An antioxidant is any substance that promotes health by removing reactive species that may otherwise exert harmful effects in the body. The origins of the biological effects of antioxidant goes back to antiquity e.g. the time of Egyptians as evidenced by the remarkable preservation of dead bodies in part due to the use of plant polyphenols in the embalming process. Years later such antioxidants were considered “elixirs” of youth and the interest in antioxidants began to spike. Since the 1980’s, both the number of research papers on the subject and the number of natural products on the market with an antioxidant claim have grown exponentially. Today, the term antioxidant is so widely perverse that it has become an almost meaningless term!
There are tens of thousands of natural compounds that have demonstrated antioxidant activity and hundreds of thousands of natural products (dietary supplements) on the market with an antioxidant claim.
The plant and marine kingdom are full of natural compounds with antioxidant activity. These include flavonoids; a huge category that is further subdivided into six subcategories which includes the colourful anthocyanins, which gives berries their striking colours; quercetin, which is abundant in apples and onions and also polymethoxy flavones from citrus fruits. Polymethoxy flavones, especially, are generating much excitement due to their potent anti-cancer activity. Resveratrol, is another ingredient abundantly found in wine and other herbs that is associated with increased life span at least in yeast and worms and with possible implications for humans.
Similarly, various carotenoids including zeaxanthin from paprika to lutein from marigold flowers to fucoxanthin from the algae offer exciting possibilities for health. Likewise, the powerful curcumin from the turmeric root which is widely used in Asian cuisine to catechins from green tea all exhibit powerful antioxidant effects.
All these natural chemicals are able to quench the nasty free radicals generated from oxygen, nitrogen and sulphur, all of which are so reactive they cause damage as soon as they come into contact with the various compounds in tissues of the body. This includes the DNA found in the nucleus, lipid molecules of cell membranes and proteins and amino acids that form the structural components of skin, joints, nerve cells etc.
Antioxidants have a long history of use in the nutrition and the food industry. The traditional understanding has been that antioxidant chemicals promote health by removing these reactive species. According to this definition, most reactive species were considered to be harmful, implying that maximizing antioxidant concentrations could minimize the risk of disease. The public has become too familiar with the term antioxidant and equates it to a chemical that is good for our well-being. Antioxidant foods, drinks, cosmetics and supplements abound.
Extensive research has found that quenching these radicals is normally associated with good health. After all, if you neutralize these reactive species one can mitigate molecular and cellular damage.
Physicians and the natural health industry have enthusiastically embraced antioxidants overwhelmingly, to the extent that antioxidants are recommended for any and every disease.
From a commercial, retail and a physician’s viewpoint a major difficulty occurs - how to select the best antioxidant from a list of tens of thousands? Various assay systems have been developed to measure or assess the antioxidant capacity of such molecules. These include: total radical-trapping antioxidant parameter (TRAP), trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP), etc. One popular assay system called the Oxygen Radical Absorbing Capacity or ORAC is a widely used assay. Essentially, the compound being tested (the antioxidant) is added to a liquid mixture containing a fluorescent dye and a known oxidant (the nasty free radical) in a test tube. The oxidant causes the dye to fluoresce. The antioxidant combats this action and the rate of disappearance of the fluorescence is a measure of the ORAC.
ORAC is widely used by supplement and food companies. Labels and charts are often created that show the "ORAC potency” of their product or food compared to their competitor and have blatantly advertised this “fact” to the general public with the mindset that the higher the ORAC value the more potent the antioxidant and thus superior and healthier the product. An ORAC value of less than a thousand is regarded as “low” antioxidant potency while anything between the ranges of 2,000 to 5,000 is considered an “average” potency and anything around a value of 10,000 is considered highly potent.
ORAC values are being used by many manufacturers to differentiate their products. From berry extracts to tea bags, antioxidant claims are ripe. In fact, antioxidants are becoming an ORAC race, the more ORAC you could measure the better. However, something is amiss here. First, the ORAC test is a chemical assay, it is not a biological assay. It takes place in a test tube, an isolated system under conditions that are far removed from the real life situation of a dynamic biological system in our bodies. Moreover, the test tube conditions are unrealistic when it comes to the pH, temperature, concentrations of antioxidants used etc. What happens in people cannot be modeled under test tube conditions. There is a big difference.
Second, ORAC is limited to one reactive oxygen species, the peroxyl radical, it does not measure the quenching of other oxygen species like the hydroxyl, superoxide and singlet oxygen. Finally, ORAC does not measure activity against other non-oxygen free radicals like nitrogen and sulphur. In fact the peroxynitrite free radical aptly termed ONOO is particularly nasty and damaging.
Recently, one company actively marketed their black tea extract as having an ORAC value of up to 1,000,000! What does such a figure even mean? Is such a product 100 times more potent than a compound with an ORAC value of 10,000? Does it mean that one can take it at 100 times a lower dose? Will it be 100 times more effective?
In reality there is no dose-response relationship, meaning that ORAC values have no significance to physiological effects or health benefits and thus are biologically irrelevant. Just increasing ORAC value provides no guarantee of greater health benefit. It is pure marketing. No wonder regulators world-wide do not equate antioxidant claims with any health benefits. Recently, the Indian FDA confiscated Brooke Bond tea from Unilever India which made a claim, “A rich source of antioxidant flavanoids that protect the cells and tissues of the body”. Likewise China does not permit any health claims to be associated with antioxidant activity. In the opinion of European Food Agency (EFA), “No evidence has been provided to establish that having antioxidant content or activity has any beneficial physiological effect”. Furthermore, even the induction or stimulation of endogenous antioxidant enzymes like catalase or SOD etc alone cannot be considered as evidence for claims of an antioxidant defense system.
One US expert on antioxidants has gone as far as demanding that the term antioxidant should be banished from food and supplement labels with more specific claims about health benefits. There seems to be considerable support for such a proposition at least from the scientific community but unfortunately, supplement and food companies still persist in such nonsense!
It is time for food and supplement companies to step up to the plate and substantiate implicit and explicit claims of performance based on antioxidant performance. This can only be achieved by assay systems that are significantly better than ORAC, like the recently developed cellular antioxidant activity (CAA) assay or better still linking antioxidant with a specific health benefit.
You may also be interested in: "Antioxidants Part 2: What Are Free Radicals?"