Effect of Cooking on the Soluble and Insoluble Oxalate Content of Some New Zealand Foods

Savage, Geoffrey P.; Vanhanen, Leo P.; Mason, S.M.; Ross, Alastair B.

doi:10.1006/jfca.2000.0879

Cited by 208 publications

(258 citation statements)

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“…They went on to show that the consumption of six cups of tea made from either loose black tea or black tea in tea bags would result in an intake of between 16 and 102 mg soluble oxalate=day. These levels are modest when compared with the amounts of soluble oxalate found in common foods (Noonan & Savage, 1999;Savage et al, 2000;Albihn & Savage, 2001a). Tea drinking, however, tends to occur on a daily basis, confirming the observation made by Zarembski and Hodgkinson (1962) that 'tea is a significant source of oxalate intake in English diets'.…”

Section: Introductionmentioning

confidence: 77%

“…This indicates that there is a major uptake of oxalate from the small intestine in healthy humans. The relationship between soluble and insoluble oxalate in the small intestine seems to have a major effect on oxalate bioavailability, since ingestion of calcium together with oxalate-rich foods has been shown to lower the uptake of both calcium and oxalates (Marshall et al, 1972;Barilla et al, 1978;Heaney et al, 1988;Masai et al, 1995;Holmes et al, 1996;Weaver et al, 1997;Savage et al, 2000). This indicates that insoluble calcium oxalate has a much lower bioavailability than the soluble from of oxalate, and that an oxalate rich=low calcium diet leads to a greater uptake of oxalate.…”

Section: Introductionmentioning

confidence: 99%

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Bioavailability of soluble oxalate from tea and the effect of consuming milk with the tea

2003

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Objectives: To measure the availability of oxalate normally extracted when making tea from two commercially available black teas bought from a supermarket in Christchurch, New Zealand in July 2001. Design, subjects and intervention: A randomized double crossover study. Six students and four staff consumed six cups of each brand of tea both with and without added milk over a 24 h period. A total urine collection was taken for the initial 6 h followed by a further 18 h. The oxalate content of the urine voided was measured using an enzyme kit method and the availability of the soluble oxalate consumed was measured for the 6 h and the total 24 h sample. Setting: University campus. Results: The mean soluble oxalate content of black tea in the two different commercial tea bags was respectively 6.1 and 6.3 mg soluble oxalate=g tea. The mean availability of the oxalate extracted from tea measured over a 6 h period ranged from 1.9 to 4.7% when tea was consumed without milk. The availability of the soluble oxalate from tea ranged from 73.0 to 2.3% for each of the two brands of tea investigated over a 24 h period. Conclusion: These studies show that consuming black tea on a daily basis will lead to a moderate intake of soluble oxalate each day, however the consumption of tea with milk on a regular basis will result in the absorption of very little oxalate from tea. Sponsorship: Lincoln University.

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Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Bioavailability of soluble oxalate from tea and the effect of consuming milk with the tea

2003

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“…Cooking the fruits in a wok with a small amount of oil would be a more common way to cook bitter gourd fruits in the regions where it is consumed. Overall, the oxalate contents of the wok‐fried fruits of bitter gourds were not high when compared to other commonly consumed vegetables (Noonan & Savage, 1999; Savage et al., 2000). Also, bitter gourd fruits were not usually consumed as a separate vegetable in a meal.…”

Section: Discussionmentioning

confidence: 99%

“…(2000). Three replicates of 5 g of each sample of freshly chopped bitter gourd fruits and wok‐fried fruits and 5 g of the extracted juice were used to measure the total oxalate content, and three replicates were extracted to measure the soluble oxalate contents.…”

Section: Methodsmentioning

confidence: 99%

“…A number of food plants contain oxalates, but these tend to occur in higher concentrations in the leafy parts of vegetables rather than in the roots or stalks (Juajin, Vanhanen, Sangketkit, & Savage, 2012; Savage, Vanhanen, Mason, & Ross, 2000), and there are few reports of oxalates being found in the fleshy parts of edible fruits. Studies on the oxalate content in the leaves and fruit of bitter gourds are limited.…”

Section: Introductionmentioning

confidence: 99%

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Oxalate content of raw, wok‐fried, and juice made from bitter gourd fruits

Bong

Savage

2018

Food Science & Nutrition

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The total, soluble, and insoluble oxalate contents of fresh and wok‐fried bitter gourd (Momordica charantia) fruits were extracted and measured using HPLC chromatography. Frozen bitter gourds were imported from Vietnam, and two cultivars characteristic of bitter gourd fruits grown in India and Malaysia were grown locally in the North Island of New Zealand. The mean total oxalate contents of ripe fruits from Vietnam, India, and Malaysia were 85.90 ± 8.60 mg/100 g wet matter (WM), while the mean total oxalates fell to 88.06 ± 0.95 mg/100 g FM when the fruits were wok‐fried. The mean soluble oxalate content of the total oxalate was 54.42% of the ripe fruits and 58.14% of the wok‐fried fruits. The three cultivars of bitter gourds were processed into juice by the addition of standard ingredients and then processed through a screw press to remove excess fiber. The final juices had an overall mean value of 27.11 mg of total oxalates/100 g WM; the mean soluble oxalate content was 85.5% of the total, which was much higher than that measured in the cooked gourds (mean 70.7%).

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