The availability of soluble oxalates in stir-fried silver beet (Beta vulgaris var. cicla) leaves eaten with yoghurt

Abstract

Silver beet (Beta vulgaris var. cicla) leaves contain oxalates, and the addition of yoghurt, a food rich in calcium, to stir-fried leaves was investigated as a way of reducing the soluble oxalate content. Fourteen participants ingested 115 g stir-fried silver beet leaves with or without standard yoghurt and low-fat yoghurt, respectively. Stir-fried silver beet leaves contained 209.1 ± 0.1 mg of total oxalates per meal fresh weight (FW) and 109.2 ± 0.1 mg of soluble oxalates per meal FW. The proportion of soluble oxalates was reduced from 52% to a mean of 30% of the total oxalates when standard yoghurt or low-fat yoghurt was added. The mean absorption of oxalate was determined by measuring the output of oxalate in the urine over a 6-h period following ingestion of the meals. The mean absorption of oxalate from stir-fried silver beet leaves was 2.41%, which reduced to 1.10% and 0.89% when consumed with standard yoghurt and low-fat yoghurt, respectively.