Sugar and Your Brain

Did you ever wonder why children’s documented behavioral problems and learning difficulties became such an epidemic over the past few decades? Look no further than the sweeteners added to their diets, at home and at school, over that same period of time.

Ever wonder why Alzheimer’s disease and dementia in general became an epidemic beginning in the 1970s? Look no further than the trend in elevated consumption levels of added sugars over that time period. How about chronic depression? Did it occur to you that ‘sugar on the brain’ could be a responsible factor in the onset of depression and a range of other psychiatric disorders, including schizophrenia? If not, think again!

Medical science has learned a lot about sweeteners and the human brain in just the past few years. After neglecting the connection for so long, researchers suddenly began to wake up and see with growing distress what many of us had been warning about. In my case, 1980 marked the year that I, as Director of the Hippocrates Institute, removed all sugar, including fruit, from the diet of those people facing mental or physical challenges.

“It is alarming that commonly consumed low-cost foods with high sugar and fat contents have the potential to determine mental health,” commented the authors of a May 2012 scientific report in The Journal of Physiology, which examined the impact of added sugars, including high fructose corn syrup, on human brain function. Most disturbing is the research showing high sucrose diets can have effects on brain function transferred from mother to child in the womb. A 2014 study published in the Journal of Nutrition & Biochemistry, for instance, found learning deficits and cognition disorders in offspring born to mothers fed a diet high in sugars. Though this experiment was done with lab animals, the researchers were able to extrapolate the findings to humans with the observation it would explain many of the observed “cognition disorders in young children.”

In the British Journal of Nutrition, a team of researchers described in 2013 how they studied 40 children, aged 10 to 12 years, after they had consumed glucose beverages. Their cognitive performance, including memory and attention, was monitored each hour. Girls in particular demonstrated memory deficits, recalling fewer words on memory tests than when they just drank water. Despite the floodgates of research beginning to open on the links between sweeteners and disordered behavior, U.S. government health agencies and those of other countries remain largely behind the curve in accepting or acknowledging these links.

The normally very conservative U.S. National Library of Medicine, a part of the National Institutes of Health, did concede some of the link between added sugars and children’s behavior (hyperactivity) in a 2013 post on its website: “Refined (processed) sugars may have some effect on children’s activity. Refined sugars and carbohydrates enter the bloodstream quickly. Therefore, they cause rapid changes in blood sugar levels. This may make a child become more active.” Much of the best research on sugar and brain function has occurred outside the U.S., largely beyond the reach of influence by the U.S. food corporations, sugar production interests, and other financial concerns that try to protect their profits by keeping a lid on damaging research findings. For example, it was a research team in Denmark, at the University of Copenhagen, which found in 2014 a link between refined sugars and mood, not just in children but in adults.

Similarly, it was scientists from Serbia, at the University of Belgrade, who published the results of a study showing how high fructose diets produce brain problems, in particular cognitive deficits. Interestingly, it was a joint French/American team of researchers in 2013 that made a finding about how the spice cinnamon could be used to counteract the memory impairment and other Alzheimer-associated brain changes coming from consumption of high fructose food and beverages.

Evidence: Alzheimer’s Disease & the Role of Sugars

“Preventing or postponing the onset of Alzheimer’s disease and delaying or slowing its progression would lead to a consequent improvement of health status and quality of life in older age. Poorer cognitive function and an increased risk of vascular dementia were found to be associated with consumption of milk or dairy products, and a diet high in added sugars.” Diet and Alzheimer’s disease risk factors or prevention: the current evidence. Solfrizzi V. Et al. Exp Rev Neurotherapeutics. 2011 May;11(5):677–708.

“Intake of saturated fats and simple carbohydrates (glucose and sucrose), two of the primary components of a modern Western diet, is linked with the development of obesity and Alzheimer’s disease. Evidence shows that consumption of a meal containing simple carbohydrates can impair postprandial memory function. It was found that the high glycemic meal led to poorer performance in memory tests given between1-2 hours after eating.”

Western Diet Consumption and Cognitive Impairment: Links to Hippocampal Dysfunction and Obesity. Kanoski SE. Davidson TL. Physiol Behav. 2011 Apr 18;103(1):59–68.

Behavioral Problems in Children

“Hyperactivity is a very common disorder in children, especially males. Chocolate, sugar, sweeteners, additives, preservatives, dyes, can enhance an incidence of this syndrome.”

Attention deficit and infantile hyperactivity. Berdonces JL. Rev Enferm (Spanish). 2001 Jan;24(1):11–4.

“Eating simple sugars has been suggested as having adverse behavioral and cognitive effects in children. This study was performed to address a physiologic mechanism for this effect. Metabolic, hormonal and symptomatic responses to a standard oral glucose load were compared in 25 healthy children and 23 young adults. Enhanced adrenomedullary responses to modest reductions in plasma glucose concentration and increased susceptibility to neuroglycopenia may be important contributing factors to adverse behavioral and cognitive effects after sugar ingestion in healthy children.”

Enhanced adrenomedullary response and increased susceptibility to neuroglycopenia: mechanisms underlying the adverse effects of sugar ingestion in healthy children. Jone TW, et al. J Pediatr. 1995 Feb;126(2):171–7.

“The meta-analysis of the studies to date found that sugar does not affect the behavior or cognitive performance of children. The strong belief of parents may be due to expectancy and common association. However, a small effect of sugar or effects on subsets of children cannot be ruled out.”

The effect of sugar on behavior or cognition in children. A meta-analysis. Wolraich ML, et al. JAMA. 1995 Nov 22–29;274(20):1617–21.

“On separate mornings each child among eight preschool children received 6 ounces of juice, sweetened on one morning with sucrose and on the other with an artificial sweetener. Following the sucrose drink the children showed a decrement in performance in the structured testing situation and they demonstrated more ‘inappropriate’ behavior during free play. These differences in behavior were most pronounced approximately 45 to 60 minutes after the drinks.”

Behavioral effects of sucrose on preschool children. Goldman JA, et al. J Abnorm Child Psychol. 1986 Dec;14(4):565–77.

Brain Function & Memory Problems

“High fructose diet has been shown to have damaging effects on the hippocampus, a brain region critical for learning and memory. Fructose induced hippocampal dysfunction may arise from insulin resistance and inflammation. Our results showed that long-term consumption of 10% fructose solution induces hippocampal insulin resistance and inflammation. Rats fed with higher concentrations of fructose displayed impaired plastic responses of the hippocampus which may provide a basis for cognitive deficits.”

The impact of different fructose loads on insulin sensitivity, inflammation, and PSA-NCAM-mediated plasticity in the hippocampus of fructose-fed male rats. Djordjevic A. Et al. Nutr Neurosci. 2015 Feb;18(2):66–75.

“The hippocampus plays a crucial role in learning and memory, and neuronal apoptosis in the hippocampus contributes to learning deficits. This study determined the influence of maternal high sucrose diets on behavior and hippocampal neurons in the young offspring. The results demonstrated that prenatal high sucrose diets could induce the spatial acquisition deficits in the young offspring associated with hippocampal apoptosis and might play a critical role in cognition disorders in young children.”

Hippocampal apoptosis involved in learning deficits in the offspring exposed to maternal high sucrose diets. Kuang H. Et al. J Nutr Biochem. 2014 Sep;25(9):985–90.

“Here we examined the effects of sucrose and high fructose corn syrup intake during adolescence or adulthood on cognitive and metabolic outcomes. Adolescent or adult male rats were given 30-day access to chow containing either water, sucrose solution, or HFCS (high fructose corn syrup) solution. These data show that consumption of added sugars, particularly HFCS, negatively impacts hippocampal function, metabolic outcomes, and neuroinflammation.”

Effects of sucrose and high fructose corn syrup consumption on spatial memory function and hippocampal neuroinflammation in adolescent rats. Hsu TM. Et al. Hippocampus. 2014 Sep 20. {Epub ahead of print.}

“A total of 40 children (10–12 years) completed a double-blind, randomized, crossover trial, receiving three isoenergetic drinks, including a glucose beverage. For three hours post-consumption, subjective appetite and cognitive performance (speed of processing, memory, attention and perceptual speed) were measured hourly.” After consuming the glucose drink girls demonstrated less word recall with short-term memory deficits.

The effect of beverages varying in glycaemic load on postprandial glucose responses, appetite and cognition in 10-12 year old school children. Brindal E. Et al. Br J Nutr. 2013 Aug 28;110(3):529–37.

“Overall dietary energy intake, particularly the consumption of simple sugars such as fructose, has been increasing steadily in Western societies, but the effects on the brain are poorly understood. Here, we used functional and structural assays to characterize the effects of excessive caloric intake on the hippocampus, a brain region important for learning and memory. Rats fed with a high-fat, high-glucose diet supplemented with high-fructose corn syrup showed alterations in energy and lipid metabolism similar to clinical diabetes, with elevated fasting glucose and increased cholesterol and triglycerides. Rats maintained on this diet for 8 months exhibited impaired spatial learning ability, reduced hippocampal dendritic spine density, and reduced long-term potentiation at Schaffer collateral-CA1 synapses. We conclude that a high calorie diet reduces hippocampal synaptic plasticity and impairs cognitive function.”

Diet-induced insulin resistance impairs hippocampal synaptic plasticity and cognition in middle-aged rats. Stranahan AM, et al. Hippocampus. 2008;18(11):1085–8.

“We have investigated a potential mechanism by which a diet, similar in composition to the typical diet of most industrialized western societies rich in saturated fat and refined sugar, can influence brain structure and function via regulation of neurotrophins. Our results indicate that a popularly consumed diet can influence crucial aspects of neuronal and behavioral plasticity associated with the function of brain-derived neurotrophic factor.”

A high-fat, refined sugar diet reduces hippocampal brain-derived neurotrophic factor, neuronal plasticity, and learning. Molteni R, et al. Neuroscience. 2002;112(4):803–14.

Depression

“Major depressive disorder is a debilitating disease in the Western World. A western diet high in saturated fat and refined sugar seems to play an important part in disease development. Our study with 42 mice randomly assigned to one of three experimental diets—a high fat, a high sucrose, or a control diet—for 13 weeks showed that dietary fat and sucrose affect behavior.”

A possible link between food and mood: dietary impact on gut microbiota and behavior in BALB/c mice. Pyndt Jorgensen B. Et al. PLoS One. 2014 Aug 18;9(8):e103398.

“Key biological factors that influence the development of depression are modified by diet This study examined the extent to which the high-prevalence mental disorders are related to habitual diet in 1,046 women ages 20-93 years randomly selected from the population. A “western” diet of processed or fried foods, refined grains, sugary products, and beer was associated with higher odds for major depression and anxiety disorders. These results demonstrate an association between habitual diet quality and the high prevalence mental disorders.”

Association of Western and traditional diets with depression and anxiety in women. Jacka FN, et al. Am J Psychiatry. 2010 Mar;167(3):305–11.

Schizophrenia

“A higher national dietary intake of refined sugar and dairy products predicted a worse 2-year outcome of schizophrenia. A high national prevalence of depression was predicted by a lower dietary intake of fish and seafood. The dietary predictors of outcome of schizophrenia and prevalence of depression are similar to those that predict illnesses such as coronary heart disease and diabetes, which are more common in people with mental health problems.” International variations in the outcome of schizophrenia and the prevalence of depression in relation to national dietary practices: an ecological analysis. Peet M. Br J Psychiatry. 2004 May;184:404–8.