For a long time, antioxidants have been considered to be one of the leading approaches in reducing chronic health conditions… but what if I told you that they actually may be causing more harm than good? In this blog we’ll give you the ins and outs of what antioxidants actually are, how they may be both good and damaging to your health based on the current science and whether you should be supplementing or getting them from foods.

What are antioxidants? 

Antioxidants are compounds that can be both man made or found naturally in foods that we eat such as fresh fruit and vegetables, nuts, whole-grains, some meats, poultry and fish. Some of the more well-known antioxidants include nutrients such as vitamin A, vitamin C, vitamin E, copper, zinc, and selenium (1).

What happens if you don’t get enough antioxidants?

We can’t talk about antioxidants without first explaining what both free radicals and oxidative stress are! Oxidation is a chemical reaction that involves the moving of (or loss of) electrons. It is normal bodily process, however, results in the damage of cells and DNA in the body. When this ‘oxidation’ occurs, it creates unstable molecules called ‘free radicals’, that steal electrons from other molecules, this is where the damage occurs (aka oxidative stress)! 

Confused? Think about it like this. You go to the big dance with your date, then someone comes along and steals your date – you are now the free radical because your date is gone (sorry!). Now these free radicals aren’t all that bad, in fact your body can cope with some free radicals. However, complications can arise when there is an overload of free radicals causing oxidative stress (2).

Oxidative stress is believed to play a role in a variety of diseases including cancer, cardiovascular disease, diabetes, Alzheimer’s disease, Parkinson’s disease eye diseases such as cataracts and age-related macular degeneration, and advanced ageing (3).

Your body can also be exposed to free radicals from a variety of environmental sources, such as cigarette smoke, air pollution, and sunlight.

What does the science have to say about antioxidants? 

Research into how antioxidant rich foods may protect against disease has been ongoing for more than 70 years and is one of the most researched aspects in nutritional science. 

Antioxidant molecules have shown to counteract oxidative stress in lab studies (eg. in animals and cells). However, whether consuming large amounts of antioxidants through supplements is beneficial for health is up for debate! Furthermore, consuming antioxidant supplements in excessive doses may actually be harmful! (4)

Observational studies have indicated that people who consume more vegetables and fruits had a lower risk of many diseases that include cardiovascular disease, stroke, cancer and cataracts. The problem is that these studies can’t identify one single factor (eg. antioxidants) as the reason for the reduction in these disease (5)

For example, people who ate more of these antioxidant rich foods may also exercise more, drink less and smoke less that are also factors that have health benefits (that’s why we can’t say for certain that it’s the antioxidants!). This is where clinical studies come into play (skip the next two paragraphs if you find this stuff boring...)

Studies for antioxidant supplements

• The Age-Related Eye Disease Study (AREDS) found a that a combination of antioxidants (vitamin C, vitamin E, and vitamin A) and zinc reduced the risk of developing the advanced stage of age-related macular degeneration by 25 percent in people who had the intermediate stage of this disease or who had the advanced stage in only one eye. Antioxidant supplements used alone reduced the risk by about 17 percent. In the same study, however, antioxidants did not help to prevent cataracts or slow their progression (6).

Studies against antioxidant supplements

• 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. (7)
• The Women’s Antioxidant Cardiovascular Study found no beneficial effects of vitamin C, vitamin E, or beta-carotene (vitamin A) 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 brain function among women in this study who were aged 65 or older (8).
• 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 haemorrhagic stroke in this study (9).

So why don’t antioxidant supplements work?

So, based on this evidence it’s pretty clear that antioxidant supplements are likely to do more harm than good… but why? Let’s break it down.

• The beneficial health effects of a diet high in antioxidant rich foods may have to do with other nutrients found in the same foods, other dietary factors or lifestyle choices rather than antioxidants.
• The dosages of antioxidants in the studies are much larger than smaller amounts typically found in foods.
• Differences in the types of antioxidants found in foods compared to supplements (eg. there are 8 forms of vitamin E found in foods, whereas studies typically use only one).
• Specific antioxidants may be more effective for specific diseases. For example, antioxidants that are present in the eye such as lutein (type of vitamin A) may be more effective than antioxidants not found in the eye such as beta-carotene (type of vitamin A).
• The relationship between free radicals and health is far more complex than we think. For example, free radicals may be beneficial in certain circumstances.
• Studies assessing antioxidants may not have had a long enough time to have a beneficial effect on chronic diseases that typically develop over decades. 

What’s the take home message?

Based on the current evidence antioxidants may be doing more harm than good when consumed as supplements. Once again nature is smarter than human! Considering the positive effects of high intakes of fruit and vegetables in reducing chronic health conditions, it’s probably best to get your antioxidants through your diet. Food is always the number one priority and supplementing secondary if you are unable to obtain those nutrients in certain circumstances (eg. sometimes a vegan/vegetarian diet).

If you have any questions or would like to are interested in a nutrition consultation, feel free to email our head nutritionist Ben at ben@13seeds.com.au

Disclaimer:

This article does not constitute medical advice and does not take into consideration your personal circumstances. Please see your medical professional before implementing the above. 

References:

1. https://www.nccih.nih.gov/health/antioxidants-in-depth
2. https://www.sciencedirect.com/science/article/abs/pii/S1369527499800332
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5927356/
4. https://pubmed.ncbi.nlm.nih.gov/21207517/
5. https://pubmed.ncbi.nlm.nih.gov/22684631/
6. https://www.nei.nih.gov/research/clinical-trials/age-related-eye-disease-studies-aredsareds2
7. https://pubmed.ncbi.nlm.nih.gov/18067963/
8. https://pubmed.ncbi.nlm.nih.gov/17698683/
9. https://pubmed.ncbi.nlm.nih.gov/19066368/