Everything you need to know about antioxidant supplements

Taking antioxidant supplements is believed to prevent some of the damage caused by free radicals to our cells, thus promoting longevity and disease prevention. However, as with vitamins, taking antioxidant supplements in very large amounts can have some side effects.

Some years ago, antioxidants had an excellent reputation and foods that contained several such molecules were called “superfoods”, precisely because of their high antioxidant capacity. In 1991, an assessment tool called the Oxygen Radical Absorbance Capacity (ORAC) was developed by scientists at the US National Institute on Aging and the US Department of Agriculture (USDA) and used to measure the antioxidant capacity of food [1].

The USDA provided an ORAC database on its website, identifying foods that had a high ORAC rating, such as berries, spices, cocoa and legumes. Cranberries and berries were at the top of the list. However, 20 years later, the USDA abolished this database as it found that antioxidants were not always associated with free radical activity. This example shows that there are constantly new findings in the nutrition science that revise older views.

Oxidative stress

The body’s cells face a variety of threats, from a lack of nutrients to a virus infection. But there is also a constant threat posed by the normal process of metabolism, free radicals and other toxic molecules. The body creates free radicals as inevitable by-products of the conversion of food into energy.

There is a natural metabolic side effect of oxygen: oxidative stress. In mammals, under normal conditions, cells metabolize about 95% of oxygen in water without forming toxic intermediates. The research revealed the “paradox of O2”, that 5% of the amount of oxygen is metabolized in water but following four stages, of which in the first three they form certain toxic molecules such as free radicals – in the last stage water is formed . More free radicals are also obtained through exercise, exposure to cigarette smoke, air pollution and sunlight.

Free radicals, and reactive oxygen species in general (ROS) can, under certain conditions, be beneficial, e.g. used by the immune system as a way of attacking and killing pathogens. On the other hand, when these molecules are found in excess in the cells, they cause damage either directly or by acting as intermediate signals. This is called oxidative stress and can destroy proteins, lipids and nucleic acids leading to various diseases. Reactive nitrogen species (RNS) have similar behavior.

The body produces antioxidant enzymes to fight free radicals, three of which are basic: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). In addition to antioxidant enzymes, there are exogenous antioxidants obtained through diet. Three vitamins and one mineral have a direct antioxidant effect. Vitamins are beta carotene (a precursor to vitamin A), vitamin C and vitamin E, while the antioxidant metal is selenium. There are also minerals that are indirectly antioxidants, zinc, copper, manganese and iron, in the sense that they are incorporated into the body’s antioxidant enzymes, promoting the body’s antioxidant capacity. Other vitamins such as K, D, niacin, pyridoxine and riboflavin may have antioxidant potential.

Antioxidants are also phenolic compounds, such as quercetin (found in apples, red wine, onions), catechins (found in tea, cocoa, berries), resveratrol (red wine, grapes, peanuts, berries), coumaric acid ( spices and berries), and anthocyanins (blueberries and strawberries). In addition to β-carotene, other carotenoids have antioxidant activity, for example lycopene, lutein and zeaxanthin.

Antioxidant supplements

Antioxidant supplements are popular and this is due to the fact that fruits and vegetables, which are rich in antioxidants, are associated with many health benefits. These supplements contain concentrated forms of antioxidants that keep cells healthy because they fight free radicals. The general public began to hear more about antioxidants in the 1990s, when free radicals were linked to atherosclerosis, vision loss and a host of other chronic conditions.

However, clinical trials on the benefits of individual antioxidants in the form of supplements have not lived up to expectations. The beginning was made with β-carotene and vitamin E. The results of the research were mixed, and most studies did not find the expected benefits. Vitamin E and other antioxidant supplements have not been shown to protect against heart disease or cancer. One reason may be that vitamin E is made up of eight slightly different molecules present in food while dietary supplements usually contain only one form, alpha-tocopherol [2].

Some studies have also reported beneficial properties of β-carotene, for example, after 18 years of follow-up by thousands of physicians, beta-carotene supplementation was found to be associated with a moderate reduction in cognitive impairment [3].

Using an antioxidant supplement that contains a single substance may not be an effective disease prevention strategy. For example, a cup of fresh strawberries contains about 80 mg of vitamin C, which has a high antioxidant effect. But a dietary supplement containing 500 mg of vitamin C does not contain the polyphenols found in strawberries which also have antioxidant activity and work together with vitamin C to fight disease. Taking just some antioxidants may not work. For example, vitamin C neutralizes certain free radicals, as does vitamin E, but the body may need a balance of many antioxidants.

Some people believe that there may be “bad” and “good” free radicals and that the body needs, as a point, oxidative stress. Free radicals are more than just toxic molecules as they are involved in certain signaling. Studies have shown that exposing cells to very high concentrations of antioxidant supplements (including vitamins C and E) can partially block certain signals and therefore inhibit favorable physiological adaptations that occur during exercise. So if antioxidant supplements are consumed in very large quantities they can have side effects. This is known to happen with vitamins or minerals. Vitamin A is important for fetal development, but in high doses through supplements it can increase the risk of genetic abnormalities. Almost any nutrient can have side effects in large doses and antioxidants may be no exception.

Another review and meta-analysis published in 2017 examined the role of antioxidants in patients with type 2 diabetes (these patients have greater oxidative stress). The results revealed that supplementation of certain vitamins, and moreover vitamin E, can have a significant effect on antioxidant status and glycemic control, benefiting diabetics [7].

In conclusion, to minimize the chronic damage of oxidative stress, follow a variety in your diet, including seeds, whole grains, legumes, fruits and vegetables of different colors [8]. Taking antioxidant supplements makes sense in case of deficiencies while a moderate dosage is recommended [9]. According to one study, antioxidant intervention, when based on specific deficiencies, has a positive effect [10]. The antioxidant therapeutic utility against cancer and aging still has many open fronts and should be further explored in future studies.

At Vita4you.gr you will find a variety of antioxidant supplements!

References

1. USDA Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 (2010).
2. National Center for Complementary and Integrative Health (NCCIH). Antioxidants: In Depth.
3. Grodstein F, Kang JH, Glynn RJ, Cook NR, Gaziano JM. A randomized trial of beta carotene supplementation and cognitive function in men: the Physicians’ Health Study II.
4. Antioxidants, free radicals and melanoma spread – what’s going on?.
5. Antioxidants as precision weapons in war against cancer chemotherapy induced toxicity – Exploring the armoury of obscurity.
6. Antioxidants: Positive or Negative Actors?
7. Weighing the Benefits of Dietary Antioxidant Supplements.
8. Antioxidants in Personalized Nutrition and Exercise.