Table 3 Nutritional deficiencies and their management strategies prior to entering the intervention trial

Vitamin D

Participants with serum 25(OH)D concentrations <25 nmol/L will be offered supplementation of 400 IU per day^a

Iron

Children with iron deficiency will be offered iron supplements and postponed entry into the trial after 3 months. Children will not be retested A child will be iron deficient when two of the following pools are abnormal: red cell pool (haemoglobin <111 g/L, red blood cell distribution width >14 %), transport iron (iron saturation <16 %) and/or storage iron (serum ferritin ≤15 μg/L)^a. Criteria for treatment will be according to the New Zealand Ministry of Health guidelines^b

Vitamin B₁₂

Children with serum levels <110 pmol/L will be offered the option of prescribed supplements or dietary advice to improve status