title: Variability in the antioxidant activity of dietary supplements from pomegranate, milk thistle, green tea, grape seed, goji, and acai: effects of in vitro digestion.
abstract: The antioxidant activity (AA) of fruits and vegetables has been thoroughly investigated but less is known about the AA of dietary supplements (DS). We therefore assessed the AA of three to five DS each from pomegranate, milk thistle, green tea, grapes, goji, and acai using four widely used standard methods. The secondary objective was to determine the effects of in vitro digestion on their AA. The AA of the DS prior to digestion ranked as follows: pomegranate > resveratrol > green tea > grape seed > milk thistle and very low in goji and acai with significant group variability in AA. The AA after in vitro simulated digestion of the mouth, stomach, and small intestine compared to undigested supplement was decreased for green tea and grape seed but increased for pomegranate, resveratrol, milk thistle, goji, and acai to various extents. Although polyphenols provide the major antioxidant potency of the tested supplements, our observations indicate that digestion may alter antioxidant properties depending in part on the variations in polyphenol content.
authors.affiliation: Center for Human Nutrition, David Geffen School of Medicine, University of California , Los Angeles, California 90095, United States.
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Henning
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Victoria G
authors.initials: VG
authors.lastname: Rontoyanni
authors.forename: Jianjun
authors.initials: J
authors.lastname: Huang
authors.forename: Ru-Po
authors.initials: RP
authors.lastname: Lee
authors.forename: Amy
authors.initials: A
authors.lastname: Trang
authors.forename: Gloria
authors.initials: G
authors.lastname: Nuernberger
authors.forename: David
authors.initials: D
authors.lastname: Heber
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D028241:Camellia sinensis / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis*; D004063:Digestion; D065748:Euterpe / Q000737:chemistry; D005638:Fruit / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D032305:Lycium / Q000737:chemistry; D029561:Lythraceae / Q000737:chemistry; D019684:Magnoliopsida / Q000737:chemistry*; D020944:Silybum marianum / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis; D012639:Seeds / Q000737:chemistry; D027843:Vitis / Q000737:chemistry
chemical_list: D000975:Antioxidants; D010936:Plant Extracts