Foods and drinks high in sugar can cause serious health problems quite apart from obesity or diabetes.
Avoiding sugar-rich diets will increase our lifespan by many years, however a high sugar intake causes the accumulation of uric acid in the body resulting in early death.
Uric acid is a natural waste product from the breakdown of substances called purines that are fundamental building blocks of DNA.
However, uric acid has the ability to crystallize and form kidney stones as a study in fruit flies has found.
Dr Helena Cochemé, study co-author, said:
“Just like humans, flies fed a high-sugar diet show many hallmarks of metabolic disease—for instance, they become fat and insulin resistant.
Obesity and diabetes are known to increase mortality in humans, and so people always assumed that this was how excess sugar is damaging for survival in flies.”
Fruit flies, when fed a high-sugar diet, were dehydrated so researchers added more water to their diet.
Thirst is an early indicator of elevated blood sugar and so diabetes.
Dr Cochemé said:
“Water is vital for our health, yet its importance is often overlooked in metabolic studies.
Therefore, we were surprised that flies fed a high-sugar diet did not show a reduced lifespan, simply by providing them with an extra source of water to drink.
Unexpectedly, we found that these flies still exhibited the typical metabolic defects associated with high dietary sugar.”
Seeing the effect of water made the research team examine the fly urinary system.
They noticed that the high sugar intake led to accumulation of uric acid and build up of kidney stones in flies.
But they prevented the stones issue by reducing uric acid production with a drug or by diluting the fly’s food with water.
Consequently, this protected the flies from dying due to their sugar-rich diet.
Could this mean if we drink lots of water then we can eat as many as sweet treats we like?
Dr Cochemé explained:
“The sugar-fed flies may live longer when we give them access to water, but they are still unhealthy.
And in humans, for instance, obesity increases the risk of heart disease.
But our study suggests that disruption of the purine pathway is the limiting factor for survival in high-sugar-fed flies.
This means that early death by sugar is not necessarily a direct consequence of obesity itself.”
To see if dietary sugars would cause any damage to kidney function in humans, the researchers carried out an experiment on a group of healthy adults.
Professor Christoph Kaleta , study co-author, said:
“Strikingly, just like flies, we found that dietary sugar intake in humans was associated with worse kidney function and higher purine levels in the blood.”
Uric acid build up has been known to cause gout and kidney stones in human.
With aging the levels of uric acid increase in the body.
An increased level of uric acid will also foretell the beginning of metabolic disorders like diabetes.
Dr Cochemé concluded:
“There is substantial evidence that what we eat influences our life expectancy and our risk for age-related diseases.
By focusing on the purine pathway, our group hopes to find new therapeutic targets and strategies that promote healthy ageing.”
About the author
Mina Dean is a Nutritionist and Food Scientist. She holds a BSc in Human Nutrition and an MSc in Food Science.
The study was published in the journal Cell Metabolism (Van Dam et al., 2020).