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Summary and conclusionsThe effects of iron-deficiency anaemia on worker productivity were studied in a tea plantation in Sri Lanka. The quantity of tea picked per day was studied before and after iron supplementation or placebo treatment. After one month's treatment significantly more tea was picked when the haemoglobin (Hb) concentration was-increased by iron supplementation than when it was not. The degree of improvement was greater in more-anaemic subjects (those with concentrations of 6 0-9 0 g Hb/dl). The level of physical activity of anaemic subjects in their everyday environment was also recorded for four or 24 hours continuously both before and after treatment. After three weeks these levels were significantly greater in the iron-treated than matched placebo-treated subjects.The economic implications of increased work productivity with iron treatment are evident, particularly in developing countries. These results also provide strong evidence for the clinical impression that people with iron-deficiency anaemia suffer from tiredness and weakness.

Changes in haemoglobin (Hb), work performance, heart rate and postexercise blood lactate were studied in iron deficient, anaemic subjects for 16 d following total dosage infusion of iron dextran, i.v. (30-50 ml). Six adult men and 14 women were subjects with initial Hb levels of 6.6 +/- 0.6 g/dl (mean +/- SEM) for the iron treatment group (n=10) and 8.0 +/- 0.7 for the placebo group (saline infusion, n=10). Serum levels were 0.51 +/- 0.15 and 0.67 +/- 0.12 mg/l for the two groups, respectively. Haemoglobin and maximal work time increased significantly within 4 d after iron treatment and continued to increase up to 16 d. No changes were found in the placebo subjects. Heart rates at a given exercise intensity were lower in the iron treatment group than in control subjects who had the same Hb levels but had not been treated with iron. Post-exercise venous blood lactate was similar on succeeding days after iron treatment even though the subjects reached higher work loads. These results demonstrate the treatment of iron deficient, anaemic subjects with iron dextran results in improved work capacity within 4 d and a lower heart rate at a given work load after treatment which cannot be accounted for totally by the elevation of Hb concentration.