Oxalate content of silver beet leaves (Beta vulgaris var. cicla) at different stages of maturation and the effect of cooking with different milk sources

The work presented here indicates that people who have a tendency to develop kidney stones should avoid consuming regrowth and developed silver beet (Beta vulgaris var. cicla) leaves. Soluble oxalate contents of leaves range from 58% of the total oxalate for the mature leaves up to 89% for the regrowth tissue, with regrowth tissue containing the highest levels of soluble oxalate at 7267 ± 307 mg/100 g of dry matter (DM). Leaves cooked in milk contained significantly (p < 0.05) lower levels of soluble oxalate compared to the leaves that were cooked in water. Leaves cooked in low fat milk contained significantly lower levels (p < 0.05) of soluble oxalate (1.9%) than leaves cooked in standard milk (5.3%) or cream (6.3%). To maximize the reduction of soluble oxalate during the cooking of high oxalate foods such as spinach and silver beet, a low fat milk cooking medium with neutral pH should be utilized. © 2009 American Chemical Society