Almost everyone knows eating more fruits and vegetables is beneficial. These foods contain numerous vitamins, minerals, dietary fiber, and plant chemicals that confer health. Does this mean that others - infants and very young children, the very ill, or those who do not like these foodstuffs - face increased health risks?
Facts
- The human body is protected by endogenous (self-produced) and dietary antioxidants, either natural or synthetic, and a built-in immune system
- Health risks are influenced by genetic inheritance and lifestyle factors such as smoking, sedentary living, air pollution, occupational hazards, and pre-existing medical condition(s), and
- Health risks increases with advancing age,
Natural Antioxidants in Meat
Meat contains inherent substances that protect it from degradation. Vitamin E, carnosine, glutathione, selenium, and conjugated linoleic acid are among its most notable antioxidants.
Vitamin E in meat delays oxidation of polyunsaturated fatty acids in tissue membranes and the conversion of myoglobin (red pigment) in muscle to methmyoglobin (brown pigment). It prevents the propagation of the radical chain by preventing the formation of new radicals.
Carnosine - a dipeptide made of the amino acids alanine and histidine prevents rancidity caused by iron, hemoglobin, lipooxidase (an fat enzyme), and singlet oxygen. It can also "bind" metals, scavenge free radicals, and donate hydrogen electrons.
Being water-soluble, carnosine inactivates fat oxidation catalysts and free radicals in muscle "watery" regions.Its inhibit oxidation in the absence or shortage of vitamin E. It predominates in white skeletal muscles.
Glutathione, a tripeptide (made of glutamate, cysteine, and glycine) is found mammalian cells and is a cofactor of glutathione peroxidase (GPx) an enzyme. It protects water-soluble proteins, detoxifies drugs, pollutants, poisons and oxidants such as hydrogen peroxide, and dehydroascorbic acid.
Selenium - a mineral antioxidant is a component of glutathione peroxidase. It prevents the oxidation of polyunsaturated fatty acids in tissues, prevents hardening of tissues by preserving its elasticity, delays aging, and inhibits cell proliferation thereby preventing some types of cancers.
Egg Antioxidants
Vitamin A, betacarotene (prevents night blindness), lutein and zeaxanthin (prevents macular degeneration), and phosvitin ( inhibits iron and copper catalyzed fat oxidation) abounds in egg yolks.
Betacryptoxanthin, also found in egg yolks, protects cells from UV light, and aids in DNA repair by rejoining broken strands and removing oxidized purines by excision repairs.
Eggwhite antioxidants include the essential amino acids: glutamic acid, methionine, alanine, asparagine,valine, aspartic acid,serine, lysine,trptophan, and histidine. They protect egg proteins from oxidation.
Milk and Dairy Antioxidants
Vitamin A, lutein, zeaxanthin, lycopene, alpha and beta carotene naturally exists in whole bovine milk. Vitamin A and its carotenoids comes from fresh forage consumed by dairy cows. They pass into their milk.
Whole milk is also rich in conjugated linoleic acid (CLA), alpha, beta, and gamma tocopherols,and the antioxidant saturated fatty acids - lauric and myristic fatty acids. In the human body, lauric acid is converted into monolaurin - a powerful antioxidant, antibacterial, antiviral, antifungal and antiprotozoal compound. Lauric acid is one of the predominant saturated fatty acids found in human milk.
References
Collins et al. "Beta cryptoxanthin stimulates the repair of DNA oxidation damage in addition to acting as an antioxidant in human cells." Carcinogenesis 2009;30(2):308-314
Butler et al. "Fatty acid and fat-soluble antioxidant concentration in milk from high and low input converted and organic systems:seasonal variation" J Sci Food & Agric. 2008;88:1431-1441
Chan KM et al. "Effects of dietary carnosine on plasma and tissue, antioxidant concentrations in lipid oxidation in rat muscle" Lipids 1994; 29:461-466
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