Feature articles

A taste for carbohydrates

Professor Russell Keast is from the Centre for Advanced Sensory Science (CASS) at Deakin University. His research is primarily focussed on the sense of taste and how it affects food choices.

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  1.       CASS achieved significant International attention for your evidence supporting the idea of a seventh taste for complex carbohydrates. What exactly did you find?

We have now published three papers with a fourth out in the next few months. In the published papers we have shown at low concentrations, carbohydrate taste is independent of sweet taste, however at higher concentrations there is some overlap.  This is interesting as there may be some interaction between sweet taste and carbohydrate taste.  Also, we have shown being more sensitive or experiencing high intensity for carbohydrate taste was associated with greater energy and starch intakes, and a greater waist circumference. 

 2.       How did you develop the idea that there might be a complex carbohydrate taste?

The hypothesis came from exercise science.  There is quite a bit of information that shows performance is enhanced after an oral rinse (no swallowing) with maltodextrin carbohydrate. (Read more about starches in previous issues here and here). The increase in performance did not happen with sugars or water indicating some form of oral receptor responsive to maltodextrin. 

We started to look at this in 2012 and Julia Low began her PhD investigating sweet and carbohydrate taste in 2013. The first results were published 2015 by Dr Juyun Lim’s laboratory at Oregon State University and to date I believe we are the only two labs who have published in the carbohydrate taste area in humans. Our lab is the only one working on the link with diet and anthropometry.

3.       What are the effects of our ability to detect complex carbohydrates in food?

More work needs to be completed in this area.  We have published two papers, both using taste assessment protocol and associations with diet. In one study we had fewer participants (n=34) and more detailed dietary assessment, and in second study we had more participants (n=92) but less detailed dietary assessment.  In the more detailed dietary assessment we an interesting association – if you were more sensitive to carbohydrate taste you consumed more starch and had a higher energy intake. You also had a larger waist circumference, but not BMI. 

In the second, less detailed dietary assessment, we did not find the associations and only measured BMI and not waist circumference.  This is part of the problem with any science, reproducibility.  The lack of similar results could be explained by the different dietary assessment methods. In a study yet to be published, research does show that increased carbohydrate taste sensitivity leads to increased starch and energy intake.

 4.       What are the public health implications of a seventh taste for complex carbohydrate?

Factors that lead to increased consumption and overweight and obesity warrant further research, along with the development of strategies to limit consumption.  What we have observed is that there is a link between an increased taste signal from carbohydrate and increased consumption of starchy foods. We have also linked this with increased waist circumference, which is a very good indicator of excess central adiposity, the metabolically active stored fat.

 5.       There is no data to link sweet taste sensitivity, BMI and dietary intake. Can the same be said for complex carbohydrate taste sensitivity?

I like the question. As previously mentioned we believe that there are associations between carbohydrate taste and diet, and yes there is much evidence that sweet taste, diet and BMI are not linked. Part of our research going forward is looking at carbohydrate as a whole – sugars and complex carbohydrate together to see if this provides greater insight.

 6.       Scientific evidence that lower carbohydrate diets can provide metabolic benefits in some people is building. Being more sensitive to the taste of carbohydrates and prone to consuming more may not be ideal for these people. What are your thoughts?

This is also a future intervention research area.  Can we modify a person’s carbohydrate taste (as we have done with fat) and what 

influence will this have on diet?  For example, if we can decrease an individual’s sensitivity to carbohydrate we would hope that they would naturally decrease their consumption of starchy foods.

 7.       Last time we spoke in 2016, it was about the new sixth taste for fat, and CASS has published research on the new seventh taste for carbohydrates. Are there any other ‘new’ tastes on the horizon?

Yes, perhaps too many. This is due to increases in technologies, increased knowledge and decreases in costs for some of the advanced techniques to investigate taste receptors.  Having said that, we still have not identified the carbohydrate taste receptor/s. There is potentially a taste named kokumi (it may be associated with MSG or umami), as well as calcium, phosphorous, metallic- and potentially many more. Perhaps we need to reframe what a taste is. ​

You can read more about CASS carbohydrate taste research here and here. 

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