A further study of oxalate bioavailability in foods.
We extended the study of oxalate bioavailability by testing 7 additional food items: brewed tea, tea with milk, turnip greens, okra, peanuts and almonds. Nine normal subjects ingested a large serving of each of these items. The bioavailable oxalate was calculated from the increment in urinary oxalate during 8 hours after ingestion and bioavailability was determined as the percentage of total oxalate content in a given food item represented by bioavailable oxalate. Brewed tea and tea with milk, with a high oxalate content, had a low bioavailable oxalate level (1.17 and 0.44 mg. per load) because of the low oxalate availability (bioavailability of 0.08 and 0.03%). Turnip greens, with a satisfactory oxalate bioavailability (5.8%), had a negligible effect on urinary oxalate excretion, since oxalate content was relatively low (12 mg. per load). Okra, with a moderate oxalate content (264 mg. per load) had a negligible bioavailable oxalate (0.28 mg. per load). Only peanuts and almonds provided a moderate increase in oxalate excretion (3 to 5 mg. per load) due to the modest oxalate content (116 and 131 mg. per load) and oxalate bioavailability (3.8 and 2.8%). Thus, the ability of various oxalate-rich foods to augment urinary oxalate excretion depends not only on oxalate content but on the bioavailability.
Brinkley
L J
LJ
Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical School, Dallas 75235.
Gregory
J
J
Pak
C Y
CY
D000328:Adult; D001682:Biological Availability; D005260:Female; D005502:Food; D006801:Humans; D008297:Male; D009754:Nuts / Q000032:analysis; D010070:Oxalates / Q000032:analysis / Q000493:pharmacokinetics* / Q000652:urine; D013662:Tea / Q000032:analysis; D014675:Vegetables / Q000032:analysis
D010070:Oxalates; D013662:Tea