Urine
24 h urine was collected on the last day of each intervention period. Participants were provided with 2 × 3L containers, 4 × 400 ml containers, ice packs and storage bags. Participants were instructed to discard the first urine sample produced on the morning of day 14 and to collect all urine produced thereafter for 24 h. The samples were kept refrigerated during collection and brought to the UCD Intervention suite on their study visit day (day 15). The total volume of urine produced was recorded. Two 50 ml tubes were filled and placed in the centrifuge at 4 degrees for 10 min (RCF 1500, RAD 154). 10 × 1 ml aliquots were then taken and stored at − 80 until analysis. Urinary calcium was measured using a photometric method via a Cobas 8000- c702 autoanalyser (Roche, UK).