24 July 2020

“I only had one french fry”: New method will shield food studies from untruthful answers


A great deal of food research hinges upon the honesty of participants in relation to what they say they have eaten. In a new study, researchers from the University of Copenhagen, among others, deployed a method that in the future, will be able to validate whether alcohol or french fries were consumed.

Photo of a woman eating french fries and drinking a coke looking shameful
Photo: Getty Images

Did you really only pinch one fry from your partners plate while otherwise faithfully tending to your cabbage salad last night? Or, was it two? It can be tough to remember – and also admit to – when you’ve racked up more food sins than intended.

Correspondingly, there is a high degree of uncertainty when it comes to the honesty of participants reporting back what they have eaten. Indeed, one might end up with false conclusions – for example, about how much junk food our bodies can manage — if participants do not tell the whole truth about how many dip-laden chips actually went down the hatch last Monday night.

However, in a new study from April 2020, University of Copenhagen researchers, together with research partners, tried a method that might eventually help research validate what happens in our bodies as we consume various foodstuffs.

"Many people forget to — or don’t want to — truthfully report back what they’ve eaten. As such, we found a method that uses urine tests to examine the substances present in our body after various foods are consumed. By doing so, we hope to contribute to eventually being able to conduct improved, more objective research," explains Cristian De Gobba, an assistant professor at the University of Copenhagen’s Department of Food Science.

Together with Chinese, Rumanian, Italian and Danish researchers all from the Department of Nutrition, Exercise and Sports — Cristian De Gobba analyzed urine samples from 10 people living in Denmark to identify which substances were present after ingesting potatoes cooked in various ways. 

The effect of boiled versus french-fried potatoes

Five men and five women, ages 24­–46, were given a special dietary plan to follow for one week. Some had to eat boiled potatoes, others potato chips and others french fries. Thereafter, the researchers examined the participants’ urine samples to look for differences in the substances found.

"We used mass spectrometry, an analytical technique that separates chemical substances by their mass. To give an example, the mass of sugar is different than the mass of protein," explains De Gobba, adding:

"In doing so, we measured the exact mass of individual molecules allowing thousands of different compounds to be analyzed simultaneously and made it possible for us to group substances. Our study showed that certain substances are more present in french fries and chips than in boiled potatoes."

For example, some pyrroles — associated with poor nutritional value and the potential to damage our ability to regulate sugar — are more abundant in deep-fried potatoes than in boiled ones.

Cannot yet determine what is healthy and unhealthy

While there are indications that the substances in the deep-fried foods are unhealthy, researchers still lack much of the knowledge needed to map the health effects of those substances found in the participants’ urine.

"We have yet to discover if the substances are specific to potato products, or if they are found more broadly, among all types of heated foods. Nor are we able to claim with certainty whether the substances present increased health risks," states Lars Ove Dragsted, a professor and section head at UCPH’s Department of Nutrition, Exercise and Sports.

While more studies are required to fully determine the health characteristics of specific food products, the new method is a small step towards improved and more valid food and nutrition research.