Food Oxalate: Factors Affecting Measurement, Biological Variation, and Bioavailability

Department of Food Science and Human Nutrition, Washington State University, Spokane, WA 99210-1495, USA.
Journal of the American Dietetic Association (Impact Factor: 3.92). 08/2007; 107(7):1191-4; quiz 1195-6. DOI: 10.1016/j.jada.2007.04.007
Source: PubMed


Food and nutrition professionals provide medical nutrition therapy for patients with kidney stones. If the stones contain oxalate or the patient has been diagnosed with hyperoxaluria, reduction of dietary oxalate may be appropriate. Differences in oxalate values for a single food may be due to analytical methods, and/or biological variation from several sources, including cultivar, time of harvest, and growing conditions. Bioavailability of food oxalate and, thus, urine oxalate, will also be affected by salt forms of oxalate, food processing and cooking methods, meal composition, and the presence of Oxalabacter formigenes in the patient's gut. Dietary advice for reducing urinary oxalate should include both reduction of dietary oxalate and simultaneous consumption of calcium-rich food or supplement to reduce oxalate absorption.

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    • "This decrease may be attributed to the condensed tannin in 147 cassava leaves due to the indigestible tannin-protein complexes or negative effect on the 148 enzyme activity (Lancaster & Brooks, 1983). 149 150 Oxalate as a simple di-carboxylic acid [(COO)2 2− ] is considered as an antinutrient, which 151 negatively affects the bioavailability of magnesium and calcium (Massey, 2007). Oxalates 152 bind calcium and excrete through urine or form crystals which might cause kidney stones. "
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    ABSTRACT: Cassava is mainly grown for its roots whereas leaves are mostly considered as a byproduct. Cassava leaves are a rich source of protein, minerals, and vitamins. However, the presence of antinutrients and cyanogenic glucosides are the major drawbacks in cassava leaves which limit its human consumption. These antinutrients and toxic compounds of cassava leaves cause various diseases depending on the consumption level. Hence these antinutriens and toxic potential of cassava leaves should be addressed during cassava leaf processing (CLP) before human consumption. Several CLP methods have been developed but every method has its own limitations. Some CLP methods successfully detoxify cassava leaves but simultaneously destroy the nutrients. Efforts have also been made for cassava leaf protein extraction in the form of cassava leaf protein concentrate (CLPC) but protein recovery was very low. This review summarizes the nutrient, antinutrient and toxic composition of cassava leaves, CLPC, different CLP methods, human consumption and diseases caused by cassava leaves. Furthermore, recommendations have been made in order to encourage cassava leaves consumption as an important source of protein and micronutrients.
    Trends in Food Science & Technology 04/2015; 44(2). DOI:10.1016/j.tifs.2015.04.006 · 4.65 Impact Factor
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    • "Some reports cite meat intake as a factor in hyperoxaluria (Nguyen et al. 2001) and also hydroxyproline, an amino acid and major component of the protein collagen (Patel et al. 2011). Because reported food concentrations of oxalate are variable, due to inter-laboratory variability and food preparation and other factors (Massey 2007), and because foods that are high in oxalate do not necessarily result in high urinary excretion, the restriction of high-oxalate foods in kidney stone prevention is controversial. This controversy is heightened by the fact that many high-oxalate foods are healthy foods that are recommended for certain specific and also general health benefits and frequently are the same foods that are fiber-and phytate-rich. "
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    ABSTRACT: Diet influences the formation and growth of most types of urolithiasis. Medical nutrition therapy is a recognized and safe intervention that may be used alone or in concert with pharmacologic therapy. Patients frequently ask about dietary changes they can make to prevent stone recurrence. Urologists are increasingly managing patients with urinary tract stones between events and offering preventive strategies. Urologists must be familiar with basic preventive nutrition concepts for urolithiasis and with how dietary changes affect recurrence risk, even when a registered dietitian is available for patient counseling. In this chapter, the various risk factors for recurrence of the most common types of urolithiasis are reviewed with respect to the specific, evidence-based nutrition therapy that addresses each one. Frequently asked patient questions about understanding and complying with nutrition therapy, derived from the author’s clinical experience, are addressed.
    Clinical Management of Urolithiasis, 01/2013: pages 193-205; , ISBN: 978-3-642-28731-2
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    • "The soluble salt can be absorbed by the human body and contributes to the oxalic acid concentration in the urine (Holmes et al., 1995) while insoluble oxalate is directly excreted in the faeces. Once the urine becomes supersaturated oxalate may crystallise as an insoluble salt, calcium oxalate, in the soft tissues, i.e. the kidneys, and form kidney stones (Massey, 2007). Some people either suffer from an increased endogenous oxalate production or have a higher oxalate absorption from food and, hence, a higher urinary oxalate output. "
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    ABSTRACT: Cocoa and dark chocolate have been promoted as health foods due to the high levels of antioxidants found in cocoa beans (Theobroma cacao L.) and their products but they also contain moderate to high levels of oxalates which can cause some health concerns. Fifteen samples of commercially available cocoa powder were collected from four different countries and the total and soluble oxalate content was analysed by HPLC chromatography. The total oxalate contents ranged from 650 to 783mg/100g dry matter (DM), mean 729±8.4mg/100g DM, while the soluble oxalate contents ranged from 360 to 567mg/100g DM, mean 469±15mg/100g DM. The total oxalate contents of 34 samples of dark chocolate collected from 13 different countries ranged from 155 to 485mg/100g DM, mean 254±12mg/100g DM while the soluble oxalate contents ranged from 157 to 351mg/100g DM, mean 216±10mg/100g DM. Oxalate bioavailability was determined by feeding 68.0±0.7g of dark chocolate containing 232.0±2.3mg total oxalate as a test meal to 14 volunteers. The mean availability of total oxalate in the chocolate measured from the increase in urinary oxalate output over the following 6h was 1.82±0.27%.
    Journal of Food Composition and Analysis 11/2011; 24(7):916-922. DOI:10.1016/j.jfca.2011.03.008 · 1.99 Impact Factor
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