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Time for antioxidants v2.0

17-Dec-2007

'Antioxidants' crop up every where, from beverage cans to cereal packets. But industry must wake up to over use of the antioxidant tag before the term loses meaning for consumers.

The term antioxidant has high awareness among consumers, so it is natural that is used extensively to attract consumer attention. But without some kind of change to include a measure of biological activity, we risk branding everything an antioxidant without meaning anything. This poses a very real threat to an industry that has worked so hard to build up consumer awareness. Facing up to the situation now and introducing a new v2.0 system could prevent it ever becoming a real issue. Extra antioxidants from the diet or supplements help redress the scales often tipped in favour of the pro-oxidants by factors such as ageing, exposure to pollution, smoking, and excessive exercise. The term antioxidant is a catch-all, encompassing a mind-boggling number of phytochemicals, as well as the more well-known vitamins. Health claims regulations will prevent brash claims about potential health benefits, but until the introduction of these in 2010, the antioxidant 'brand', if I can call it that, has such consumer appeal that it appears tempting to be able to state "a (rich) source of antioxidants". There are currently no rules and regulations to prevent people from stamping statements such as "high in antioxidants" or "a rich source of antioxidants" on a label. But what defines "high" or "rich"? There does not seem to be a cut-off point. This will of course change when the health claims legislation comes into play because the statement "contains antioxidants" implies a health benefit. But for the moment, we're going through a period of transition, and that means things can be fuzzy. We have already started to see a backlash of sorts. In October, the UK's Innocent was rapped on the knuckles for making a health claim about its smoothie having a high antioxidant content and detoxifying effect. The Advertising Standards Authority (ASA) said an advert by the firm, which claimed its fruit juice contained more antioxidants than the "five-a-day" portion, was not truthful or substantiated. A week earlier, and the UK Tea Council was criticised for exaggerating the benefits of tea, and banned from making further claims about the drinks' antioxidant potential after running a series of adverts. The message is clear: It is time for a spring-clean of the antioxidant house. But how should we go about doing this? I don't pretend to have the answers, but I do have a couple of suggestions. How about we settle on a definitive way of classifying antioxidant activity, and levels that could be classed as low, medium, or high in terms of antioxidants levels? Moreover, we need to link antioxidant content to an endpoint - for example, the dose of antioxidant needed to reduce a certain biological marker linked to the risk of a specific disease, like tomato extracts and prostate specific antigen (PSA) levels in relation to prostate cancer. Not convinced? Only last week, Ming Hu from the University of Houston issued a "call to arms" in an editorial in the journal Molecular Pharmaceuticals for more relevant research for antioxidants, and polyphenols in particular. In his expert opinion, there is a lack of data on bioavailability and utilisation of these compounds. Interestingly, Hu stated that the bioavailability of a typical polyphenol is only about 10 per cent. In other words, the original food or supplement may contain a lot of the polyphenol, but only a tenth of this will be absorbed in the intestine. Currently, antioxidant activity is based on lab assays, but do these enable us to really appreciating the potential physiological benefits? There are numerous ways of quantifying the antioxidant activity, but these are only adding to the confusion. We regularly see new antioxidant league tables, with such and such a fruit or berry topping the standings. But what does a good performance in the ORAC or FRAP test really mean for a specific health benefit? The antioxidant activity of selected compounds has been measured using a range of lab-based assays, including the ferric reducing ability of plasma (FRAP) assay, the oxygen radical absorbance capacity (ORAC) and Trolox equivalent antioxidant capacity (TEAC). There is considerable debate about which method is best. Disciples of the ORAC test can find fault with FRAP, while FRAP can find fault with ORAC. We must not lose sight of the fact that these tests are done in a test tube. Only recently, scientists at Cornell proposed a new measure of antioxidant activity called the cellular antioxidant activity (CAA) assay and dubbed it the 'next step' in quantifying antioxidant activity. The new assay reportedly moves the quantification of antioxidant activity from the test tube to measuring bioactivity inside cells. However, I have already received emails highlighting potential 'issues' with this new method, and anticipate other cellular-based assays to follow. We have a plethora of data now, each proposing a measure of antioxidant activity. It is all getting a bit confusing. The time for action is now, before more companies get their knuckles rapped for overstating or misrepresenting the antioxidant issue. It is all well and good tapping into kudos attached to the term, but only by using it responsibly will we all benefit. Stephen Daniells is the science editor for NutraIngredients.com and FoodNavigator.com. He has a PhD in chemistry from Queen's University Belfast and has worked in research in the Netherlands and France. If you would like to comment on this article, please email stephen.daniells'at'decisionnews.com


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