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Plant Science Panel

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'The Ugly Truth'

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Ask for Evidence - Negative Claims

VoYS is calling on supermarkets to put evidence at the heart of their policies. Members of VoYS have been asking supermarkets for evidence behind claims and policies such as 'no GM', 'no parabens' and 'no MSG' - 'negative claims'.

Negative Claim products

The supermarkets were asked to give reasons for advertising products as “free from” these substances. Without exception, those supermarkets which responded did not provide evidence of health effects. Instead they blamed customer concerns. In response, VoYS has written an open letter to ten supermarket CEOs, calling on supermarkets to stop misleading customers about health risks. Some replies have been received - see the supermarkets' responses to the letter.

Supermarkets seriously misinforming customers about health risks

VoYS accuses the supermarkets of playing on unfounded fears about health effects from GM, MSG, parabens and aspartame. The rumoured health effects are not supported by scientific evidence, and excluding these substances does not provide a health benefit. VoYS says that the supermarkets know there is no evidence and the negative claims are cynical marketing. See further comments about this campaign.

Want to get involved?

  • Email Joanne to add your name to the letter.
  • Read example case studies from VoYS members who contacted the supermarkets, and the response they received.
  • Contact us for hints and tips on how to ask for evidence.

Low Sodium Drain CleanerWhat do we mean by 'negative claims'?

On some products, supermarkets use negative claims to promote them on the basis of what they don’t contain: , “paraben-free baby wipes”, “MSG-free crisps”, spinach leaves with “no weird science” (ie GM), or “sulphate-free shower gel”. Would you choose a negative claim product?

Why is it important?

Acid Free OJ
Supermarkets that market their products as MSG-free, GM-free, paraben-free and free from artificial sweetener are misleading customers who are concerned about making healthy choices. The supermarkets are also undermining public efforts by the scientific community to communicate the risks and benefits of food choices. Negative claims reinforce and legitimise customers' unfounded concerns. Supermarkets need to base their policies on evidence because if consumers demand something is removed from products but it is not easy or cheap for the supermarkets to do so, will the supermarkets then respond based on evidence? 


How can you help? 

Ask for Evidence

VoYS is exposing this issue to explain that negative marketing is a serious problem, calling on supermarkets to stop making cowardly decisions, and holding supermarkets to account both publicly and privately. You can add your name to the letter and Ask for Evidence when you see negative claims and let us know how you get on.

Thanks to Eliza Wolfson for the wonderful illustrations.



Guardian Science posted a blog about the issue, by Victoria Murphy 'Supermarkets cash in on unfounded fears about food and health'

MeatInfo 'Researchers urge retailers not to mislead on health risks'

Food Manufacture 'Supermarkets must stop scaremongering say scientists'


Simon Rees, VoYS: “Lidl makes their products with 'No Added MSG' because that's what they think customers want. No science. No evidence. Simple marketing.”

Lucy Brooks, VoYS: "It seems Iceland's decision not to sell GM products is based on customer demand. If science and logic are to prevail then change needs to start somewhere: first by supermarkets using evidence as the basis of their policies.”

Duncan Casey, VoYS: “I contacted ASDA to ask about the basis for their policy, which is, "led by our customers" according to their policy statement. However, the company was unwilling, or unable, to provide any further information beyond the vague statements on the website; I can only conclude that their stance is led more by scare stories in the press than by any real evidence.”

Victoria Murphy, VoYS co-ordinator: “Hundreds of researchers in the VoYS network are involved in tackling public misinformation about science and health. They make incredible efforts alongside their research work, but they have been frustrated about product and marketing claims. While the media and others have become a good deal more balanced in their presentation of research into MSG, GM, parabens and sweeteners, supermarkets aremisleading thousands of people every day. People who want better communication of food risks and benefits are forced to struggle uphill against this tide.”

Professor Rob Chilcott (Chair of the UK Register of Toxicologists): “There are many examples of the public being misled by baseless opinion masquerading as scientific fact. A case in point is the current outbreak of measles, which may be largely attributable to the continued yet totally unfounded distrust of the MMR vaccine. Therefore, it is refreshing to see a new generation of scientists who are prepared to openly challenge misconceptions that may be adversely influencing public debate on important issues such as the safety of GM crops and food additives.”

Dr John Emsley, toxicologist: “It is good to see the VoYS network taking issue with some enduring myths. MSG occurs naturally in many foods and is especially high in cheese, peas and tomatoes. It has the food code number E621 which indicates it is regarded as safe to use in EU countries.”


VoYS pinboard

  • Top tip 1: Ask for Evidence. If you’re being sold a product or asked to believe a claim then you deserve to know whether it’s based on evidence – or imagination.

  • Top tip 2: Detox. It’s a marketing myth – our body does it without pricey potions and detox diets.

  • Top tip 3: Superfood. There is no such thing, just foods that are high in some nutrients.

  • Top tip 4: Cleansing. You shouldn’t be trying to cleanse anything other than your skin or hair.

  • Top tip 5: If it sounds too good to be true… it probably is.

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