Thursday, January 28, 2010

Heh! Eating too many "superfoods" can harm health

For years they have been hailed for their apparently age-defying effects on the body. From sweet potatoes to blueberries, from lentils to broccoli, the health conscious couldn't get enough of so-called superfoods. But now it seems you really can have too much of a good thing.

Scientists say the delicate balance of nutrients required by the body could be affected by stuffing it full of the antioxidants contained in the foods. Nutritionists claim these antioxidants can lengthen your life by cutting the risk of heart disease and cancer. They have even linked them to better sex. But researchers say too much of the superfoods could mean there are not enough 'pro-oxidants' - usually considered the evil twin of antioxidants - in the body. While the antioxidants slow down the damage to muscles and other organs by the process known as oxidisation, the pro-oxidants speed it up. But too many antioxidants can tilt the balance and make it harder for the elderly to breathe and stop them from doing the exercise that could help them stay fit.

The researchers, from Kansas State University in the U.S. tested animals with different doses of antioxidants. Those that were given too much showed impaired muscle function, reported the study published in the Journal of Applied Physiology.

Researcher Steven Copp said: 'I think what a lot of people don't realise is that the antioxidant and pro-oxidant balance is really delicate. 'One of the things we've seen in our research is that you can't just give a larger dose of antioxidants and presume that there will be some sort of beneficial effect. In fact, you can actually make a problem worse.'

Nutrionists claim that antioxidants can slow down and even reverse some of the effects of ageing - which is why foods like blueberries have been hailed for their benefits on dementia victims. But some of these changes are not good for an ageing body as it stops some of ways in which blood cells flow by taking out the chemicals known as vasodilators which help open blood vessels. This makes older people get out of breath more quickly, for instance, which in turn prevents them from exercise and keeping fit.

Mr Copp said: 'If you have a person trying to recover from a heart attack and you put them in cardiac rehab, when they walk on a treadmill they might say it's difficult. 'Their muscles get sore and stiff. We try to understand why the blood cells aren't flowing properly and why they can't get oxygen to the muscles, as happens in healthy individuals. 'We're now learning that if antioxidant therapy takes away hydrogen peroxide - or other naturally occurring vasodilators - you impair the body's ability to deliver oxygen to the muscle so that it doesn't work properly.

'It's really a cautionary note that before we start recommending people get more antioxidants, we need to understand more about how they function in physiological systems and circumstances like exercise.'


Uphill battle to conceive after 35

Lots of women turn a blind eye to this so it cannot be stressed enough

THE speed at which female fertility declines has been highlighted by the first study to track a woman's supply of eggs from conception to the menopause. The average 30-year-old will have just 12 per cent - barely an eighth - of her eggs left, the research shows. By her 40th birthday the situation is even more bleak, with just 3 per cent of the two million or so eggs she was born with remaining.

Only about 450 of the two million eggs will fully mature over a woman's lifetime. Many others will start to mature before dying off. The more eggs the woman has, the greater the odds of one maturing enough to allow her to become pregnant.

Researcher Dr Tom Kelsey, of St Andrews University, said there were "women waiting for the next promotion or waiting to meet Mr Right". "Women often do not realise how seriously their ovarian reserve declines after the age of 35," he said. "Every year that goes by you are losing a big proportion of your ovarian reserve. A lot of people get to their menopause in their mid or late 40s."

The rapid decline of a woman's store of eggs - and fertility - was known before, but this study is the first to trace its entire path, from before birth through to the end of child-bearing years. Working with Edinburgh University experts, Dr Kelsey counted the number of eggs in the ovaries of 325 women of a variety of ages. The information was then fed into a computer program which worked out how the supply declined with time.

The analysis, which is reported in the journal PLoS ONE, also showed that until the age of 25 lifestyle factors such as smoking or alcohol have little effect on a woman's fertility. But after this point the way a woman looks after her body has a marked effect on fertility.

He said unlocking the workings of female biological clocks could help doctors better advise young cancer patients on how to preserve their fertility.


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