Defining Free Radicals Antioxidants and Related Terms

The terms reactive oxygen species (ROS) and reactive nitrogen species (RNS) describe both radicals and nonradical reactive oxygen and nitrogen-containing molecules. These molecules can enter reactions that can result in production of free radicals or directly damage organic biochemical substrates. The nomenclature used within the field of free radical biology has not been established by any one organization. However, there is a consensus within the field from several sources, including the...

Recommendations

Study results from the 1986 NHIS found that 26 percent of American adults took a vitamin A supplement. NHANESIII, 1994-1996 data found the highest mean intake amount of preformed vitamin A for any gender and life stage group was between 895 and 1,503 (g d, and, of those who took vitamin A supplements, approximately 1,500 to 3,000 (g d was the maximum ingested. Therefore, the Food and Nutrition Board of the IOM of the National Academies concluded that the risk for exceeding the UL for vitamin A...

Polyphenols

Polyphenols are compounds found in plants that exhibit antioxidant activity and are theorized to reduce risk of cancers by blocking the action of enzymes and deactivating substances associated with cancer growth, reduce cardiovascular disease risk, and bind nonheme iron from plant sources thus decreasing absorption by the body. They include tannins, lignins, anthocyanins, catechins, epicatechin, stilbenes gallic acid, and flavonoids. In recent years, polyphenols have received almost daily media...

Carotenoids and Human Studies

The concept that carotenoids, by their capacity to trap peroxyl radicals and quench singlet oxygen are cardioprotective, appears to be borne out in observational epidemiological studies of the effects of carotenoid-rich foods on CVD.131 Supporting this concept is a study that 3,254 people followed from 1989 to 1995, which showed that higher serum levels of carotenoids with pro-vitamin A activity significantly reduces the risk of mortality from cardiovascular disease and colorectal cancer.132...

Making Sense of It

As research studies till date show, consistent evidence supporting antioxidant benefits in human trials has been disappointing. In vitro and animal studies suggest antioxidant supplementation provides benefits, however, some recent research demonstrates that in some cases antioxidant supplementation may actually do more harm than good. Individual antioxidants in the form of dietary supplements are more potent and bioavailable than they are in food matrices, and they do not exhibit the...

Vitamin A and Carotenoids

Carotenoids are the red, orange, and yellow pigments found in fruits and vegetables that give them their colorful appearance. There are more than 600 different forms of carotenoids and they are actually vitamin precursors, also known as provitamins. Vitamin A and carotenoids are closely connected. Many theories exist about the functions of carotenoids, but their only known function is conversion into vitamin A when vitamin A stores are low. Forms of vitamin A included retinol, retinal, retinoic...

Antioxidants and the Redox Biology of Life

According to a November 30, 2006 Wall Street Journal1 article, resveratrol supplements are the current hot supplements in America. They have become so popular with Americans that retailers are unable to keep up with consumer demand. A plant phytochemical, flavonoid and stilbene, and antioxidant molecule, media portrayal of resveratrol as a possible antiaging elixir that is life-prolonging has greatly boosted sales of this dietary supplement. The buzz about resveratrol commenced when...