Could 'Taste-Bud Deficiency' Partly Explain Obesity?

Marlene Busko

August 03, 2017

When 51 slim young people were given a substance to dull their taste buds for perceiving sweetness, they preferred a more highly sweetened beverage or cookie, with more calories. Thus, further study is needed to see how weakened taste buds might be linked to obesity, the researchers conclude.

"Our study is the first to show that weakened gustatory input is linked with a gravitation toward more intensely tasting sweet stimuli," Corinna A Noel, PhD, from the department of food science, at Cornell University, Ithaca, New York, and colleagues write in an article in the October issue of Appetite.

"With this in mind, we reason that taste dysfunction should be considered in the establishment of obesity." 

However, they acknowledge that their study made many assumptions to estimate that weaker taste buds would lead to consuming an extra 12 pounds of sugar a year.

"Although we stress this is a much-simplified view and assumes that increased desire for sweet translates to changes in sugar intake, nonetheless consuming an additional 12 pounds of sugar is enough to gain 5 pounds per year, while holding all other factors constant," Dr Noel and colleagues stress.

More research is needed to look at taste buds and weight gain, they say.

"Despite numerous simplifications in logic here, this must make taste deficiency an eating disorder of concern, giving it relevance in the national conversation on obesity and highlighting the taste bud as a possible locus for therapeutic intervention, if such interventions could adequately reach the taste bud."

Taste Buds and Sugar Intake

Previous studies have reported that obese people have a diminished sense of taste, and when they lose weight, food and drink are tastier.

Dr Noel and colleagues hypothesized that diminished ability to taste sweetness may represent a form of eating disorder, and if healthy participants were given an agent to temporarily dull their taste buds, they would prefer sweeter food and beverages.

The researchers enrolled 42 women and nine men who had a mean age of 21 and a mean body mass index (BMI) of 23. Half were white and a third were Asian.

More than two-thirds (70%) reported regularly consuming moderate or high amounts of sweets.

The participants took part in four experimental sessions on four days, where they were given a herbal tea (control) or one of three different strengths (1.2 g/L, 3.6 g/L, or 10.8 g/L) of solutions of Gymnema sylvestre, a native plant from South Asia that temporarily suppresses sweet taste.

In each session, using a sip-and-spit method, the participants were asked to rate the sweetness of three solutions that contained 81 mM/L, 243 mM/L, and 729 mM/L of sucrose — before and after they rinsed their mouth with the control or Gymnema sylvestre solution.

Last, they were asked to rate diet Coca-Cola, regular Coca-Cola, or a sugar cookie, for level of sweetness (from -100 for not sweet enough to 100 for much too sweet), and to also rate how full they were and how strong their desire was to eat more (from 0 to 100, for both).  

When the participants were given the solution that suppresses sweet taste, they perceived the solutions to be less sweet, and their preferred level of sweetness was higher (both < .001), compared with the control herbal tea.

The model predicted that every 1% reduction in perceived sweet taste was associated with a 0.40-g/L increase in optimal sucrose content.

"We hypothesize that a participant with a 20% reduction in sweet taste would desire about 1 teaspoon (3.8 g) extra sucrose in a beverage to reach his or her optimal level of sweetness compared with someone with unaltered gustatory response," the researchers write.

"Since the USDA estimates that the average American consumes between 150 and 170 pounds of sugars in 1 year, a person with a 20% reduction in gustatory input may desire up to an extra 12 pounds of sugar each year to compensate for this reduced input," they add.

The shift in preferred level of sweetness of food and drinks "suggests that those with a diminished sense of taste may desire more intense stimuli to attain a satisfactory level of reward," causing them to eat more, according to the authors.

The study was partly supported by a grant from the American Heart Association. The authors report no relevant financial relationships.  

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Appetite. 2017; 117:74-81. Abstract

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