Copyright 2006 Sylvia Riley
Wouldnt we all like to age gracefully (if at all for that matter!) and ward off the wrinkly signs and ill symptoms for as long as possible. Keys to longevity may be more accessible than we think, and it appears our diets play a critical role. Antioxidants are the knights in shining armor that subjugate the attack of free radicals in the body, the hazardous molecules that damage cells and procure aging and disease. Though antioxidants are produced naturally in the body, these decline with age, hence an increasing need to acquire them from the foods in our diet.
Before examining antioxidants more closely, it is important to take a look at the free radicals they serve to neutralize.
Free radicals are created as by-products in our use of oxygen during metabolism such as the burning of food for energy. They are essentially oxidant molecules that are missing an electron and seek to restore themselves by targeting nearby cells in an attempt to recover this electron, potentially harming enzymes, DNA, proteins and cell membranes in the process. This damage can mutate cells and alter cell function, increasing the risk of numerous diseases and chronic conditions including arthritis, diabetes, cataracts, cancer, heart disease and stroke. Free radical damage is implicated in the onset of aging and its degenerative symptoms and diseases.
As well as generated within the body, free radicals come from environmental sources such as pollution, radiation, unhealthy foods, bacteria, viruses, cigarette smoke and UV light.
Antioxidants serve to mitigate the harmful effect of free radicals by giving up an electron and stabilizing them in the process. Although we produce many of our own antioxidants within the body, food provides an essential source for these key players of our defense system. Vitamins, minerals and phytonutrients all have antioxidant properties. The most common examples include vitamins A, C and E, selenium and zinc, carotenoids, flavonoids, co-enzyme Q10, alpha-lipoic acid and glutathione.
As there are many different types of free radicals in the body a variety of antioxidants are required to protect against them. Antioxidants function best as a team, with each other and other nutrients and phytochemicals, which is why incorporating a wide range of plant foods into your diet is recommended. Phytochemical groups such as flavonoids and carotenoids correspond to the colour, taste and smell attributes of plants, hence eating a rainbow array of vegetables and fruits can offer a diverse selection of these potent antioxidants.
Antioxidant Rich Foods
Foods especially high in antioxidants include berries, plums, pomegranates, oranges, spinach, green tea, avocado, kale, broccoli, peas, onions, grapes and pure chocolate.
Scientists at the USDA (United States Department of Agriculture) have developed a rating scale that measures the total antioxidant capacity of a given food. This is known as the ORAC score (Oxygen Radical Absorbance Capacity).
Of 40 common fruits and vegetables measured by the USDA, top ranking scores were those of prunes(5770), raisins (2830), blueberries (2400 highest of all fresh foods with other berries close behind), kale (1770), spinach (1260), Brussels sprouts (980), plums (949), alfalfa sprouts (930), broccoli florets (890), beetroots (840), oranges (750 ), red peppers (710 ) and red grapes (739).
Pure cocoa surpasses all these foods with a whopping score of 26,00 units, more than 10 times the prestigious blueberry (though one is likely to eat far less in quantity). The extraordinary goji berry from Tibet also has outstanding antioxidant capacity with a score of 18,500 units; hardly surprising as they contain 500 times more vitamin C than oranges and even more beta-carotene than carrots!
According to studies on animals and human blood at the Human Nutrition Research Center on Aging at Tufts in Boston, high-ORAC foods may slow aging processes in the body and brain. Results found that high ORAC foods such as blueberries and spinach could increase the antioxidant power of human blood by 10-25%, prevent loss of long-term memory and learning ability in middle-aged rats, and protect rat blood vessels against oxygen damage.
Antioxidants and Aging
As we age, free radical levels rise and yet the body falls short in producing necessary amounts of antioxidants to meet this challenge. For example, cells generate more of the oxidants hydrogen peroxide and superoxide, yet levels of the necessary antioxidant glutathione required to neutralise these decline. The Free Radical Theory of Aging, first proposed by Harman in 1954, is supported by cross-species examination of animals with regard to life span, free radical damage and antioxidant defence. For example, the white-footed mouse lives about twice as long as the house mouse (8 versus 4 years), and is found to generate less oxidants and have higher levels of antioxidants. As Beckman and Ames write in The Free Radical Theory of Ageing Matures (1998), Together, interspecies comparisons of oxidative damage, antioxidant defences, and oxidant generation provide some of the most compelling evidence that oxidants are one of the most significant determinants of life span.
Very recent evidence comes from a study on dogs at the University of Toronto by Dr. Dwight Tapp and colleagues who found that old dogs that were on an antioxidant diet performed better on a variety of cognitive tests than dogs that were not on the diet. In fact, the dogs eating antioxidant-fortified foods performed as well as young animals.
Additional research by Dr. Rabinovitch and his team, studying aging at the University of Washington, Seattle, found that mice engineered to produce high levels of an antioxidant enzyme (catalase) lived 20 per cent longer and had less heart and other age-related diseases than controls.
In light of the role free radicals play in the onset of aging and disease, it is important to ensure our diets include a rich and diverse supply of antioxidants. These protective agents can be found abundantly in vegetables, fruits, nuts and seeds and are particularly high in superfoods.