They feed us a constant diet of fads and fancies, from detoxifying drinks to colon cleansers. But there were signs in 2012 that some celebrities at least are beginning to realise that many of the more bizarre health crazes of the rich and famous are nothing more than junk science.

A review of the scientific evidence behind the celebrity fads of the past 12 months has revealed that this could be the year when some famous names have turned their backs on the unsubstantiated claims of the alternative treatments industry, according to the campaign group Sense About Science.

It was the year when Jennifer Aniston, who played the wholesome Rachel in Friends, announced that "fads are too much" and that fasting and cleansing may actually be bad for your health.

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Gary Kemp, former singer with Spandau Ballet, came to the aid of medical science by declaring that acupuncture as performed by his chiropractor didn't do much for him and that "hardcore science" should be everyone's first port of call when dealing with a serious illness.

Despite signs of intelligent life in celebrity cuckoo land, there were still many examples of the sublimely ridiculous, from rubbing coffee granules into your skin to believing that homeopathy is more than just the placebo effect.

"We seem to be seeing a celebrity divide on science. The implausible and frankly dangerous claims about how to avoid cancer, improve skin or lose weight are becoming ever more ridiculous," said Tracey Brown, managing director of Sense About Science.

"On the other hand, this year we have had more examples than ever sent to us of people in the public eye who clearly do check their facts," she said.

January Jones The actress who played Betty Draper in Mad Men declared that she was not "witch-crafty" or anything but she admitted to eating her own placenta after the birth of her baby son and recommended it for all new mums. Catherine Collins, principal dietician at St George's Hospital, London, said: "Nutritionally, there's little to be gained from eating your placenta – raw, cooked or dried… [in fact] your placenta will provide toxins and other unsavoury substances it had successfully prevented from reaching your baby in utero."

Patsy Palmer The EastEnders actress was reported to rub coffee granules into her skin as a beauty treatment against cellulite. Gary Moss, a pharmaceuticals scientist, said: "Caffeine may have an effect, but coffee granules won't… there's a perception that coffee might tackle cellulite because caffeine, in an aqueous solution, can penetrate the skin. However, as coffee granules won't allow the caffeine to penetrate the skin barrier, the only unintended effect is perhaps exfoliation."

Mario Balotelli The Manchester City footballer is one of several sporting superstars who was seen in 2012 wearing Kinesio coloured sports tape that purports to "mend" injuries. Professor Greg Whyte, sports scientist, said: "It's unclear how [the tape] can positively affect inflammation deep within the muscle. There's insufficient evidence to support its use over other more traditional treatments such as taping or strapping."

Simon Cowell The TV and music producer said he carried small, inhalable bottles of oxygen around with him to reduce the effects of tiredness, stress and signs of ageing. Kay Mitchell, researcher into extreme environments, said: "Breathing 100 per cent oxygen under pressure allows oxygen to dissolve into the blood plasma.… While this is thought to improve recovery rates from sports injuries...more research is needed. Doctors are also concerned about the damage caused by oxygen levels that are too high."

Sheryl Crow The singer said that she spent hours on her old mobile phone and questioned whether this may have been the cause of her brain tumour. Mireille Toledano, epidemiologist and expert on mobile phone risks, said: "Overall, the evidence to date is clear that short-term use of mobile phones is not linked to brain cancers… people who have had cancer are more likely to over-estimate their phone use than those who have not had cancer."

Goldie Hawn The actress said that teaching children about the function of the brain helped them to understand where their emotions come from. Professor Sergo Della Sala, neuroscientist, said such teaching would not work, any more "than understanding the chemical components of a ball would help them to kick it better".

Jennifer Aniston The actress said she had stopped dieting and just ate regularly and moderately because "fads are too much". She also said fasting and "cleansing" were bad for the body. Ursula Arens, of the British Dietetic Association, said: "Extreme diets and fasts will make you feel unwell and do not support good health. A fantastically sensible comment, Jennifer."

Al Murray The comedian said that popping vitamin pills is a waste of time and money, apart from perhaps cod liver oil. Lucy Jones, of the British Dietetic Association, said: "Al, you are right… supplements are like glasses: not everyone needs them and you need to get the right pair with the right prescription."