Honey as a Source of Natural Antioxidants

146 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.Dietary antioxidants might prevent oxidative damage to tissues and therefore protect against chronic diseases. Previous research demonstrated that honeys from various floral sources exhibit significant antioxidant activity, rendering honey effective as a food antioxidant. The objective of the research presented in this dissertation was to extend the knowledge of the protective antioxidant effects of honey in food systems and in in vitro assays into determining the potential of honey as a dietary source of antioxidants. In vitro antioxidant activity of honey as measured by the oxygen radical absorbance capacity (ORAC) assay, was found to be similar to the antioxidant activity of many fruits and vegetables on a fresh weight basis. The ORAC values of honeys from various floral sources were significantly correlated with the in vitro inhibitory effect of honeys on copper-catalyzed serum lipoprotein oxidation. Wide variation in antioxidant activity was observed among honeys from different floral sources, with the darker colored honeys having higher antioxidant capacity. Specific honey components responsible for the observed antioxidant capacity were identified and quantified, including phenolics, proteins, gluconic acid, enzymes, hydroxymethylfuraldehyde and ascorbic acid. A linear correlation was observed between ORAC activity of the investigated honeys and their phenolic and protein content. In addition, the first evidence for an ex vivo antioxidant effect of honey was established in a human intervention study. Consumption of water with buckwheat honey significantly increased deproteinized serum antioxidant capacity relative to water consumption. A hypercholesterolemic rabbit model was used to further elucidate the in vivo effect of soy and buckwheat honey consumption on atherosclerosis. Feeding the rabbits soy or buckwheat honey in addition to cholesterol did not significantly change their serum lipid profiles, serum antioxidant capacity or atherosclerotic plaque formation as compared to feeding the rabbits cholesterol alone. These studies are the first to examine the biological potential of honey as a dietary antioxidant. Now it becomes crucial to study factors such as bioavailability and tissue distribution of honey phenolics and other components to fully understand its biological activity in vivo before incorporation of honey as a source of dietary antioxidants into the human food supply can be supported.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD