Queensland biomedical scientists have published world-first findings that show used coffee grounds could be a fat-fighting food, but dietitians have urged caution on the research as human trials are yet to be held.
- Biomedical scientists say the study results find eating coffee grounds may help manage obesity
- However, dietitians urge caution before sprinkling food with coffee grounds
- There have been no clinical human trials conducted yet
Researchers at the University of Southern Queensland (USQ) have been investigating the properties of leftover coffee grounds for almost seven years to uncover their potential as a functional food, or a food that can prevent or reverse disease.
Led by USQ biomedical scientist Professor Lindsay Brown, the team has found eating coffee grounds may help manage obesity.
Professor Brown said the research focused on male rats fed a high-carb, high-fat diet over four months, supplemented with 5 per cent of spent coffee grounds during the last eight weeks of the study.
“They [the rats] got lots of fructose, lots of condensed milk, lots of saturated fat, and the result was they got obese, impaired glucose tolerance, and cardiovascular and liver damage — all of those things happen the same in humans,” he said.
“When we feed the coffee grinds to them, after eight weeks we see blood pressure coming back to normal, we see blood glucose concentration coming back to normal, we see the fatty liver being improved.
“We also looked at the bacteria in the gut and how that correlated with the reduction in obesity and improvement in glucose tolerance and systolic blood pressure.”
No human trials held yet
Professor Brown said eating spent coffee grounds might help manage weight and the risk of diabetes, stroke and heart disease.
While there have been no human trials on eating coffee grounds, Professor Brown said he had been experimenting on himself.
“If you make your own coffee each morning then collect the grounds, dry it in the oven at 60 degrees [Celsius] for an hour or two and simply add a spoonful to your muffin mix or bread mix,” he said.
“I’ve actually put it [coffee grounds] in my bread maker — you can put it into muffins, into cakes — into all the things that coffee may be used in.
“You’re not going to notice an overnight change, however, it’s likely to decrease obesity and improve your blood pressure over time.”
However, dietitians urge caution before people start sprinkling food with coffee grounds.
Clare Collins, a professor of Nutrition and Dietetics at the University of Newcastle, said the research was “interesting but it’s early days”.
“It makes sense, but you can’t tell from the rat study what human dosage [of ground coffee] is required,” Professor Collins said.
“Before you start saving up your coffee grounds and putting it in your porridge, I’d be waiting for the human trials.
“We may eventually see this as a food product but for now, watch this space.”
Less food waste a possible benefit
Professor Brown said aside from the potential health benefits, it was also a great way to address food waste.
“In Sydney alone, more than 3,000 tonnes of coffee waste is produced every year, so it’s exciting to think about the impact diverting that waste away from landfill could have while also assisting with healthier lifestyle choices,” he said.
Professor Brown said there was remarkably little research on the topic and it was still to be clinically tested on humans.
“We think that this is the first study in the world to show this connection [between coffee waste and waistlines],” he said.
He said researchers needed funding to begin human trials.
“Human trials are costly but if someone is willing to finance us, then we’ll do it because I think this is really exciting stuff,” Professor Brown said.
The findings have been published in the FASEB Journal — a US journal of biomedical science.