People who consume more than one diet soda a day are nearly three times more likely to develop dementia or stroke. Surprisingly, no such association was found for sugared drinks. These are the latest findings from a study published in the journal Stroke on the 20th of April 2017.

This study comprised of more than 4000 participants enrolled in the Framingham Heart Study Offspring Cohort. Dietary intake of sugared drinks and artificially sweetened drinks were recorded at 3 different time points over 10 years. Participants were followed up for another 10 years and were observed for the development of stroke or dementia.

Interestingly, the association between artificial sweeteners and the risk of stroke or dementia were not influenced by potentially confounding factors, such as age, gender, smoking status, physical activity levels, and total calorie intake. Despite this, the researchers concluded that pre-existing diabetes or hypertension may be partially to blame for the correlation between artificial sweeteners and dementia. However, it is unclear if patients with these conditions could in fact be consuming more artificial sweeteners in an attempt to reduce sugar intake.

Nevertheless, the abovementioned study fuels emerging concerns that artificial sweeteners may not be the ‘safe alternative’ to sugar. As the first study to associate diet sodas to dementia, it underscores the potential harm that artificial sweeteners may have on the brain.

Moderate amounts of glucose are important for ensuring proper brain function. As the only source of energy for brain cells, glucose is responsible for powering neurons and for producing neurotransmitters that are vital for neuron to neuron signalling in the brain. Brain cells that support and maintain the neurons, such as astrocytes and microglia, also depend on glucose.

Neurons are exquisitely sensitive to drops in glucose levels. Epileptic syndromes have been ascribed to neurons that are deficient for a protein called glucose transporter type 1 (GLUT1), rendering brain cells unable to draw up glucose from the blood. Neurological conditions such as migraines, strokes, and traumatic brain injury all have a component of altered glucose metabolism in the brain.

On the other side of the coin, too much of a good thing is never a good idea. Excessive sugar intake induces a myriad of diseases, such as type 2 diabetes mellitus, metabolic syndrome, dental problems, and many others. According to the National Health and Nutrition Examination Survey from 2011–2014, half of all adults in the U.S. drank at least one sugary beverage a day.

What is behind our seemingly innate attraction to sweetness? The concept of ‘sugar addiction’ has stemmed from observing binging, withdrawal, and craving-like behavior in rats that were exposed to sugar. The current theory holds that intermittent, excessive sugar consumption causes altered neurochemical transmissions (one of them being a large release of the neurotransmitter dopamine) in the nucleus accumbens, the brain’s feelgood center. These brain changes are strikingly similar to those that occur in response to addictive drugs.

Excess amounts of sugar may also predispose us to developing brain diseases. Another study, which also utilized the data from the Framingham Heart Study Offspring cohort, discovered that people who drank two sugary drinks a day had lower total brain volume, smaller hippocampal volumes (an area of the brain responsible for forming memories), and poorer memory.

Given mankind’s insatiable appetite for sugar, artificial sweeteners were introduced to help the masses limit their sugar intake. Also known as low calorie sweeteners, FDA-approved artificial sweeteners include aspartame, neotame, acesulfame-K, sucralose, and saccharin. Low calorie sweeteners can be up to 13,000 times sweeter than regular sugar but with a fraction of the calories.

In recent years, evidence has sprung up rebutting the perceived beneficial health effects of artificial sweeteners. A large systemic review of 37 studies on these sweeteners revealed that increased intake actually resulted in increased weight and waist circumference, as well as higher occurrences of type 2 diabetes, obesity, metabolic syndrome, hypertension, and heart disease.

Furthermore, artificial sweeteners and regular sugar act differently on the brain. Brain scans of people who sipped regular sugary drinks showed stronger activation of more regions involved in reward centers compared to those who sipped drinks with sweeteners. This means that artificial sweeteners may not be as satisfying as regular sugar, leaving a person craving for more sweet foods that ultimately leads to a higher total calorie intake.

All these factors are especially worrying when taking into consideration the estimated 1 in 4 children and 2 in 5 adults who consume low calorie sweeteners on a daily basis.

Does this mean that artificial sweeteners do more harm than good? The jury’s still out on that one, as artificial sweeteners are helpful in certain populations, like diabetics. Regardless, both sugar and artificial sweeteners are best consumed in moderation—whether or not artificial sweeteners confer health benefits remains to be elucidated.

References

Pase M.P. et al. Sugar and artificially sweetened beverages and the risks of incident stroke and dementia. Stroke. 2017;48:1139-1146. Doi: 10.1161/STROKEAHA.116.016027.

Mergenthaler, P., Lindauer, U., Dienel, G. A., Meisel, A. Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends in Neurosciences. 2013; 36(10):587–597. doi: 10.1016/j.tins.2013.07.001.

Rosinger A., Herrick K., Gahche J., Park S. Sugar-sweetened beverage consumption among US adults, 2011-2014. NCHS Data Brief. 2017 Jan;(270):1-8. PMID: 28135185

Avena, N. M., Rada, P., & Hoebel, B. G. Evidence for sugar addiction: Behavioral and neurochemical effects of intermittent, excessive sugar intake. Neuroscience and Biobehavioral Reviews. 2008; 32(1):20–39. doi: 10.1016/j.neubiorev.2007.04.019.

Pase M.P. et al. Sugary beverage intake and preclinical Alzheimer’s disease in the community. Alzheimers Dement. 2017 Mar 6. pii: S1552-5260(17)30050-X. doi: 10.1016/j.jalz.2017.01.024.

Bellisle F., Drewnowski A. Intense sweeteners, energy intake and the control of body weight. Eur J Clin Nutr. 2007; 61:691–700; doi: 10.1038/sj.ejcn.1602649.

Meghan B. Azad et al. Non-nutritive sweeteners and cardiometabolic health: a systematic review and meta-analysis of randomized controlled trials and prospective cohort studies. CMAJ July 17, 2017 189:E929-E939; doi: 10.1503/cmaj.161390.

Frank G.K. et al. Sucrose activates human taste pathways differently from artificial sweetener. Neuroimage. 2008 Feb 15;39(4):1559-69. doi: 10.1016/j.neuroimage.2007.10.061.

Sylvetsky AC, Jin Y, Clark EJ, Welsh JA, Rother KI, Talegawkar SA. Consumption of low-calorie sweeteners among children and adults in the United States. J Acad Nutr Diet. 2017. doi: 10.1016/j.jand.2016.11.004.

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