Antioxidants are a commonly promoted feature of health foods and supplements. They are described as the good forces that fight free radicals, harmful molecules that cause damage believed to accelerate aging and cause chronic disease.
The simple logic that antioxidants are “good” and free radicals are “bad” has led to the idea that simply introducing more antioxidants into our bodies, from food or supplements, can outweigh the effects of free radicals.
Unfortunately, biology is never that simple and antioxidants are no pass for free radicals.
We are daily exposed to free radicals; they are produced in our body as part of normal functioning. These normal levels are easily tolerated.
But habits such as smoking, drinking, and eating processed foods all increase exposure. These extra free radicals can increase the risk of lifestyle and age-related diseases, such as cancer and cardiovascular disease.
Free radicals explained
Free radicals are very [reactive](http://en.wikipedia.org/wiki/Reactivity_(chemistry) molecules. In the body, a chemical reaction takes place between free radicals and the molecules that make up our cells.
This inactivates the free radical, but turns the other molecule into a new free radical. The process continues in a chain reaction, damaging each molecule as it goes.
These reactions can alter the structure and function of molecules; when enough molecules are damaged, cells can stop working properly or die.
DNA damage by free radicals can lead to mutations and promote cancer. Free radicals can also oxidizes low density lipoproteins or LDL (the “bad” cholesterol), which makes it more likely to get stuck in artery walls, clogging blood vessels and leading to cardiovascular disease.
Sometimes free radicals are very useful, for example, in an oxidative burst. This happens when special immune cells, called phagocytesdeliberately release free radicals as part of a cocktail of chemicals to kill and digest bacteria and viruses.
Our antioxidant heroes
Antioxidants can stop the chain reaction of free radicals. They can react with free radicals without being damaged or becoming free radicals themselves.
There are hundreds of substances that can act as antioxidants. Well-known antioxidants include vitamin C and Vitamin Eboth present in fruits and vegetables.
Vitamin C is mainly found in citrus fruits and berries, while vitamin E is abundant in nuts and green leafy vegetables.
The ability of antioxidants to scavenge free radicals has led to the suggestion that consuming large amounts of antioxidants may reduce free radical damage that leads to chronic diseases and aging.
And there’s no question that a diet that includes sources of antioxidants is necessary for good health. Indeed, studies have shown that cancer rates are lower in people with a diet rich in fruits and vegetables.
Not all roses
But the benefits of supplementing diets with additional antioxidants have yet to be demonstrated. In fact, some studies have shown that taking antioxidant supplements can sometimes increase the risk of cancer.
This could be because antioxidants can actually be harmful under certain conditions. In high concentrations, substances that normally act as antioxidants can have the opposite effect and act as a pro-oxidant. This may be because antioxidant compounds, such as vitamin C, react with other molecules in the body, not just free radicals.
Some of these reactions, such as Fenton reaction, actually produce additional free radicals. When antioxidant concentrations become too high, the free radical producing effect can outweigh the free radical scavenging effect.
Also, not all antioxidants are the same. each has unique chemical behaviors and biological properties. This means that no substance can replace the multiple functions of a variety of antioxidants.
A growing industry
Despite these uncertainties about their effectiveness, supplemental antioxidants are a booming industry, sold as a health panacea and added to a range of processed foods, including juices, cereals, chocolate bars and alcoholic beverages. .
But the benefits of antioxidant-rich foods are likely due to the overall nutrition that comes from eating a diet rich in natural, whole foods. Adding antioxidants to processed foods means that many healthy components of whole foods are missing.
Antioxidant supplements are therefore unlikely to be as effective in preventing disease as a healthy, varied and balanced diet. And while antioxidants can help protect the body against free radical damage, as is often the case in nutrition, more isn’t always better.
The myriad of other food components that are natural sources of antioxidants may also be responsible for their beneficial effects.
The best thing you can do for good health is to continue to eat between five and eight servings of fruit or vegetables each day and avoid unnecessary and potentially harmful supplements.
