Your body comprises trillions of cells. Cells, in turn, are made up of many molecules. Molecules consist of atoms joined by chemical bonds. Atoms consist of neutrons, protons, and electrons. The number of positively charged protons in the atom’s nucleus determines the number of negatively charged electrons surrounding the atom. Electrons orbit an atom in one or more shells. When the innermost shell has two electrons, it is full; when the second shell has eight electrons, it is full, and so on. Chemical reactions involve the transfer of electrons, which bond atoms together to form molecules. The number of electrons in an atom’s outer shell is an important way to determine its chemical behavior. A substance that has a full outer shell tends to be inert and tends not to react chemically. Atoms reach this state of stability by gaining electrons to fill their outer shells, or by bonding together with other atoms and sharing electrons in order to complete their outer shells.
When molecules split, they normally don’t leave molecules with unpaired electrons. But when weak bonds split, they leave one or more molecules with unpaired electrons, called free radicals. Free radicals are positively charged, very unstable, and react quickly with other molecules, to acquire the electron they need to gain stability. Generally, free radicals acquire an electron from the nearest stable molecule. The molecule that loses an electron then becomes a free radical itself, beginning a chain reaction. Once the process is started, it can cascade. Excessive free radicals in your cells can attack the cell membranes, causing cell and tissue damage. Free radicals can also break strands of DNA (the genetic material in your cells), which can lead to cancer.
A substance is oxidized when electrons are removed and reduced when electrons are added. The mitochondria in your cells generate energy by combining oxygen with glucose to gradually oxidize food in a controlled manner and store it in the form of chemical potential energy, called adenosine triphosphate or ATP. This oxidation of glucose releases energy, but it can also let free electrons escape. This process generates oxygen-based free radicals called reactive oxygen species (ROS). Anywhere from 2 to 5% of your total oxygen intake during both rest and exercise can form these highly damaging free radicals. During exercise, your oxygen consumption increases 10 to 20 fold. In turn, your cells can create more free radicals. The inflammatory response that occurs after strenuous exercise is also associated with oxidative stress. The immune system response to the damage done by exercise includes free radical production by neutrophils to remove damaged tissue.
Oxygen is essential for life, but it’s also inherently dangerous, because it results in free radicals. The same process that causes a cut apple to turn brown or iron to rust is the cause of all chronic degenerative diseases and even the aging process itself, including wrinkles, sagging skin, and age spots. This aging of the skin is an outward manifestation of oxidative damage or oxidative stress, which is occurring within every cell in your body.
Your immune system can also make free radicals to destroy pathogens. Some other things that can make free radicals in your cells include ultraviolet light (which is why people who spend too much time in the sun are more likely to get skin cancer and cataracts) and toxins such as tobacco smoke, air pollution, herbicides, and pesticides. While your body can neutralize some free radicals, all these stressors combined can be more than your body can handle, resulting in damage to your cells. On average, every cell in your body comes under attack from a free radical once every ten seconds. This damage tends to accumulate with age.
Cell membranes are made of unsaturated lipids, which are particularly susceptible to damage from free radicals, and readily contribute to the uncontrolled chain reaction. Oxidative damage can lead to a breakdown or even hardening of lipids, which makeup all cell walls. If the cell wall is hardened (lipid peroxidation) then it becomes impossible for the cell to properly get its nutrients, get signals from other cells to perform an action (such as firing of a neuron) and many other cellular activities can be affected.
In addition to the cell walls, other biological molecules are also susceptible to damage, including ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein enzymes. Every cell contains an enormous set of molecules called DNA which provide chemical instructions for a cell to function. This DNA is found in the nucleus of the cell, which serves as the “command center” of the cell, as well as in the mitochondria. The primary site of free radical damage is the DNA found in the mitochondria. Mitochondria are the energy factories of the cell: small membrane-enclosed regions of a cell that produce the chemicals a cell uses for energy. The cell automatically fixes much of the damage done to nuclear DNA. However, the DNA in the mitochondria cannot be as easily fixed. Extensive DNA damage accumulates over time and shuts down mitochondria, causing the cells to die and the organism to age.
In ideal conditions, your body can handle a certain number of free radicals by using antioxidants. Antioxidants neutralize free radicals by giving them one of their own electrons. The antioxidant molecules don’t become free radicals themselves by losing an electron because they are stable in either form (oxidized or reduced). They act as scavengers, helping to prevent cell and tissue damage that could lead to disease. Your cells produce the antioxidant enzymes glutathione, catalase, superoxide dismutase (SOD), and some others which neutralize free radicals naturally in the cell, but due to oxidative stress, your body may not be able to produce enough of these enzymes, especially as you age.
- Vitamin E is the most abundant fat-soluble antioxidant in the body. It is one of the most efficient chain-breaking antioxidants available, and it is a primary defender against oxidation and lipid peroxidation, which is the creation of unstable molecules containing more oxygen than is usual. Vitamin E may protect against cardiovascular disease by defending against LDL oxidation and artery-clogging plaque formation. It’s found in spinach, turnip greens, chard, mustard greens, cayenne pepper, sunflower seeds, almonds, bell peppers, asparagus, collard greens, kale, tomatoes, cranberries, broccoli, Brussels sprouts, papaya, raspberries, and carrots.
- Vitamin C is the most abundant water-soluble antioxidant in your body. It acts primarily in cellular fluid, combating free-radical formation caused by pollution and cigarette smoke. It also helps return vitamin E to its active form, and helps form glutathione. Many studies have correlated high vitamin C intakes with low rates of cancer, particularly cancers of the mouth, larynx and esophagus. It’s found in broccoli, bell peppers, parsley, Brussels sprouts, cauliflower, lemons, strawberries, mustard greens, kiwifruit, papaya, kale, cabbage, Romaine lettuce, turnip greens, oranges, cantaloupe, summer squash, grapefruit, pineapple, chard, tomatoes, collard greens, raspberries, spinach, green beans, fennel, cranberries, asparagus, watermelon, and winter squash.
- Vitamin B2 (Riboflavin) also helps protect cells from oxygen damage, supports cellular energy production, and maintains your supply of other B vitamins. It’s found in crimini mushrooms, spinach, summer squash, asparagus, chard, shiitake mushrooms, green beans, mustard greens, broccoli, collard greens, and turnip greens.
- Betalains are a group of 24 substances including
- Terpenes are a group of substances that occur in nearly every plant, protecting them from the same reactive oxygen species that attack human cells. They include:
- Monoterpenes are found in the essential oils of many plants including bergamot, carrots, coriander, lavender, limes, nutmeg, rose, blueberries, blackberries, oranges, lemons, tangerines, grapefruits, and other citrus fruits and their peels, lavender, cherries, spearmint, sage, celery seeds, thyme, ajwain, and horsemint.
- Carotenoids are largely responsible for the red, yellow, and orange color of fruits and vegetables, and are also found in many dark green vegetables, including carotenes, found in sweet potatoes, carrots, kale, spinach, turnip greens, winter squash, collard greens, cilantro, fresh thyme, cantaloupe, Romaine lettuce, broccoli, tomatoes, green beans, chard, apples, and avocadoes; lycopene, found in tomatoes, pink grapefruit, watermelon, guava, and persimmons; xanthophylls, found in raw and lightly steamed kale, spinach, turnip greens, collard greens, Romaine lettuce, broccoli, zucchini, corn, peas, squash, pumpkin, Brussels sprouts, microalgae, and yeast, red bell peppers, papaya, oranges, watermelon, serrano pepper, avocadoes, grapefruit, chanterelle mushrooms, green algae, and paprika. Beta-carotene is a more powerful anti-oxidant than retinoid vitamin A and not only protects epithelial cells (the cells that form the lining of numerous body structures including your blood vessels) from free radical damage, but also helps prevent free radicals from oxidizing cholesterol in your blood stream. Only after it has been oxidized does cholesterol build up in blood vessel walls, initiating the development of atherosclerosis, whose end result can be a heart attack or stroke. Free radical damage is a contributing factor in many other conditions as well, including asthma, osteoarthritis, and rheumatoid arthritis.
- Saponins, found in red wine, peas, beans, lentils, peanuts, soybeans, alfalfa, ginseng, fenugreek, wild yam, soapwort, paprika, oats, spinach, garlic, leeks, onions, chives, tea, sugar beet, quinoa, licorice, capsicum peppers, eggplant, tomato seeds, asparagus, and bean sprouts.
- Polyphenols, numbering over 4,000, include:
- Cannabidiol, found in hemp seed.
- Curcumin, found in turmeric.
- Lignans found in flax seeds, pumpkin seeds, sesame seeds, sunflower seeds, whole grains, vegetables, fruits, cruciferous vegetables, cucumbers, and olives.
- Phenolic acids found in blackberries, cranberries, pecans, pomegranates, raspberries, strawberries, walnuts, wolfberries, grapes, peaches, hot chile peppers, apricots, asparagus, broccoli, cabbage, cocoa, grapefruits, green tea, lemons, limes, melons, oranges, peas, pineapples, spinach, wine, celery, parsley, rosemary, oregano, sage, lemon balm, marjoram, perilla, wild mint, hyssop, comfrey, thyme, wild oregano, and dill weed.
- Hydroxycinnamic acids, found mainly in coffee, but also in apples, artichokes, basil, cabbage, cauliflower, kale, oregano, pears, radishes, thyme, turnips, pears, and tea.
- Ferulic acid, in apples, asparagus, coffee, oranges, pineapples, and whole grains.
- Hydroxybenzoic acids, found in blackberries, blueberries, cantaloupes, dates, raisins, kiwifruits, guavas, apricots, green pepper, olives, tomatoes, radish, mushrooms, chicory, almonds, water chestnuts, peanuts, raspberries, pomegranate, rooibos and white tea, and grape seeds.
- Hydroxytyrosol, found in olives.
- Stilbenoids, found in grape skins, red wine, peanuts, blueberries, cranberries, and grapes.
- Flavonoids, found in bilberry, blackberry, blueberry, cherry, cranberry, elderberry, hawthorn, loganberry and raspeberry, apples, pears, peaches, and plums, black beans, black-eyed peas, eggplant, red grapes, black rice, chokeberries, strawberries, cherries, black bananas, black currants, onions, tea, red wine, broccoli, grapefruit, cabbage, kale, leeks, ginkgo bilboa, St. John’s Wort, beans, walnuts, cocoa, Saskatoon berries, seabuckthorn, almonds, chives, dill weed fennel leaves, turnip greens, green tea, apricots, nectarines, fava beans, barley, raisins, rhubarb, persimmon, pomegranate, carob flour, black tea, oolong tea, endive, tomato, Brussels sprouts, buckwheat, prunes, rose hips, citrus rind, green peppers and their core, lemons, oranges, yellow peppers, whole grains, tangerines, peppermint, soy, chickpeas, kudzu, and red clover.
- Indoles are found in crushed or chopped garlic, chopped watercress, mustard greens, Brussels sprouts, horseradish, kale, turnip, cabbage, broccoli, kohlrabi, bok choy, cauliflower, broccoli sprouts, and cauliflower sprouts.
- Other organic acids that act as antioxidants include:
- Inositol (phytic acid), found in bran from corn, oats, rice, rye and wheat, nuts, soybeans and soy products (tofu, soy milk, edamame, etc).
- Oxalic acid, found in tea, buckwheat, star fruit, black pepper, parsley, poppy seed, rhubarb, chives, purslane, cassava, amaranth, spinach, chard, beet leaves, cocoa, chocolate, most nuts, carrot, radish, collards, snap beans, Brussels sprouts, garlic, lettuce, watercress, sweet potato, chicory, turnip, broccoli, celery, eggplant, cauliflower, asparagus, endive, cabbage, okra, onion, peas, potatoes, tomatoes, turnip greens, pepper, parsnip, rutabaga, cucumbers, kale, squash, coriander, sweet corn, most berries, and beans.
Scientists developed techniques to measure the antioxidant capacity of foods, of which Oxygen Radical Absorbance Capacity (ORAC) is one. The ORAC assay, developed at the National Institute on Aging, measures the degree of inhibition of peroxy-radical-induced oxidation and includes both inhibition time and the extent of inhibition of oxidation. While ORAC scores do provide some measurable means to compare foods and antioxidant products, there are some problems with ORAC testing. One of the biggest problems is that the results are based on weight or volume, and can be manipulated based on removing water. Dried fruit, therefore, scores higher than fresh fruit.
A better measure is probably the Aggregate Nutrient Density Index (ANDI) score, which measures calcium; the carotenoids beta carotene, alpha carotene, lutein, zeaxanthin, and lycopene; fiber; folate; glucosinolates; iron; magnesium; niacin; selenium; vitamins B1 (thiamine), B2 (riboflavin), B6, B12, C, and E; and zinc, plus the ORAC score X 2. Most importantly, the ANDI scores are based on calories, not volume or weight of food, so a lower-calorie food with more nutrients scores higher than a calorie-dense food.
Antioxidants help protect the body from free-radical damage. The best way to ensure adequate intake of the antioxidant nutrients is through a balanced diet consisting of whole foods, notably fruits and vegetables that have a variety of colors—from red, orange, and yellow to blue and green. Even some white fruits and vegetables are rich in antioxidants, as are whole grains, nuts, and legumes.
You can watch a good introductory video of the antioxidant process here.
This blog uses the latest nutritional data available from the USDA (United States Department of Agriculture), and the FDA (United States Food and Drug Administration), as well as nutritional data provided by food growers and manufacturers about their products. We believe the information on this website to be accurate. However, we are not responsible for typographical or other errors. Nutrition information for recipes is calculated by Living Cookbook based on the ingredients in each recipe based on statistical averages. Nutrition may vary based on methods of preparation, origin and freshness of ingredients, and other factors.
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