Antioxidants: It’s More Than Vitamin CFayyaz Alam
- Free radicals cause direct damage to cell structures that trigger various diseases, including cardiovascular problems and neurodegenerative diseases.
- There are various types and different forms of antioxidants in nature, and each one of them has something distinct to offer and specific food groups you can target in your diet.
- Using antioxidants is associated with a plethora of health benefits, including the prevention of various types of cancer, Alzheimer’s disease, and improvements in physical performance.
- Each antioxidant substance has its own requirements to fulfill its effects, and there are ways to measure antioxidant capacity in foods.
- Using antioxidants is relatively easy because there are plenty of options and modalities according to your lifestyle and preferences.
Antioxidants are commonly known as a good thing, and you don’t need to be a doctor to know that. However, it is slowly transforming modern medicine. We have realized that chronic disease has much to do with unstable substances in the body called free radicals.
Free radicals are highly reactive molecules that lack an electron. They are always trying to balance their chemical structure by stealing electrons. Thus, free radicals interact with other biochemical substances and cause cellular damage. We always produce antioxidants, and they are essential to protect our bodies against microbes and other pathogens. There is also an innate production of antioxidants in the human body. However, lifestyle and environmental toxins commonly tip the balance in favor of free radicals and oxidative stress (1).
The benefits of antioxidants were detected by ancient cultures before their molecular mechanism was revealed by science. In the ancient Vedas, the oldest scriptures of Hinduism, it is described how food provides healing properties, including castor oil with its high levels of vitamin E, and ginger with gingerol, an antioxidant similar to that found in chili peppers. In the Indus Valley, the pomegranate was also highly valued. It was thought to treat heart and blood conditions, which is a very accurate statement given their limited understanding of the human body (2).
Nowadays, we know much about antioxidants, how they work, how to measure their activity, and their clinical applications. In this article, we are covering the topic of antioxidants thoroughly and briefly. You will find scientific facts and data you can confirm by yourself, and will realize how to apply science to our daily life.
There are many types of antioxidants
The primary purpose of antioxidants is scavenging free radicals and preventing cellular damage by neutralizing their chemical instability. It is possible to do this in various ways. Thus, there are three main types of antioxidants, followed by many subtypes.
Antioxidants can be either enzymes, molecules with no enzymatic activity, or single elements. They are very different from each other, as you can see next (2):
This type of antioxidant breaks down free radicals and removes them from the body. They convert your free radicals into an intermediary molecule (hydrogen peroxide) and then turn this molecule into water. In other words, they dissolve free radicals and neutralize them. An example of enzymatic antioxidants is glutathione peroxidase.
In contrast, non-enzymatic antioxidants do not break down or dissolve anything. They engage free radicals and stabilize the chemical structure of the molecule. As a result, it won’t seek an extra electron anymore. Examples of non-enzymatic antioxidants are beta-carotene, vitamin C, and vitamin E.
They are simple substances with potent antioxidant potential. In this group, we have selenium, copper, manganese, and zinc. They are single elements in the periodic table without much more to it. However, these elements boost the innate activity of enzymatic antioxidants.
Common and widely acclaimed antioxidants
Under the category of non-enzymatic antioxidants, there is a wide array of substances with varying molecular weight and chemical structure. We have phenols, anthocyanins, flavonoids, and many other subcategories.
They include vitamins, such as vitamin C and vitamin E, as well as substances such as Epigallocatechin gallate (EGCG), which is found in green tea. Others include cyanidin 3-glucoside, the most important polyphenol in elderberry.
Here is a non-exhaustive list of non-enzymatic antioxidants and how they work:
It is an essential micronutrient for human consumption and a potent free radical scavenger. It successfully neutralizes the most dangerous free radicals, including oxygen-derived species and hydrogen peroxide. It is one of the most affordable and efficient antioxidants. You can obtain vitamin C in broccoli, Brussels sprouts, spinach, and fruits like elderberry (3, 4).
It is a subgroup of vitamins that includes many different fat-soluble substances with potent antioxidant activity. They are very efficient in preventing the peroxidation of unsaturated lipids and reduces the incidence of various medical problems, including coronary heart disease and macular degeneration (5, 6).
A group of antioxidant substances capable of transferring hydrogen atoms to reactive oxygen groups (free radicals). They have a phenol group, which is an aromatic ring with a hydroxyl attached to it. The hydrogen atom that neutralizes free radicals usually comes from this hydroxyl group (7, 8).
They are natural pigments in plants that protect them against various environmental insults. They are common in the majority of berries. Anthocyanins are the reason why wine is different from other alcoholic beverages (9).
They are a subgroup of polyphenol substances with anti-inflammatory and antioxidant activity. Proanthocyanidins are made of many epicatechin units bound together, and they have been found to contribute to reducing the incidence of chronic disease in humans (10).
A very large group of molecules and secondary metabolites in plants. Flavonoids protect plants against environmental harm and free radicals. They are polyphenols. This means they have multiple phenol rings attached to their molecular structure (11, 12)
It is a subgroup of flavonoids found in chocolate and cocoa, and their molecular structure shares similarities to that of the rest of flavonoids. They are also known as flavan-3-ols, and they have subtypes as well, including epicatechin and catechin (13).
Antioxidant-rich foods and dietary choices
As you see, there’s a wide classification and subclasses of antioxidants. Thus, it might be confusing trying to choose the right food groups to obtain all of the benefits of different vitamins and phytonutrients. Is there a way to make it simple?
If you buy smart, you will have the full benefits of antioxidants without spending much. This is a list of must-have foods for your grocery store list and the antioxidants each one of them has.
Green leafy vegetables
Consuming green leafy vegetables every day is a great idea to replenish your levels of vitamin A, and vitamin C. Spinach and kale are among the most nutritional foods in this group. Due to its antioxidant nature, they have been studied for the prevention of heart disease and cancer (14, 15).
They have varied sources of antioxidants, according to each type. The most active antioxidants are found in berries (covered below), plums, apricot, and apples. You can have a great source of antioxidants in guava and mango, as well. They mostly contain phenolic compounds, including proanthocyanidins and flavonoids (15).
These fruits deserve special mention because they have the richest content of antioxidants in the whole spectrum of foods. You can find plenty of them in strawberries, which are more common than others. However, if you really want to obtain the best source of anthocyanins, you need to include others. So, look for rose hips (also known as god rose or Rosa canina), blackberries, and elderberry, which contain very high levels of anthocyanins and phenolic compounds (15, 16).
There are many spices you can add to your foods. In enhancing their flavor, some spices will also contribute to the antioxidant potential of your dish. Spices contain a lot of flavonoids and polyphenols. So, don’t refrain from using cloves, cinnamon, coriander, saffron, turmeric and ginger (15, 17).
Health benefits associated with use of antioxidants
Why would you take extra time to search for ingredients and learn new recipes?
Regardless of your age and preferences, antioxidants hold many different uses and health properties you can benefit from. We can highlight the following:
Many different clinical trials have been conducted to test antioxidants in cancer prevention. Free radicals contribute to DNA damage, which gives rise to various types of cancer. By neutralizing free radicals and boosting the immune response, antioxidants may be useful to reduce the incidence of various types of cancer (18).
Antioxidants and Alzheimer’s disease
Dementia, Alzheimer’s and Parkinson’s disease are all neurodegenerative disorders. In these ailments, free radicals increase the oxidation of proteins and lipids and accelerate the degenerative process. That is why it is possible to slow down the progression and reduce the incidence of these neurodegenerative diseases by using antioxidants (19).
Reduction of cardiovascular risk
Atherosclerotic plaques are created after lipid particles are oxidized by free radicals. This contributes to myocardial infarction and other cardiovascular problems. By reducing oxidative stress, antioxidants stand as a potential therapy and preventative measure for patients with a higher cardiovascular risk (20).
Skincare and aging
Our skin is the first defense barrier against the sun, environmental pollutants and free radicals all around us. All of these contribute to deteriorate the skin and induce premature aging. Antioxidants are becoming a promising solution to these problems in the cosmetic industry, and both topical and systemic applications can significantly improve our skin health (21).
Antioxidant benefits for athletes and physical performance
Exercise induces the creation of reactive oxygen species, one of the most active free radicals. Excessive production of these free radicals results in a reduction of physical performance. Thus, antioxidants are useful for athletes undergoing high-intensity physical activity, especially in cases of endurance exercise (22).
Is there a recommended dietary allowance? Any side effects?
The recommended dietary allowance (RDA) to obtain these health benefits is not always clear. And we cannot generalize because there are many types and subtypes of antioxidants. Instead, they are studied and recommended individually. For example, we know the RDA of vitamins A, C, and E, which depends on your gender and age. However, in general, some USDA researchers have suggested a daily intake of 3000-5000 Total ORAC of antioxidants. Of course, the more broad spectrum the antioxidant intake, the better.
Still, other substances besides vitamins have been studied thoroughly enough to provide a minimum dose to trigger significant effects in humans and a maximum dose to prevent toxicity. One clear example is EGCG in green tea among others, which has been found beneficial at a minimal dose of 400-500 mg. Still, in this case, a toxic dose is not completely clear and has been set to be 4.2 grams/m2 (23, 24).
Overdose and side effects depend on the substance and the mode of administration. It might include rash and allergies in cases of topical antioxidants, and mostly diarrhea and gastrointestinal complaints in oral antioxidants (23).
Is there a way to test antioxidant capacity?
Trying to test the antioxidant capacity of various foods and biological samples, a series of antioxidant assays have been developed over the years. They test different biochemical mechanisms, and each one of them measures total antioxidant capacity in different ways. So, you may have come across one of these nomenclatures before, and this is what they mean (25, 26):
It stands for Oxygen Radical Absorbance Capacity, and it uses a fluorescent molecule mixed with free radicals. The antioxidant would prevent the breakdown of the fluorescent molecule, and their action would be measured by the remaining fluorescence in the assay.
It stands for Total Radical-Trapping Antioxidant Parameter, and it is very similar to ORAC but more useful to measure antioxidant protection in plasma proteins.
It stands for Ferric Reducing Antioxidant Power. A spectroscopic assay that uses iron molecules and detects how antioxidants are capable of reducing them by using their electron-donor properties.
Total phenolic content
As mentioned above, phenol groups in biologically-active substances provide a powerful electron-donor property. Thus, what a total phenolic assay does is measure the concentration of phenols in a given substance or food.
It stands for Trolox Equivalent Antioxidant Capacity, and it is basically comparing the antioxidant capacity of a given substance with that of Trolox, an analog of vitamin E. This similar technique is applied in FRAP assays and others as well.
There are many types and subtypes of antioxidants, and each one of them has different properties. However, they all share the same principle and that is to neutralize free radicals. That is why all types of antioxidants are good and have specific purpose to protect the body from tissue damage, premature aging, cancer growth, and chronic disease. Antioxidants are readily available in nature, and one of the most important sources are berries. It is important to get the full array of antioxidants in your diet, by incorporating a broad spectrum of colorful berries, and combining them with high-quality whole-food based antioxidant supplements may optimize health positively.