We have all found ourselves standing in a supermarket aisle, staring at packets and cans, struggling to choose between different versions of the same thing: Do I choose the product that is "free from artificial sweetener" or has "no MSG"? What about the one that "contains no GM" or is "paraben-free"?

But these are false choices: supermarkets are misinforming their customers about health risks. There is no scientific evidence to support rumours about adverse health effects from the flavour enhancer monosodium glutamate (MSG), or from foods containing material from plants that were genetically modified, or from the sweetener aspartame, or from parabens, which are used to preserve toiletries.

By marketing products as "free from" supermarkets are playing on people's fears, which are based on the rumours that have circulated about these substances.

Frustrated by this cynical marketing, a group of junior researchers that I coordinate (the Voice of Young Science network) wrote an open letter calling on supermarkets to stop misleading customers and review their negative claim policies.

We had asked the supermarkets to give their reasons for marketing products as "free from". Without exception, the supermarkets that responded provided no evidence for any negative health effects. Instead, they told us their policies are a response to customer concerns. For example Marks & Spencer responded: "The reason why we decided as a business to remove GM ingredients from our foods was due to our customer concerns."

This puts the blame on the customer … but how on earth are people supposed to work out which health concerns are well founded, and which are not, if supermarkets arbitrarily exploit health fears as a sales tool? Customers who would be better off reducing their salt and sugar intake to help prevent heart disease and obesity – significant public health issues – are instead wasting effort worrying about MSG and aspartame.

While scientists are working hard to get sound science and evidence into public discussion about food risks, and science journalists now stop much of the worst media reporting of unfounded scare and miracle stories, the supermarkets are busy promoting these unfounded fears to thousands of customers every day, undoing all that good work. When supermarkets promote the idea that MSG-free or paraben-free products are a good thing, they are helping to drive this misinformation.

There is no justification for consumers' worries about these substances. Take aspartame. Before any low-calorie sweetener is approved for use in food and beverages in the UK, the science supporting its safety is thoroughly reviewed. All of the low-calorie sweeteners approved for use, including aspartame, have been shown to be safe.

What about MSG? Research has shown it to be safe and that there is no need to set an upper limit on intake. Suspected adverse reactions and allergies to MSG have been investigated, including by the Scientific Committee on Food (the predecessor of European Food Standards Agency). There are people who claim to be sensitive to MSG, but in studies where these individuals are given MSG or a placebo no link between MSG and a reaction has been found.

And yet the supermarkets provide a choice between a product with, and a product without these substances. Supermarkets are effectively telling customers they would benefit in some way from choosing the "free-from" version, which reinforces any existing but unfounded concern. Supermarkets are shirking their responsibility to inform their customers and this needs to change.

Perhaps supermarkets don't realise the scale of the effect they have on customer opinion. When it comes to public misunderstanding of GM, for example, supermarkets have contributed to widespread public distrust. GM-free supermarket products imply that GM is "weird science", even though the European Commission has found no evidence of higher risk of negative health outcomes from GM food compared with conventional food in any of the research it has funded.

Negative marketing by supermarkets based on unsubstantiated concerns exploits people's attempts to choose healthy products, even pushing them towards alternatives that may not be good for them. It undermines our efforts to help people make sense of stories about food. Products and policies based on evidence are vital to give customers a real, informed choice. Supermarkets need to promote evidence not unfounded fears.