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8 July 2009

When Should You Eat to Fuel Exercise?

No matter what kind of exercise you do, you need food and water to fuel the effort. But when’s the best time to eat before exercise?

According to Leslie Bonci, director of sports nutrition at the University of Pittsburgh Medical Center, your food is just like your running shoes or your skis. If you think of it this way, you’ll have a better outcome when you’re physically active.

There are two common mistakes. One is not eating anything before exercise, and that means you’re not putting fuel into your body -- you’ll be more tired and weaker. The second issue is eating too much. Bonci says the right quantity is a fist-sized amount of food an hour before exercise.

At that same time, you should have about 20 ounces of liquid. It takes about 60 minutes for that much liquid to leave the stomach and make its way into the muscle. If you have liquid ahead of time, you’ll be better hydrated when you start to be physically active.

Coffee 'may reverse Alzheimer's'

Drinking five cups of coffee a day could reverse memory problems seen in Alzheimer's disease, US scientists say.

The Florida research, carried out on mice, also suggested caffeine hampered the production of the protein plaques which are the hallmark of the disease.

Previous research has also suggested a protective effect from caffeine.

But British experts said the Journal of Alzheimer's disease study did not mean that dementia patients should start using caffeine supplements.

The 55 mice used in the University of South Florida study had been bred to develop symptoms of Alzheimer's disease.

First the researchers used behavioural tests to confirm the mice were exhibiting signs of memory impairment when they were aged 18 to 19 months, the equivalent to humans being about 70.

Then they gave half the mice caffeine in their drinking water. The rest were given plain water.

The mice were given the equivalent of five 8 oz (227 grams) cups of coffee a day - about 500 milligrams of caffeine.

The researchers say this is the same as is found in two cups of "specialty" coffees such as lattes or cappuccinos from coffee shops, 14 cups of tea, or 20 soft drinks.

When the mice were tested again after two months, those who were given the caffeine performed much better on tests measuring their memory and thinking skills and performed as well as mice of the same age without dementia.

Those drinking plain water continued to do poorly on the tests.

In addition, the brains of the mice given caffeine showed nearly a 50% reduction in levels of the beta amyloid protein, which forms destructive clumps in the brains of dementia patients.

Further tests suggested caffeine affects the production of both the enzymes needed to produce beta amyloid.

The researchers also suggest that caffeine suppresses inflammatory changes in the brain that lead to an overabundance of the protein.

Earlier research by the same team had shown younger mice, who had also been bred to develop Alzheimer's but who were given caffeine in their early adulthood, were protected against the onset of memory problems.

'Safe drug'

Dr Gary Arendash, who led the latest study, told the BBC: "The results are particularly exciting in that a reversal of pre-existing memory impairment is more difficult to achieve.

"They provide evidence that caffeine could be a viable 'treatment' for established Alzheimer's disease and not simply a protective strategy.

"That's important because caffeine is a safe drug for most people, it easily enters the brain, and it appears to directly affect the disease process."

The team now hope to begin human trials of caffeine to see if the mouse findings are replicated in people.

They do not know if a lower amount of caffeine would be as effective, but said most people could safely consume the 500 milligrams per day.

However they said people with high blood pressure, and pregnant women, should limit their daily caffeine intake.

Rebecca Wood, chief executive of the Alzheimer's Research Trust, said: "In this study on mice with symptoms of Alzheimer's, researchers found that caffeine boosted their memory. We need to do more research to find out whether this effect will be seen in people.

"It is too early to say whether drinking coffee or taking caffeine supplements will help people with Alzheimer's.

Neil Hunt, chief executive of the Alzheimer's Society, said previous research into caffeine had suggested it could delay Alzheimer's disease and even protect against vascular dementia.

"This research in mice suggests that coffee may actually reverse some element of memory impairment.

"However much more research is needed to determine whether drinking coffee has the same impact in people.

"It is too soon to say whether a cup of coffee is anything more than a pleasant pick me up."

6 July 2009

Walnuts can cut cholesterol

A meta-analysis of walnuts by Harvard scientists has found diets rich in walnuts can significantly reduce cholesterol levels, supporting growing evidence to suggest these popular nuts can improve healthy blood lipid ratios.

In their investigation of thirteen studies, the researchers demonstrated that walnut-rich consumption decreased total and low-density lipoprotein (LDL) cholesterol during short term trials.

However the scientists suggested that "larger and longer-term trials" are needed to observe the effects of eating walnuts, rich in polyunsaturated fatty acids, on cardiovascular risk and weight management.

Their analysis joins a blossoming body of science that has linked nut consumption – including almonds and macadamias – to improvements in markers of cardiovascular health.

Coronary heart disease places a significant financial burden on all European states, and in the UK alone costs the health system more than €5bn per year. Governments, scientists and the food industry itself continue to invest time and money in pinpointing potential dietary solutions that could boost cardiovascular health.

Design of the meta-analysis

Published in a recent issue of the American Journal of Clinical Nutrition, researchers Deirdre Banel and Frank Hu conducted the meta-analysis to, "estimate the effect of walnuts on blood lipids".

Literature databases were searched for published trials that compared a specifically walnut-enhanced diet with a control diet.

"We conducted a random-effects meta-analysis of weighted mean differences of lipid outcomes," said the scientists.

The 13 studies selected represented some 365 participants, with diets lasting between four and 24 weeks and walnuts providing between 10 and 24 per cent of total calories.

"When compared with control diets, diets supplemented with walnuts resulted in a significantly greater decrease in total cholesterol and in LDL-cholesterol concentrations," the Harvard researchers wrote.

Further, the meta-analysis results gave a nod to the widening circle of potential health benefits contained in walnuts.

"Other results reported in the trials indicated that walnuts provided significant benefits for certain antioxidant capacity and inflammatory markers and had no adverse effects on body weight," stated the researchers.

Source: American Journal of Clinical Nutrition

May 2009, Volume 90, Pages 56-63, doi:10.3945/ajcn.2009.27457

‘Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review’

Lack of sleep 'hits women harder'

Lack of sleep raises a woman's risk of heart disease more than it does for a man, research suggests.

Sleeping less than the recommended eight hours a night has been linked to a raised risk of heart problems.

Researchers found levels of inflammatory markers - indicators of heart disease - vary significantly with sleep duration in women, but not men.

The study, by University College London and the University of Warwick, appears in the journal Sleep.

Previous research has suggested people who sleep less than five hours a night have an increased risk of dying from cardiovascular disease, compared to those who get the full eight hours.

The latest study found levels of a molecule called interleukin-6 (IL-6), which is known to trigger inflammation, were much lower in women who reported sleeping eight hours, compared to those who slept for seven hours.

Levels of another molecule, high-sensitivity C-reactive protein (hs-CRP) - which is linked to heart problems - were significantly higher in women who reported sleeping for five hours or less.


Researcher Dr Michelle Miller said the findings added to the growing body of evidence suggesting that sleep duration played a key role in heart health.

She said: "The results also are consistent with the idea that sleeping seven or eight hours per night appears to be optimal for health."

Dr Miller said more work was required to pin down why lack of sleep potentially had a greater effect on women.

However, she said differences in hormone levels might be key. There is work to suggest that inflammatory marker levels are different in pre- and post-menopausal women.

The study was based on data from more than 4,600 London-based civil servants aged 35 to 55, of which 73% were men.

Dr Janet Mullington, of Harvard Medical School, said there were many questions still to be answered about the effect of sleep deprivation.

She said it was possible that the change to inflammatory markers produced in sleep deprivation experiments were merely short-term reflections of the battle against sleepiness.

They might also be influenced by the unusual conditions, such as the interaction between the participants and the researchers.

June Davison, a cardiac nurse at the British Heart Foundation, said: "Previous research suggests that a good night's sleep may help to keep our heart and circulation healthy, and this study could point to an underlying reason behind that finding.

"We should all try to get enough sleep - as it's likely to be good for heart health as well as overall health."