, reactive oxygen species, faulty anti-oxidation system. Meridium XN
has been proven effective against Oxidative stress and free radicals.
More researchers have come to the conclusion that oxidative stress caused by free radicals (the modern term is "Reactive oxygen species", ROS) may be the main and primary cause of aging. This idea was first suggested by Denham Harman in 1956, and research on the concept was comprehensively reviewed by him more recently (Harman, 1986). Currently this theory is being researched by numerous workers; see for the example the papers by Beckman and Ames (1998), Sohal and Weindruch (1996). Internally produced ROS have been found to damage macromolecules like DNA, proteins, and lipids inside cells. These damaged macromolecules may in some cases be subsequently removed by the action of anti-aging forces, or they may irreversibly accumulate (thus constituting aging forces). Reactive oxygen species (ROS) are molecules that are more reactive than ground-state molecular oxygen. These species include true radicals such as superoxide anion radical (*O-O--*), hydroxyl radical (*OH), hydroxy-oxyl radical (HO-O*), nitric oxide (*N=O), lipid peroxyl radical (L-O-O*), and non-radical molecules such as singlet oxygen (O-O*) and various hydro-peroxides (ROOH, LOOH, H2H2). ROS formation is attributed to many vital cellular processes.
The mitochondrion is the main endogenous source of these free radicals. About 90% of the oxygen consumed in a cell is consumed in the mitochondria, and about 2% of that oxygen is converted to superoxide anion radical (*O-O--*) in the electron-transport system in the mitochondrial inner membrane (Chance et al., 1979). Scientists believe that the mitochondria and the mitochondrial genome are the main targets for damage by ROS (Beckman and Ames, 1998, Miquel 1991, Wallace 1992). Many scientists consider that the gradual weakening of body functions as we get old, known as aging, is a result of the slow but insidious work of these "little enemies". What are these "free radicals", and where do they come from? They are in fact very simple compounds of oxygen, in which the originally harmless molecule has acquired an extra electron. Unfortunately, the formation of free radicals is a natural process, which will continue to occur as long as one breaths oxygen. But the formation of free radicals is accelerated by several factors, such as environmental pollutants, UV light, and nuclear radiation. Free radicals are very reactive particles and they aggressively attack all the surrounding molecules within the cell. The attacked molecules become oxidized, making them structurally damaged and even toxic for the body. Free radicals are rather indiscriminate in what they their attack, so everything that they come in contact with - such as DNA molecules, proteins, or lipids (the scientific name for fats) - becomes oxidized. The initial damage caused by free radicals can lead to further alteration of cellular function. It is known that our cells have the potential to divide quickly and to grow much faster than they do normally. The normal growth and regular development of the human body requires very complex interactions between hundreds of genes within the fragile DNA molecule. Cells in which the "genetic messenger" DNA is damaged by free radicals sooner or later lose the ability to control their own division; and uncontrolled growth leads to the appearance of malignant tumors (cancer).
Other consequences of free radical activities are cardiovascular disorders such as atherosclerosis. In this case lipids (fats) oxidized by free radicals play the major role. The oxidized lipids are toxic for the organism and they induce chronic inflammatory reactions within the walls of the blood vessels. This gradually leads to the blockage of the vessels, which thus constrict the blood-supply; and so their ability to supply blood to the organs is lost. The arteries of the heart are most frequently affected, thus giving rise to heart disease and later to myocardial infarction (heart attack). In the case of the brain, the blockage of blood-vessels leads to a "stroke", often causing permanent brain damage, partial paralysis, etc. Due to the high incidence of atherosclerosis in the population, the oxidation of lipids has attracted much attention from scientists. In the laboratory it is easy to observe that the lipids from blood (normally light yellow) are quickly converted into brown oxidation products. Outside the laboratory a similar process can be easily observed if butter (which consists mostly of saturated lipids) is kept without refrigeration for a long time. The results are even more visible on hot summer days when the temperatures are closer to the 37°C (98°F) of our body.
Talking about foods and oxidation it is interesting to consider vegetable oils, which are highly recommended as a healthy substitute for saturated animal fats like butter. Every housewife knows that unlike butter, vegetable oils stay fresh for months without refrigeration. The same is happening inside our bodies - unsaturated vegetable fats successfully resist the attacks of free radicals and (if they are present in appropriate quantities) provide a powerful protection against atherosclerosis.