Session II: What Is Typical Lycopene Exposure and Metabolomic Response? Moderator: Dr. Beverly Clevidence, ARS, USDA How Can the Metabolomic Response to Lycopene (Exposures, Durations, Intracellular Concentrations) in Humans Be Adequately Evaluated? Dr. Steven Schwartz, Ohio State University Physical and thermal treatment of foods causes degradation of plant cell structural constituents. Thermal processing brings about disruption of the carotenoid protein complexes, and the inactivation of oxidizing enzymes results in less degradation and greater stability of carotenoids. These changes result in enhanced uptake and efficiency of lycopene absorption. For example, lycopene is more bioavailable from processed tomato paste than from fresh tomatoes. Dr. Schwartz’s preliminary data suggest that: 1) the physical state of lycopene in the plant tissue (crystalline, amorphous, or soluble within the lipid phase) affects uptake from the matrix, which influences blood and tissue levels; 2) the concentrations of lycopene in blood and tissues can be altered by the consumption of commercial tomato products within relatively short intervention periods; 3) food processing, through physical and thermal treatments, has the potential to enhance absorption by disrupting the plant tissue matrix, disassociating carotenoid-protein complexes, enhancing surface area, and increasing solubility; 4) structural considerations influencing solubility, molecular size, and geometrical isomerization to cis lycopene isomers can enhance bioavailability; and 5) lycopene is absorbed poorly relative to other carotenoids in the diet; however, co-consumed lipid is critical and can enhance absorption from the tomato matrix. Discussion One participant asked if lutein levels have been measured in the tangerine variety of tomato and if the isomers are a result of lycopene oxidation. Dr. Schwartz replied that the levels of xanthophylls such as lutein and zeaxanthin have not been measured in the tangerine variety, but the lutein level in most tomatoes is low. The same low lutein level is expected in the tangerine variety; however, significant levels of 9-cis- â-carotene have been observed. Because the isomerase is missing, there must be some retention of the isomeric forms (from lycopene through the cyclization reactions to â-carotene) further down the biosynthetic pathway. Dr. Schwartz added that it is not known whether the isomers are a result of oxidation. Lycopene and other carotenoids might isomerize with oxidative stress, but the evidence is not definitive at this point. Another participant asked about the sources of tomato that were used in the studies conducted by Dr. Schwartz. Dr. Schwartz replied that the sources included a tomato salsa (with no fat but avocado) and a commercial tomato sauce (formulated with some lipid). He indicated the co-consumed lipid in the tomato sauce most likely accounts for the rise in plasma levels compared to the groups consuming V8 juice or tomato soup. Dr. Schwartz noted that homogenization appears to affect â-carotene absorption more than lycopene absorption, but the reverse was true for fat (i.e., fat had more of an effect on lycopene absorption than on â-carotene absorption). One participant asked about the consistency of these findings across studies. Dr. Schwartz responded that â-carotene already is associated with lipid inside the plastoglobulin membrane of the tomato tissue, whereas lycopene is not. Thus, fat influences lycopene absorption more than â-carotene absorption by providing the lipid necessary for enhanced lycopene solubility and uptake. â-carotene in the tomato matrix already is somewhat soluble; therefore, fat may not have as significant an effect. These results should be consistent with other studies. 2/05 NIH Meeting February 2005 NIH February 2005 NIH February 2005 NIH February 2005 NIH Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.