Hydrothermal treatment and malting of barley improved zinc absorption but not calcium absorption in humans

Objective: To study whether hydrothermal treatment or malting of barley (cv. Blenheim) improves zinc and calcium absorption in humans. Design: Two groups of 10 and 12 healthy subjects, respectively, were in a period of 2 months in a fasting state, served two single meals each containing porridge or breakfast cereals prepared from processed or unprocessed (control) barley (60 g). The meals included 200 g of milk, extrinsically labelled with Zn-65 and Ca-47. Whole-body retention of both minerals was measured. Setting: The study was carried out at the Department of Radiation Physics, Sahlgrenska University Hospital, Goteborg. Subjects: The subjects were recruited among students at the Goteborg University. None dropped out. Interventions: The activities of Zn-65 and Ca-47 were measured by whole-body counting four to five times over a 4-week period after each meal. Results: Zinc absorption from hydrothermally treated barley porridge, containing 28 mg P as inositol tri- to hexaphosphates (InsP(3)-InsP(6)), was significantly higher (P<0.001) than from control porridge containing 111 mg P as InsP(3)-InsP(6), 25.2 +/- 6.9 vs 11.0 +/- 2.5% (n=12). Calcium absorption did not differ (P>0.05), 21.1+/-6.8 vs 19.5+/-4.7% (n=12). Zinc absorption from breakfast cereals of malted barley with phytase activity and containing 70 mg P as InsP(3)-InsP(6), was significantly higher (P<0.05) than from flakes of barley, containing 108 mg P as InsP(3)-InsP(6) and no phytase activity, 22.9 +/- 5.8 vs 14.8 +/- 4.6% (n=10). The calcium absorption was 21.3 +/- 6.5 vs 18.5 +/- 4.3% (n=10) and did not differ significantly (P>0.05). Conclusion: Improvements of zinc absorption in breakfast meals can be achieved by optimised hydrothermal treatment or malting of barley. Calcium absorption was not influenced in the meals in this study. Sponsorship: Supported by Semper AB, Sweden, Oy Lahden Polttimo, Finland, the SL-Foundation, Sweden, Swedish National Board for Industrial and Technical Development (NUTEK), the Nordic Industrial Foundation, Swedish Council for Forestry and Agricultural Research (SJFR, project no 50.0306/97).