All About Antioxidants

There are many reasons to consume foods such as fruits and vegetables: fiber, water, vitamins and minerals are all important.  If you’ve reached for a fruit or vegetable in your life (and god I hope you have), then antioxidants are a familiar buzzword.

The consideration for antioxidants really picked up traction in the 90s, when researchers were looking for contributing factors to heart disease and atherosclerosis. Participants in the trials who consumed more fruits and vegetables had lower risk of these diseases. Since these individuals were consuming more antioxidants, it was posited that they had the capacity to lower risk of disease.

Unfortunately like with many studies, correlation does not equal causation and antioxidants like beta-carotene did not have any inhibitory effect on heart disease. As in the claims that people who eat meat are less healthy (as evidenced by higher risks of disease for meat eaters), it has to do with correlating factors like meat eaters tend to smoke more, drink more, exercise less and consume more calories.  So if you eat meat, don’t smoke, exercise and live a healthy lifestyle there are really no indicators that you are at risk of anything.

In fact, most data will always have something that contradicts it in some way.  For instance, there are higher incidences of mental illness and depression with vegetarians and vegans.  Clearly being vegan doesn’t cause mental illness or depression directly but there may be outside influences that correlate meat-avoidance with decreased mental health.

The problem with assuming people who do “X” experience “Y” directly because of “X”, misses the point that there are dozens if not hundreds of contributing factors to health outcomes that cannot be pinpointed to one specific choice.

Alas, the obsession with antioxidant consumption stuck in our zeitgeist and many products tout their antioxidant content on shelves in every grocery store. Personally, I love the idea that consuming fruits or veggies “boosts” the immune system like it’s a battery being recharged. It’s a fun mental image but does not convey what’s happening physiologically.

What are antioxidants?

Antioxidants are substances, man-made or naturally occurring, that help prevent or slow damage to cells caused by free radicals. Fruits and vegetables are specifically high in antioxidants alongside dark chocolate, tea and coffee.

What are free radicals?

Free radicals are molecules produced by cells from breaking down food, exercising or environmental factors like smoke, sunlight and pollution.

Free radicals can cause oxidative stress on cells, which damages them. Now, oxygen metabolism itself causes some free radical production but many outside influences compound this (like smoking) which causes an imbalance between free radical production and clearance.

Mitochondria, which are the energy-producing organelle of the cell produce free radicals. Some other cellular organelles help clear them but not enough to do the job; enter antioxidants.  These help put the system back into balance, reducing free radical damage to cells. Unchecked, high oxidation rates from free radical damage can cause induction of disease and speed up the aging process.

Here are some causes for high free-radical production:

  • cigarette smoke
  • pollution
  • alcohol intake
  • toxins
  • high blood sugar levels
  • high intake of polyunsaturated fatty acids
  • radiation, including excessive sunbathing
  • bacterial, fungal, or viral infections
  • excessive intake of iron, magnesium, copper, or zinc
  • intense and prolonged exercise, which causes tissue damage
  • excessive intake of antioxidants, such as vitamins C and E
  • antioxidant deficiency

How antioxidants balance free radicals

Free radicals are damaging because these molecules have an unpaired electron; most molecules have electrons in pairs, making them stable. With an unpaired electron, these free radicals are unstable and attack cellular components causing damage and stress. Unchecked, free radicals can scavenge electrons from other molecules and produce more free radicals.  Yikes!

Antioxidants neutralize free radicals by breaking them down or providing the missing electron. Since we use antioxidants to combat free radicals, we need to produce and consume them.​​​​​​​

Normal breathing, metabolism of food, exercise, sun exposure and more daily functions cause some sort of free radical production which our bodies can balance.  With high pollution exposure, smoking or obesity for example, we cause an imbalance in free radical production and neutralization which puts greater oxidative stress on the body. This accelerates disease and aging.

Antioxidants are necessary, but supplements don’t really work

Clearly antioxidants are necessary and a critical component of our health and immunity. Knowing that excess free radical formation and oxidative damage accelerates disease and aging, it would make sense that supplementing with antioxidants would have, if nothing else, protective benefits on our health.

Despite the National Institute of Health (NIH) conducting clinical trials on thousands of participants, results have been very disappointing.

Taken directly from the NIH:

  • The Women’s Health Study, which included almost 40,000 healthy women at least 45 years of age, found that vitamin E supplements did not reduce the risk of heart attack, stroke, cancer, age-related macular degeneration, or cataracts. Although vitamin E supplements were associated with fewer deaths from cardiovascular causes, they did not reduce the overall death rate of study participants.
  • The Women’s Antioxidant Cardiovascular Study found no beneficial effects of vitamin C, vitamin E, or beta-carotene supplements on cardiovascular events (heart attack, stroke, or death from cardiovascular diseases) or the likelihood of developing diabetes or cancer in more than 8,000 female health professionals, aged 40 years or older, who were at high risk for cardiovascular disease. Antioxidant supplements also did not slow changes in cognitive function among women in this study who were aged 65 or older.
  • The Physicians’ Health Study II, which included more than 14,000 male physicians aged 50 or older, found that neither vitamin E nor vitamin C supplements reduced the risk of major cardiovascular events (heart attack, stroke, or death from cardiovascular disease), cancer, or cataracts. In fact, vitamin E supplements were associated with an increased risk of hemorrhagic stroke in this study.
  • The Selenium and Vitamin E Cancer Prevention Trial (SELECT)—a study of more than 35,000 men aged 50 or older—found that selenium and vitamin E supplements, taken alone or together, did not prevent prostate cancer. A 2011 updated analysis from this trial, based on a longer followup period of study participants, concluded that vitamin E supplements increased the occurrence (my emphasis) of prostate cancer by 17 percent in men who received the vitamin E supplement alone compared with those who received placebo. There was no increase in prostate cancer when vitamin E and selenium were taken together.

Reasonable conclusions

As stated by the NIH, there are several factors which may explain why simply taking an antioxidant supplement does not prevent disease.

For one, the chemical composition of supplement vs naturally occurring antioxidants can play a role. Amounts found in food are typically much lower than in supplements and specific dosing (less vs more) might play a role in effectiveness.

Specific antioxidants may play more critical roles in disease prevention and simply giving a standard dose to thousands of participants might not be specific enough to address individual needs.

Time also plays into effectiveness.  Even a three year trial may not replicate the benefits of a lifetime consuming fruits and vegetables in one person and almost none in another.

Like the research on meat consumption and disease, simply focusing on antioxidants might not be effective enough.  Fruits and vegetables contain vitamins, minerals, fiber, water and help off-set more calorie dense foods.  Perhaps these factors contribute or play a larger role in disease prevention.

Lastly, and this is my favorite:

“The relationship between free radicals and health may be more complex than has previously been thought. Under some circumstances, free radicals actually may be beneficial rather than harmful, and removing them may be undesirable” (NIH, November 2013)

Sometimes we’re so smart that we’re dumb

To sum it up, these trials did not produce promising results and some actually showed an increase in disease risk with excess antioxidants. I am grateful that the authors concluded that not only are there many correlating factors but that we simply don’t have enough information yet to say why antioxidant supplements don’t work.

I feel that this perfectly encapsulates so much of the fitness and nutrition industry.  Something like consuming fruits and vegetables is good for us and marketing takes one aspect like antioxidants and promotes them as our savior.  Despite not having evidence and overlooking very basic factors like low-calorie density and high fiber density, fruits and vegetables are reduced to how chock full of antioxidants they are rather than excellent sources of nutrients and fiber that happen to be low in calories.

We have so much technology and science to explain our food, physiology and health.  But often we miss the forest for the trees simple because society becomes reductionist. We want things to be simple so we can make easy, informed choices. In that reductive path it’s far too easy to focus on one exciting variable but miss that the sum is more effective than it’s parts.


Exercise burns calories, burning calories helps you lose weight, being leaner is healthier thus calorie burn from exercise is all that matters.


Exercise burns calories but also encourages muscle mass gain. More muscle means more glucose disposal and strength as we age. We also lean out which helps improve glucose disposal and stress on the system. Training the cardiac system reduces our resting heart rate and blood pressure which is great for health. Exercise is also social which is excellent for our psychology. Achieving goals in the gym is a great way to build confidence.

Antioxidants are a crucial part of our function and health and consuming fruits, vegetables, chocolate, tea and coffee helps contribute to that system. However, trying to overload that one component of our cellular health has proven to be less beneficial than focusing on the habitual nature of consuming those foods.

If you’re consuming fruits and veggies habitually, you’re there. Don’t waste energy and resources trying to rig the system with antioxidant supplements, at least until research can give us more hard data. Forest > tree!