Extraordinary claims need extraordinary evidence: The importance of skepticism

Check any newspaper today and you will find advice on what to eat or drink to lose weight or look good. Advertisers exploit our fixation with diet to sell products – from superfoods and “detox” treatments to diet supplements and even this extraordinary weight loss string. Buying into these fads can affect not just your bank balance but, more importantly, your health. So make sure you Ask for Evidence behind claims before believing everything you read.

Trust me, I’m a celebrity…

Many companies use celebrities to sell their products. You have probably seen Vitabiotics adverts where athletes feature with quotes like “Anyone competing or living a healthy lifestyle needs Wellman in their life. I'm a champion and I recommend it.” When Sparkle Ward asked Vitabiotics for evidence, they responded saying that the claims made in their adverts are based on individual testimonies only and not scientific evidence. That’s clearly not a great tagline for selling a product! Companies also promote their products as “natural” and “chemical-free”. Well, “natural” doesn’t necessarily mean safe, and everything is made of chemicals. Apples (PDF), for example, contain toxic chemicals (PDF) which would kill you if taken in a large enough dose.

But it’s “scientifically proven”…

Not everyone buys into celebrity endorsements or the idea that “natural” is best. But advertisers have another tactic up their sleeve – scientific-sounding claims to make you think there’s evidence. Danone yoghurt brand Actimel, for example, was advertised as “scientifically proven to help support your kids’ defences” but the Advertising Standards Authority (ASA) ruled that its evidence “wasn’t good enough to prove the claim”. The ASA can’t stop all misleading claims though, so it’s a good idea to be skeptical when you hear claims like “clinically proven” or “dermatologically tested” – vague terms which tell you nothing about the reliability of the evidence.

Often there is an element of truth to scientific claims, but it is twisted or exaggerated. In a Daily Mirror article on beauty secrets, a co-founder of Lush declared “Getting more honey in your diet is great for the face. It’s good at helping the skin absorb moisture.” It’s true that honey itself absorbs moisture but does eating honey help the skin absorb moisture? I asked Lush for evidence and they replied to say that the Lush co-founder “doesn’t remember saying that” but added that honey is “much easier for our body to digest” than sugar and she “feels that it fuels the muscles for longer”. Would you buy a product if the evidence to back it up was based on someone’s feelings?

Exceptional ingredients – are they special or just trendy?

Lush also told me that “Honey has been used as a skin ointment for over 2000 years”, as if that means it must be good for your skin. (Lead, which is poisonous, has been used in cosmetics since Roman times, but they didn’t mention that.) A lot of fuss is made out of the fact that honey and other products are traditional. For example, the Director of the Honey Research Unit at the University of Waikato in New Zealand has said, “I’m a great believer that if anything is traditional then it works. There may be no rational explanation, but that’s because we haven’t found it”. Flawed reasoning like this is at the core of the craze over Manuka honey, which supposedly has “curative powers” superior to regular honey. This belief is so widespread that manufacturers get away with selling it in small jars priced at £60, and there are even fake Manuka honeys on the market – normal honeys falsely advertised as Manuka so sellers can up the price.

Want to lose weight? Ask for Evidence before buying into fad diet claims

Misrepresenting the science seems to be the basis of all fad diets. Some diets have nothing to do with sound science, such as the clay diet which is said to “remove negative isotopes, helping you detox and stay in shape”. Diets such as this one are so ridiculous that they might as well have been made up. In fact, some are indistinguishable from diets that have just been made up. If you don’t believe it, have a go at the Spoof Diets quiz, which challenges you to spot fad diets from fictional ones – it’s harder than you might expect. So how are you supposed to tell what’s good for you and what to avoid? The answer is to Ask for Evidence. Scientists from the Voice of Young Science network helped us look at the evidence behind 13 diets – fad and fiction – and the results show just how important it is to Ask for Evidence behind claims, especially where your health is concerned.

Guest post by Grace Gottlieb, Sense About Science volunteer (@Grace_Gottlieb)

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