LONDON (Reuters) - Science campaigners laid bare some of the most dubious celebrity-endorsed health tips on Wednesday, rubbishing ideas such as reabsorbing sperm and wearing silicone bracelets to boost energy.

In an annual list of what it sees as the year’s worst abuses against science, the Sense About Science (SAS) campaign group debunked diet and exercise suggestions made by actors, pop stars and others in the public eye in an effort “to help the celebrities realize where they are going wrong and to help the public make sense of celebrity claims.”

In the health and fitness section, SAS noted that soccer player David Beckham and Prince William’s fiancee Kate Middleton have both been spotted wearing hologram-embedded silicone bracelets which makers claim can improve energy and fitness.

It also listed a diet reportedly used by supermodel Naomi Campbell and actors Ashton Kutcher and Demi Moore in which followers survive on maple syrup, lemon and pepper alone for up to two weeks. Campbell told U.S. TV host Oprah Winfrey in an interview in May: “It’s good to clean out your body once in a while.”

But SAS said in a statement: “Many of these claims promote theories, therapies and campaigns that make no scientific sense.”

Pop star Sarah Harding told Now magazine in April that she crumbles charcoal over her food, saying: “It’s doesn’t taste of anything and apparently absorbs all the bad damaging stuff in the body.”

Dr John Elmsley, a chemical scientist and writer asked by SAS to comment on this idea, said charcoal is known to absorb toxic molecules when used in gas masks and sewage treatment, but is “unnecessary when it comes to diet because the body is already quite capable of removing any ‘bad damaging stuff’.”

One of the highlights for SAS was a tip from cage fighter Alex Reid, who told The Sun tabloid newspaper in April that he “reabsorbs” his sperm to prepare for a big fight.

“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 raaaaahh,” he said.

John Aplin, a reproductive research scientist at the University of Manchester, said sperm cannot be reabsorbed once they have formed in the testes. “In fact sperm die after a few days, and the nutritional content of the ejaculate is really rather small,” he said in a comment on the SAS list.

To try and counter the effects of some of the wildest health and fitness tips, SAS published its own “easy-to-remember pointers for celebrity commentators”:-

* Nothing is chemical-free: everything is made of chemicals, it’s just a case of which ones

* Detox is a marketing myth: our body does it without pricey potions and detox diets

* There’s no need to boost: bodily functions occur without boosting

* Energy and fitness come from...food and exercise: there are no shortcuts.