Flies Fed Sugar-Rich Diets Are Damaged for Life, and Die Faster

The rec­om­mended daily intake of sugar for an adult with a nor­mal body mass index is about 25 grams per day, or about 5 per­cent of your daily calo­rie intake, accord­ing to the World Health Organization. A sin­gle can of Coke has 39 grams of sugar.

Sugar, often found in ​‘inno­cent’ foods like fat-free salad dress­ings or multi-grain cere­als, leads to higher cho­les­terol, heart dis­ease, obe­sity, uncon­trolled growth and mul­ti­pli­ca­tion of cells, dia­betes, meta­bolic syn­drome and more. A log­i­cal debate has ensued about whether it should be con­sid­ered white gold or white poi­son.

Ironically, first-world coun­tries, where infor­ma­tion flows abun­dant, like the US, Germany or the Netherlands, still con­sume 126, 103 and 103 grams of sugar on a daily basis respec­tively, occu­py­ing the three first places on the list of the top 10 sugar-con­sum­ing coun­tries in the world.

Timelier than ever, research from the University College London, which was pub­lished in the January issue of the jour­nal Cell Reports, now rings the alarm bells for one more over­looked dan­ger of eat­ing sugar at face value: Sugar over-con­sump­tion may bear long-last­ing effects even after a healthy diet has been adopted.

The research team, com­pris­ing sci­en­tists from UCL and Australia’s Monash University, com­pared the lifes­pans of female flies fed on a diet con­tain­ing 5 per­cent sugar (a healthy one) to flies given eight times this amount. Both groups of flies were fed for three weeks before going on a healthy diet.

The team found that no mat­ter the healthy diet in the later stage, the flies pre­vi­ously fed a high-sugar diet started to die ear­lier, and on aver­age had 7 per­cent shorter lifes­pans ( flies live up to 90 days).

At a mol­e­c­u­lar level, this was attrib­uted to a ​“gene repro­gram­ming” caused by the sugar-rich diet con­sumed in early adult­hood. In a nut­shell, sugar repressed the activ­ity of a type of gene asso­ci­ated with longevity, FOXO.

“FOXO is a type of gene called a tran­scrip­tion fac­tor,” Adam Dobson, a researcher at the UCL’s Institute of Healthy Ageing explained to Olive Oil Times.

“Transcription fac­tors are inter­est­ing because they reg­u­late other genes. So, if you change the activ­ity of a tran­scrip­tion fac­tor, in this case, by eat­ing a high-sugar diet, you can indi­rectly change the activ­ity of many other genes and cause exten­sive sec­ondary effects.”

“We don’t know yet pre­cisely what hap­pens down­stream of FOXO,” Dobson said, ​“but we think it is prob­a­bly one of these sec­ondary effects, with FOXO reg­u­lat­ing genes which change the phys­i­cal struc­ture of DNA. This might explain the repro­gram­ming of gene expres­sion and lifes­pan, because the struc­ture of DNA can affect which genes are turned on or off.”

“Importantly, flies and worms that don’t have FOXO don’t appear to be repro­grammed by sugar,“Dobson added.

With the FOXO gene con­tribut­ing to longevity in a wide vari­ety of species includ­ing humans, the UCL study’s find­ings are salient for our under­stand­ing of how changes in diet and gene expres­sion are related to the pace of age­ing.

Would it be arbi­trary or pre­ma­ture to claim the dam­age too much sugar does to our organ­isms is irre­versible?

“We can’t say any­thing about humans for cer­tain because we have only looked in flies and worms,” said Dobson. ​“But we have shown that those organ­isms do bear long-term mol­e­c­u­lar impli­ca­tions of their past diets, because of sugar sup­press­ing FOXO.

“There is some evi­dence that FOXO is impor­tant for human longevity and we know that sugar con­sump­tion is rock­et­ing in humans. So while we don’t know if what we have shown in flies and worms is also true for humans, all the pieces are there.”

• Adam Dobson


• World Atlas