Carotenoid study theory

As has already been stated, the carotenoids are lipophilic and are therefore absorbed and transported in association with the lipoprotein particles. In theory, this fortuitous juxtaposition of lipid and carotenoid should confer protection on the lipid through the antioxidant properties of the carotenoid. No doubt some antioxidant protection is afforded by the presence of the carotenoids derived from the diet. However, with one or two exceptions, human supplementation studies have not supported a role for higher dose carotenoid supplements in reducing the susceptibility of the low-density lipoproteins to oxidation, either ex vivo or in vivo (Wright et al, 2002 Hininger et al, 2001 Iwamoto et al, 2000). 

Numerous studies of carotenoid aggregates have focused on the molecular organization of the aggregates (Simonyi et al. 2003), but little is known about aggregation-induced effects on carotenoid excited states. Classical exciton theory can qualitatively explain the aggregation-induced shifts of absorption bands (Section 8.3.1), but a detailed understanding of the parameters governing the... 

DL Dexter (1953) A theory of sensitized luminescence in solids. J Chem Phys 21 836-860 T Gillbro and RJ Cogdell (1989) Carotenoid fluorescence. Chem Phys Lett 158 312-316 T Katoh, U Nagashima and M Mimuro (1991) Fluorescence properties of the allenic carotenoid fucoxanthin Implication for energy transfer in photosynthetic pigment systems. Photosynthesis Res 27 221-226 AP Shreve, JK Trautman, TG Owens and AC Albrecht (1991) A femtosecond study of electronic state dynamics of fucoxanthin and implication for photosynthetic carotenoid-to-chlorophyll energy transfer mechanisms. Chem Phys 154 171-178... 

The ability of lycopene to act as an antioxidant and scavenger of free radicals is frequently cited as the most likely mechanism that could account for the hypothesized beneficial effects on human health.Supporting this theory, protection against oxidative stress has been shown in parallel with a preferential destraction of lycopene relative to P-carotene in a study of human skin irradiated with ultraviolet (UV) light. Further, the ability of carotenoids to act as antioxidants has been hypothesized as the mechanism underlying the protection of the human retina from photooxidation, a process that over time can result in the pathologies of age-related macular degeneration (AMD) and cataracts. ... 

See also Antioxidants Diet and Antioxidant Defense Observational Studies. Ascorbic Acid Physiology, Dietary Sources and Requirements. Carotenoids Chemistry, Sources and Physiology Epidemiology of Health Effects. Coronary Heart Disease Lipid Theory. Selenium. Vitamin E Metabolism and Requirements Physiology and Health Effects. 

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