The importance of antioxidants – written by Anita László

What is the relationship between free radicals and antioxidants?

Throughout our lives, the cells of our body are exposed to many threats, including the negative effects of free radicals, which, in large quantities, can damage cells and genetic material.

Free radicals are unstable molecules that are produced by the body in response to environmental factors and various forms of stress. The presence of free radicals can increase the likelihood of inflammation and have adverse effects on human health. Free radicals can also be generated during some metabolic processes as the conversion of nutrients into energy, or as a result of environmental influences. Factors contributing to the increased formation of free radicals in the body include inflammatory processes, polluted environments, ultraviolet radiation and smoking. The inefficient processing and removal of free radicals leads to oxidative stress, which can damage our cells and body functions. Factors that can trigger oxidative stress include mitochondrial activities, excessive training, tissue damage, consumption of certain foods (refined and ultra-processed foods, trans fats, artificial sweeteners and additives), smoking, environmental pollution, radiation, chemicals and ozone. Researchers have found links between oxidative stress and a number of health problems, including cardiovascular disease, cancer, visual impairment, arthritis, stroke, respiratory disorders, immune deficiencies, Parkinson’s disease and various other inflammatory processes.

Antioxidants are substances that can inhibit or mitigate cell damage caused by free radicals. They can come from natural or synthetic sources. These beneficial substances have external sources such as certain plant foods that are high in antioxidants, but the human body can also produce them, they are known as endogenous antioxidants. The purpose of antioxidants is to facilitate the neutralisation of free radicals in the human body and protect against cellular damage caused by them, thereby potentially improving overall health. Some studies suggest that dietary supplements containing antioxidants may help reduce vision impairment in older adults due to age-related macular degeneration. However, there is little convincing evidence to support the claim that increased intake of specific antioxidants can reduce the risk of the disease, and in many cases the results are contradictory.

What are the types and sources of antioxidants?

It is thought that there are thousands of compounds that can act as antioxidants. Each compound has a specific role, but can interact with other substances to facilitate optimal physiological function. The word ‘antioxidant’ itself does not specifically refer to a single compound, but rather describes the functional capabilities of different substances.

Antioxidants from external sources include: vitamin A, vitamin C, vitamin E, beta-carotene, lycopene, lutein, selenium, manganese and zeaxanthin. Antioxidants from plant sources include flavonoids, flavones, catechins, polyphenols and phytoestrogens. Each antioxidant has a unique role and is not interchangeable with any other; hence, it is important to consume a great variety of foods. The best sources of antioxidants are plants, especially fruits and vegetables. Foods that are rich sources of antioxidants are often referred to as ‘superfoods’ or ‘functional foods’.

Some examples of wantioxidants and their dietary sources:

– Vitamin A: dairy products, eggs and liver

– Vitamin C: fruits and vegetables (berries, oranges and peppers)

– Vitamin E: nuts, seeds, vegetable oils and leafy green vegetables

– Beta-carotene: brightly coloured fruits and vegetables (carrots, peas, spinach and mangoes)

– Lycopene: pink and red fruits and vegetables (tomatoes and melons)

– Lutein: green leafy vegetables, corn, papaya and oranges

– Selenium: rice, corn, wheat and other whole grains, as well as nuts, eggs, cheese and legumes

Other food sources that are beneficial due to their high antioxidant content: aubergines, pulses, green and black teas, grapes, dark chocolate, pomegranates and goji berries.

The relationship between the colour of different foods and their antioxidant capacity is significant. Research has shown that certain shades of colour indicate higher antioxidant levels: dark blue and purple plants rich in anthocyanins are higher, while shades of green and yellow tend to indicate lower levels. Blueberries, blackberries, apples, broccoli, spinach and lentils are known to be great sources of antioxidants.

It’s not just the colour of the ingredients that matters, but also the way the food is prepared, as the latter can increase or decrease antioxidant levels. Lycopene is the antioxidant responsible for the rich red hue of tomatoes. It is important to know that heating can increase the bioavailability of lycopene. In contrast, research has shown that the antioxidant activity of cauliflower, peas and courgettes is significantly reduced during the cooking process. It is worth stressing that a varied consumption of cooked and raw antioxidant-rich foods is of paramount importance.

How to increase antioxidant intake?

– Include a fruit or vegetable with every meal

– Drink some green or matcha tea daily

– Have as many colourful plant-based ingredients as possible on your plate

– Use spices such as turmeric, cumin, oregano, ginger, cloves or cinnamon to improve the taste and antioxidant content of your food

– Eat nuts and seeds instead of unhealthy snacks

Benefits or risks?

Although a number of studies have found a link between the consumption of fruit and vegetables and health benefits, it is not clear to what extent this link can be attributed to antioxidants. It is also worth being cautious about the use of supplements. It is important to emphasise that excessive consumption of dietary supplements containing antioxidants can pose significant health risks. For example, higher intakes of beta-carotene are associated with an increased risk of lung cancer in smokers. Likewise, high levels of vitamin E are associated with an increased likelihood of prostate cancer, and the use of certain antioxidant supplements is associated with an increased risk of tumour growth. It should also be borne in mind that antioxidants may interact with various medicines and it is therefore recommended that you seek the advice of a healthcare professional before taking supplements.

Summary

Free radicals are linked to many diseases, including cardiovascular disease, cancer and visual impairment. Antioxidants can help to neutralise these harmful substances, but this does not mean that increased consumption of antioxidants can prevent these conditions. Antioxidants from synthetic sources may increase the risk of certain health complications. In conclusion, it makes sense to favour natural sources of antioxidants through a varied, colour-rich and nutritious diet.

The consumption of fruit and vegetables has been associated with a reduced incidence of chronic disease, and antioxidants may have a potential role to play in this. However, it is unlikely that the use of antioxidants artificially added to foods, especially processed foods, would provide significant health benefits. In any case, a healthcare professional should be consulted when using food supplements.

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