antioxidant

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antioxidant

[an″te-ok´sĭ-dant]

a substance that in small amounts will inhibit the oxidation of other compounds.

an·ti·ox·i·dant

(an'tē-oks'ĭ-dănt),

An agent that inhibits oxidation; any of numerous chemical substances including certain natural body products and nutrients that can neutralize the oxidant effect of free radicals and other substances.

Free radicals, formed in the course of normal cellular respiration and metabolism, and more abundantly under the influence of certain environmental chemicals and sunlight, have been inculpated in various types of tissue damage, particularly those involved in atherosclerosis, the aging process, and the development of cancers. A free radical is any atom or molecule that has 1 or more unpaired electrons and is therefore highly reactive, seeking to acquire electrons from other substances. Free radicals are normally scavenged from tissues by the antioxidant enzymes superoxide dismutase and glutathione peroxidase. Ubidecarenone (coenzyme Q10) is also thought to act as an antioxidant in mitochondrial respiration reactions. In addition, a number of nutrient substances, vitamins, and minerals have been shown to contribute to antioxidant functions, generally by serving as cofactors or coenzymes. These include selenium beta-carotene, and vitamins C and E. It has been postulated that an imbalance between the production of free radicals and natural antioxidant processes may be a major causative factor in aging and in many chronic and degenerative disorders, and some researchers have speculated that antioxidant nutrients may have a role in disease prevention. Oxidation of low-density lipoprotein cholesterol does indeed seem to be responsible for foam cell formation in the genesis of atherosclerotic plaques. In addition, free radicals have been shown to damage DNA in ways that can culminate in malignant change. Oxidations also occur in many beneficial processes, however, including chemotaxis of cells with immunologic functions, phagocytosis, clotting mechanisms, and apoptosis. Moreover, antioxidants do not exert their effects in only one way, but can act during initiation or propagation of reactions at a variety of intracellular sites, and in some circumstances can be prooxidant. Claims that vitamins and other nutrients, when taken in massive doses, can prevent heart attack or cancer or retard aging are not based on scientific evidence. Although a high intake of antioxidants from food sources appears to offer some health advantages, there is at present no unequivocal evidence that any antioxidant nutrient, when taken in excess of normal dietary amounts, has value in the prevention or treatment of cardiovascular disease, cancer, or any other abnormal process except such as may be associated with frank nutritional or vitamin deficiency. A controlled, double-blind, randomized study of antioxidant supplementation in more than 20,000 people at risk of coronary artery disease found no effect whatsoever on all-cause mortality, cardiovascular mortality, nonfatal myocardial infarction, stroke, or cancer incidence. A controlled trial of beta-carotene and retinol not only failed to show any benefit but was aborted when statistics showed large increases in the risk of death from lung cancer and cardiovascular disease.

Farlex Partner Medical Dictionary © Farlex 2012

antioxidant

(ăn′tē-ŏk′sĭ-dənt, ăn′tī-)

A substance that inhibits oxidation, especially one, such as vitamin E, vitamin C, or beta carotene, that protects cells from the sometimes damaging effects of oxidation.

antioxidant

Any agent—e.g., vitamin A, vitamin C, selenium—which is capable of reducing highly histotoxic oxygen-reduction products and reactive oxygen species (e.g., hydroxyl radical), which derive from superoxide anion (O2-) and H2O2, the univalent and bivalent reduction products of oxygen, and are generated during the normal intermediary metabolism of the respiratory chain. Other antixodants include glutathione, alpha-tocopherol (vitamin E) and bilirubin.

antioxidant

Nutrition Any agent–eg, vitamins A, C, and E, selenium, and others, that is capable of reducing highly histotoxic O₂ reduction products and reactive O₂ species—eg hydroxyl radical, which derive from superoxide anion–O₂·– and H₂O₂, the univalent and bivalent reduction products of O₂, generated during the normal intermediate metabolism of the respiratory chain; other antixodants include glutathione, α-tocopherol–vitamin E, bilirubin. See Catalase, Ceruloplasmin, Free radical, Glutathione, Peroxidase, Superoxide dismutase, Transferrin.

an·ti·ox·i·dant

(antē-oksi-dănt)

Any substance that may prevent organ damage by scavenging free radicals, including catalase, glutathione, peroxidase, superoxide dismutase, and vitamins A, C, and E.
See also: free radical

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

Antioxidant

Any substance that reduces the damage caused by oxidation, such as the harm caused by free radicals.

Mentioned in: Smoking

oxidative stress

A term used to describe the effect of oxidation in which an abnormal level of reactive oxygen species (ROS), such as the free radicals (e.g. hydroxyl, nitric acid, superoxide) or the non-radicals (e.g. hydrogen peroxide, lipid peroxide) lead to damage (called oxidative damage) to specific molecules with consequential injury to cells or tissue. Increased production of ROS occurs as a result of fungal or viral infection, inflammation, ageing, UV radiation, pollution, excessive alcohol consumption, cigarette smoking, etc. Removal or neutralization of ROS is achieved with antioxidants, endogenous (e.g. catalase, glutathione, superoxide dismutase) or exogenous (e.g. vitamins A, C, E, bioflavonoids, carotenoids). Oxidative damage to the eye, particularly the retina and the lens, is a contributing factor to age-related macular degeneration and cataract.

an·ti·ox·i·dant

(antē-oksi-dănt)

An agent that inhibits oxidation; one of many chemical substances including some natural body products that can neutralize the oxidant effect of free radicals and other substances.

Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about antioxidant

Q. What are “antioxidants”? and what do they do? I’ve been hearing about antioxidants for quite some time now, they are supposedly help to keep us younger. What do they do and is it true?

A. When every biological system works- it creates oxidants. These are materials that are very active and they “look for” something to react with. So when you eat (an example) there are a lot of oxidants created. they move around in the colon and they usually react with colon cells, thus destroying them. This also happens while breathing, cell metabolism and a lot of biological processes. Antioxidants counteract these free oxidants and stop their harmful reaction.

More discussions about antioxidant

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References in periodicals archive ?

Antioxidants may also help slow aging, give glowing skin, cut cancer, heart disease and stroke risk, and fight dementia.

Top Antioxidant-Rich Foods You Should Be Eating

There is also greater understanding about the relationship between health and the gut, relating to inflammation and free radical imbalances, and how certain antioxidant substances can modulate a healthy balance of these complicated systems and networks within the body, Bush added.

Antioxidants & Aging: Putting Theory to Practice: Natural products have a long history of traditional use matched by modern support from scientific research on safety and efficacy

For example, one study assessed three different measures of antioxidant capacity in tea.

Why drinking tea without sugar is healthier -Experts

Common antioxidants include Vitamins A, C, and E, and members of the carotenoids family, including betacarotene, lycopene, and lutein.

Antioxidants in foods

Vitamins C and E, and the trace metal selenium are micronutrients that act as key antioxidants in the body.

Antioxidants: Antidote to Disease: Maximize your dietary intake of antioxidants to keep your cells--and yourself--healthy

* Strawberries: This berry is rich in the antioxidant fisetin, a compound that has been found to have anti-cancer and neuroprotective properties.

Boost Brain Health by Strengthening Your Body's Natural Antioxidant System: Empowering your body's production of antioxidants is essential to fighting cell-damaging free radicals and oxidative stress

Their antioxidant activity is due to their redox properties functioning through single oxygen quenching, free radical scavenging and metal ion chelating etc., [9].

In Vitro Antioxidant and Inhibitory Effects of Myristica fragrans, Illicuim verum, Curculigo orchioeides, Glycyrrhiza glabra and Embelia ribes against Lipid Peroxidation in Mice Liver

Synthetic antioxidants, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), are commonly used because of their effectiveness and low cost.

Enrich antioxidant activity of pear juice with oregano, wild thyme extracts

Calculation of Total Antioxidant Capacity of Serum.

Determination of the total mass of antioxidant substances and antioxidant capacity per unit mass in serum using redox titration

Washington, February 21 ( ANI ): Contrary to previous research, a new study has revealed that the total level of antioxidants in people's diets may not help reduce their risk of developing stroke or dementia.

Antioxidants in your diet may not help protect against stroke and dementia

According to Begoun, “When it comes to using skin-care products loaded with antioxidants, you simply can't get enough of these ingredients.” Antioxidants help prevent environmental damage, build collagen, help skin heal, and produce healthier skin cells.

Five Ways to Give Your Skin More Antioxidants from Beauty Expert Paula Begoun and the Paula's Choice Research Team