Right balance of nutrients more important than cutting calories
A new study published this week in the journal Nature says that maintaining the correct balance of types of proteins in one's diet is more important for health than reducing calorie intake. The study, carried out at the Institute of Healthy Ageing, part of University College London (UCL) in the UK, found that drastically reducing calories (a technique called 'dietary restriction' or 'calorie restriction') while maintaining a sufficient amount of vitamin and mineral consumption appears to have a positive effect on health, including a longer lifespan. These benefits have been noticed in many living creatures including fruit flies, mice, rats and Rhesus monkeys, and there is evidence that it may be true in humans too. But cutting down on calories can have also have negative effects including a reduction in fertility. In the institute's study, tests were carried out on fruit flies, which were found to reproduce less frequently and have smaller litters on a calorie-restricted diet, although the fruit flies' reproductive period lasted longer. The fruit flies were fed a diet of yeast, sugar and water, but with differing amounts of important nutrients such as vitamins, lipids and amino acids. The research team found that varying the amounts of amino acids affected the lifespan and fertility of the fruit flies, but changing the amounts of the other nutrients had negligible effects. Of particular note in the tests was the effect of an amino acid called methionine. This had a crucial effect on maximising the lifespan of the fruit flies without decreasing their fertility. The researchers also found that reducing methionine in a high-calorie diet prolonged the lifespan of the fruit flies. 'By carefully manipulating the balance of amino acids in the diet, we have been able to maximise both lifespan and fertility,' said Dr Matthew Piper, one of the authors of the study. 'This indicates that it is possible to extend lifespan without wholesale dietary restriction and without the unfortunate consequences of lowering reproductive capacity.' Amino acids play a vital role in metabolism. They are the building blocks of life since they form the basis of proteins; methionine is one of the most important amino acids as it is essential to the formation of all proteins in a living organism. Methionine occurs in many different foods and is particularly abundant in wheatgerm, sesame seeds, fish, Brazil nuts and meat. 'In the past, we have tended to think that the amount of protein is what is important to our diet,' said Dr Piper. 'We've shown here that in flies - and this is likely to be the case for other organisms - the balance of amino acids in the diet can affect health later in life. If this is the case for humans, then the type of protein will be more important. 'It's not as simple as saying 'eat less nuts' or 'eat more nuts' to live longer - it's about getting the protein balance right, a factor that might be particularly important for high protein diets, such as the Atkins diet or body builders' protein supplements.'
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