass.
Key numbers
Concentrations reported as µg per daily dose (µg/d.d.); tablet n=10, capsule n=14, powder n=13. Data from Table 2 of the source.
Cd (µg/d.d.) — only in samples above LOQ:
- Tablets (n=2 above LOQ): mean 34, SD 43, range 3–64
- Capsules (n=3 above LOQ): mean 28, SD 43, range 2.3–78
- Powders: all samples above LOQ but Cd concentrations reported relative to PTMI
Five products were “significantly contaminated with Cd (4–134% of PTMI Cd).” EU ML for Cd in dietary supplements: 1 mg/kg.
Pb: below LOQ (0.035 mg/kg) in all 37 samples.
Al (µg/d.d.):
- Tablets (n=10): mean 14, SD 9.1, range 2.6–28
- Capsules (n=14): mean 51, SD 162, range 0.70–614
- Powders (n=13): mean 471, SD 817, range 1.6–2420
Two products delivered 11–12% of the PTWI for Al per daily dose (JECFA PTWI for Al: 2 mg/kg b.w./week).
Ba (µg/d.d.):
- Powders: mean 517, SD 473, range 0.96–1331; three products at 1085–1331 µg/d.d. (compared to RfD threshold)
Methods (brief)
MP-AES (Agilent 4210) at element-specific wavelengths after microwave acid digestion (HNO3; Anton Paar Multiwave Go). LOQ (mg/kg): Pb 0.035, Cd 0.066, Al 0.26, Ni 0.021, Cr 0.0082, Ba 0.63. Recoveries 80–120%; R² 0.986–1.000. Triplicates for all samples. Note: MP-AES is a total-metals technique; all arsenic and chromium would be total values if measured, but As was not among the 19 reported analytes; Cr was measured as total Cr.
Implications
Certification: Beetroot dietary supplements on the Polish market show Cd contamination at levels reaching 134% of PTMI in some products, concentrated in capsule and powder forms. Pb was universally below LOQ. These findings are relevant to the supplement category where beetroot is a significant ingredient.
Courses: Illustrates the risk-tiering of supplement physical form: powders deliver far higher metal doses per daily use than tablets or capsules, due to larger per-serving weights. Beetroot as a root vegetable is a known Cd accumulator, and concentrated dried forms amplify that signal.
App: Beetroot dietary supplements (PL): Cd in 5/37 products at 4–134% of PTMI per daily dose; Pb <LOQ in all; Al up to 2420 µg/d.d. in powders.