The stars who are bad for your health

Celebrities have been urging us to copy their lifestyles, but the experts are less enthusiastic.

Sprinkling charcoal on your food, a diet of maple syrup or "reabsorbing" your sperm are just some of the health tips celebrities have espoused this year.

Today, however, the charity Sense About Science has issued its annual report in an attempt to counter what it sees as faddish myths. "When people in the public eye give opinions about causes of disease, cures, diets, or products we should buy or avoid, it goes worldwide in seconds," said assistant director Lindsay Hogg. "So if it's wrong, we're stuck with the fall-out from that."

This year's report includes the "Master Cleanse" diet, whose fans include model Naomi Campbell and actress Demi Moore. It involves eating nothing but maple syrup, lemon and pepper for up to two weeks. Ms Campbell explained: "It's good just to clean out your body once in a while." But Anna Raymond of the British Dietetic Association claimed: "Essentially it's not cleaning your body – it's starving it! A severe diet might actually lead to the creation of potentially harmful chemicals called ketones."

The report was equally sceptical of cage fighter Alex Reid's claim that unprotected sex without ejaculating helped him prepare before a match because "reabsorbing" the sperm had the nutritional value of steak, eggs, lemons and oranges. Reminding him of the dangers of unprotected sex, Professor John Aplin said sperm cannot be reabsorbed once it had left the testes, adding: "The nutritional content of the ejaculate is really rather small."

Girls Aloud singer Sarah Harding believes crumbling charcoal tablets on her food absorbs all the "damaging stuff" but junior doctor Juliet Stevens retorted that while charcoal is useful for life-threatening overdoses and poisonings, it has less everyday benefit.

Cheryl Cole

Cheryl Cole, X Factor judge: "Eat Right 4 Your Type (a diet that says you should eat according to your blood group) has made such a difference – not so much to my shape but to how I feel and my energy levels. Before, I was like 'energy schmenergy' and didn't believe it. But now I believe it 100%."

Sian Porter, dietician, British Dietectic Association: "Your blood group cannot affect digestion or the way food is broken down. This theory is really just another spin on reducing overall calorie intake. It is surprising that Cheryl feels her energy levels have improved, as cutting out food groups can lead to flagging energy levels."

Gisele Bundchen

Model Gisele Bundchen criticised women who do not breastfeed: "I think: 'Are you going to give chemical food to your child when they are so little?'."

Stuart Jones, clinical scientist, said: "Gisele, there is no such thing as chemical-free food. Everything we eat is made of chemicals, no matter how it is produced or where it comes from, whether it is natural or man-made."

Alex Reid

Cage fighter Reid, above, said: "It's actually very good for a man to have unprotected sex, as long as he doesn't ejaculate. Because I believe that all that semen has a lot of nutrition. A tablespoon of semen has your equivalent of steak, eggs, lemons and oranges. I am reabsorbing it into my body and it makes me go raaaaaaahh."

Professor John Aplin, reproductive research scientist, University of Manchester:

"Alex, sperm can't be reabsorbed once they have formed in the testes! In fact sperm die after a few days and the nutritional content of ejaculate is really rather small. And it's worth remembering that unprotected sex might result in pregnancy or passing on of a sexually-transmitted infection."

Sarah Harding

Sarah Harding, Girls Aloud singer: "I crumble up charcoal and put it on my food. It doesn't taste of anything and apparently absorbs all the bad, damaging stuff in the body. It's not the regular charcoal you put in fires – I'm not that mad. I think it's good for hangovers, too."

Dr John Emsley, chemical scientist and writer: "Charcoal is known to absorb toxic molecules when used in gas masks and in sewage treatment. However, it is unnecessary when it comes to diet because the body is already quite capable of removing any "bad, damaging stuff" it encounters in ordinary consumption.

"It might help prevent smelly farts, though."

Julia Sawalha

Julia Sawalha, actress, said: "I don't get inoculations or take anti-malaria tablets when I go abroad. I take the homeopathic alternative, called 'nosodes' and I'm the only one who never goes down with anything."

Professor Jayne Lawrence, chief scientific advisor, Royal Pharmaceutical Society: "Julia has been fortunate in not getting malaria on her travels, as there is no active ingredient in homeopathic treatments that would protect her against the disease."