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Supplement manufacturers and food companies maintain antioxidants will help to prevent a host of diseases and medical conditions. But research findings are inconclusive, and there is evidence that antioxidant supplements do not provide health benefits.

Less than two decades ago antioxidants were hailed as the new hope for better health. Claims were that they could minimize the risks of chronic conditions and diseases including atherosclerosis and cancer. Health pundits urged the population to eat foods that were high in antioxidants, and supplements high in antioxidants were touted as the best way to slow disease and age-related degeneration.

Then the clinical trials began, with researchers testing realities. Like most research studies, there have been mixed results, but overall the evidence is that antioxidant supplements are not effective in protecting against cancer, heart disease or any other chronic medical conditions. Some trials have simply been inconclusive while others have reported negative rather than positive effects. While most researchers agree that fruit, vegetables and whole grains rich in antioxidants should be included in a healthy diet, because they do seem to help prevent some chronic diseases, they concur that other natural substances including minerals and fiber also play an important role – not just the antioxidant content.

The National Institutes of Health (NIH) acknowledges that there is ample evidence that eating a diet with lots of fruit and vegetables is healthy and that it will lower the risk of some diseases. But they question whether this is because of the antioxidants they contain or because of other factors. 

Additionally, the NIH warns that high-dose antioxidant supplements might carry a health risk, particularly of some types of cancer and stroke. Antioxidants can also interact with some medicines, which can also be dangerous.

What Are Antioxidants?

Simplistically, an antioxidant is a substance (or molecule) that is able to inhibit oxidization and remove potentially damaging oxidizing agents from living organisms (including food.) There are thought to be thousands of different substances that act as antioxidants, including vitamins C and E, certain minerals including manganese and selenium, beta-carotene and a few related carotenoids, as well as flavonoids, phenols, polyphenols, glutathione, lipoic acid, and coenzyme Q10.

Antioxidants occur naturally in some fruits and vegetables, and some are manufactured so that they can be taken in the form of supplement. But as the experts at Harvard’s School of Public Health point out, antioxidants are not a regular single substance. They all have their own unique chemical behavior and biological properties, and some act as electron donors (or “electron grabbers.”) What this means in reality is that one antioxidant is not the same as another, and so the claim that antioxidants (in general) do good is in a way nonsensical.

However, the generalization is that “antioxidants” can fight the free radicals that threaten our health.

Adding to the antioxidant puzzle, free radicals are described by the Harvard team as “nasty chemicals” that have the ability to damage cells and genetic material in the body. They come from food we eat and air we breathe, even from the effect of sunlight on our skin and eyes. Some free radicals are generated as byproducts when our bodies turn food into energy. An alarming effect is that it encourages so-called “bad” cholesterol – low-density lipoprotein (LDL) – into the bloodstream and it then runs the risk of getting trapped in the walls of the arteries. It can also alter the membrane of cells.

Antioxidants first made headlines in the 1990s when scientists found that early stages of atherosclerosis (caused by arteries becoming clogged), was related to free radical damage. They also linked free radical damage to a number of other chronic conditions including cancer, heart disease, Alzheimer’s, and loss of vision. Early studies showed that people who did not consume antioxidant-rich fruit and veg were more likely to develop these chronic conditions than those who did.

Today the antioxidant industry is worth millions of dollars. The antioxidant supplement industry alone is worth more than $500 million, and it keeps growing, in spite of the fact that there is no proof they do what the manufacturers claim. Instead, say the experts at Harvard, their “claims have stretched and distorted the data.”

But it hasn’t only been the “industry” that has promoted the idea that antioxidants can reverse the effects of free radicals on the body. 

In November 2007 the US Department of Agriculture (USDA) released a comprehensive database for the oxygen radical absorbance capacity (ORAC) of 277 items of food. This database was updated in May 2010, bringing the total of foods to 326. Additions included acai, goji berries and maple syrup. Foods with the highest ORAC scores were:

  • Ground cinnamon, cloves and turmeric
  • Dried oregano, rosemary, sage and thyme
  • Acai
  • Rosehip
  • Black and hi-tannin sorghum bran

However the ORAC list did not include data that indicated whether the antioxidants played any biological role. It was simply a list of foods that could be used as a guide to antioxidants.

Two years later, in 2012, the USDA withdrew the database stating that while antioxidant molecules have a wide range of functions in food, many of these “are unrelated to the ability to absorb free radicals.” Further, they stated that companies manufacturing food and dietary supplements had been routinely misusing the ORAC values to promote their products. 

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