Konishi 2001.

Study characteristics
Methods	Study design: cross‐over RCT Time frame: 1998 to 2002 Duration of study (weeks): total (3); run in (1); interventions (1); no washout
Participants	Country: Japan Setting: single centre, Osaka City General Hospital Inclusion criteria: IgA nephropathy as diagnosed by percutaneous kidney biopsy Baseline characteristics GFR: not reported BP: not reported Number: 38 Mean age ± SD: 45 ± 15 years Sex: 14/27 Exclusion criteria: other kidney or heart disease; taking any medication
Interventions	Low salt group Sodium intake: 87 mmol/day (meals provided) Duration: 1 week High salt group Sodium intake: 209 mmol/day (meals provided) Duration: 1 week Other information Study diets contained the same amount of protein (1.2 g/kg body weight/day) and calories (35 kcal/kg/day) Participants were asked to maintain usual levels of physical activity and to refrain from drugs for 1 week before and during the study Co‐interventions: none
Outcomes	24‐hour BP (hourly measurements) 24‐hour proteinuria Serum markers (electrolytes, renin, aldosterone) Renal plasma flow, CrCl Measurement of sodium intake: 24‐hour urine (3 days) Measurement of confounders: assumed medications recorded from medical charts
Notes	Funding: not reported Additional data: provided by authors
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information to permit judgement
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Information not provided however outcomes were objective and unlikely to be influenced by performance bias
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Information not provided. However, given nature of outcomes (objective and results not available immediately)
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Selective reporting (reporting bias)	Unclear risk	No evidence of reporting bias; however, study registration could not be located
Carry‐over effect	Unclear risk	Short interventions with no washout ‐ carry over effect may be present
Bias from confounders	Unclear risk	Standardised meals were provided reducing risk of dietary confounders, but as confounders (e.g. potassium intake, weight loss) were not discussed, risk of bias is unclear. Medications not reported but protocol was to refrain from medications
Other	Unclear risk	Funding not reported