Antioxidant Vitamins for Seniors
By: Dr. Obikoya

Seniors are prone to nutritional and vitamin deficiencies because they are at risk for being malnourished. They are at risk for many reasons including poor appetite due to medications, disability, or reduced food intake due to intestinal disorders, diabetes, or restrictive diets. It is estimated that 40% of the U.S. population takes vitamin supplements, and recently much public and scientific interest has been directed toward antioxidants in particular.1

Antioxidant nutrients are believed to play a role in the prevention and treatment of a variety of chronic diseases, ranging from asthma to cardiovascular disease (CVD) and cancer. The proposed mechanism by which antioxidants protect cells from oxidative stress is by scavenging free radicals and halting lipid peroxidation chain reactions, which can cause damage to DNA, our genetic blueprint. 2

In light of new research on the importance of these vitamins to overall heath, the Institute of Medicine (IOM) recently released new dietary guidelines for intake of the antioxidant nutrients vitamin C, vitamin E, carotenoids, and selenium. In addition, a variety of other nutrients are believed to be involved in antioxidant processes.

Two forms of chemical reactions, oxidation and reduction, occur widely in nature. Oxidation is the loss of electrons, and reduction is the gain of electrons. Oxidation and reduction reactions always occur in pairs, i.e., when one atom or molecule is oxidized, another is reduced. Highly reactive molecules can oxidize molecules (i.e., remove electrons from molecules) that were previously stable, and may cause them to become unstable species, such as free radicals.

A free radical is a chemical species with an unpaired electron that can be neutral, positively charged, or negatively charged. Although a few stable free radicals are known, most are very reactive. In free radical chain reactions, the radical product of one reaction becomes the starting material for another, propagating free radical damage. This is essentially the oxidative process.

A certain amount of oxidative function is necessary for proper health. For example, oxidation processes are used by the body's immune systems to kill microorganisms.3 However, the level of toxic reactive oxygen intermediates (ROI) can sometimes overcome the antioxidant defenses of the host, resulting in an excess of free radicals and a state called oxidative stress. These free radicals can induce local injury by reacting with lipids, proteins, and nucleic acids. The interaction of free radicals with cellular lipids leads to membrane damage and the generation of lipid peroxide byproducts. Seniors are particularly prone to this state of affairs because of their often-poor nutritional status. This is why seniors need ample supplies of antioxidants.

The major water-soluble antioxidant metabolites are glutathione (GSH), the B vitamins, and vitamin C. Vitamin E and the carotenoids are the principal lipid-soluble antioxidants. Vitamin E is the major lipid-soluble antioxidant in cell membranes that can break the chain of lipid peroxidation. Therefore, theoretically, it is the most important antioxidant in preventing oxidation of these fatty acids. Vitamin E is recycled by a reaction with vitamin C

Despite the actions of antioxidant nutrients, some oxidative damage will occur, and accumulation of this damage throughout life is believed to be a major contributing factor to aging and disease.3 We can, therefore, minimize this effect of free radicals by starting to take antioxidants daily and regularly.

Free radicals cause oxidative damage to cells and DNA, which can be reduced by antioxidants. Antioxidant nutrients appear to play an important role in protection against various disorders. However, isolation of specific antioxidant nutrients may not confer the same health benefits as do whole foods. For smokers, the use of beta-carotene may be detrimental, particularly if it is administered in isolation.

Observational studies provide fairly consistent data for an inverse association between high intake of antioxidant vitamins and cancer risk. Data are strongest for beta-carotene and vitamin C.

For cardiovascular risk, beta-carotene and vitamin E appear to modify the oxidation of LDL-C, making it less prone to cause thickening of the walls of the blood vessels, and vitamin C appears to reduce hypertension. These effects combine to reduce risk of cardiovascular disease.

Research studies show that it beta -carotene from fruits and vegetables and supplemental vitamin E are beneficial in the prevention of cardiovascular disease, whereas you should avoid synthetic beta-carotene.

The carotenoids, vitamin E, and vitamin C are implicated in the maintenance of ocular function, and vitamins C and E appear to offer some protection against asthma.

In general, seniors should be encouraged to eat a balanced diet but they also need a daily and regular consumption of antioxidants in order to protect them from the ravages of free radicals, which they tend to have in abundance.

References
1. Meyers DG, Maloley PA, Weeks D. Safety of antioxidant vitamins. Arch Intern Med. 1996; 156: 925-35.

2. Sun Y. Free radicals, antioxidant enzymes, and carcinogenesis. Free Radic Biol Med. 1990 ; 8: 583-99.

3. Winkler BS, Boulton ME, Gottsch JD, Sternberg P. Oxidative damage and age-related macular degeneration. Mole Vis. 1999; 5: 32