Diet and Weight Loss News

Dieting in the winter can weaken the immune system

Written By Betty van der Mark on Friday, January 2, 2009 | 1:38 AM

Scientists have shown that having a healthy appetite in the winter protects against flu. People on strict calorie-controlled diets also take longer to recover from viral infections. Researchers are now advising people not to try to lose weight until spring arrives. Their findings support the popular idea that nourishing winter meals can stave off colds and bugs.

Dr Elizabeth Gardner of Michigan State University, who carried out the study, said: 'Our research shows that having a body ready to fight a virus will lead to a faster recovery and less severe effect. 'Adults can restrict their diet eight months out of the year, but during the four months of the flu season they need to bump it up. 'You need the reserves so your body is ready for any additional stress, including fighting a virus.' Dr Gardner believes that cutting down on food impairs the immune system and reduces the production of antibodies to fight infection.
The findings come from a study of mice infected with flu, published in the Journal of Nutrition.
Half of the mice were put on a diet where their calories were cut by 60 per cent, but with enough vitamin and mineral supplements to stay healthy. The rest were given normal food.
Those on the calorie-controlled diet were more likely to die during the first few days after infection than their well-fed counterparts. While the disease made both groups of mice less hungry, those on the diets took longer to recover and lost more weight.
Mice eating normal levels of food regained their appetites more
quickly and recovered faster. The researchers say the findings also apply to people - and that eating sensibly in the flu season can protect against viruses. Dr Gardner said: 'If you are exposed to a new strain of influenza, to which your body has not yet made adequate antibodies, your body relies on cells that will kill the virus. 'The natural killer cells are important in controlling the early stages of infection. 'Our studies show that calorically restricted mice have increased susceptibility to influenza, and their bodies are not prepared to produce the amount of natural killer cells needed to combat the stress of fighting an infection.'
The findings also suggest that even people who have had the flu vaccine need to eat properly.
Dr Gardner said: 'If the strain of flu a person is infected with is different from the strain in the flu vaccination, your body sees this as a primary infection and must produce antibodies to fight it off. 'A calorically restricted body is not as well prepared to do this and cannot control early infection, which impedes recovery.' Britain's leading influenza expert, Professor John Oxford of London Queen Mary's School of Medicine and Dentistry, said: 'I would go along with these findings.

'During the biggest outbreak of flu in history, in 1918, societies that were well nourished got through the pandemic better than those that weren't as well nourished.
'Mice are a good model for flu in people - the development of new vaccines is dependent on mice - so these findings are extremely interesting.' The flu season, now in full swing in the UK, normally lasts into February before the number of cases starts to drop dramatically.

Source: DailyMail.co.uk

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