Free Radicals – What Are They and Why Do We Talk About Them?

What are free radicals?

Free radicals are small, highly reactive molecules that are formed in the body all the time. They have an unpaired electron, which makes them unstable – and that is why they try to steal an electron from another molecule. This can cause a chain reaction that damages cells.

Although it sounds bad, free radicals are not only harmful. They are part of the body’s normal functioning and arise, for example, when the body produces energy or fights bacteria and viruses. External factors such as smoking, air pollution and UV radiation can also increase the amount of free radicals in the body (Lobo et al., 2010).

What is oxidative stress – when the balance is upset?

Normally the body keeps the amount of free radicals in check with the help of antioxidants. The problem arises when too many free radicals are formed or there are too few antioxidants. This state is called oxidative stress.

Over time, oxidative stress can damage cells and contribute to the development of many diseases, such as cardiovascular disease, cancer, type 2 diabetes and neurodegenerative diseases such as Alzheimer’s disease (Valko et al., 2007; Betteridge, 2000).

In heart disease, for example, one key factor is “bad” LDL cholesterol, which is oxidised by free radicals and begins to accumulate in the walls of blood vessels. This can lead to hardening of the arteries, or atherosclerosis (Steinberg, 1997).

How does the body fight back – antioxidants to the rescue

Fortunately the body is not defenceless. It has its own effective defence system made up of antioxidants. These substances can “donate” an electron to free radicals without becoming dangerous themselves. In this way they stop the harmful reaction.

The body produces some antioxidants itself, but they are also obtained from food. Good sources include:

• Berries (blueberries, lingonberries, raspberries)
• Green tea
• Dark chocolate
• Vegetables and fruit (especially those containing vitamins C and E)
• Wholegrain cereals and nuts

Studies have found that a varied, plant-based diet can reduce oxidative stress and protect cells from damage (Riso et al., 2013; Scalbert et al., 2005).

Should you take antioxidant supplements?

Many people think that the more antioxidants, the better. But this is not entirely true. Although antioxidants are important, excessive use in supplement form is not automatically beneficial – and in some cases may even be harmful.

For example, according to studies, high-dose vitamin C and E supplements have not prevented heart disease or cancer. Some studies have even found a slight increase in mortality in certain population groups (Bjelakovic et al., 2007).

In other words: the best antioxidants come from food, not from a bottle.

How do exercise and stress affect free radicals?

Exercise is a good example of how free radicals are not always harmful. When you exercise, the body produces more free radicals, but at the same time it strengthens its own antioxidant systems. Moderate exercise thus works like “training” for the body’s protective mechanisms (Ristow & Schmeisser, 2011).

Constant mental or physical stress, on the other hand, can increase the oxidative load. That is why rest, recovery and good sleep quality are also important.

Balance is what matters

Free radicals are not just villains – they are part of the body’s normal functioning. Problems begin only when too many are formed or the defence systems do not work properly. The good news is that you can influence this yourself:

• Eat a varied diet with plenty of vegetables
• Exercise regularly but do not burn yourself out
• Avoid smoking and excessive alcohol
• Sleep enough and avoid long-term stress

With these means you help your body keep the balance between free radicals and antioxidants in order – and at the same time support your health in the long term.

Sources

• Lobo V. et al. (2010): Free radicals and antioxidants in the human body
• Betteridge D. (2000): Oxidative stress and its significance
• Steinberg D. (1997): LDL cholesterol and hardening of the arteries
• Valko M. et al. (2007): The effect of free radicals on diseases
• Riso P. et al. (2013): The effect of polyphenols on oxidative stress
• Bjelakovic G. et al. (2007): Supplements and mortality
• Ristow M. & Schmeisser S. (2011): The beneficial stress of exercise
• Scalbert A. et al. (2005): Polyphenols in food