In search of the perfect sweetener

Too much refined sugar is blamed for a wave of obesity and ill-health, so the search is on for the perfect sweetener. But it's not an easy task, writes Michael Mosley.

I have had a love affair with sugar that has lasted all of my life. I adore the sweet stuff and in my youth knocked back gallons of sugary drinks and ate as many desserts as I could sink my teeth into.

Unfortunately it is a love affair that has brought me nothing but grief. The sugar I gleefully ate and drank rotted my teeth, so that almost every tooth in my face has had to be filled, drilled or replaced. All those sugary carbs also helped pile on the fat, which sent my blood sugar levels soaring.

Recently I have managed to cut down my sugary intake but never quite managed to quit. So, not surprisingly I've been on a quest to find a substitute, something that will satisfy my sweet teeth (or what remains of them) without the unfortunate side effects. I've tried aspartame, saccharin, xylitol and stevia. I haven't found any of them convincing, though pure stevia isn't bad when you mix it with sugar and add to stewed fruit.

So I was intrigued when the team making a new series for BBC One, Tomorrow's Food, invited me to try the extract of an African fruit, called the miracle berry. Derived from a plant called Synsepalum dulcificum, it is unlike any artificial sugar I'd tried before - because it works not by making foods sweeter, but by making them taste sweeter.

The so-called miracle berries contain a molecule called miraculin which binds to receptors on your tongue, changing their shape. This makes sour foods taste sweeter. One advantage of temporarily changing your taste buds, rather than the food itself, could be the effect this has on your gut bacteria.

For years now there has been a vigorous debate as to whether using artificial sugars will help you lose weight or not. A recent meta-analysis which looked at the results of more than 100 different human studies concluded that when artificial sweeteners replace sugar in the diet (rather than simply being added on top) then this can lead to weight loss.

The Harvard School of Public Health, however, points out that there are lots of conflicting studies, including those which suggest that drinking artificially sweetened drinks may increase your risk, not just of weight gain, but of type 2 diabetes.

Sweeteners - NHS Choices

No-one really knows how artificial sugars could do this but a study done by a group in Israel suggests it might be via the impact of artificial sugar on your gut bacteria.

In this study, published last year in the science journal, Nature, the Israeli researchers asked a group of lean and healthy volunteers who didn't normally use artificial sweeteners to consume the maximum acceptable dose for a week.

At the end of the week half the volunteers were showing signs of glucose intolerance, an early step in the journey to type 2 diabetes. The researchers think this could be because the bacteria in their guts reacted to the artificial sugars by secreting substances that cause inflammation. This is certainly what they have seen in animals.

What was really interesting was that when they collected faeces samples from the volunteers, they saw changes in the gut bacteria of those who had responded badly to the sweeteners and no change in those who had not.

As one of the researchers, Dr Eran Elinav, put it: "Our relationship with our own individual mix of gut bacteria is a huge factor in determining how the foods we eat affects us." Clearly not a fan of artificial sweeteners, he went on to add that there should be a "reassessment of today's massive, unsupervised consumption of these substances".

Whatever the health effects or otherwise of artificial sweeteners, consumers are wary of them, which is where those promoting the joys of natural miracle berries hope to score. The trouble is that the berries are expensive to grow and don't last long, so scientists in Japan (where the berry is popular) are now trying to produce the all-important miraculin molecule by genetically engineering tomato plants. That is obviously some way off. For now the simplest and cheapest way to get a dose of miraculin is to buy tablets which contain the dehydrated pulp of the fresh berries.

So what are they like? Eagerly I put one on my tongue, waited about five minutes for it to dissolve and then I was good to go. I had read enthusiastic claims that it would make foods, such as oranges, taste as if they had been 'freshly plucked from the Garden of Eden" and kill my sugar cravings stone dead.

That was not my experience. The tablet I tried certainly took the bitter edge off licking a lemon, but the aftertaste was flat and remarkably unpleasant. An expensive red wine was transformed by the tablet into a sweet, fizzy abomination. I tried eating a segment of orange. Far from making the orange irresistible, the tablet made it inedible. The only good thing, as far as I was concerned, is it put me off eating anything at all until the effects had worn off (about an hour).

Others may have a better experience, but for me the quest for a perfect artificial sweetener continues.

A naturally-sourced sugar substitute called stevia apparently has no calories, no carbohydrates, and does not raise blood sugar levels. Is it too good to be true?

How did Stevia become mainstream? (June 2013)

Tomorrow's Food is presented by Dara O'Briain and broadcast on BBC One at 21:00 GMT on 23 November 2015 - watch on BBC iPlayer

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