January 10th, 2018
Role of anti-oxidants in nutrition and health – Why Antioxidants are needed for Health
The role of antioxidants in health has been buttressed by a number of epidemiologic studies that have showcased the part played by food – or lack thereof – in development and progression of chronic diseases. With many antioxidants having been found vegetables and fruits (as reviewed earlier), Bazzano (2006), in a research editorial, presents a case of why these two types of food should form a constant diet in the population for better health outcomes to accrue. Through a review of literature the editorial presents a link between consumption of fruits and prevention of conditions such as coronary heart disease (CHD), Stroke, high blood pressure, obesity and type II diabetes (Bazzano, 2006). Some of these diseases (e.g. CHD) could be promoted by oxidation hence the protective role of fruits and vegetables suggested could be brought about by their high antioxidant contents.
In a different study, Yang (2009) evaluates the composition of Brazilian nuts and the health benefits associated with their intake. Through a review of literature the study evaluates the macronutrients found in nuts noting that various types of lipids – polyunsaturated fatty acids (PUFA) and monosaturated fatty acids (MUFA) – found in the nuts to beneficial health units in such diseases as coronary illnesses (Yang, 2009). Similarly the nuts have a high mineral composition with high Selenium content associated with various enzymatic process such as those in glutathione-mediated inactivation of free radicals; and high phytochemical composition (phenolics, tocopherols, and phytosterols) that have been associated with a reduced risk of atherosclerosis and cancer out of their antioxidant and antiproliferative properties (Yang, 2009).
Yet another study evaluates health benefits of berry flavonoids, a group of antioxidant compounds, with respect to menopausal women (Huntley, 2009). Through a review of literature the paper presents the flavonoids subclasses (flavanols, flavonols and anthocyanins) present in polyphenols found in many fruits and nuts which have beneficial health outcomes (Huntley, 2009). Since menopausal women have increased risk of diseases such as cancer and heart diseases due to reduced hormonal levels, the review evaluated the studies that have researched the effect of flavonoids in such subjects with respect to suggested “cardiovascular benefits, cancer prevention and cognitive improvement” (Huntley, 2009, p.297). After this review the study concluded that such suggested health benefits of antioxidants on menopausal women to hold especially with regard to antioxidants derived from berries.
Various other studies have elucidated the link between consumption of beverages such as tea and cancer prevention and suggested a significant involvement of the antioxidants found in these beverages in such a role (e.g. Weisburger, 1997). Such studies have buttressed the role of antioxidants in preventing diseases such as cardiovascular disorders, cancer and atherosclerosis thus bearing some implications for the role of nutrition in combating illnesses mediated by ROS that have become more common in modern society.
Free Radicals and their Prevention
Free radicals are some of reactive chemical substances that are generated in body processes such as those of the immune system to confer protection against microbes. These species have at least one free-floating electron making them highly unstable and thus highly reactive (Bagchi & Puri, 1998). Though free radicals could arise in many atoms, most of those that occur in the human body are involve oxygen and include superoxide radical (O.2), hydroxyl radical (OH.), lipid peroxyl radical (LOO.) and nitric oxide radical – NO. (Bagchi & Puri, 1998). In the body these radicals can arise either from enzymatic reactions in such processes as the respiratory and cytochrome P450 (cytP450) mediated reactions; or from non-enzymatic oxygen-mediated or ionizing radiations- mediated reactions (Bagchi & Puri, 1998). If left inactivated, free radicals can initiate damaging reactions by bonding with cellular components (e.g. proteins, lipids and nucleic acids) thus bringing adverse health outcomes such as development of cancer (Bagchi & Puri, 1998). Some of the free radical reactions have for instance been linked to immune reactions that play a significant role in the pathogenesis of alcoholic liver disease (Albano, 2002).
To counteract free radical and other reactive species’ effects the body possesses various mechanisms including enzymes (e.g. glutathione peroxidases and catalase) that catalyze reactions reducing the level of the harmful species in the tissues (Bagchi & Puri, 1998). Various nutritional components such as minerals are needed to promote functions of these enzymes thus implying a significant role of nutrition (Yang, 2009; Bagchi & Puri, 1998). Once such primary defense mechanisms are depleted by high levels of ROS then nutrition also bears a role in provision of a secondary defense mechanism – antioxidants. Antioxidants such as phenolic compounds found in many foods could inactivate the reactive compounds by forming complexes thus preventing the ROS’s reaction with cellular components (Bagchi & Puri, 1998; also reviewed earlier). Some of the compounds that have been shown to exhibit antioxidant properties include Vitamin E, Vitamin C, and ß-carotene (Bagchi & Puri, 1998). These compounds occur in many natural foods (e.g. vegetables, fruits and fish) and thus consumption of such foods could present better health outcomes for the population.
Albano, E. (2002). Free radical mechanisms in immune reactions associated with alcoholic liver disease [Serial Review: Alcohol, Oxidative Stress and Cell Injury], Free Radical Biology & Medicine, 32, (2), 110–114. doi:10.1016/S0891-5849(01)00773-0.
Alexandropoulou, I., Komaitis, M. & Kapsokefalou, M. (2006). Effects of iron, ascorbate, meat and casein on the antioxidant capacity of green tea under conditions of in vitro digestion. Food Chemistry, 94(3), 359-365. doi:10.1016/j.foodchem.2004.11.023.
Bagchi, K. & Puri, S. (1998). Free radicals and antioxidants in health and disease. Eastern Mediterranean Health Journal, 4(2), 350-360. Retrieved July 19, 2010 from http://www.emro.who.int/publications/emhj/0402/21.htm
Bazzano, L. A. (2006). The high cost of not consuming fruits and vegetables. Journal of the American Dietetic Association, 106(9). doi: 10.1016/j.jada.2006.06.021.
Blasa, M., Candiracci, M., Accorsi, A., Piacentini, M. P., & Piatti, E. (2007). Honey flavonoids as protection agents against oxidative damage to human red blood cells. Food Chemistry 104(4), 1635–1640. doi:10.1016/j.foodchem.2007.03.014.
Erba, D., Riso, P., Foti, P. Frigerio, F., Criscuoli, & Testolin, G. (2003). Black tea extracts supplementation decreases oxidative damage in Jurkat T cells. Archives of Biochemistry and Biophysics, 416(2), 196-201. doi:10.1016/S0003-9861(03)00315-1
Huntley, A. I. (2009). The health benefits of berry flavonoids for menopausal women: Cardiovascular disease, cancer and cognition. Maturitas, 63(4), 297-301. doi:10.1016/j.maturitas.2009.05.005
Ismail, A., Marjan, Z. M. & Foong, C. W. (2004). Total antioxidant activity and phenolic content in selected vegetables. Food Chemistry, 87(4), 581-586. doi:10.1016/j.foodchem.2004.01.010
Kapsokefalou, M., Zhu, L. & Miller, D. D. (2006). Adding iron to green tea may decrease its antioxidant capacity in rats after an oral dose of the mixture. Nutrition Research, 26(9), 480-485. doi:10.1016/j.nutres.2006.07.004.
Lako, J., Trenerry, V. C., Wahlqvist, M., Wattanapenpaiboon, N., Sotheeswaran, S. & Premier, R. (2007). Phytochemical flavonols, carotenoids and the antioxidant properties of a wide selection of Fijian fruit, vegetables and other readily available foods. Food Chemistry 101(4), 1727–1741. doi:10.1016/j.foodchem.2006.01.031.
Møller, P. & Loft, S. (2006). Dietary antioxidants and beneficial effect on oxidatively damaged DNA, Free Radical Biology & Medicine, 41(3), 388-415. doi:10.1016/j.freeradbiomed.2006.04.001.
Palozza, P., Luberto, C., Bartoli, M. G. (1995). The effect of fatty acid unsaturation on the antioxidant activity of ß-carotene and α-tocopherol in hexane solutions. Free Radical Biology & Medicine,18(5), 943-948, doi:10.1016/0891-5849(94)00223-7.
Rietjens, I. M. C. M., Boersma, M. G., de Haan, L., Spenkelink, B., Awad, M. H., Cnubben, N. H. P., van Zanden, J. J., … Koeman, J. H. (2002). The pro-oxidant chemistry of the natural antioxidants vitamin C, vitamin E, carotenoids and flavonoids. Environmental Toxicology and Pharmacology, 11(3/4), 321-333. doi:10.1016/S1382-6689(02)00003-0.
Riso, P., Erba, D. Criscuoli, F. & Testolin, G. (2002). Effect of Green tea extracts on DNA repair and oxidative damage due to H2O2 in Jurkat T cells. Nutritional Research, 22(10), 1143-1150. doi:10.1016/S0271-5317(02)00424-4.
Tijburg, L. B. M., Wiseman, S. A., Meijer, G. W. & Weststrate, J. A. (1997). Effects of green tea, black tea and dietary lipophilic antioxidants on LDL oxidizability and atherosclerosis in hypercholesterolaemic rabbits. Atherosclerosis, 135(1), 37-47. doi:10.1016/S0021-9150(97)00139-1.
Weisburger, J. H. (1997). Tea and health: A historical perspective. Cancer Letters, 114(1/2), 315-317. doi:10.1016/S0304-3835(97)04691-0.
Yang, J. (2009). Brazilian nuts and associated health benefits: a review. LWT-Food Science and Technology, 42(10), 1573-1580. doi:10.1016/j.lwt.2009.05.019.
Yoshihara, D., Fujiwara, N. & Suzuki, K. (2010). Antioxidants: Benefits and risks for long-term health, Maturitas [Article in Press]. doi:10.1016/j.maturitas.2010.05.001.