The researchers, from Monell and the QIMR Berghofer Research Institute, looked at sweet taste perception among 1,900 young adult and adolescent twins and their non-twin siblings, including 695 twin pairs. Studying identical and fraternal twins allowed the researchers to determine how much influence shared genetics had on their perception.
“If we can understand why some people have weaker sweetness perception, we might be able to adjust this attribute so we could reduce the amount of sugar in foods,” said study author Danielle Reed, a behavioural geneticist at Monell.
The researchers found that about 30% of sweet taste perception could be explained by genetics.
"Our findings indicate that shared experiences, such as family meals, had no detectable ability to make twins more similar in taste measures. The next big question is if, and how, genes and early experiences interact to affect food choice."
Nutritive vs. non-nutritive sweetness?
Study participants rated the sweetness intensity of four different sweeteners: the sugars fructose and glucose, and non-nutritive sweeteners neohesperidin dihydrochalcone and aspartame. The researchers found that those who perceived the sugars as weak also perceived the sweeteners as weak, suggesting a single response pathway for all sweet taste perception regardless of calorie content.
Previous research in mice has suggested that there may be two different ways in which the brain responds to sweetness, with non-nutritive sweeteners possibly inducing glucose intolerance through changes to gut microbiota.
However, this latest study found that sweetness intensity was not experienced differently depending on the sweetener source.
Policy implications
In addition, the finding that about 30% of sweetness perception could be explained by genetics suggests that the remainder is due to environmental factors.
Study lead author Liang-Dar Hwang told FoodNavigator that a policy of gradually reducing the sugar content in foods and drinks – as encouraged under the UK’s Responsibility Deal – was therefore feasible.
“Nevertheless, the inborn differences in sweet taste could still make this policy less likely to work with certain people,” he said.
Hwang added that at this stage researchers could not say what proportion of the population might have a weaker sweet taste, partly because it was influenced by ageing, hormonal status and diet, among other factors.
“However, our next project on sweetness genome-wide association analysis would provide some clues,” he said.
Source: Twin Research and Human Genetics
Published online ahead of print doi:10.1017/thg.2015.42
“A Common Genetic Influence on Human Intensity Ratings of Sugars and High-Potency Sweeteners”
Authors: Liang-Dar Hwang, Gu Zhu, Paul A. S. Breslin, Danielle R. Reed, Nicholas G. Martin and Margaret J. Wright