High sugar diet as dam­ag­ing to the brain as ex­treme stress, ex­perts warn

The Star (St. Lucia) - - INTERNATIONAL -

In light of mount­ing ev­i­dence in­di­cat­ing the link be­tween a high sugar diet and ill health, it is now widely ac­cepted that more should be done to en­cour­age peo­ple to re­duce their con­sump­tion of sugar. Many in­ter­est groups are push­ing for the im­po­si­tion of a “sin tax” on sweet drinks, and di­etary guide­lines in the US and UK have been tight­ened to re­flect the chang­ing sci­en­tific ev­i­dence.

The World Health Or­ga­ni­za­tion (WHO) rec­om­mends no more than 10 per­cent of a per­son’s daily en­ergy should come from added sug­ars, or those found nat­u­rally in juices and honey, which equates to around 50g or 12 tea­spoons a day.

And while the links be­tween a high-sugar diet and obe­sity, with all its ac­com­pa­ny­ing ills, are well doc­u­mented, ex­perts are now turn­ing their at­ten­tion to the other ways sugar can af­fect the body.

In a re­cent study, a team at the Univer­sity of New South Wales con­cluded that sugar is as dam­ag­ing to the brain as ex­treme stress or abuse. Re­search as­so­ciate Jayan­thi Ma­niam and pro­fes­sor of phar­ma­col­ogy Mar­garet Mor­ris were in­volved in the study and dis­cussed their find­ings with The Con­ver­sa­tion:

“The changes we ob­served to the re­gion of the brain that con­trols emo­tional be­hav­iour and cog­ni­tive func­tion were more ex­ten­sive than those caused by ex­treme early life stress,” they re­vealed.

“It is known that ad­verse ex­pe­ri­ences early in life, such as ex­treme stress or abuse, in­crease the risk of poor men­tal health and psy­chi­atric dis­or­ders later in life.

“The num­ber of trau­matic events – ac­ci­dents; wit­ness­ing an in­jury; be­reave­ment; nat­u­ral dis­as­ters; phys­i­cal, sex­ual and emo­tional abuse; do­mes­tic vi­o­lence and be­ing a vic­tim of crime – a child is ex­posed to is as­so­ci­ated with el­e­vated con­cen­tra­tions of the ma­jor stress hor­mone, cor­ti­sol.

“There is also ev­i­dence that child­hood mal­treat­ment is as­so­ci­ated with re­duced brain vol­ume and that th­ese changes may be linked to anx­i­ety.

“Look­ing at rats, we ex­am­ined whether the im­pact of early life stress on the brain was ex­ac­er­bated by drink­ing high vol­umes of sug­ary drinks af­ter wean­ing.

“As fe­males are more likely to ex­pe­ri­ence ad­verse life events, we stud­ied fe­male Sprague-Daw­ley rats.

“To model early life trauma or abuse, af­ter rats were born half of the lit­ters were ex­posed to lim­ited nest­ing ma­te­rial from days two to nine af­ter birth. They then re­turned to nor­mal bed­ding un­til they were weaned.

“The lim­ited nest­ing al­ters ma­ter­nal be­hav­iour and in­creases anx­i­ety in the off­spring later in life.

“At wean­ing, half the rats were given un­lim­ited ac­cess to low-fat chow and wa­ter to drink, while their sis­ters were given chow, wa­ter and a 25 per cent sugar so­lu­tion that they could choose to drink.

“An­i­mals ex­posed to early life stress were smaller at wean­ing, but this dif­fer­ence dis­ap­peared over time.

“Rats con­sum­ing sugar in both groups (con­trol and stress) ate more calo­ries over the ex­per­i­ment.

“The rats were fol­lowed un­til they were 15 weeks old, and then their brains were ex­am­ined. As we know that early life stress can im­pact men­tal health and func­tion, we ex­am­ined a part of the brain called the hip­pocam­pus, which is im­por­tant for both mem­ory and stress.

“Four groups of rats were stud­ied – con­trol (no stress), con­trol rats drink­ing sugar, rats ex­posed to stress, and rats ex­posed to stress who drank sugar.

“We found that chronic con­sump­tion of sugar in rats who were not stressed pro­duced sim­i­lar changes in the hip­pocam­pus as seen in the rats who were stressed but not drink­ing sugar.

“Early life stress ex­po­sure or sugar drink­ing led to lower ex­pres­sion of the re­cep­tor that binds the ma­jor stress hor­mone cor­ti­sol, which may af­fect the abil­ity to re­cover from ex­po­sure to a stress­ful sit­u­a­tion.

“An­other gene that is im­por­tant for the growth of nerves, Neu­rod1, was also re­duced by both sugar and stress.

“Other genes im­por­tant for the growth of nerves were in­ves­ti­gated, and just drink­ing sugar from a young age was suf­fi­cient to re­duce them.

“The rats were ex­posed to high sugar in­takes dur­ing de­vel­op­ment, and the im­pact of the sugar is wor­ry­ing as it may af­fect brain de­vel­op­ment, al­though fur­ther work is re­quired to test this.

“In this study, com­bin­ing sugar in­take and early life stress did not pro­duce fur­ther changes in the hip­pocam­pus, but whether this re­mains the case over time is un­clear.

“The changes in the brain in­duced by sugar are of great con­cern given the high con­sump­tion of sugar-sweet­ened bev­er­ages, with par­tic­u­larly high con­sump­tion in chil­dren aged nine to 16 years.

“If sim­i­lar pro­cesses are at play in hu­mans to what was found in our rat study, re­duc­ing the con­sump­tion of sugar across the com­mu­nity is im­por­tant.

“The fact that drink­ing sugar or ex­po­sure to early life stress re­duced the ex­pres­sion of genes crit­i­cal for brain de­vel­op­ment and growth is of great con­cern.

“While it is im­pos­si­ble to per­form such stud­ies in hu­mans, the brain cir­cuits con­trol­ling stress re­sponses and feed­ing are con­served across species.

“Peo­ple who were ex­posed to early life trauma have changes in the struc­ture of their hip­pocam­pus. In hu­mans, those con­sum­ing the most ‘western’ diet had smaller hip­pocam­pal vol­umes, in line with data from an­i­mal mod­els. Taken to­gether, th­ese find­ings sug­gest fu­ture work should con­sider pos­si­ble long-term ef­fects of high sugar in­take, par­tic­u­larly early in life, on the brain and be­hav­iour.”

Changes to the brain re­gion that con­trols emo­tional

be­hav­iour and cog­ni­tive func­tion were more ex­ten­sive than those caused by early life stress.

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