Beetroot juice was claimed as the elixir of sporting life by some athletes at the London Olympics.

Paralympic superstar, David Weir, drank it during his winning wheelchair marathon race. But what’s the truth?

Andy Jones, professor at the sport and health sciences department at Exeter University, says the active ingredient is nitrate, a nutrient found in soil that helps build protein. This converts into nitrite in the body and then into nitric oxide, which has a “double whammy” effect, widening blood vesselsand increasing blood flow. it also reduces the oxygen needed by muscles, enabling them to work more efficiently.

Jones says, “We found this works most effectively in high-intensity exercise, typically races that last up to 30 minutes”. However, the average runner might feel the benefits of beetroot more than elite athletes whose muscles are already efficient.

So if you are far below top level, but still want to beat your personal best, try beetroot juice. Experts say the best way to get the benefits is to drink the juice.

“Shots” containing 7cl of concentrated juice, and 0.4g of nitrate, have been developed as a sports drink and for use in studies, by the James White drinks company in Ipswich. Managing director Lawrence Mallinson, who supplied shots to Team GB, says that beetroot juice now accounts for half of the firm’s £5 million turnover.

You would need to drink about 500ml (half a litre) of ordinary strength juice to get the same nitrate levels.

In a counter-intuitive article in the New York Times, which quotes researchers in Germany and Boston, exercise and antioxidants don’t mix. “If you exercise to improve your metabolism and prevent diabetes, you may want to avoid antioxidants like vitamins C and E.”

Dr. Michael Ristow, a nutritionist at the University of Jena in Germany, said, “If you exercise to promote health, you shouldn’t take large amounts of antioxidants. … antioxidants in general cause certain effects that inhibit otherwise positive effects of exercise, dieting and other interventions.”

It seems that exercise encourages muscle cells to metabolize glucose by combining carbon atoms with oxygen. In the process, highly reactive oxygen molecules are released which then attack various parts of the body damaging the tissues.

The Jena team found that in the group taking antioxidant vitamins, like vitamins C and E, there was no improvement in insulin sensitivity and almost no activation of the body’s natural defence mechanism against oxidative damage.

Once again, what we thought was done and dusted has been called into question by more research.

However, the advice does not apply to fruits and vegetables, Ristow said, even though they are high in antioxidants, it may be that other substances they contain outweigh any negative effect.

Andrew Shao of the Council for Responsible Nutrition, a trade association of dietary supplement makers, said, “I wouldn’t change recommendations for anyone based on one study. This is one small piece of the puzzle.”

The amount of oxidative damage increases with age, and according to one theory of aging it is a major cause of the body’s decline.

The findings appear in this week’s issue of The Proceedings of the National Academy of Sciences.

John Evans

According to research at the University of California, people with a sunny disposition live on average seven and a half years longer than gloomy types.

Moreover, the risk of dying early from any disease is 55pc lower for optimists than for pessimists.

People with a pessimistic outlook will have higher levels of anxiety and an increased risk of developing Parkinson’s disease in later life.

Dr James Bower of the Mayo Clinic said, “What we have shown for the first time is that there’s a link between an anxious or pessimistic personality and the future development of Parkinson’s.”

The theory is that optimism increases the will to live and to participate in life. This may lower levels of the stress hormone cortisol.

Researchers at Carnegie Mellon University, Pittsburgh, also say that optimism boosts the immune system and protects from psychological stress.

Over a 30-year period, say the researchers, optimists had fewer disabilities and less chronic pain.

Can you develop an optimistic lifestyle? We will be writing about that soon.