It seems that almost daily we’re bombarded with food and marketing that claims “superior” anti-oxidant health benefits. But in the process of reading about all these super-foods, have you ever questioned what exactly antioxidants do?
To understanding their importance we first need to dig a little deeper and gain some basic knowledge about anti-oxidants’ counterpart – free radicals. Antioxidants are generally cast as nutritional heroes, whereas free radicals are viewed as villains, but in reality, both are essential to health. Neither is inherently good or bad.
Our diet and lifestyle choices, however, are critically important because those choices maintain the healthy balance between the two. Particularly when it comes to ensuring that free radicals don’t become overrepresented.
What are Free Radicals?
Briefly speaking, a free radical is a molecule with an unpaired electron in its atomic orbit – which basically means it’s missing an electron. This makes it unstable and highly reactive. Free radicals seek stability, which they can attain by “stealing” electrons from nearby molecules. When this happens, the “victimized” molecule itself becomes a free radical. It too must attain stability by stealing an electron from yet another nearby molecule.
As you can see, a single free radical is capable of initiating a debilitating chain reaction. Luckily, free radicals can be neutralized by coming into contact with special molecules, broadly referred to as antioxidants, which have extra electrons to “donate.”
Most free radicals are oxygen-derived molecules, although nitrogen-derived molecules are also significant. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generally seen as dangerous compounds, but they result from normal metabolic processes and actually provide some health benefits.
“As usual, it’s a case of everything in moderation,” says Håkan Westerblad, a Professor in the Department of Physiology and Pharmacology at the Karolinska Institutet. “In normal conditions, free radicals act as important signal substances, but very high levels or long-lasting increases can lead to disease.1 In 2011, Westerblad led a study demonstrating that free radicals have essential modulatory roles – for example, causing the heart to beat with the correct force.2
A disproportionately high level of free radicals leads to a condition called oxidative stress. Chronic oxidative stress can cause serious cellular damage, including:
- Miscoding or otherwise damaging DNA3
- Making LDL more likely to accumulate along arterial walls4
- Structural changes to cell proteins and corresponding losses of enzyme activity5
- Damage to cell membranes, thus changing the flow of inter- and intracellular materials and possibly accelerating the aging process6
In both the scientific literature and popular media, oxidative stress, caused by excessive free radicals, has been implicated in a long list of degenerative diseases7, including the following.
- All inflammatory diseases (arthritis, vasculitis, glomerulonephritis, lupus erythematous, adult respiratory diseases syndrome)
- Ischemic diseases (heart diseases, stroke, intestinal ischema)
- Acquired immunodeficiency syndrome (AIDS)
- Gastric ulcers
- Neurological disorders (Alzheimer’s disease, Parkinson’s disease, muscular dystrophy)
- Smoking-related diseases
Remember that free radicals are not a problem in themselves as long as they are kept in check. Normal metabolic functions produce free radicals, but so do external factors including poor diet and lifestyle choices. Consequently, unhealthy choices can greatly tip the balance toward oxidative stress.8,9,10,11 Some of these external factors include:
- Exposure to X-rays
- Air pollutants
- Industrial chemicals
- Exposure to heavy metals (arsenic, lead, cadmium, chromium, and mercury)
- Excessive consumption of omega-6 fatty acids (seed oils are the most significant source in Western diets)
- Excessive consumption of sugar
Antioxidants: The Counterbalance
Thousands of different molecules serve as antioxidants, including various vitamins, minerals, peptides, and fatty acids. What they all have in common, and what makes them antioxidants, is their ability to “donate” electrons to free radicals without becoming free radicals themselves. We can broadly categorize antioxidants as either,
- Non-enzymatic antioxidants, or
- Enzymatic antioxidants.12
Antioxidants from food sources are non-enzymatic antioxidants. They work by interrupting free radical chain reactions. Examples include vitamin A, vitamin C, vitamin E, polyphenols, flavonols, and carotenoids.
Non-enzymatic antioxidants are generated within the body. Their role is to break down and eliminate free radicals. To work properly, enzymatic antioxidants typically require key minerals, called cofactors, to function. These minerals include zinc, iron, and magnesium. Examples of non-enzymatic antioxidants include superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx).
How Much is Too Much?
As with most nutrients, antioxidants have a “Goldilocks zone.” In other words, consuming too few causes problems as does consuming too many. Luckily, the “just right” zone is easily accomplished through a whole-foods Paleo diet. Whereas overconsumption is unlikely via food, high-dose antioxidant supplements can have harmful effects, including:13
- Pro-oxidation: damage to DNA, proteins, lipids, etc.
- Pro-glycation: glycation of proteins and DNA
- Nitrosative stress: excessive production of reactive nitrogen species (RNS)
- Inflammation: increase in pro-inflammatory compounds
- Endocrine disrupting activities
Supplements linked to the above effects include vitamin C, vitamin E, and beta-carotene, all of which are readily accessible through food. According to a 2010 review, “[Antioxidant] compounds within plant foods may therefore be considered as being more safe and healthy compared to isolated, high doses, such as present in supplements.”14 Similarly, a 2012 review observed that tinkering with the delicate balance between antioxidants and reactive species can promote antioxidant-induced stress. The authors concluded, “the best advice would be to ingest antioxidants from food sources rather than from self-prescribed supplements.”15
Keeping the Balance
Normal physiology requires free radicals and antioxidants to engage in a perpetual ebb-and-flow dance. You can think of yourself as the leader the band. Your job is to keep the music going, thereby keeping the crowd entertained and ensuring a harmonious flow of events. In practical terms, this means you must limit your exposure to external factors that promote free radicals while consuming a broad array of antioxidant-containing foods, particularly vegetables, fruit, nuts, omega-3-rich seafood, and more. Fortunately, keeping this balance is as easy as following the Paleo Diet.