NARRATION

Artificial sweeteners offer a delicious promise - the sugariness we love without any calories or consequences.

Dr Zeeshan Arain

But do the quickest online search and you will be hit by a mass of conflicting information.

voxpop1

I don't think artificial sweeteners are safe.

voxpop2

You're looking to maintain that sweet taste but also trying to lose weight at the same time, so there is that benefit.

voxpop3

I don't know what they are actually made of. I think it'd be scary to find out, maybe.

Geoff Parker

Artificial sweeteners are perfectly safe. People can consume them with confidence. They've been tested hundreds of times.

Professor Susan Swithers

The question really ought to be - what is the evidence they are good for us?

Dr Katherine Samaras

Some of the data that is out there suggests they are not as benign as we have been told they are.

Dr Zeeshan Arain

I'm Zeeshan Arain, a GP, and I've decided to sort out the sense from the nonsense and work out what effect, if any, artificial sweeteners have on our health and bodies.

NARRATION

The first artificial sweetener, saccharine, became popular during the world wars, providing a sweet alternative when sugar was scarce.

Newsreader

World sugar supplies are still far short of demand.

TV advertisement

Boy, does that look good. But, honey, what'll these calories do to my waistline?

NARRATION

The post-World War II decades saw the rise of the first mass-marketed artificially sweetened products. Ads like this let consumers know that sweeteners had changed the equation between calorie intake and restraint.

TV advertisement

Metrecal helps you restrict calories.

TV advertisement

Introducing The Sweet Life.

NARRATION

By the '70s and '80s, advertisements emphasised indulgence, taste and sex appeal, and told us we could lose weight by consuming.

Dr Kieron Rooney

These products do get what we call a 'health halo'. We think that we can eat them to excess because they're not going to have any negative effects to us, or we do make other compromises in our choices because we're consuming that product.

NARRATION

Today, artificial sweeteners are found in a wide variety of products. And it's easy to see where the confusion starts.

Dr Zeeshan Arain

"Diet cordial, contains sweeteners 950 and 951."

NARRATION

Even the term "artificial sweeteners" is confusing. Their actual scientific name is intense sweeteners and there are ten approved for consumption in Australia. Each one is a different chemical compound but they share one important characteristic - they are many times sweeter than sugar. - so you only need a minute amount to get the same sweetness...and they turn up in surprising places.

Dr Zeeshan Arain

Toothpaste - saccharin. Mouthwash - saccharin. Dietary supplement - aspartame. So, even if you're avoiding them in your food, you may be getting them from other sources.

NARRATION

But what exactly are artificial sweeteners and how do they work? Dr Rebecca LeBard is a biomolecular scientist from the University of New South Wales.

Dr Rebecca LeBard

Artificial sweeteners are things that give us the nice taste that we like of sugar, but our bodies don't extract the same energy from them. So, this one that I can put in my coffee has something called aspartame in it. That is really interesting because it's made up of two amino acids, and amino acids are the building blocks of protein. So, you could say it has more in common with a steak than a sugar. And it is a lot sweeter, which means you only need a small amount of it.

Dr Zeeshan Arain

So, Rebecca, how do they make them so sweet?

Dr Rebecca LeBard

Well, it all comes down to the chemistry.

NARRATION

To be perceived as sweet, a molecule must be the right shape to bind with the sweet taste receptors on our tongue. This sends a message to our brain we've had something sweet. Artificial sweeteners fit these receptors better than sugar, which is why they can taste hundreds of times sweeter.

Dr Zeeshan Arain

Rebecca, are there any problems with having artificial sweeteners?

Dr Rebecca LeBard

This one in particular, aspartame, has something called phenylalanine - an amino acid - in it, which some people can't metabolise. Babies in hospitals are tested for it. It's something you'd know if you had that problem with it.

NARRATION

About one in 10,000 people can't process aspartame, but for the rest of us, research from around the world says overwhelmingly that artificial sweeteners are safe.

Geoff Parker

Sweeteners have been thoroughly tested and world-renowned food agencies continue to confirm their safety for regular human consumption.

Waitress

Just the usual today?

Professor Paul Brent

(to waitress) Yeah, just a skinny flat white. Thank you.

Sweeteners are very, very safe. Before they can come onto the market, they have to be safety assessed.

NARRATION

Professor Paul Brent was chief scientist at Food Standards Australia New Zealand and advised the UN and World Health Organisation about food additive safety.

Waitress

There we go. Flat white.

Professor Paul Brent

That safety process is very, very similar to that that's applied to a medicine. Certainly, we can put the idea that sweeteners cause cancer, we can completely dispel that because all of the studies show very, very clearly that these sweeteners do not cause cancer.

NARRATION

Like many Australians, Paul himself consumes artificial sweeteners on a regular basis, using them for weight management or to reduce sugar intake.

Professor Paul Brent

I'm trying to cut down on my consumption of sugar. When I go and have a coffee, I try and use a sweetener instead of sugar.

NARRATION

So, there appears to be consensus around the idea that artificial sweeteners aren't dangerous. But does that mean that they're inert? What effect, if any, are they having on our health and bodies? At the University of Sydney, new research on fruit flies and mice is suggesting that the sweetener sucralose may be fuelling rather than fighting weight gain.

Assoc Professor Greg Neely

After about five days, we noticed that the animals that had had artificial sweetener began eating more. They ate 30% more calories. They also became hyperactive and had problems with sleeping.

NARRATION

Normally, a sweet taste signals that energy is on the way, but in this case, sweet tastes without calories seemed to be tricking the animal's brain.

Assoc Professor Greg Neely

When there was an imbalance between sweet taste and energy, it triggered kind of a fasting response in the animal and it made them hungrier and made real sugar taste better, and then they ate more.

NARRATION

When the expected calories failed to show up, the animal's brain tried to compensate by driving up appetite.

Assoc Professor Greg Neely

Sweeteners, or at least the ones we've tested, are having an impact on the animal's nervous system, and so it would be possible that they have an effect on the human nervous system.

NARRATION

And it seems its effect might not be limited to the brain. At Purdue University in the United States, Professor Susan Swithers has been looking at how sweet tastes without calories might affect the body, this time with the sweetener saccharin.

Professor Susan Swithers

When animals were given artificial sweeteners and also had a regular food that had sugar in it, then we would routinely see that the animals given the artificial sweeteners would gain excess weight and that they were fatter, even though they were getting fewer calories from the sweetened foods that we were giving them.

We've actually measured a number of metabolic changes that seem to be caused by exposure to artificial sweetener in our animals.

NARRATION

Swithers' research showed that the animals' physiological response to normal sugar was disrupted.

Professor Susan Swithers

We gave all of our animals what is known as an oral glucose tolerance test. It is the way that we identify diabetes in people. What we saw was that the animals that had previously gotten the artificial sweeteners were hyperglycaemic - their blood sugars went up higher than animals that had not been given the artificial sweeteners.

NARRATION

In addition to not being able to control their blood sugar levels, they also released less of a peptide called GLP-1, which controls how fast food empties from your stomach.

Professor Susan Swithers

So, if your stomach empties more rapidly because you don't release as much GLP-1, that may lead you to overeat.

NARRATION

It is important to note here that the specific effects have only been shown in animals. Humans, however, were the subjects of a 2013 study published in the medical journal Diabetes Care, which found that sucralose could affect the way our body responds to sugar in other food we are eating.

Dr Kieron Rooney

Whilst the sweeteners themselves might not have a direct metabolic effect on you, it could be that they influence how you metabolise the foods you consume with them.

Dr Zeeshan Arain

I want to see if the artificial sweetener sucralose affects how my body deals with sugar. Hi Cody.

Cody

Hey, Doctor Z. So, got you in for the modified glucose tolerance test.

Dr Zeeshan Arain

Today, I drink my meal substitute - a 75ml bottle of glucose - and then chase it with an artificially sweetened drink. That wasn't too bad. My blood is taken every 30 minutes for 2.5 hours to track changes in my sugar levels and insulin. Now, this is in no way a scientifically valid experiment, it is just to satisfy my curiosity. I'm visiting endocrinologist Dr Katherine Samaras to discuss the results of my tests.

Dr Katherine Samaras

In the one with the sweetener, what we see is even though you start with quite a really great glucose level, you have this very, very rapid rise in glucose.

Dr Zeeshan Arain

In my first test - without sweetener - my blood sugar level rose 40% at the 30-minute mark. In the second test, where I followed my meal substitute with an artificially sweetened drink, it rose 53%.

Dr Katherine Samaras

This mimics some of the literature that is out there in the scientific arena. Indirectly, whilst artificial sweeteners have no calories themselves, they could be seen through the downstream effects as promoting obesity.

NARRATION

One possible explanation for this is in the last decade, sweet taste receptors have been discovered throughout the body, including the gut. Animal studies have found that artificial sweeteners activate these gut sweet taste receptors, increasing the absorption of glucose. This means when you consume sweeteners with your meal, sugar enters your bloodstream earlier and faster.

Professor Susan Swithers

So, the idea that the sweeteners have no effect and that they are completely inert, that was really based on our lack of understanding of exactly how complicated the digestive system is.

Dr Zeeshan Arain

When we look at data from long-term population studies, we can see some interesting associations between artificial sweeteners and health outcomes.

Professor Susan Swithers

What we see with these real-world observational studies is that people who drink typically about one or more diet sodas a day are more likely to gain weight, to gain belly fat, to be diagnosed with type 2 diabetes, to develop high blood pressure, to develop metabolic syndrome and to develop cardiovascular disease.

Professor Paul Brent

There is an equal number of studies, which I think are better designed and are more robust, which actually show no effect on these particular disease states.

Dr Zeeshan Arain

Here, grab this letter. As a new dad, one observational study particular caught my attention. I am Skyping Associate Professor Meghan Azad, an investigator on the child study who published her findings in May 2016.

Associate Professor Meghan Azad

It's an incredible study that we are doing here in Canada, where we recruited over 3,500 pregnant women and followed them and their babies as they grow up. So, in this particular study, we used data from the mums' nutritional surveys, and so what we found, surprisingly, was that women who consumed one or more artificially sweetened beverage per day were more than twice as likely to have an infant who was overweight at one year of age, compared to women who didn't consume these beverages at all. Our study didn't go as far as establishing mechanisms, but we have some ideas. So, one involves the gut microbiome, or the bacteria in our intestines. So, if the maternal consumption of sweeteners is changing the microbiome, this could be passed on to the babies at birth and influence their weight gain during infancy.

The other possibility is that these artificial sweeteners are changing the mother and infant's metabolism, although more research needs to be done to confirm that.

NARRATION

With these types of population studies, there are many factors at work, which is why scientists can't exactly draw a direct cause and effect between sweeteners and these negative health outcomes.

Professor Susan Swithers

Well, we can't say they cause the problems, because they're not experiments, they're observations. So, it could just be the case that the people who are choosing to use diet sodas are people who are already unhealthy.

Geoff Parker

Those studies are really in contradiction to that broad totality of the evidence base that shows that they're perfectly safe to be consumed in moderation.

NARRATION

So, what do we make of all this? There does seem to be a growing number of studies suggesting sweeteners may not be inert and certainly deserve closer scrutiny. But what is the big picture?

Professor Peter Rogers

It is about, really, ultimately, diet and health.

NARRATION

Where does the weight of evidence in all this seem to lie? Professor Peter Rogers was involved in a review of studies investigating the impact of artificial sweeteners on energy intake and body weight. Although comprehensive, it's worth noting that the study was funded by an organisation with industry ties.

Professor Peter Rogers

We carried out this review on low-calorie sweeteners because there seemed to us to be a lot of confusion in the area. So, claims that low-calorie sweeteners were actually unhelpful to energy intake control and weight control.

NARRATION

In total, 90 animal and 155 human studies were examined.

Professor Peter Rogers

We were able to conclude very clearly from our review that low-calorie sweeteners, when they're used in place of sugar, are helpful in reducing energy intake and body weight.

NARRATION

However, experts also warn that if you use artificial sweeteners to help in weight loss, you need to be mindful you don't replace calories saved with other foods.

Dr Kieron Rooney

And that is the removal-of-restraint effect. "I'm having a diet drink today, "so therefore I can have a larger serving of chips." In which case, any of the benefit that you would have gained from having a lower calorie or a lower energy intake is counteracted by the fact that you've eaten more of something else.

NARRATION

Whether you include sweeteners as part of your weight management plan or not, there's one thing most of the experts we've spoken to agree on - you should always consider how they fit into your overall diet and lifestyle.

Professor Peter Rogers

On their own, low-calorie sweeteners won't provide the entire solution, so they have to be consumed in relation to otherwise healthy diets.

Dr Katherine Samaras

Whether you have natural sugar or whether you have artificial sweetener, perhaps just don't have it as regularly as we're having it now.

Geoff Parker

If your concern over artificial sweeteners is likely to drive you back to sugar, or to sugar, that would be a bad health choice to make. There's the third option, which is the unsweetened product, and that is where we should be encouraging people to go.

INFORMATION ABOUT CLINICAL TRIAL

Dr. Rooney and colleague, Prof Boakes, are currently conducting a clinical trial on sugar and artificially sweetened beverages.

More information can be found here https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=368612&isReview=true

or email psych.sugardrinks@sydney.edu.au to participate.

CONFLICTS OF INTEREST - OUR EXPERTS RESPOND

Professor Paul Brent- No I do not have any conflicts.

Professor Peter Rogers has received grant support from Sugar Nutrition UK for research on the effects of sugar on human appetite, payments for consultancy services from Coca Cola Great Britain, and speaker's fees from the International Sweeteners Association. He is also co-chair of ILSI-Europe's Eating Behaviour and Energy Balance Task Force.

Dr Katherine Samaras : I have no conflicts of interest. I do not receive any funding (direct or indirect) from any industry or company, either in sponsorship, research funding, meals, conferences, travel. I decline pens or any other "gifts".

Assoc Prof Greg Neely: I don't own any stocks in any companies, and I don't receive any money from anyone for this work.

Professor Susie Swithers : I have no conflicts of interest. My research is funded by the National Institutes of Health and Purdue University.

Dr Kieron Rooney : All my funding COIs are available on my Uni home page http://sydney.edu.au/health-sciences/about/people/profiles/kieron.rooney.php

In 2009 I was an Investigator on a $10 000 grant from (then Gatorade but now registered as PepsiCo) to do a pilot study on hydration status and accuracy in cricket bowling.

Since 2010, I have been a named investigator on a cumulative total of just over $500 000 of funding from Meat and Livestock Australia for a series of projects looking at lower carbohydrate, higher protein diets for weight loss, cognition and iron metabolism in young overweight women.

In 2013 I was CIB on an ARC funded grant which is specifically covering the animal and human sugar / artificial sweetner experiments we are currently running

In 2015 I was CIA on a small seed grant from "Healthy Sydney Uni" to investigate the community attitudes and perceptions of SSBs and their regulation.

Assoc Prof Meghan Azad - No conflicts to declare.