Overview
Hosojima and colleagues ran a randomized, double-blind, crossover pilot trial of rice endosperm protein supplementation in maintenance hemodialysis patients. The trial is primarily a clinical nutrition study, but its source material includes a measured composition table for the rice endosperm protein (REP) powder used in the intervention. Five REP powder batches were analyzed, and Table 1 reports cadmium at 0.14 +/- 0.17 ppm after the preparation process that washed the REP aggregate to reduce minerals and heavy metals. The paper does not report lead values, and the soy and casein reference columns list cadmium as not available, so its routeable occurrence evidence is narrow: cadmium (Cd) in REP powder, not lead (Pb) in casein.
Key numbers
- REP powder batch count: five batches, reported as average +/- standard deviation in Table 1.
- REP powder cadmium: 0.14 +/- 0.17 ppm in Table 1. For solid food basis, ppm is equivalent to mg/kg, so this corresponds to 0.14 +/- 0.17 mg/kg, or 140 +/- 170 ug/kg.
- Soy protein and casein protein reference columns: cadmium is reported as “N/A” in Table 1; these reference columns do not provide extractable Cd occurrence values for soy or casein.
- Other REP powder composition values in Table 1: protein 91.2 +/- 1.0%, phosphorus 95 +/- 16 mg/100 g, potassium <1 mg/100 g, sodium 17.3 +/- 2.7 mg/100 g, calcium 31.4 +/- 5.3 mg/100 g, and magnesium 5.1 +/- 0.7 mg/100 g.
- The paper does not report Pb, arsenic (As), mercury (Hg), nickel (Ni), aluminum (Al), chromium (Cr), tin (Sn), or uranium (U) concentration values for the REP powder.
Methods (brief)
REP was extracted from 100 kg of regular Japonica rice flour (Koshihikari) using alkaline extraction with 0.2% NaOH, heating, pH adjustment with HCl, washing, neutralization, pasteurization, dehydration, and lyophilization. The authors state that the REP aggregate was washed four times with diluted HCl after pH adjustment to remove minerals and heavy metals such as potassium and cadmium. Cadmium was measured by atomic absorption spectrophotometry. Protein was measured by the Kjeldahl method; phosphorus by ammonium vanadomolybdate absorption photometry; potassium and sodium by atomic absorption spectrophotometry; and calcium and magnesium by inductively coupled plasma atomic emission spectroscopy.
Implications
Certification: This source contributes a single low-N summary statistic for Cd in rice endosperm protein powder used as a clinical nutrition supplement. It is useful as a narrow occurrence point for rice-derived protein powders and non-soy protein ingredients, but it is not benchmark-ready for casein, infant formula, or lead.
Courses: The paper is a useful example of how a nutrition-intervention article can contain routeable contaminant data in a composition table even when the main study endpoint is clinical rather than food-safety surveillance.
App: Route as rice-derived protein powder context for Cd. Do not surface it as evidence for casein Pb or infant-formula Pb despite the auto-fetched filename.
Microbiome: Not applicable.
Related evidence
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