Antioxidants and free radicals often come up in conversations pertaining to disease and aging. The reason for this is that, unlike trace minerals, free radicals have the freedom to roam throughout the body and cause damage. However, antioxidants serve as defenders of the body’s cells by blocking free radicals’ effects.
As you may have guessed, fruits and vegetables represent the best sources of antioxidants. And in addition to that, fruits and vegetables supply high amounts of vitamins, minerals, and fiber which contribute to fighting disease and slowing the aging process as well.
What You’ll Learn
This article explains all you need to know about free radicals, antioxidants, and their roles in causing or preventing disease, respectively. You will also find a convenient list of which fruits and vegetables provide reliable supplies of antioxidants along with easy ways to add them to your diet.
What are Free Radicals and where do they come from?
Free radicals are molecules that have become electrically charged and thus unstable. In an effort to lose their charge, free radicals interact with other molecules found in cells and that interaction results in damage to the molecule, cell, or both. One example of a molecule that free radicals interact with is DNA. This process is especially harmful to the body because it can produce a domino effect in which molecules damaged by free radicals then become free radicals themselves.
We digest the food we eat between our mouth, stomach, and small intestine. Then, we absorb nutrients from the food from our large intestine and into our bloodstream. Our bloodstream delivers those nutrients to our cells which convert those nutrients into energy. Each of these main events consist of many steps, but this process is collectively referred to as metabolism.
Metabolism is all about breaking down larger units, like carbohydrates and proteins, into smaller units, like glucose and amino acids. Accordingly, some byproducts are formed during the process and free radicals are among them. It is important to point out that free radicals are a natural product of metabolism and thus serve some functions in the body which are essential for overall health. An example of this is the immune system’s use of free radicals to fight bacterial infections.
When it’s Problematic
Free radicals become problematic only when their concentration exceeds the body’s concentration of antioxidants. In that case, free radical removal has either slowed or is not occurring at all allowing them more time to damage the body. This imbalanced ratio of free radicals to antioxidants is referred to as oxidative stress. Yet, excess free radicals in the body usually do not come about by metabolism alone. Indeed, several other lifestyle and environmental factors contribute to oxidative stress including:
- Air pollution exposure
- Alcohol consumption
- Antioxidant deficiency
- Bacterial, viral, or fungal infection
- Excessive sun exposure
- First- or second-hand cigarette smoke
- Heavy metal toxicity
- High blood sugar
- Oxygen toxicity or oxygen deficiency
- Prolonged, intense exercise
- Trace mineral toxicity (copper, iron, magnesium, zinc)
It is this oxidative stress that induces lung disease, heart disease, and several forms of cancer while speeding up the aging process.
What makes an Antioxidant…an Antioxidant?
Many antioxidants exist and there is really no laboratory test available to determine whether or not a compound is an antioxidant. Instead, researchers must monitor how a compound acts in the digestive system, blood stream, and whichever organ it concentrates in to determine if it functions as an antioxidant.
Alternatively, it is much easier to observe how the body responds to specific foods. If a specific food generates antioxidant-like activity, then researchers are able to at least narrow down which foods must contain antioxidants. One particular technique researchers use to evaluate the antioxidant capabilities of a particular food is called the Oxygen Radical Absorbance Capacity (ORAC) assay.
The ORAC assay essentially tests the effects of different foods against the same free radical called peroxyl radical. Nevertheless, a new method based on the ORAC assay is now used to test potentially antioxidant-rich foods against the free radicals most commonly found in the human body. The new method is called Oxygen Radical Absorbance Capacity using Multiple Radicals (ORAC-MR) and it tests against these free radicals:
- (ROS) Reactive oxygen species – peroxyl radical, hydroxyl radical, superoxide anion, singlet oxygen
- (RNS) Reactive nitrogen species – peroxynitrite
- (RCS) Reactive chlorine species – hypochlorite
Research studies indicate that superoxide anion functions to form other free radicals in the body making oxidative damage that much more widespread. Therefore, ORAC-MR has been especially helpful for discovering food with antioxidant activity that can combat superoxide anion, specifically.
How Antioxidants Fight Free Radicals and Their Classifications
Antioxidants fight free radicals by giving free radicals what they need to no longer be electrically charged. This process is called neutralization and it prevents free radicals from causing damage. One of the most effective antioxidants for this process is glutathione.
Glutathione is an antioxidant made by the body; nevertheless, antioxidants are so essential to overall health that they are found in a variety of animal and plant products. This fact describes one of the fundamental reasons why it is important that our diet consists of a variety of foods of animal and plant origin. The greater the variety of food consumed, the more antioxidants individuals obtain from their diet.
All in the Food
Other powerful antioxidants include vitamin C and vitamin E. These as well as other antioxidants are abundant in the following foods:
- Fruits (especially berries)
- Meat and fish products
- Green tea
- Dark chocolate
The effectiveness of antioxidants in fighting free radicals and slowing aging makes them ideal preservatives in packaged foods as well. For this reason, you may see vitamin C listed among the ingredients of many processed foods.
Also, make sure not to overlook herbs and spices; as, they often supply a high number of antioxidants. These herbs and spices include:
Antioxidants can be classified into two main groups: fat-soluble and water-soluble. Fat-soluble work mostly within the fatty layer that surrounds cells called the cell membrane. Water-soluble work either inside the cell membrane (within the cell) or outside the cell membrane.
After glutathione, the next most powerful antioxidants are as follows:
- Vitamin A, a fat-soluble antioxidant absorbed from the diet
- Vitamin C, a water-soluble antioxidant absorbed from the diet
- Flavonoids, a family of antioxidants
- Vitamin E, a fat-soluble antioxidant also absorbed from the diet
- Selenium, a trace mineral with significant antioxidant properties
Plentiful Sources of Antioxidants
While glutathione is made in the body, other antioxidants are obtained from your diet. Here are some foods you should eat daily to maintain a regular supply:
- Apples (including the skin)
- Bell peppers
- Berries – blackberries, cranberries, raspberries, and strawberries
- Citrus fruits – grapefruit, kiwi, lemons, limes, and oranges
- Ground flaxseed
- Legumes – edamame, kidney beans, lentils
- Red cabbage
- Red wine
- Sesame seeds
- Stone fruits – apricots, cherries, nectarines, peaches, plums, and prunes
- Sunflower seeds
- Sweet potatoes
- Tropical fruits – banana, dates, guava, and mango
- Whole grains
Eating these foods raw as a snack or as a topping on cereal, oatmeal, or salad will increase your chances of absorbing their maximal antioxidant content. Additionally, lightly cooking these foods along with some of your favorite recipes will still provide your body with a beneficial supply of antioxidants. Overall, you should strive to eat five to seven servings of fruits and vegetables every day. The more colorful they are the better, as their bright coloration indicates a higher concentration of antioxidants.
What about Antioxidant supplements?
As someone once said, “Too much of a good thing can be bad for you.” And this is certainly the case for antioxidants. You will find antioxidant supplements available for purchase, but they are not the most ideal way to optimize your body’s antioxidant level. Thus, it is best to consult a medical professional prior to using supplementation for any nutrient deficiency.
Similar to vitamin or nutrient toxicity, it is possible to induce a toxic state within the body from antioxidants. While an excess of them may sound like a good thing, it can actually be quite harmful to your health and potentially fatal. As a matter of fact, some research studies show that antioxidants supplied by the diet were more effective in reducing oxidative damage than antioxidants supplied by a supplement. This means you will likely need to take more doses of supplemented antioxidants to get the same benefits that of dietary.
In other words, you are at a greater risk of toxifying your body with antioxidants from a supplement than you are with antioxidants from the diet. If you are going to take any supplement for your health, a multivitamin is usually the safest. Multivitamins offer lower doses of vital vitamins and nutrients, so it is harder to develop toxicity. Still, multivitamins are expected to simply fill in what you are not getting from your regular diet. So, start adding antioxidant-rich foods to your diet today and you most likely will not need an antioxidant supplement at all.
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Ou, B., & Nemzer, B. (2014). ORAC using multiple radicals (ORAC-MR): New horizons in total antioxidant capacity measurement. Nutraceuticals World, 17(2): 50-52.