Sugar leads to early death, but not due to obesity
by MRC London Institute of Medical Sciences
Close up of glass jar with sugar cubes inside and a stack of six sugar cubes to the side. Credit: Suzy Hazelwood via Pexels
Sugar-rich diets have a negative impact on health independent of obesity reports a new study led by the MRC London Institute of Medical Sciences, UK.
Researchers discovered that the shortened survival of fruit flies fed a sugar-rich diet is not the result of their diabetic-like metabolic issues.
The findings, published in the journal Cell Metabolism, instead suggest that early death from excess sugar is related to the build-up of a natural waste product, uric acid.
We all know that consuming too much sugar is unhealthy. It increases our risk of developing metabolic disorders, such as obesity and diabetes, and can shorten our life expectancy by several years. While this reduction in lifespan is widely believed to be caused by metabolic defects, this new study in fruit flies reveals that this may not be the case.
"Just like humans, flies fed a high-sugar diet show many hallmarks of metabolic disease—for instance, they become fat and insulin resistant", says Dr. Helena Cochemé, the principal investigator of the study. "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".
However, like salt, sugar also causes dehydration. In fact, thirst is an early symptom of high blood sugar and diabetes. Dr. Cochemé continues: "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".
Based on this water effect, the team decided to focus on the fly renal system. They showed that excess dietary sugar caused the flies to accumulate a molecule called uric acid. Uric acid is an end-product from the breakdown of purines, which are important building blocks in our DNA. But uric acid is also prone to crystallise, giving rise to kidney stones in the fly. Researchers could prevent these stones, either by diluting their formation with drinking water or by blocking the production of uric acid with a drug. In turn, this protected against the shortened survival associated with a sugar-rich diet.
So, does this mean we can eat all the sugary treats we want, as long as we drink plenty of tea? "Unfortunately not," says Dr. Cochemé, "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 understand the impact of dietary sugars on human health, collaborators from Kiel University in Germany explored the influence of diet in healthy volunteers. "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", says Prof. Christoph Kaleta, co-author of the study.
Accumulation of uric acid is a known direct cause of kidney stones in humans, as well as gout, a form of inflammatory arthritis. Uric acid levels also tend to increase with age, and can predict the onset of metabolic diseases such as diabetes. "It will be very interesting to explore how our results from the fly translate to humans, and whether the purine pathway also contributes to regulating human survival", concludes Dr. Cochemé. "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".
Explore furtherUric acid pathologies shorten fly lifespan, highlighting need for screening in humans
More information: "Sugar-Induced Obesity and Insulin Resistance Are Uncoupled from Shortened Survival in Drosophila", Cell Metabolism (2020). DOI: 10.1016/j.cmet.2020.02.016
Journal information: Cell Metabolism
Provided by MRC London Institute of Medical Sciences
Sugar-rich diets have a negative impact on health independent of obesity reports a new study led by the MRC London Institute of Medical Sciences, UK.
Researchers discovered that the shortened survival of fruit flies fed a sugar-rich diet is not the result of their diabetic-like metabolic issues.
The findings, published in the journal Cell Metabolism, instead suggest that early death from excess sugar is related to the build-up of a natural waste product, uric acid.
We all know that consuming too much sugar is unhealthy. It increases our risk of developing metabolic disorders, such as obesity and diabetes, and can shorten our life expectancy by several years. While this reduction in lifespan is widely believed to be caused by metabolic defects, this new study in fruit flies reveals that this may not be the case.
"Just like humans, flies fed a high-sugar diet show many hallmarks of metabolic disease—for instance, they become fat and insulin resistant", says Dr. Helena Cochemé, the principal investigator of the study. "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".
However, like salt, sugar also causes dehydration. In fact, thirst is an early symptom of high blood sugar and diabetes. Dr. Cochemé continues: "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".
Based on this water effect, the team decided to focus on the fly renal system. They showed that excess dietary sugar caused the flies to accumulate a molecule called uric acid. Uric acid is an end-product from the breakdown of purines, which are important building blocks in our DNA. But uric acid is also prone to crystallise, giving rise to kidney stones in the fly. Researchers could prevent these stones, either by diluting their formation with drinking water or by blocking the production of uric acid with a drug. In turn, this protected against the shortened survival associated with a sugar-rich diet.
So, does this mean we can eat all the sugary treats we want, as long as we drink plenty of tea? "Unfortunately not," says Dr. Cochemé, "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 understand the impact of dietary sugars on human health, collaborators from Kiel University in Germany explored the influence of diet in healthy volunteers. "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", says Prof. Christoph Kaleta, co-author of the study.
Accumulation of uric acid is a known direct cause of kidney stones in humans, as well as gout, a form of inflammatory arthritis. Uric acid levels also tend to increase with age, and can predict the onset of metabolic diseases such as diabetes. "It will be very interesting to explore how our results from the fly translate to humans, and whether the purine pathway also contributes to regulating human survival", concludes Dr. Cochemé. "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".
Explore furtherUric acid pathologies shorten fly lifespan, highlighting need for screening in humans
More information: "Sugar-Induced Obesity and Insulin Resistance Are Uncoupled from Shortened Survival in Drosophila", Cell Metabolism (2020). DOI: 10.1016/j.cmet.2020.02.016
Journal information: Cell Metabolism
Provided by MRC London Institute of Medical Sciences
Studying a single food or commodity such as sugar may seem like an incongruous project for an anthropologist who claims to work mostly with living people. Still, it is a rich subject for someone interested in the history and character of the modern world, for its importance and popularity rose together with tea, colonial slavery, and the machine era. Had it not been for the immense importance of sugar in the world history of food, and in the daily lives of so many, I would have left it alone.
Sugar, or sucrose (C12H22O11), is manufactured photosynthetically by green plants. We humans can't make sugar. The best we can do is to extract it, and change its form. We have been doing so zealously, for more than 2,000 years. Sugarcane was domesticated about ten millennia before that, and is the most important plant from which sucrose is extracted. Today, corn sweeteners have begun to overtake sucrose in the West; but cane sugar and beet sugar still have promising futures in the poor, or “less developed” world.
My work on sugar, Sweetness and Power, situates it within Western history because it was an old commodity, basic to the emergence of a global market. The first time I was in the field I'd been surrounded by it, as I did my fieldwork. That led me to try to trace it backward in time, to learn about its becoming domesticated, and how it spread and gained importance in the growing Western industrial world. I became awed by the power of a single taste, and the concentration of brains, energy, wealth and -- most of all, power -- that had led to its being supplied to so many, in such stunningly large quantities, and at so terrible a cost in life and suffering.
I follow it still – as well as honey, carob, aspartame, estevia, palm sugar, high fructose corn syrup (HFCS), and so on. I want to know what will happen with sweetness next: how its desirability confronts the costs it poses to health, physical appearance, the environment, and the world order.
How do we get from one child's sweet tooth to the history of slavery, of war, and of corporate lobbying in the Congress? And how do we retrace our steps backward, this time to the significance of that child's sweet tooth? Do these issues ever become so powerful that there may be thought of legislating the availability of this or other foods – the health implications of which can be debated? These are the kinds of questions that have arisen in recent years. Alongside them are the shacks of the cane cutters, scattered in so many of the earth’s tropical corners, which deserve at least equal attention from anthropologists.
No comments:
Post a Comment