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Strontium isotopes and concentrations in cremated bones suggest an increased salt consumption in Gallo-Roman diet

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This archaeological study measured strontium isotope ratios and strontium concentrations in cremated human bone from Belgian cemeteries spanning the Metal Ages and the Roman period. Roman-period individuals had higher bone strontium and isotope ratios clustered near the seawater value. The authors attribute this mainly to marine strontium from salt used to preserve meat and fish.

Key numbers

  • Destelbergen bone strontium (normalized to 40 wt% calcium): Gallo-Roman IQR 144 to 205 ppm versus Metal Ages IQR 87 to 130 ppm; Mann-Whitney U 191.5, p below 0.0001 (Results, p. 5).
  • Blicquy: Metal Ages IQR 67 to 92 ppm versus Roman IQR 118 to 160 ppm; Fize-le-Marsal (Gallo-Roman) IQR 139 to 176 ppm; Herstal (Metal Ages) IQR 89 to 110 ppm (Results, p. 5).
  • Destelbergen isotope ratios: Metal Ages 0.7091 to 0.7117 (n = 89), Roman 0.7090 to 0.7100 (n = 33), near modern seawater at 0.7092 (Results, p. 5; Abstract).
  • Literature values summarized by the authors (not measured here): marine and rock salts 10 to 153 ppm strontium; ten commercial unrefined salts 95.2 plus or minus 78.5 (2SD) ppm; pork fat and meat 0.1 to 1.1 ppm; salted hams up to 4.6 ppm (Discussion, p. 4).
  • The authors cite an earlier estimate that 9.2 g of salt per day could shift isotope ratios toward seawater in a calcium-rich diet, against a World Health Organization recommendation of 5 g per day (p. 4).

Methods (brief)

Cremated bone fragments were cleaned and dissolved; strontium isotope ratios were measured by multi-collector ICP-MS and concentrations by sector-field ICP-MS, with concentrations normalized to 40 wt% calcium. Modern plants around Destelbergen defined the local bioavailable baseline. Groups were compared with Mann-Whitney U and Wilcoxon tests.

Evidence fitness

Supports the statements that bone strontium reflects dietary strontium and that salt, especially marine salt, can be a meaningful dietary strontium source. The food concentrations it quotes come from earlier studies and should be treated as secondary. It does not support modern intake or toxicity statements.

Limitations

Cremation removes organic tissue, so diet is inferred indirectly. Salt intake is an interpretation, not a measurement. The concentration figures for salt and foods are cited from other work and were not verified against those primary sources here.

Update history

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