Comparison of the effect of advanced glycation end-products restricted diet and combined supplementation of zinc, pyridoxine and curcumin, on kidney functional indices in diabetic nephropathy patients

Comparison the effect of advanced glycation end-products (AGEs) restricted diet and combined supplementation of zinc, pyridoxine and curcumin, on kidney functional indices in diabetic nephropathy patients

Randomized, double-blind, placebo-controlled clinical trial

Individuals referred to Motahhari Clinic in Shiraz, were evaluated by the kidney specialist (clinical partner of the project), if the initial inclusion criteria were confirmed, further evaluation were performed, then randomized to one of 3 study groups and received the desired intervention. The patients and the outcome assessor of the study were blind to the study group.

Study population: patients (male / female) with diabetes mellitus Inclusion criteria: Willingness to participate، diagnosis of diabetes by a specialist, diagnosis of nephropathy by a specialist (patient with a minimum GFR equal to or more than 30 ml per minute and microalbuminuria or macroalbuminuria stage), no alcohol and tobacco usage, stable weight during the last 6 months (self-report), constant type and dose of drugs used in the last 6 months (self-report) Exclusion criteria: Acute heart diseases, liver, gastrointestinal, thyroid and parathyroid, rheumatoid and infectious diseases, stroke, pregnancy and lactation, use of any dietary supplement in the last 6 months (self-report)

Study duration: 10 weeks for all groups Control group: Diabetic diet (DD) plus 3 placebo capsules (non-absorbale starch); Intervention group 1: DD plus 3 placebo capsules plus dietary instructions to reduce the content of AGEs; Intervention group 2: DD plus 3 capsules (pyridoxine (100mg) plus zinc (30mg) plus curcumin (1g) - 1 after each main meal). Drugs and placebo are provided by Abu Reihan pharmacy company.

Estimated glomerular filtration rate, urinary microalbumin

Participants were randomly assigned to one of three groups according to the block-randomization protocol (produced by Random Allocation Software): 1-control 2-intervention (dietary) 3-intervention (pyrodoxin + zinc + curcumin supplement) in 1: 1: 1 fashion. Since allocation sequence is made by computer software and the output is only the list of assigned participant numbers, the research team will not interfere or know how individuals are assigned (randomization and concealment).

This study will be conducted in a double-blind manner for more accuracy, so that the researcher is aware of the type of interventions distributed among the study subjects, but the participants and outcome assessor are not aware of the type of intervention applied. Placebo capsules are same in size, color, and odor compared to the intervention capsules, and none of the participants will know which of the three groups they are classified into. Also, outcome assessor has no information about which group the participants were in.