What are antioxidants?
By definition, antioxidants are substances capable of inhibiting or delaying the oxidation of an oxidizable substrate. The role of antioxidants is to protect healthy cells of the organism against the oxidizing action of free radicals.
free radicals antioxidants relation x
Free radicals (oxidants) are molecules that, by not having an even number of electrons in the last electronic layer, are highly unstable. They are always seeking to achieve stability fighting chemical reactions of electron transfer (redox) with neighboring cells. Although fundamental to the health, when in excess, free radicals begin to oxidize healthy cells, such as proteins, lipids and DNA.
The constant attack leads to lipid peroxidation (destruction of polyunsaturated fatty acids that make up cell membranes). The increase in lipid peroxidation in turn, is associated with development of chronic diseases such as atherosclerosis, obesity, diabetes, hypertension, and the development of degenerative diseases such as Alzheimer's and Parkinson, and some cancer.
The importance of antioxidants is precisely the fact that they are able to regulate the amount of free radicals in the body.
A diet rich in antioxidant intake contributes to the reduction of oxidative stress (imbalance between the levels of free radicals and antioxidants)
antioxidant defense systems
enzyme system (endogenous), formed by a set of enzymes (superoxide dismutase, catalase and glutathione) produced naturally by the body. However, the efficiency of this production system tends to decrease over the years. Therefore, it is important to maintain the quality of the second defense system, non-enzymatic, by eating foods rich in antioxidants.
System non-enzymatic (exogenous): composed of groups of substances such as vitamins, minerals and plant substances that can be ingested through diet.
Antioxidants act in two ways under free radicals: by inhibiting their formation and repairing already caused injuries. The first is related to the inhibition of chain reactions involving their training; and second, the removal of damaged cells, followed reconstitution of cell membranes.
Antioxidants also intercept and prevent free radical attack on these lipids, amino acids, proteins, polyunsaturated fatty acids and DNA bases, protecting the cells lesions. Antioxidants obtained through diet (vitamins, flavonoids and carotenoids, etc.) are crucial in this process.
The human body has two antioxidants self defense systems: the enzyme system (endogenous) and non-enzymatic (exogenous).
Some antioxidants such as vitamin E, are soluble in lipids (fat soluble) and protect cell membranes from lipid peroxidation, helping to remove damage and to replenish the cell membrane.
The endogenous self-defense system, however, tends to be reduced with the natural aging process, as the production of antioxidant enzymes will lose their effectiveness over the years.
The main non-enzymatic antioxidant system are:
• Beta-Carotene and Lycopene: are carotenoids, natural pigments present in fruits and vegetables. They act as antioxidants, for sequester oxygen, reducing the availability of free radicals to carry out oxidative reactions. They are associated with carcinogenesis and prevention of atherogenesis, by being able to protect molecules such as lipids, proteins and DNA undergo oxidation. Moreover, they are precursors of vitamin A in the body.
Where to find: they are found in reddish, orange and yellow foods such as carrots, tomatoes, orange, peach, pumpkin; and dark green vegetables such as broccoli, peas and spinach.
• Curcumin: is a pigment that occurs naturally in the roots of turmeric. Widely used as a seasoning in Indian cuisine, turmeric sequesters free radicals and inhibits the degradation of polyunsaturated fatty acids of cell membranes.
• FLAVANOIDS: the flavonoids are a group of naturally produced by vegetable substances to assist in protection against solar radiation and fight pathogenic organisms. They have the ability to inhibit the activity of enzymes responsible for the production of free radicals, preventing thus their training.
Where to find: they are found in fruits such as grape, strawberry, apple, pomegranate, blueberry (blueberry), raspberry and other red color fruit; in vegetables such as broccoli, spinach, parsley and kale; walnuts, soybeans, flaxseed; and they are found in drinks such as red wine, tea, coffee and beer, and even chocolate and honey.
• Vitamin A (retinol): vitamin A has the ability to combine with some free radicals before they cause damage. Vitamin A also participates in the production process of the skin.
Where to find: in animal foods such as whole milk and beef liver. Those who do not consume animal products should consume vegetables containing high concentrations of beta-carotene and lycopene, as these are precursors of vitamin A in the body.
• Vitamin C (ascorbic acid): water soluble (hydrosoluble) therefore reacts with free radicals available in an aqueous medium, such as exists within the cell. Vitamin C is also able to regenerate vitamin E and keep the enzymes endogenous antioxidant system at low states, particularly saving glutathione.
Where to find: in fruits: melon, cantaloupe, citrus fruits (oranges, lemons, tangerines) kiwi, mango, papaya, pineapple, blueberry (blueberry), strawberry, raspberry and cranberry (cranberry); and vegetables: broccoli, cauliflower Brussels sprouts, cauliflower, red and green peppers, spinach, potatoes, sweet potatoes, squash and tomatoes.
• Vitamin E (tocopherols): Vitamin E is a group of tocopherols, as being the most important antioxidant, alpha-tocopherol. Vitamin E is fat soluble (fat soluble) thus acts protecting cell membranes (composed of lipids) the action of free radicals. It also protects low density lipoproteins (LDL) which act on cholesterol transport.
Where to find: vegetable oils and derivatives, green leaves, oilseed (Brazil nuts, hazelnuts, almonds, walnuts) and seeds, whole grains and leafy vegetables: spinach, watercress, arugula, among others.
• Copper: essential to the proper functioning of the self endogenous defense system as it influences the action of superoxide dismutase.
Where to find: kids, seafood, whole grains and dark green vegetables.
• Selenium: works together with vitamin E, fighting the action of free radicals. also contributes to the normal formation of tireróide.
Where to find: in animal products such as kids and seafood; in plant foods such as whole cererais and Brazil nuts.
• Zinc: the same way as copper, influences the activity of superoxide dismutase.
Where to find: sea food like oysters, lobster, crab. In other animal products such as red meat and poultry, milk and dairy products. And in products of plant origin: beans, nuts and whole grains.
Thus, it is essential to maintain the quality of exogenous antioxidant defense system through the intake of antioxidants.
Since people have different vitamin needs, taking vitamins capsule may not be desirable in all cases (see further herein).
Despite the wide variety of vitamin supplements on the market, it is indicated that supplementation is made only on the basis of a medical recommendation, followed by due professional monitoring
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