Submitted to: National Nutrient Databank Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/19/2007
Publication Date: 5/1/2007
Citation: Thomas, R.G., Gebhardt, S.E., Phillips, K. 2007. Examining phytosterols in nuts and seeds for the usda national nutrient database for standard reference. National Nutrient Databank Conference, May 1, 2007, Washington, D.C. Interpretive Summary:
Technical Abstract: Objective: The current release of the USDA National Nutrient Database for Standard Reference (SR) includes total phytosterols for 30 of the 128 nut and seed items. Twenty-two of those have values for individual sterols – Beta-sitosterol, stigmasterol, and campesterol. The current literature was studied for the purpose of expanding phytosterol data for nuts and seeds in SR. Methods and Materials: Examination of the current phytosterol literature revealed 15 papers with analytical data, 10 of which included analysis of 1 or more nuts and seeds. While all ten used gas chromatography to determine sterol content, only 3 applied an additional acid hydrolysis step which enabled the extraction of glycosidic sterols to be included with the total free and esterified sterol forms. Results: Eight of the 10 nut and seed papers reported more than the 3 types of sterols reported in SR. One paper (Phillips 2005) had the most comprehensive study of nuts and seeds, including 11 nuts and 6 seeds. This paper reported results for beta-sitosterol, brassicasterol, campesterol, stigmasterol, delta-5-avenasterol, sitostanol, campestanol and other sterols analyzed with the additional acid hydrolysis step to extract the glycosidic sterols. The Phillips (2005) total phytosterol values ranged from 95 mg (Brazil nuts) to 280 mg (pistachio nuts) per 100g of nuts, and 185 mg (poppy seeds) to 400 mg (sesame seeds) per 100g of seeds. The results represent a 25% (hazelnuts) to 108% (poppy seeds) increase over SR values. These higher values reflect the inclusion of additional specific sterols (especially delta-5- avenasterol) and the glycosidic sterol form. This review of new data formed the basis for updating nut and seed phytosterol data in SR via evaluation and compilation of available data. Significance: Nuts and seeds are major sources of phytosterols in the diet. Enhanced phytosterol data in SR, reflecting current analytical methodology, will provide researchers with more accurate estimates of individuals’ intakes and aid in research of phytosterols’ cholesterol-lowering effects.