Using Endogenous And Exogenous Antioxidants Biology Essay


Despite the usefulness of oxidation reactions to life, it could also cause a great harm to humankind. Human beings have body that generates free radicals very continuously and these are always produced from the oxidation reaction that constantly takes place in living cells. Apart from the radicals that results from oxidation, some other ones are generated from immune cells to combat bacteria and viruses and also from ingestion, inhalation, and or absorption from our immediate environment during burning by sun or ultraviolet rays.

Damage caused by free radicals includes aging, destruction of DNA and clogging of arteries. It is also believed that free radicals may play a role in cancer, strokes, and heart disease. Oxidative stress may also damage or kill cells. Free radicals cause damage to skin's structural support and decrease its elasticity, resilience, and suppleness.

Antioxidants stop the chain reactions of free radical, and inhibit other oxidation reactions. An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. There are two types of antioxidants: exogenous and endogenous.

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Exogenous antioxidants are antioxidants we get from our diet and endogenous antioxidants are made by our bodies. Endogenous antioxidants repair free radical damage on the inside by initiating cell regeneration; exogenous antioxidants repair some free radical damage from the outside on in by stimulating cell regeneration.

The role of endogenous and exogenous antioxidants

Exogenous antioxidants are antioxidants we get from our diet by eating antioxidant-rich foods and by taking supplements. Some well known examples of exogenous antioxidants are vitamins A, C and E. Even though exogenous antioxidants can be obtained from food sources, in our modern day world it is nearly impossible to get enough exogenous antioxidants from our diet to neutralize all of the free radicals generated. This is why antioxidant supplementation is so vital.

Endogenous antioxidants are made by our bodies. Because they are produced by our own bodies and not obtained from food sources, endogenous antioxidants are far more potent than exogenous antioxidants. Endogenous antioxidants repair all of the free radical damage by initiating cell regeneration from the inside on out, whereas, exogenous antioxidants only repair some of the free radical damage from the outside on in by stimulating (not initiating) cell regeneration.

An illustration of a regenerating skin cell:

There are five extremely powerful endogenous antioxidants. They are: Glutathione (GSH), Alpha Lipoic Acid (ALA), Superoxide Dismutase (SOD), Catalase and Coenzyme Q10 (CoQ10).

Unfortunately, the body's production of endogenous antioxidants declines as we age. For example, our glutathione levels decline about 10-15% per decade as we grow older. This decrease in endogenous antioxidants is found to be a strong factor in contributing to premature aging and degenerative diseases.

There is more than enough studies to verify that by increasing our endogenous antioxidant cellular levels, such as our glutathione levels, we can greatly help prevent many age-related health issues and degenerative diseases like Diabetes, Alzheimer's, Cancer, Heart Disease, and many other health concerns. (Curr Cardiol Rev.2008 Nov; 4(4):259-68.) (Kaneto et al, 1999)

Sources of Antioxidants

All plants produce antioxidants. Even meat, dairy products, and eggs contain some antioxidants, which mainly come from the nutrient-rich plants the animals fed on. Plants and animals maintain complex systems of multiple types of antioxidants, such as glutathione, vitamin C, and vitamin E as well as enzymes such as catalase, superoxide dismutase and various peroxides.

Antioxidants protection against diabetes

Diabetics have high levels of oxidative stress, which basically means too many free radicals and not enough antioxidants to neutralize them. It would be beneficial for anyone suffering from Diabetes to increase their antioxidant supplementation. Glutathione, being the master antioxidant, would naturally be the best choice.

Furthermore, inflammation leads to and contributes to insulin resistance. Glutathione, on top of being the most potent antioxidant, is also a powerful ant-inflammatory.

"Increasing evidence in both experimental and clinical studies suggests that oxidative stress plays a major role in the pathogenesis of both types of diabetes mellitus. Free radicals are formed disproportionately in diabetes ….Abnormally high levels of free radicals and the simultaneous decline of antioxidant defense mechanisms can lead to ….development of insulin resistance. These consequences of oxidative stress can promote the development of complications of diabetes mellitus." (Wiley 2003) "…there is evidence for increased oxidative stress in diabetes….With regard to diabetes, antioxidants…supplementation have been shown to be beneficial…Thus, it appears that, in diabetes, antioxidant therapy could alleviate the increased attendant oxidative stress and emerge as an additional therapeutic modality." (Vega-Lopez et al, 2004) "Researchers at the University of California, San Diego (UCSD) School of Medicine have discovered that inflammation…leads to insulin resistance and Type 2 diabetes." Science Daily (Nov. 7, 2007)

Antioxidants protection against cancer, coronary heart disease and stroke

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Apples, and especially apple peels, have been found to have a potent antioxidant activity and can greatly inhibit the growth of liver cancer and colon cancer cells (Wolfe et al. 2003) (Eberhardt et al. 2000). The total antioxidant activity of apples with the peel was approximately 83 μmol vitamin C equivalents, which means that the antioxidant activity of 100 g apples (about one serving of apple) is equivalent to about 1500 mg of vitamin C. However, the amount of vitamin C in 100 g of apples is only about 5.7 mg (Eberhardt et al.2000). Vitamin C is a powerful antioxidant, but research shows that nearly all of the antioxidant activity from apples comes from a variety of other compounds. Vitamin C in apples contributed less than 0.4% of total antioxidant activity. (Liu et al. 2001)

Prospective studies suggest that people with high intakes of fruit and vegetables or blood antioxidant concentrations (Pandey et al. 1995) (Enstrom et al. 1992) in the highest quintile of the distribution have low risks of epithelial cancers,( Steinmetz and Potter 1991) coronary heart disease,(Gaziano et al.1995) and stroke. At least 10 prospective studies have shown that high intakes of fruit and vegetables confer protection against cancer, cardiovascular disease, and stroke (Steinmetz and Potter 1991) (Gillman et al.1995)

Abundant evidence proves the role of virgin olive oil in protecting against cardiovascular disease. While it has long been known that olive oil helps decrease total cholesterol and low-density lipoprotein (LDL) levels (Covas et al.2006) new research is shedding light on its additional cardiovascular benefits. According to the Food and Drug Administration, "Eating about 2 tablespoons of olive oil daily may reduce the risk of coronary heart disease. To achieve this possible benefit, olive oil is to replace a similar amount of saturated fat and not increase the total number of calories you eat in a day."(Fito et al. 2005). Scientists have proposed that several constituents of olive oil may be responsible for its anti-cancer effects. These include its anti-oxidant polyphenols as well as the lipid oleic acid, which is highly resistant to peroxidation. (Owen et al. 2004)

However, there are a number of dietary antioxidants that have been identified that would help us to understand how the antioxidants function, and some are still in the process of development and testing. (Uddin and Ahmad 1995) A group of chemists at University of Scranton in Pennsylvania says that adding a mixture of antioxidants to sunscreen may help enhance protection of cancer. In animal studies, they found that a mixture of various topical antioxidants was more effective than single antioxidants in preventing the formation of skin tumors induced by ultraviolet light.

In another study, the same research team found that black tea, green tea, grape seed and cranberry extracts were all promising antioxidants for fighting skin cancer when applied topically. Both studies were presented at the 229th national meeting of the American Chemical Society, the world's largest scientific society, in San Diego on March 14, 2005.


We need to eat a healthy diet with a variety of fruits and vegetables. We cannot depend on any single "super" antioxidants, a variety of antioxidants are needed. Currently only antioxidants from food compounds with vitamins (vitamins A, C and E) have been proven with antioxidant efficacy. Environmental factors that produce free radicals could be avoided.

In numerous epidemiological studies, apples have been associated with a decreased risk of chronic diseases such as cardiovascular disease, cancer, and asthma. In vitro and animal studies have demonstrated that apples have high antioxidant activity, can inhibit cancer cell proliferation, decrease lipid oxidation, and lower cholesterol, potentially explaining their role in reducing risk of chronic disease. The potential health benefits of apples are numerous. Regular consumption of fruits and vegetables, including apples, as part of a healthy diet may aid in the prevention of chronic disease and maintenance of good health.