Randomization and masking
For the first part of the study, patients were randomized to one of the four study groups based on computer generated random numbers in a 1:1:1:1 ratio using a random block size of four. For the second part of the study, patients were randomized to one of the two groups based on computer generated random numbers in a 1:1 ratio using a random block size of two. The random number list was generated by QuickCalc GraphPad Software Inc. The randomization was performed by an independent statistician. Allocation concealment was done by sequentially numbered sealed opaque envelopes. The diet allocation was concealed in an opaque envelope that was only opened after all baseline data had been collected. The randomization was blinded for both the patients and the investigators. Allocation to diet was masked throughout data collection, laboratory analysis, data input, and data analysis.