Antioxidants are compounds capable of slowing or preventing the oxidation of other molecules. They are also known as free radical scavengers of the body for their ability to terminate chain oxidation reactions in two ways – by removing radical intermediates and by getting oxidised themselves.
All about antioxidants
Although oxidation reactions are critical for life, they also result in cell damage which, research shows manifests in ageing. Other reasearch is on investigating the role of Antioxidants in the treatment of many diseases like cancer, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Animals maintain complex systems of multiple types of antioxidants, such as Vitamin A, Beta Carotene and Vitamin E.
How Do They Work?
Antioxidants prevent cellular damage, which leads to ageing. Cellular damage could also lead to cancer and a variety of diseases. Antioxidants fight cell-killing Free Radicals, which are atoms or groups of atoms with an odd (unpaired) number of electrons and can be formed when oxygen interacts with certain molecules.
These chemically active particles are by-products of many of the body’s normal chemical processes, but can increase due to environmental assaults, such as smoking, chemicals, toxins, and stress. In higher levels, oxidants can be very harmful in the following ways:
- They can damage cell membranes and cause changes in the DNA, which could possibly cause many diseases including cancer and heart disease and result in the developent of cataracts. This also hastens the ageing process.
- Free radicals can also enhance the negative effects of low-density lipoprotein (LDL) and cholesterol, a major player in the development of atherosclerosis.
Types of Antioxidants
Although there are several enzyme systems within the body that scavenge Free Radicals, the principle micronutrient (vitamin) antioxidants are Vitamin E, Beta Carotene, and Vitamin C. Different Antioxidants work in different ways.
- Beta Carotene plays a major role in protein synthesis when it is converted to fat-soluble Vitamin A. It helps in maintaining healthy skin.
- Vitamin C prevents skin damage and helps build collagen, the fibrous protein that gives skin elasticity.
- Vitamin E protects the body tissues from damage by harmful free radicals.
- Apart from Vitamins, Selenium, a trace metal is also required for proper functioning of the body's antioxidant enzyme systems.
Antioxidants in Food
Good sources of Vitamin C or Ascorbic Acid are fruit and vegetables like green bell pepper, orange, strawberry and papaya. For Vitamin E (Tocopherols and tocotrienols), vegetable oils, seeds and nuts are some good sources. Polyphenolic Antioxidants (Resveratrol and Flavenoids) are best sourced from green tea, chocolate, coffee, soy, oregano and Yerba Mate, to name a few). Fruits and vegetables like Carrots are the best sources of Carotenoids (Lycopene and Carotene). Brazil nuts are the best source of selenium.
Antioxidants and health
Positive Research Findings on Antioxidants
Although research opinion is mixed about the exact health benefits of antioxidants, these compounds have been found to be beneficial in three ways – in protecting the heart, preventing or mitigating effects of strokes and in protecting the body against cancer.
- Heart Protection -- Studies have reported that diets rich in fruits and vegetables containing Vitamins like beta carotene, lycopene, and other carotenoids may reduce the risk of heart attack. For example, lycopene-poor diets (particularly lycopene in tomatoes) were associated with a significantly higher risk of heart disease and stroke.
- Evidence suggests that certain Phytochemicals (chemicals found in plants) are also good for the heart. For example Organosulfurs found in onions and garlic possibly reduce cholesterol levels. Isoflavones from soy protein may also be beneficial for the heart. Some research has shown that there has been an improvement in at least one of the cholesterol components in people who consumed at least 25 grams of soy protein. Soy may also reduce other heart risk factors, as shown by one 2002 study, in which soy was found to have reduced blood sugar and LDL in postmenopausal women with type 2 diabetes. In another study, soy protein was associated with lower systolic blood pressure in men. The best sources of soy are soy products (tofu, soy milk) or whole soy protein. Also, Flavonoids found in both black and green tea, dark chocolate, onions, red wine or red grape juice, and apples, appear to have qalities that protect the heart. In a 2003 study it was found that people who consumed the most flavonoids in foods had a 20% lower risk of getting heart disease compared to those who did not consume so many flavenoids.
- Protection Against Stroke -- An Antioxidant rich diet, which is a diet rich in fruits and vegetables may significantly lower the risk of a first stroke. Vitamin B or folic acid may also protect against stroke. Reserach findings suggest that higher levels of Folate in the body reduce the risk of stroke. Reasearchers surmise that this could be because Folate appears to reduce levels of homocysteine, an amino acid strongly linked to an increased risk of coronary artery disease, stroke, and Alzheimer's disease. Other studies report that people with diets rich in carotenoids, including beta carotene and lycopene, have lowered risk of stroke.
- Protection against cancer -- Many fresh fruits and vegetables contain cancer-fighting chemicals. Examples include cruciferous vegetables (like Cabbage, Brussels sprouts, Broccoli), tomatoes (which contain lycopene) and carrots (which contain alpha carotene. Further, the efficacy of chemotherapy is sometimes enhanced by antioxidants. A 2000 study concluded that patients with good antioxidant levels could withstand the strain of chemotherapy better, compared to those with low antioxidant levels. Other Antioxidants like Vitamins E and C, beta carotene, isoflavones found in soy, and quercetin (found in red wine and purple grape juice), have actually been reported to mitigate chemotherapy's side effects. A number of studies have reported that lycopene may protect against prostate, colon, lung, and bladder cancer.
- Phytochemicals like Isothiocyanates and sulforaphane, found in cruciferous vegetables, may block the effects of carcinogens and suppress the growth of tumours. In one study, for example, women who consume the maximum cruciferous vegetables had a 24% lower risk of breast cancer compared to women who consumed significantly lower amounts. Resveratrol has also been found have tumor-suppressing properties.
Negative Research Findings about Antioxidants
Although it is clear that Antioxidant vitamins (A, C, and E), carotenoids, and many phytochemicals can neutralize free radicals, there is no real evidence that taking these in the form of synthetic supplements is of any use.
The strongest evidence on negative effects to date are studies reporting an increase in lung cancer and overall mortality rates among smokers who took beta carotene supplements. In determining reasons for this disturbing effect, one animal study suggested that beta carotene increased enzymes in the lungs that actually promotes cancerous changes. A 2000 study also reported a higher risk for cancer in male smokers who took multivitamins plus A, C, or E.
And, even more worrisome is the fact that in people with existing cancer, high doses of antioxidant vitamins, such as vitamin C or beta carotene, may actually protect cancer cells (just as they do healthy cells). For example, a 2003 study reported a higher risk in melanoma in people with vitamin-C rich diets.
Some evidence also exists that high doses of vitamin C may speed up atherosclerosis. In a 2003 study, it was observed that women with heart disease who took antioxidant vitamins had a higher risk for heart attack or death than those who didn't take one.
A 2002 study also reported a higher incidence and greater severity of respiratory infections in older adults who took 200 mg of vitamin E daily. Some researchers speculate that certain immune factors generate oxidants to fight bacteria. This antioxidant vitamins then may block that action.
But are antioxidants actively harmful? Based on data from randomized trials completed to date, it is likely that they are usually not harmful. But while the jury is out on the benefits of Antioxidants, eating lots of fruits and vegetables - in other words, following a good diet - seems the most prudent course at the moment.
What can I do?
Quick Tips To Maximise Our Food's Antioxidant Power
- Heating lycopene-rich tomatoes makes their nutrients easier to absorb. When making your favourite curry or pasta, make sure to cook tomatoes first. Another way is to halve tomatoes lengthwise, arrange on a baking sheet, drizzle with olive oil, and season with salt and pepper. Grill for 15 to 20 minutes, until slightly shrivelled. Use this to make a quick paste. Or eat lots of ketchup with your food!
- High temperatures destroy allinase, garlic's most important cancer-fighting and immunity-boosting enzyme. One way of using garlic in cooking is to let crushed garlic stand for about 10 to 15 minutes before adding it to a sizzling pan. This allows the pungent herb to generate compounds that blunt the damaging effects of heat. Or add crushed fresh garlic after the food has cooked. Crushed garlic in a salad or green chutney will enhance the flavour of the food as well as its health quotient.
- Using fresh herbs as salad may more than double its cancer-fighting punch. Use lemon balm, marjoram (available at exclusive food stores), coriander, mint, basil and other similar herbs for best effect.
- Adding nuts, olive or other healthy fat sources to red, green, orange and yellow fruits and veggies (bell peppers and tomatoes to name some) increases the amount of fat-soluble vitamins, such as A, E and K. These nutrients boost vision, improve immunity and protect against stroke and osteoporosis.
- Save yourself some time-and some key nutrients by not peeling eggplant, apples, potatoes and other produce before using. The peel acts as a natural barrier against nutrient loss, and many vitamins and minerals are found in the outer skin, or just below it.
- Antioxidants are commonly used to treat various forms of brain injury. Experimental Antioxidant compounds are also being developed to treat stroke. These compounds appear to prevent oxidative stress in neurons and prevent neurological damage. Antioxidants are also being investigated as possible treatments for neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis.
- There are several Anti-ageing Beauty Products in the market today, that claim to contain antioxidants. Spas today offer many antioxidant treatments like chocolate therapy and red wine wraps.
- To buy antioxidant beauty supplements online, see Body Beautiful
- Antioxidants and Free Radicals
- Vitamins, Carotenoids, and Phytochemicals
- Criticisms about Antioxidants
- Antioxidants and Green Tea