Exploring sweetness

January 26


Eating a lemon seemed unbelievable. First, I had a tiny tablet without taste on my tongue. It was made from the powder of a fruit found in West Africa, called the miracle berry from the Synsepalum dulcificum shrub. Later, when I bit into a lemon slice, my mouth filled with sweet instead of sour.


In Benin, people have used the miracle berry for a long time to make tart foods sweet. It has a protein in its pulp that makes things taste sweet when there are acids around. Now, it might become famous worldwide as an important part of our search for healthier ways to enjoy sweetness.


Too much sugar is not good for us. It causes problems like obesity and type 2 diabetes. So, instead of sugar, many foods and drinks have substitutes like aspartame, stevia, and sucralose. But now, these substitutes are causing arguments. In May, the World Health Organization said not to use them for losing weight and avoiding type 2 diabetes, which they were once thought to help with.


Now, we’re learning more about how these sweeteners affect our health. New plant-based alternatives, like sweeteners from the miracle berry, rare sugar from figs, and a different kind of sugar crystal, want to be the best. Will they be a healthy way to enjoy sweetness, or do we need to change how we feel about sweet things?


People like sweet things because our ancestors needed the energy from sugary foods to survive. But now, we get too much-added sugar from things like table sugar, taken from sugar cane and beets.


This isn’t good for our health, and the World Health Organization says we should have less than 25 grammes (equal to six teaspoons) of added sugar each day. This can be hard because sugar is almost everywhere in our diets. In the US, for example, people have around 17 teaspoons of added sugar on average every day. Nenad Naumovski at the University of Canberra in Australia says finding a better alternative to sugar is essential.


To fix this, food companies use sweeteners that taste sweet but have few or no calories. The first artificial sweetener, saccharin, was accidentally found in the 1870s. A chemist, Constantin Fahlberg, didn’t wash his hands after studying coal tar and realized his dinner was strangely sweet. Saccharin is 300 to 450 times sweeter than sugar.


Many different sweeteners have been discovered over time. Some, like aspartame in 1965 and sucralose in 1976, are artificial. Others, like extracts from the stevia plant, have been used by people in South America for a long time and were first sold in the 1970s. Most sweeteners have no calories, but a few, like aspartame, have a little. They are usually much sweeter than apples or oranges, at least 100 times. Some sweeteners come from sugar alcohols, like sorbitol and xylitol. These are as sweet as table sugar but have fewer calories. The sugar substitutes market globally is worth about $20 billion each year, and they have to pass strict safety tests before they can be sold.


“They all have different properties, like aftertaste, sweetness, and what they are made of,” says Cherie Russell at Deakin University in Melbourne. “You can mix them to be good for almost any food.” Russell’s research found sweeteners in many products, not just diet soda and gum, but also yoghurt, cereal, ice cream, flavoured milk, and kombucha. They are also in toothpaste and mouthwash to avoid causing cavities. A study found that even people who said they didn’t eat low-calorie sweeteners had some in their urine. Babies can get sweeteners from breast milk.


In a 2022 survey, Russell and her colleagues found that many countries use sweeteners more in drinks and packaged foods. It’s more common in places that have rules to reduce sugar. But replacing sugar with these sweeteners is not easy. Sugar gives food its taste and texture. It stops cookies from falling apart and makes some sorbets creamy. “Taking out just 10 per cent of the sugar and replacing it with something else causes all sorts of havoc with a biscuit,” says Naumovski. “It also doesn’t colour up, and the texture doesn’t seem quite right.” Some sweeteners don’t work well in heat, some lose sweetness, and others have a bitter taste. So, even though they are sweet, they are often only used in certain things, like diet drinks or gum, and not to replace all the sugar in food.


Health is also a complicated issue. Sweeteners should be good because they help us eat less sugar. But not everyone agrees on this.


People have been worried for a long time about using certain sweeteners. In July, the World Health Organization (WHO) said that aspartame, a kind of sweetener, might be “possibly carcinogenic to humans”. This means it might be related to causing liver cancer, but not everyone agrees. Other health experts at the WHO said that the amount of aspartame people usually eat is okay.


Some studies with many people over a long time have found links between sweeteners and cancer. In 2022, a study in France looked at records from over 100,000 adults and found that those who ate more aspartame and another sweetener called acesulfame-K had more cancer. Mathilde Touvier, who led the study, says this and similar studies “suggest signals regarding sweeteners and increased cancer risk in humans”.


Some studies say using sweeteners for a long time might make people gain weight, have heart problems, or get type 2 diabetes. One idea is that sweeteners confuse the body because they taste sweet but don’t have calories. The brain still thinks it’s getting sugar and makes too much insulin, which can lead to problems. However, some people believe these studies might be wrong because they only look at people who are already overweight or have health issues.


On the other hand, some studies with animals show that sweeteners make them feel hungry, so they eat more. A study in the US found that kids and teens who drank drinks with sweeteners ate more sugar. Another study in 2020 found that sweeteners only affected the body’s sugar response when people drank them with carbohydrates, like fries.


The tiny living things in our gut, called microbes, might also play a role. A study in 2021 looked at 120 people and found that different sweeteners changed the types of bacteria in the gut and mouth. Some sweeteners, like sucralose and saccharin, increase blood sugar. When they put these changed microbes into mice, the mice gained weight and had trouble with sugar, just like people. Researchers are still trying to understand precisely how these changes in the gut affect our health.


The sweeteners we use might be affecting our health in different ways, and we haven’t found one that’s as good as sugar but without its problems yet. The search for a better option is ongoing in the food industry. One hopeful place to look is among rare sugars from certain plants, like allulose, found in small amounts in figs and raisins. Allulose tastes similar to table sugar but has only 10 per cent of the calories and doesn’t make blood sugar go up. The US Food and Drug Administration approved it for “no added sugar” products in 2019. It’s used in some energy bars and condiments but is still costly to make. A recent study showed that a modified strain of bacteria can produce allulose cheaply and in large amounts.


Another alternative is monk fruit extract, a powder made from drying the juice of berries from a Chinese vine. Used in Chinese medicine for a long time, it’s more than 200 times sweeter than sugar but has no calories. Growing it in large quantities has been a challenge, but a company in North Carolina has found a way to grow it in watermelons.


A new product called Supplant, made by using leftover parts of crops like wheat straw, is also emerging. Enzymes turn carbohydrates into a mix of sugars and fibres, creating a high-fibre product that tastes like cane sugar but with half the calories and a lower blood sugar response.


Maybe one day, we can get rid of sugar and its low-calorie substitutes and still enjoy sweetness. Some sweet proteins found in the berries of West African shrubs, like brazzein, monellin, and miraculin, offer this promise. Miraculin is well-known and comes from the berry that makes a lemon taste sweet.


The miracle berry, where miraculin comes from, disappeared from Benin’s national cuisine. Dedeou Tchokponhoue at the University of Abomey-Calavi in the country explained that it’s a slow-growing plant, taking five years to produce fruit. However, in 2019, he and his colleagues found a way to reduce the time to just 18 months, aiming to use the crop to help with the rising rates of type 2 diabetes in Benin.


Food manufacturers are interested in using miraculin or other sweet proteins in healthy but sour-tasting foods, like plain Greek yoghurt, to create a sweet taste. However, there are challenges to overcome, such as the short shelf-life of miraculin.


One way to solve the sweetness problem is through genetic engineering. In Japan, scientists at the University of Tsukuba put miraculin plant genes into tomatoes. Other researchers are trying to make sweet proteins like miraculin and brazzein without growing berries. They put their genes into microbes, and the microbes make these compounds.


In Italy, Delia Picone is studying the sweet protein monellin at the University of Naples. It comes from a shrub in West Africa. Picone thinks monellin might be better for businesses than miraculin. She says, “It’s very sweet, so you only need a little as a sugar substitute.” The problem with monellin is that it breaks down when it’s hot. But in 2021, Picone and her colleagues found a way to change its chemical structure to stay the same when cooking.


Even though these new sweeteners are considered safe by experts, we still need to learn more about their long-term effects on health. Researchers are also trying to change regular sugar to make it dissolve faster on the tongue. This way, we can have sweet-tasting foods with fewer calories.


But the real issue is that we eat too much sweet stuff in modern countries with a lot of money. According to Suez, a scientist, “We’re eating more sweetness than our bodies can handle, whether it’s sugary or not.” He thinks the most important thing is for people to realize they should eat less sweet things.


Russell, another expert, agrees. She says having a very sweet taste makes us not want to eat healthy foods like whole grains and vegetables. This is a big problem globally, especially for kids. She adds, “You start expecting everything to taste super sweet.”


So, even though we’re trying to find sweet things without sugar, there’s still work to do before we find the perfect solution.


Reference: New Scientist Nov 2023