Ingestion of wheat germ in healthy subjects does not acutely elevate plasma wheat germ agglutinin concentrations
Date
2009
Authors
Kuzma, Jessica Nichole, author
Nelson-Ceschin, Tracy L., advisor
Cordain, Loren, 1950-, advisor
Melby, Christopher L., committee member
Hickey, Matthew S., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Because the fiber content (15 g/day) of the typical U.S. diet is considerably lower than recommended values (25-30 g) the public is encouraged by USDA Dietary Guidelines to increase consumption of high fiber foods such as whole grains, fruits, and vegetables. Because whole grains are also a rich source of the lectin wheat germ agglutinin (WGA), those abiding by current recommendations would consequently increase their lectin intake. The WGA lectin has been poorly studied in humans, and it is unclear if it can breach the gut barrier, enter circulation, and influence physiology. Apart from animal studies, characterization of lectin behavior in humans is limited to tomato lectin (TL) and peanut lectin (PNA) feeding studies; both of which were able to detect lectin in systemic circulation within hours of ingestion of tomato juice and peanuts, respectively. Because lectin consumption has elicited adverse health effects in laboratory animals, a prudent first step in humans will be to determine if common dietary lectins such as WGA can enter circulation in quantities capable of influencing normal cell function. The purpose of this study was to determine if WGA enters the circulation of healthy subjects following ingestion of wheat germ and to determine the potential time course and concentration of this lectin in venous plasma. Fourteen normal males and females between 17 and 40 yrs completed preliminary screening and reported to the lab after an overnight fast. Following baseline blood measurements, subjects consumed 50 g wheat germ within a 60 min interval. Blood samples were obtained at 30, 60, 90, 120, 240 min, and at 24 hrs post ingestion. Venous plasma concentrations of WGA were determined via WGA-specific Enzyme-Linked Immunosorbent Assay (ELISA) at the six time intervals, including baseline. According to the protocol utilized, WGA was not detected in venous plasma samples from any of the subjects following consumption of 50 g of wheat germ, thereby indicating that the available WGA in wheat germ either did not breach the gut barrier, or preferentially bound tissues other than plasma proteins. These data represent an important first step in determining the safety of WGA found in common whole-wheat food products. Further research will be required to determine if WGA enters the bloodstream and binds formed elements such as erythrocytes, platelets, and leukocytes in addition to other tissues and organs.
Description
Department Head: Richard Gay Israel.