Sarah Chapman looks at a new Cochrane Reviews are systematic reviews. In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. More, published today, with evidence on whether displaying calories on menus and next to food in cafes can influence our choices and reduce our calorie intake.
With some time to spare before we were due to give a talk, my colleague and I went into the only available coffee shop, belonging to one of the chains we see in every high street and shopping centre. It felt like time for a little something, and we both spotted a square of cake that looked modest in size and surely not too calorific. All the baked goods on display carried labels, with the name of the product displayed large, price smaller, and estimated calories very small. We looked at the calorie information – after all, we’re keen on informed choice!
We were shocked to see that this small cake contained well over 400 calories, more than the much larger muffin next to it, and looking at the other labels we realized that had we been asked to rank them all from the fewest calories to the most, we would have got that badly wrong. We fancied a little something with our coffees, but did we want that enough to eat all those calories? In fact, faced with the information about how much we would be eating, we stuck with just a drink!
Having information about calories in products, when choosing from a selection of foods, would certainly affect my choices in other places too, such as in restaurants. If I like two things equally, but one has half the calories, well that’s a no-brainer for me. But, in my experience, having information about calories on menus is not commonplace. With obesity a significant problem in the UK and elsewhere, could providing this information reduce the calories we consume?
New evidence on nutritional labelling
A new Cochrane review has found that adding calorie labels to menus and next to food in coffee shops and cafes may reduce the calories that people consume.
The review draws on 28 studies, of which 11 explored the impact of nutritional labelling on purchasing while 17 looked at its effect on consumption. Individual studies have had mixed results, but this review combines the results of the studies to give us better estimates of the effects that labelling might have. Labels had to give the estimated calories, not just a symbol such as a tick or a traffic light indicator.
Evidence from three studies in real world settings, rather than in laboratories, suggests that calorie labels on menus or by food in cafes, restaurants and coffee shops, may reduce the calories that people buy by an average of 8% per meal. On a meal of 600 calories, such as a slice of pizza and a soft drink, that’s about 48 calories fewer. This tells us about what people select, but not what they actually eat and drink.
Evidence on calories consumed comes from studies testing behaviour in laboratory settings, which may differ from behaviour in the real world. Eight studies combined could not show with any certainty whether adding nutritional labels influences the number of calories consumed, but when the studies with potential flaws in their methods were taken out, the remaining three show that labels may reduce calorie consumption by about 12%.
Where does that leave us?
Professor Theresa Marteau, Director of the Behaviour and Health Research Unit and the lead author of this review, says “This evidence suggests that using nutritional labelling could help reduce calorie intake and make a useful impact as part of a wider set of measures aimed at tackling obesity.”
Review author Professor Susan Jebb, from the University of Oxford, would like to see the provision of calorie information that we see in some food outlets extended to others, and she believes that this Cochrane review “should provide policy makers with the confidence to introduce measures to encourage or even require calorie labelling on menus and next to food and non-alcoholic drinks in coffee shops, cafeterias and restaurants.”
However, the evidence is low quality, and the review authors highlight the need for more and better studies. Evaluating the impact of this type of A treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include a drug, surgery, exercise or counselling. More in the real world is challenging. There remains considerable uncertainty about the effect of nutritional labelling on food and non-alcoholic drinks bought from vending machines and shops, due to the lack of evidence, and the review authors would also like to see future research addressing the wider impacts of labelling on those who produce and sell food, as well as those who eat it.
So let’s hope that we see some reliable, real world research that can be included in an update of this review, and more nutritional labelling in food outlets, so that we can make informed choices about what we buy and eat.
References may be found here.
Sarah Chapman has nothing to disclose.