The NHS isn’t being honest about its healthy eating advice

It’s a hot day and you want a soft drink that’s cold and fizzy. Should you go for a Coke or a Diet Coke? A growing number of us are choosing drinks with artificial sweeteners, either for health reasons, or because the diet version is a little cheaper, thanks to the 2018 drinks “sugar tax”. That legislation also led to sweeteners replacing sugar in many products that aren’t even marketed as diet drinks.

But alarmingly, a government advisory committee said last week that people should minimise their intake of sweeteners and that young children should not be given them at all, due to inconsistent supporting evidence. Consumers could be forgiven for wondering what’s going on. if(window.



adverts) { window.adverts.addToArray({"pos": "inread-hb-ros-inews"}); }The U-turn is emblematic of the mess that all of dietary science is stuck in.

As a medical journalist who has been following the twists and turns of healthy eating advice for some years, it comes as no surprise.The background is that health advice has long been to avoid sugar where possible, because of its calories. Sugary drinks get an even worse rap than sugary food as they have few other nutrients, so they are branded “empty calories”.

This school of thought is why the UK introduced the drinks sugar tax. Debated for years beforehand, opponents said it was nanny state regulation. But it was generally backed by health bodies as necessary for tackling obesity – with some arguing we should go further still and introduce unhealthy food taxes too.

#color-context-related-article-3358319 {--inews-color-primary: #E33A11;--inews-color-secondary: #F7F3EF;--inews-color-tertiary: #E33A11;} Read Next square HEALTH .inews__post__label__analysis{background-color: #0a0a0a;color: #ffffff;}AnalysisSweets don’t really make kids hyperactive – and four other sugar myths debunkedRead MoreYet in the past few years, debate has been growing about whether sweeteners really are better for our health. if(window.

adverts) { window.adverts.addToArray({"pos": "mpu_mobile_l1"}); }if(window.

adverts) { window.adverts.addToArray({"pos": "mpu_tablet_l1"}); }Critics say that the evidence is conflicting on whether sweeteners help people lose weight.

Some studies suggest they are, counter-intuitively, linked with higher weight and greater risk of weight-linked conditions such as heart attacks and type 2 diabetes.One theory is that they disrupt appetite control by sending confusing signals – their sweet taste means the brain registers we have eaten something calorific but our blood sugar doesn’t rise. There have also been claims by some scientists they could disrupt gut bacteria or even cause cancer, although mainly from early-stage research in animals rather than people.

The confusion is typical for dietary science, which is beset by contradictory research claims. Think about how, one week, research may be claimed to show that eggs, for instance, are good for us, while the next week, another study will say that they are bad. The same goes for lots of food and drink, including potatoes, cheese, full-fat milk, alcohol.

..the list goes on.

The conflicting claims arise because in dietary research, it is hard to carry out studies that are high-quality and definitive. The most rigorous kind of medical research is a type known as a randomised trial, invaluable for revealing whether newly discovered drugs are effective and safe. In such a trial, typically half the volunteers take the medicine, while the other half take placebo tablets.

At the end, you see whose health was the best – for instance, which group had fewer heart attacks. Crucially, each person is randomly allocated to take the real drug or the placebo, and people don’t usually know which group they are in.It is hard to do that kind of study to investigate which foods are healthier, at least for any length of time.

Most people aren’t willing to change their diet long term based on a coin toss, and it would be impossible to keep their allocation secret too.if(window.adverts) { window.

adverts.addToArray({"pos": "mpu_mobile_l2"}); }if(window.adverts) { window.

adverts.addToArray({"pos": "mpu_tablet_l2"}); }#color-context-related-article-3590987 {--inews-color-primary: #E33A11;--inews-color-secondary: #F7F3EF;--inews-color-tertiary: #E33A11;} Read Next square NEWS .inews__post__label__big-reads{background-color: #0a0a0a;color: #ffffff;}Big ReadThe future of weight loss drugs: gummies, tablets and melt-in-the-mouth stripsRead MoreInstead, dietary research usually involves “observational” studies, where scientists merely observe what people choose to eat and then assess their health at the end.

Unfortunately, this kind of observational study is prone to producing biased results, for several reasons, including that poorer people may eat differently to the well off, and they also tend to have worse health, for reasons unconnected with diet. Scientists may try to adjust their data to account for such biases, but it’s difficult to do so completely. Plus, exactly how you should tweak the figures for each study is arguable, and different methods can lead to markedly different conclusions.

Sweeteners are the latest area where a spotlight has been shone on the nutrition field’s shortcomings. The standard NHS advice is that sugar-free drinks are a helpful way of cutting down on sugar. But the new advice to the Government from SACN, its Scientific Advisory Committee on Nutrition, is that “the evidence on non-sugar sweeteners and health outcomes is inconsistent”.

SACN has said younger children (whose age is undefined, unhelpfully) shouldn’t have drinks with sweeteners or sugar. In older children and adults, SACN believes the evidence shows sweeteners can reduce energy intake in the short term. But, “the long-term goal is to limit both sugar and [sweetener] intake”.

If NHS advice changes to follow the SACN line, it wouldn’t be the first such embarrassing U-turn. From the 1980s, we were urged to swap butter for margarine made from vegetable oils and to buy biscuits or cakes made from vegetable oil too. if(window.

adverts) { window.adverts.addToArray({"pos": "mpu_mobile_l3"}); }if(window.

adverts) { window.adverts.addToArray({"pos": "mpu_tablet_l3"}); }Unfortunately their manufacturing process meant that these products contained something called trans fats, which turned out to be far worse for the heart than butter.

#color-context-related-article-2344096 {--inews-color-primary: #46A3E0;--inews-color-secondary: #EBF5FC;--inews-color-tertiary: #46A3E0;} Read Next square HEALTH The truth about putting sweetener in your teaRead MoreIn the UK, manufacturers have reformulated their products so they now contain very little trans fats. But it shows the perils of prematurely issuing dietary guidelines based on uncertain science. Another food fight is brewing over whether low-carb diets are helpful.

NHS weight-loss guidelines have changed to say low-carbing is a useful option, but NHS type 2 diabetes guidelines shun this approach. The diabetes guidelines are now under review, amid a raging battle between low-carb advocates and those who say this goes against the usual low-fat approach. But for now, as most people with type 2 diabetes are recommended to lose weight, they face conflicting advice on how best to do it.

When it comes to sweeteners, I can’t predict what the next instalment of NHS guidelines will be. But I wish that health bodies would be more honest about the level of uncertainty behind the research. The truth is that dietary science has got itself into a sticky mess.

.