Antioxidants, dietary

HERTOG M G L, FESRENS E J M, HOLLMAN PCX, KATAN M B and KROMHOUT D (1993) Dietary antioxidant flavonoids and risk of coronary heart disease the Zutphen elderly study The Lancet 342, 1007-11. 

The antioxidant activities of carotenoids and other phytochemicals in the human body can be measured, or at least estimated, by a variety of techniques, in vitro, in vivo or ex vivo (Krinsky, 2001). Many studies describe the use of ex vivo methods to measure the oxidisability of low-density lipoprotein (LDL) particles after dietary intervention with carotene-rich foods. However, the difficulty with this approach is that complex plant foods usually also contain other carotenoids, ascorbate, flavonoids, and other compounds that have antioxidant activity, and it is difficult to attribute the results to any particular class of compounds. One study, in which subjects were given additional fruits and vegetables, demonstrated an increase in the resistance of LDL to oxidation (Hininger et al., 1997), but two other showed no effect (Chopra et al, 1996 van het Hof et al., 1999). These differing outcomes may have been due to systematic differences in the experimental protocols or in the populations studied (Krinsky, 2001), but the results do indicate the complexity of the problem, and the hazards of generalising too readily about the putative benefits of dietary antioxidants. 

EUROFEDA - European Research on the Functional Effects of Dietary Antioxidants. (2002) MolecAsp Med 23 1-291. 

Klipstein-Grobusch, K. et al.. Dietary antioxidants and risk of myocardial infarction in the elderly the Rotterdam Study, Am. J. Clin. Nutr, 69, 261, 1999. 

Despite their potential health-promoting effects as dietary antioxidants, the fate of betalains in humans has been poorly studied. Betalain bioavailability was first demonstrated in humans by the appearance of betacyanins in urines after ingestion of beetroot extract" and red beet juice," indicating that these compounds are indeed absorbed. Although intact betacyanins (betanin and isobetaiun) appeared rapidly in human urine with a maximum excretion rate observed within 2.5 to 8 hr," betacy-anin recoveries in human urine were usually low (< 1% of the dose) over 24 hr postdose, suggesting that either the bioavailabifity of betacyaiuns from red beetroot is low or that renal clearance is a minor excretion route for these compounds. 

Vulcain, E. et al.. Inhibition of the metmyoglobin-induced peroxidation of hnoleic acid by dietary antioxidants action in the aqueous versus lipid phase. Free Rad. Res., 39, 547, 2005. 

In addition, there is now epidemiological evidence that dietary antioxidants, such as vitamins A, C, D and E, phytic acid, and protease inhibitors can prevent carcinogenesis, including that of the gastrointestinal (GI) tract (Graf and Eaton, 1990 Block, 1991 Malone, 1991 Troll, 1991 Weisburger, 1991). 

Flood, V., W. Smith et al. (2002). Dietary antioxidant intake and incidence of early age-related maculopathy The blue mountains eye study. Ophthalmology 109(12) 2272-2278. 

Chong, EW, Wong, TY, Kreis, AJ, Simpson, JA, and Guymer, RH, 2007. Dietary antioxidants and primary prevention of age related macular degeneration Systematic review and meta-analysis. BMJ 335, 755. 

Reboul, E, Thap, S, Perrot, E, Amiot, MJ, Lairon, D, and Borel, P, 2007a. Effect of the main dietary antioxidants (carotenoids, gamma-tocopherol, polyphenols, and vitamin C) on alpha-tocopherol absorption. Eur J Clin Nutr 61, 1167-1173. 

Tan, JS, Wang, JJ, Flood, V, Rochtchina, E, Smith, W, and Mitchell, P, 2008. Dietary antioxidants and the long-term incidence of age-related macular degeneration The Blue Mountains Eye Study. Ophthalmology 115, 334-341. 

Reboul, E. et al. (2007b). Differential effect of dietary antioxidant classes (carotenoids, polyphenols, vitamins C and E) on lutein absorption. Br. J. Nutr. 97(3) 440-446. 

Tesoriere L, Allegra M, Butera D and Livrea M A (2004), Absorption, excretion, and distribution of dietary antioxidant betalains in LDLs potential health effects of betalains in humans , Am J Clin Nutr, 80, 941-945. 

Engelhart M, Geerlings M, Ruitemberg D, van Swieten J, Hoffman A, Wittman J and Breteler M. 2002. Dietary antioxidants and risk of Alzheimer s disease. JAMA 287 3223-3229. 

Patel B, Welch A, Bingham S, Luben R, Day N, Khaw K, Lomas D and Wareham N. 2006. Dietary antioxidants and asthma in adults. Thorax 61 388—393. 

Hollman PC, van Trijp JM, Mengelers MJ, de Vries JH and Katan M B. 1997. Bioavailability of the dietary antioxidant flavonol quercetin in man. Cancer Lett 114(1—2) 139—140. 

Regarding antioxidants, the parameter total dietary antioxidant capacity (TDAC) can be taken to reflect antioxidant intake it is defined as the antioxidant capacity of all plant foods and beverages (alcoholic and nonalcoholic) consumed daily in a diet and may represent the amount of antioxidant units (Trolox equivalents) present daily in the human gut (Saura-Calixto and Goni 2006). 

The foregoing method has been adapted by Davalos and others (2004) using a conventional fluorescence microplate reader and applied to pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole) and to wines, as well as to commercial dietary antioxidant supplements. Eberhardt and others (2005) have also proposed a similar method for the determination of the antioxidant activity in broccoli. 

Beziepkin V.G., Sirota N.P. and Gaziev A.L. The prolongation of survival in mice by dietary antioxidants depends on their age by the start of feeding this dietIIMech. Ageing Dev.-1996.-vol 92.-P.227-234. 

The study of oxidative damage has sparked a debate about the role that antioxidants might play in illness and aging. Antioxidants are reducing agents. They donate electrons to substances that have been oxidized, decreasing the damage caused by free radicals. Dietary antioxidants include vitamins C and E, beta-carotene, and carotenoids. 

Taylor SL, Tappel AL. 1976. Effect of dietary antioxidants and phenobarbital pretreatment on microsomal lipid peroxidation and activation by carbon tetrachloride. J Life Sci 19 1151-1160. 

This brief introduction demonstrates that the relationships between diet and health are far from simple and most certainly far from fully understood, but for a critical and detailed review of epidemiological data the reader is referred to an excellent paper by Arts and Hollman. The objective of the review that follows is to record recent changes in the perceived role of flavonoids as health-promoting dietary antioxidants and place these... 

Terao, J., Murota, K., and Moon, J.-H., Quercetin glucosides as dietary antioxidants in blood plasma modulation of their function by metabolic conbversion, in Free Radicals in Chemistry, Biology and Medicine, Yoshikawa, T., Toyokuni, Y., Yamamoto, Y., and Naito, Y., Eds., OIAC International, London, 2000, p. 50. 

Lamuela-Raventos, R.M., Covas, M.I., Fito, M., Marrugat, J., and de la Torre-Boronat, M.C., Detection of dietary antioxidant phenolic compounds in human LDL, Clin. Chem., 45, 1870, 1999. 

Ambrosone CB, Coles BF, Freudenheim JL, Shields PG (1999) Glutathione-s-transferase (gstml) genetic polymorphisms do not affect human breast cancer risk, regardless of dietary antioxidants. J Nutr 129 565-568... 

Popular EPR-based assays of antioxidant activity include the DPPH assay, in which the ability of compounds to quench (by H-atom transfer) the 1,1-diphenyl-2-picrylhydrazyl radical is used to rank their antioxidant activity. This method has been applied widely to the analysis of dietary antioxidants and extracts from medicinal plants.213 219 Extensive use has also been made of assays based on the competition between spin traps and test compounds for reaction with enzymatically-generated 02 and, in the presence of a metal catalyst, the OH rad-... 

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