Some people really ARE born with a sweet tooth: Genes mean some of us DO need more sugar to get the same hit
- Sweet-toothed people are born with a 'weak sweet taste', study found
- They need more sugar than others to taste the same level of sweetness
- Genes account for 30% of variation in sweetness from person to person
- Eating lots of sugar as a child does not dull a person's sensitivy to it
Many of us pile sugar into our tea and think dessert is the best part of a meal.
And now, new research has found it might be down to our genes.
Some people really are born with a sweet tooth, researchers found.
These people are born with a weaker sweet taste, meaning they may need more sugar than others to taste the same level of sweetness.
A study found a single set of genes affects a person's perception of sweetness.
Some people are born with a sweet tooth, a study found. Some people have a weaker sweet taste, meaning they may need more sugar than others to taste the same level of sweetness (file photo)
This was true whether the sweetener used was a natural sugar or an artificial sweetener, researchers found.
'Eating too much sugar is often seen as a personal weakness. However, our work suggests that part of what determines our perception of sweetness is in our genetic makeup,' said the study's author, Dr Danielle Reed, of Monell Chemical Senses Center.
'Just as people born with a poor sense of hearing may need to turn up the volume to hear the radio, people born with weak sweet taste may need an extra teaspoon of sugar in their coffee to get the same sweet punch.'
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As part of the study, Dr Reed and her team tested 243 pairs of identical twins (monozygotic), 452 pairs of non-identical twins (dizygotic) and 511 people.
Each person tasted and then rated the intensity of four sweet solutions: fructose, glucose, aspartame, and neohesperidine dihydrochalcone (NHDC).
The first two are natural sugars, while the latter two are artificial sweeteners with no calories.
Identical (or monozygotic) twins have identical genes while non-identical (or dizygotic twins) only share about half of their DNA.
Studying twins allows the researchers to determine how much their DNA contributed to their perception of the intensity of a sweet flavour.
They found that genetic factors account for approximately 30 per cent of variation in sweetness between person to person.
The study also revealed that those who perceived the natural sugars as weakly sweet experienced the sugar substitutes as similarly weak.
This suggests that there may be a shared pathway in the perception of the intensity of sweetness of natural sugar and synthetic sweeteners.
Scientists are still working to understand the mole molecular processes behind how we detect the many different types of sweet molecules.
Earlier studies with mice showed that there is one main pathway for detecting non-caloric sweeteners and natural sugars, but also a second pathway that responds only to sugars.
The current findings suggest that these two pathways might converge into a single experience of sweetness intensity.
The current study also found little evidence our environment - or how much sugar we eat as children - influences our sweet perception.
Assuming twins ate the same meals as children, this finding challenges the common belief that access to foods high in sugar may make children insensitive to sweetness.
'Our findings indicate that shared experiences, such as family meals, had no detectable ability to make twins more similar in taste measures,' Dr Reed said.
'The next big question is if, and how, genes and early experiences interact to affect food choice.'
Understanding whether someone is born with a sweet tooth may may eventually help food manufacturers reduce the amount of sugars and sweeteners they add to food, she added.
Researchers found little evidence our environment influences our sweet perception. This challenges the commonly-held assertion that eating sugary foods as children makes them insensitive to sweeness
'Even though almost everyone - consumers, physicians, and public health officials - wants to decrease the amount of sugar in our diets, right now we have no tool that has the sensory equivalence of sugar,' said Dr Reed.
'However, if we can understand why some people have weaker sweetness perception, we might be able to adjust this so we could reduce the amount of sugar in foods.'
'The genetics of bitterness have been widely studied in past decades, but there's much less genetic information on sweetness,' said lead author Daniel Hwang, a PhD candidate at the University of Queensland, who also is affiliated with the QIMR Berghofer Medical Research Institute.
'Our next steps are to identify key genes shared by people who are weak sweet tasters, in the hopes of understanding their weaker perception.'
The study was published in Twin Research and Human Genetics.
