Antioxidants

Q. Let’s start with free radicals. Why are they the bad guys?

We all need oxygen to live. The mitochondria in our cells use oxygen to produce energy, and other essential enzymes in our bodies need it to function. The by-products of these processes are free radicals – unstable molecules that steal electrons from other molecules.

The process of oxidation in our bodies over time damages cell membranes and other things such as proteins, lipids and DNA. Think of it like a bicycle left out in the elements to rust.

Our bodies cope with some free radicals – in fact, we need them to fight infection, stop tumour cells growing and help our tissues repair. However, as we get older and our antioxidant defence system wears out, we can have too many free radicals. Stress, smoking, sunlight, alcohol and pollution make it tough for our bodies to fight them off.

Free radicals can cause deterioration of the eye lens, inflammation of the joints or arthritis, and damage to nerve cells in the brain. They’re also linked to increased coronary heart disease because they encourage LDL – “bad” cholesterol – to stick to the artery walls, and they damage DNA, which can trigger cancer.

Q. So what are antioxidants?

Antioxidants protect cells against the effects of free radicals. Our bodies produce a range of their own antioxidants, but they’re also found in many foods.

There are different categories of antioxidants. There are those found in foods, such as vitamins A, C and E. The minerals copper, zinc and selenium are antioxidants. Then there are food compounds such as phytochemicals in plants and zoochemicals in animal products. Antioxidants produce the bright colours in fruit and vegetables and the flavour in foods such as tea, coffee and extra virgin olive oil. They’re also responsible for the bitter taste of dark chocolate.

Q. How do they work?

Free radicals are molecules that are unstable due to having one unmatched electron. Antioxidants neutralise the molecules by removing that electron or adding a matching electron.

Our bodies have an inbuilt anti­oxidant system which scavenges free radicals. However, this system wears down as we age. Plants and animals produce antioxidants for their own protection, so by eating them we can boost our own supplies.

Q. How effective are they?

We’re only just starting to understand the science. What we do know from population studies is that people who eat a lot of fruit and vegetables live longer and more healthily. Tests in the lab indicate that some antioxidants may prevent specific diseases: men who eat a lot of tomatoes, which are rich in the antioxidant lycopene, according to some studies could be less likely to develop prostate cancer; flavonoids found in green tea are thought to be behind the low rates of cardiovascular disease in Japan; and lutein, found in spinach and corn, protects against deterioration in the lens of the eye.