ORIGINAL COMMUNICATION Hydrothermal treatment and malting of barley improved zinc absorption but not calcium absorption in humans K Fredlund 1 *, E-L Bergman 1 , L Rossander-Hulthe ´n 2 , M Isaksson 3 , A Almgren 2 and A-S Sandberg 1 1 Department of Food Science, Chalmers University of Technology, Box 5401, SE Go¨teborg, Sweden; 2 Department of Clinical Nutrition, Institute of Internal Medicine, Sahlgrenska Academy at Go¨teborg University, SE Go¨teborg, Sweden; and 3 Department of Radiation Physics, Sahlgrenska Academy at Go¨teborg University, SE Go¨teborg, Sweden 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 65 Zn and 47 Ca. Whole-body retention of both minerals was measured. Setting: The study was carried out at the Department of Radiation Physics, Sahlgrenska University Hospital, Go ¨teborg. Subjects: The subjects were recruited among students at the Go ¨teborg University. None dropped out. Interventions: The activities of 65 Zn and 47 Ca 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 (Po0.001) than from control porridge containing 111 mg P as InsP 3 –InsP 6 , 25.276.9 vs 11.072.5% (n ¼ 12). Calcium absorption did not differ (P40.05), 21.176.8 vs 19.574.7% (n ¼ 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 (Po0.05) than from flakes of barley, containing 108 mg P as InsP 3 – InsP 6 and no phytase activity, 22.975.8 vs 14.874.6% (n ¼ 10). The calcium absorption was 21.376.5 vs 18.574.3% (n ¼ 10) and did not differ significantly (P40.05). 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). European Journal of Clinical Nutrition (2003) 57, 1507–1513. doi:10.1038/sj.ejcn.1601718 Keywords: phytate; InsP 6 ; barley; hydrothermal treatment; zinc absorption; calcium absorption; whole-body counting Introduction Cereals contribute significant quantities of minerals to the human diet. However, phytate or myo-inositol hexapho- sphate, which is a constituent of all whole grain cereals, impairs the absorption of many essential minerals (Harland & Oberleas, 1987; Rossander et al, 1992). Zinc deficiency is considered highly prevalent in developing countries, where the diet is based on cereals and legumes, and also in vulnerable population groups in industrial countries (Lo ¨n- nerdal, 2000). The depressing effect of phytate on calcium absorption may have impact in some groups, above all in children and women in developing countries who have small calcium intakes (Prentice & Bates, 1994). Thus, there is a rational for development of foods with improved mineral availability. *Correspondence: K Fredlund, Department of Food Science, Chalmers University of Technology, Box 5401, SE 402 29 Go ¨teborg, Sweden. E-mail: mlw@fsc.chalmers.se Contributors: KF, A-SS and E-LB were involved in the concept and all the authors in the planning. KF and AA performed the absorption studies. E-LB, A-SS and AA were responsible for the laboratory analysis. KF, E-LB, MI and A-SS wrote the paper. European Journal of Clinical Nutrition (2003) 57, 1507–1513 & 2003 Nature Publishing Group All rights reserved 0954-3007/03 $25.00 www.nature.com/ejcn