How Aspartame Affects the Brain:

                                                                 Aspartame’s Direct and Indirect

                                                                    Cellular Effects on the Brain.

Maggie Bomber

Unknown College

Brief Contents

    First page: Abstract

    Third page: How Aspartame Affects the Brain

    Sixth page: Method

    Seventh page: Materials

    Seventh page: Procedure

    Ninth page: Results

    Thirteen page: Discussion

    Seventeenth page:  References

                                                                    Abstract

    This study examined the effects of aspartame on neurotransmitter regulation, dopamine and serotonin production, electrophysiological responses, and effects on mitochondrial DNA and nucleic DNA.  The evaluation on wistar albino rats electrophysiological responses after 90 days of aspartame treatment. They predicted that aspartame treatment would significantly impair learning, memory and electrophysiological responses in the rats. Aspartame treatment had altered sympathovagal activity along with impairment of memory and learning. An alteration of EEG waves in both the fronto-parietal and occipital regions, which affect learning and memory in rats. (Choudhary, Arbind Kumar, et al 2015) However, rats metabolize aspartame faster than humans dose comparisons between rats and humans a normally corrected by a factor of 5. Therefore, suggesting that scientific tests on rats may not show the same exact aspects of effects on cognition and electrophysiological responses.  (Mejia, Vences, et al. 2006)

    Keywords: electrophysiological, sympathovagal activity

                                                    How Aspartame Affects the Brain

    Sweeteners are ingredients in numerous foods such as gum, ice cream, cookies, cakes, medicine and soft drinks just to name a few. Sweeteners like aspartame are of primary importance for nutritional guidance for people with diabetes a disease with growing numbers in developed nations. To some extent, people can control the amount of aspartame that they consume on a daily basis. However, the internal factors of consuming aspartame on a daily basis has on the brain. Can the brain be affected from consuming aspartame on daily basis? Does consuming aspartame lower the ability to remember things and cognitive function.? Can people increase their ability to remember and have a healthier brain by consuming less aspartame?

    One theory that prompted research on how aspartame affects the brain is the conspiracy theory. Two researchers who were against aspartame being passed in 1981 who were Dr. John Olney and James Turner. These two people were the people who began the conspiracy theory that aspartame was dangerous to people’s health. The idea was that aspartame which is hydrolyzed in the intestine to form aspartate (40%), phenylalanine (50%) and methanol (10%). (Mejia, Vences, et al. 2006) Which are then absorbed into the circulation and passed through the blood brain barrier. Methanol breaks down into formaldehyde, which is very cytotoxic and can cause blindness. (Humphries , P, et al. 451) The investigation of the general effects from aspartame’s metabolic components is headaches, seizures, insomnia, compromised learning, memory loss, and blurry vision.  (Humphries , P, et al. 451) During development of a fetus an investigation found maternal aspartame consumption, could lead to damage or impairment of the foetal nervous system, contributing to cerebral palsy and all-encompassing developmental disorders. (Humphries , P, et al. 458) Another study found that consumption of 9% aspartame in the diet for 13 weeks affected learning behavior in rats. (Mejia, Vences, et al. 453) While aspartame exposure of guinea pigs to 500 mg/kg during gestation disrupted odour-associative learning in pups. (Mejia, Vences, et al. 453) Since that time, research has focused basically on cognitive effects of aspartame and direct cellular effects on the brain. However, as Dr. John Olney, psychiatrist, neuropathologist and professor at Washington University in St. Louis (1978) point out, the effects of aspartame on rats showed a high rate of brain tumors which is not normal.  While P. Humphries states through studies on humans, rats, rabbits, mice and various species that excessive aspartame ingestion might be involved in the pathogenesis of certain mental disorders. ( Humphries , P, et al. 451)

    The relatively numerous research done on cellular effects of aspartame on the brain has left room for more possible further research. First, much of the research has been done on rats that are given certain levels of aspartame daily in either food or drink. While not enough research was done on humans who consume random amounts of aspartame at any given time. Second, some of the findings have been found to be contradictory. One study found that consuming aspartame may play a role in implicating in the pathogenesis of  developmental disorders such as autism spectrum disorder. (Humphries , P 2006) However, research has found that aspartame consumption and memory loss have been conducted on humans and rodents and no relationship was found. (Mejia, Vences, et al. 2006) Third, not all groups of people and animal studies have been sufficiently studied. The effects of aspartame on a rat is different from a human. Experimental studies on humans psychological, cognitive and electrophysiological responses to aspartame is limited for numerous safety reasons. Studies have been down on consumption during early brain development. In the study was found that prenatal consumption of aspartame might result in mental retardation, impaired vision, birth defects, and the pathogenesis of Alzheimer’s disease. (Humphries , P, et al. 2006)  Fourth, not all electrophysiological responses have been studied in complete detail. A study on rats consuming aspartame had a an index of overall HRV, was reduced. HRV is an independent indicator of adverse prognosis in cardiac disorder. (Choudhary, Arbind Kumar, et al. 2015) Another study focused on aspartame found that temperature of aspartame exceeds 86 degrees its methanol converted into formaldehyde and then formic acid, which then causes metabolic acidosis. The average human body is 98 to 97 degrees warm enough to convert methanol into formaldehyde and then into formic acid. (Humphries , P, et al. 2006)

    According to some researchers, most of the results indicate that aspartame causes neurological disturbances in sensitive individuals. Phenylalanine an metabolic component in aspartame can follow only two pathways. A part is converted into tyrosine in the liver. (Caballero and Wurtman 1988) The rest of phenylalanine that’s not converted will bind to a large neutral amino acid transporter and be carried over the blood-brain barrier. ( Humphries , P, et al. 2006) These neurotoxic agents might cross the blood-brain barrier and deteriorate the neurons of the brain. (Humphries , P, et al. 2006) To date, aspartame and its metabolic components numerous research studies show that cellular damage may occur. Although, with over 20 years of people consuming aspartame further studies need to be created to find the exact risks that aspartame has to the human health. In fact, cross-sectional research on groups of people consuming aspartame and what effects that has throughout life compared to other groups of people their age at the time. Longitudinal research on people consuming aspartame their whole lives compared to people who never consume aspartame can reveal the effects throughout life. Another study finds that aspartame mixed with other artificial ingredients changes the variability that aspartame alone is cause for neurological disturbances. Testing through electroencephalogram and magnetic resonance imaging give detail imaging aspartame related damages. Measuring mental activity of a person after taking aspartame can help give an image to parts of the brain affected by aspartame. If aspartame damages neurons, dendrites, and axons then a detailed image with magnetic resonance imaging will give researchers a view. Aspartame metabolites also showed impairment of learning and memory by alteration of EEG waves in both the fronto-parietal and occipital regions, which may affect learning and memory in rats. (Choudhary, Arbind Kumar, et al. 2015) Therefore, the study help us understand that aspartame effects fronto-parietal and occipital regions of a rat brain. That numerous studies on humans and animals result in aspartame metabolites might be causative factors in neurological changes and compromised learning. Specifically, the study on methanol and how it turns into formaldehyde and how it causes blindness, dizziness, headaches, tinnitus, vertigo, cramps, numbness in the legs, shooting pains, anxiety, slurred speech, memory loss, and spasms. (Humphries , P, et al. 2006) This predicts that large  amounts of aspartame metabolite methanol may can cause problems. Although, more research has to be done since methanol is only 10% of aspartame metabolites.

    Method

    Participants were experimental animals that were maintained under standard laboratory conditions that were allowed food and water ad libitum. (Choudhary, Arbind Kumar, et al 2015) These animals were kept in standard laboratory conditions with controlled temperature of 26 celsius. They were also kept in a controlled light exposure of 12 hours of light and 12 hours of darkness. The experimental animals were healthy, inbred adult male Wistar albino rats. (Choudhary, Arbind Kumar, et al 2015) The rats weighted around 200-220 g. The rats were divided into fours groups at random and each group contained six rats.

                                                         Materials

    The HRV monitoring by using the radio-telemetric system was used to evaluate the cardiac rhythm regulatory response to aspartame. (Choudhary, Arbind Kumar, et al.  2015) Then the time intervals were obtained with Dataquest A.R.T analysis software (version 2.20; Data Sciences International, USA). (Choudhary, Arbind Kumar, et al.  2015) After the 90 day experiment the electroencephalogram measurement was used to record brain waves and to eliminate variation due to circadian rhythms. All of the data was analyzed by using the SPSS with is for Windows statistical package (version 20.0, SPSS Institute Inc,. Cary North Carolina.) ( Choudhary, Arbind Kumar, et al. 2015) All data was summarized in a table after all tests were completed.  The information for the experiment was summarized and shared with other sciences at Tabiah University for Science.

                                                         Procedure

    The first group was the controlled rats that were administered a normal saline by a gavage needle. Then group two was consisted of animals feed a folate deficient. (Choudhary, Arbind Kumar, et al 2015) Group three was consisted of control animals that were given aspartame orally for 90 days. (Choudhary, Arbind Kumar, et al 2015) The rats in group three were given 40mg of aspartame everyday. Then group four was feed folate-deficient diet and treated with aspartame everyday for 90 days by a gavage needle. In the study the rats that were fed a folate deficient diet were used to mimic the human methanol metabolism. (Choudhary, Arbind Kumar, et al. 2015) Since humans beings do have a very low hepatic folate content. Due to the fact that methanol metabolism, which converts in formaldehyde needs a high folate content formaldehyde into carbon dioxide. To simulate this process the rats in groups 2 and 4 were fed a special dietary regime for the first 37 days, and then given methotrexate in a sterile saline for other day for the next two weeks. The folate deficiency was confirmed by estimating the urinary excretion of formiminoglutamic acid. (Choudhary, Arbind Kumar, et al.2015) The folate deficient rats showed an increase in FIGLU excretion compared to the control rats in groups 1 and 3.

    Measurements of heart rate variabilities were taken based on spectral and time domain analysis were used to analyze to cardiac rhythm regulatory reaction to aspartame. In the time domain analysis, the intervals between normal N-N waves are measured over the period of recording. (Choudhary, Arbind Kumar, et al. 2015) While the NN intervals are used to establish the SD in the NN intervals and the root mean square of sequential differences to NN intervals. (Choudhary, Arbind Kumar, et al. 2015) All measurements were obtained by the electrocardiography channel (RR) and analysed beat-to-beat basis with the use of Dataquest A.R.T analysis software. All of the errors that resulted from the R-wave detector were removed by using the criteria to secure normal-to-normal (NN) intervals. (Choudhary, Arbind Kumar, et al. 2015) The frequency domain methods are expressed in a form of spectral density function. This spectral density function will depicts spectral power as a function of frequency.  (Choudhary, Arbind Kumar, et al. 2015) While the higher frequency is solely mediated by changing levels of vagal activity whereas low frequency is mediated by both sympathetic and vagal activity. (Choudhary, Arbind Kumar, et al. 2015)

    On the last session of the treatment the rats were implanted with electrodes. The rats operations was performed to ethical guidelines by administration of saline, antibiotics to prevent sepsis and to prevent any fluid loss during surgery. The electrode was placed on the scalp and glued with dental acrylic resin, and the incision was closed and sutured, exposing the electrode. (Choudhary, Arbind Kumar, et al. 2015) After the rats recovered the electrode was connected to electroencephalography (EEG) using the model RMS EEG-24 brain new plus: RMS- Recorder and Medicare systems. (Choudhary, Arbind Kumar, et al. 2015) The electroencephalography was recorded on the rats for about ten minutes. All the signals were filtered between 1 to 70 Hz. (Choudhary, Arbind Kumar, et al. 2015) Then the recordings were analyzed by the RMS EEG-24 Super sec version 1.1 and then expressed in terms of amplitude and frequency. All of the recordings were recorded as statistical analysis. The whole experiment was performed at the exact time of day for 10-12 am. Therefore, to eliminate all variations due to the circadian rhythms.  

    Results

        All of the results were summarized in a table one. In both the group three and four (folate-deficient rats) that were treated with aspartame for the whole 90 days. Those two groups of rats showed a significant increase in their RR interval compared to the rat groups not treated with aspartame. The control and folate-deficient rats also showed significant decreases in the total spectral power and higher frequency and significant increases in lower frequency compared to groups of rats not treated with aspartame. (Choudhary, Arbind Kumar, et al. 2015) Although, the folate-deficient rats were similar to the control rats in the total numbers of NN intervals (PNN50). (Choudhary, Arbind Kumar, et al. 2015) However, in both the control and folate-deficient rats that were treated with aspartame for 90 days did significant decreases. These decreases were in the SDNN, RMSSD, and the PNN50 compared to the rats in the control and folate-deficient rats not treated with aspartame. (Choudhary, Arbind Kumar, et al. 2015) Then in both the control and folate-deficient rats treated with aspartame for those 90s day had significant decreases in frequency and increase in amplitude. Which is compared to the control and folate-deficient animals not treated with aspartame. The rats treated with aspartame in the control and folate-deficient groups has a significant differences compared to the groups not treated with aspartame.

    The prediction was the rats in control and folate-deficient groups treated with aspartame would be similar to the groups not treated with aspartame. That aspartame would have little to no effect on heart rate variability and parameters that reflect learning and memory in the fronto-temporal occipital lobes. However, after the 90 days of treatment the findings proven the prediction wrong that aspartame has little to no effect on the heart rate and the parameters that reflect learning and memory as stated above. After the experiment was completed all were euthanized. The rats after euthanasia they were sent to another laboratory for further analysis. Their liver, heart and brain were removed for a biopsy to further examine the effects of aspartame at the cellular level.

    (Choudhary, Arbind Kumar, et al. 2015)

        Laboratory animals such as Wistar albino rats have been used on an ongoing basis for experiments to study the effects of aspartame on heart rate, fronto-temporal and occipital lobes and the liver. Although, experimental studies on aspartame’s effects to human’s heart rate, occipital and frontal-temporal lobes and liver is limited do to safety reasons. (Choudhary, Arbind Kumar, et al. 2015) The folate-deficient model was designed to mimic the human methanol metabolism in the Wistar albino rats. While the time interval between heartbeats is not very constant. Due to the fact, that variability occurs due to a variety of physiological process that affect the heart rate at different frequencies. (Choudhary, Arbind Kumar, et al. 2015) The measurements of the tachogram of the HRV is basically a reflection of all the different interacting phenomena. (Choudhary, Arbind Kumar, et al. 2015) When the PSA of the HRV divides the overall variability into a separate frequency. (Choudhary, Arbind Kumar, et al. 2015) Which then enables the identification of the activity of the various affecting components. (Choudhary, Arbind Kumar, et al. 2015) Basically, this is a noninvasive technique that gives a detailed information for physiological process of the cardiac and neurogenic effects of aspartame.

    (Choudhary, Arbind Kumar, et al. 2015)

    Discussion

        The purpose of this study was to test how aspartame affects the cardiac system, the neurological system, and electrophysiological responses. In the aspartame treated rats clearly shows that the cardiac parasympathetic modulation is reduced in these animals. (Choudhary, Arbind Kumar, et al. 2015) Previously, in past experiments it was reported that aspartame could cause disturbances in the medulla. The medulla controls the involuntary life sustaining function such as breathing, heart rate and swallowing. The changes in the heart rate could be caused by aspartic acid and phenylalanine crossing the blood-brain barrier and deteriorating neurons of the brain. (Humphries , P, et al 2006) Although, no tests states about changes in abilities to breath or swallow which are controlled by the medulla. The rats could have changes in cardiac function caused by different effects other that aspartame. The animals that were treated with aspartame had an index of HRV reduced overall. An reduced HRV is an independent indicator of adverse prognosis in a cardiac disorder. (Choudhary, Arbind Kumar, et al. 2015)

    The findings of this study a consist with the study created by University City of Mexico and the Biomedical Research Institute. In their study they used twenty-four male Wistar rats in three groups. Two groups were give aspartame treatment by a gavage needle. Group one was give 75 mg/kg of aspartame daily. The second group was given 125 mg/kg of aspartame everyday.  While the third group was given no aspartame treatment whatsoever. After 30 days of treatment the rats were euthanized and had their cerebrum, cerebellum and liver removed and examined. (Mejia, Vences, et al. 2006) A finding in this study found that aspartame metabolites: aspartic acid, phenylalanine and methanol are not CYP-inducing agents in the liver. (Mejia, Vences, et al. 2006) They were able to find that aspartame consumption leads to an increment in the concentration and activity of CYP2B1/2, CY2E1 and CYP3A2 in rat cerebral and cerebellar microsomes. (Mejia, Vences, et al. 2006) Then the highest increment in a CYP-associated activity that was induced by aspartame in a rat brain was that of 4-NPH corresponding to CYP2E1. (Mejia, Vences, et al. 2006) The CYP2E1 activity was up to 25-fold over controls over the rats not treated with aspartame. The CYP2E1 is a member of the cytochrome P450 that is involved with metabolism of xenobiotics in the rat body. CYP2E1 is a variable among the different parts of the rat brain. Therefore, in this respect the enzyme systems used for metabolism and detoxification of foreign compounds ae of special interest as the changes in their function could lead to changes in the susceptibility of an organ to the harmful effects of the increasing variety of contaminants found in the environment and in food products.  (Mejia, Vences, et al. 2006)

    Research on the effects of aspartame by the Department of Anatomy and the University of Limpopo of South Africa did their own investigation. They did various studies of aspartame on humans, rabbits, mice, rats few other various species. They found no adverse effects that are visible after a single large dose of aspartame. Although, further studies revealed the effects of aspartame vary from no effects observed to severe adverse effects. A study was directed and found indirect cellular effects of excessive aspartame ingestion might be involved in the pathogenesis of of certain mental disorders and compromised learning. (Humphries , P, et al. 2006) Aspartame metabolic component phenylalanine was found in different studies to interfere with brain development and fatty acid metabolism. (Humphries , P, et al. 2006) One study by Mehl-Madrona in 2005 found that phenylalanine and aspartic acid might cross the blood-brain barrier and deteriorate the neurons of the brain causing memory loss. (Humphries , P, et al. 2006) The findings is that aspartame breaks down in 50% phenylalanine which about half turns into tyrosine in the liver. While the rest of phenylalanine passes through the blood-brain barrier and targeting neurons in the brain. Tyrosine can also pass through the blood-brain barrier be converted into dihydroxyphenylalanine by the enzyme tyrosine hydroxylase. Also oxygen, tetrahydrobiopterin and iron help break down tyrosine. In high concentrations of  tyrosine hydroxylase is very necessary to prevent a large amount of dopamine being produced. (Humphries , P, et al. 2006) However, if phenylalanine, competes with tyrosine for NAAT, then a compromised dopamine production with result. (Humphries , P, et al. 2006) Due to the fact, that phenylalanine will bind more freely and frequently with than tyrosine do to its higher concentration. (Humphries , P, et al. 2006) Therefore, their will be lower levels of dopamine concentration in the brain. Dopamine is an important inhibitory neurotransmitter. Thus, it could potentially disrupt a wide range of processes in the brain, including neuronal function, protein structure, nucleic acid integrity and endocrine balances. (Humphries , P, et al. 2006)

    In conclusion, aspartame has been found to affect numerous parts of the brain cellular structure.  Since aspartame breaks down into three metabolic components phenylalanine (50%), aspartic acid (40%) and methanol (10%).  (Humphries , P, et al. 2006) Aspartame’s metabolic components have been able to show differential effects in studies of animals and humans alike. Which the examinations that aspartame ingestion might be involved with damage to neurons and changes in neurotransmitter concentrations. That rats in studies were found to have changes in CYPs levels in their cerebral and cerebellar microsomes after aspartame treatment for 90 days. In another study heart rate variability was markedly decreased in aspartame treated rats for 90 days. These studies point to the fact the more research and experiments need to be done on a animals and humans to give a detail record on effects of aspartame to the brain and body. With aspartame on the market for over 20 years and people unsuspectingly consuming it more studies need to be done. For any risks to the public health need to found and reported to tech people that adverse effect may be caused by aspartame. With the knowledge we know today can be built upon with further research so we can find if aspartame really has any adverse effects to even an sensitive individual . The mixed results of this study do suggest that we still have a lot to learn about aspartame and its effects to brain and body of the people who are consuming it.

References

    Choudhary, Arbind Kumar, et al. “Effects of Aspartame on the Evaluation of Electrophysiological Responses in Wistar Albino Rats.” Egyptian Journal of Medical Human Genetics, Elsevier, 6 Nov. 2015, www.sciencedirect.com/science/article/pii/S1658365515001351.

    Humphries , P, et al. “Direct and Indirect Cellular Effects of Aspartame on the Brain.” European Journal of Clinical Nutrition , Nature Publishing Group , 25 Oct. 2006, www.nature.com/articles/1602866.pdf.

    Mejia, Vences, et al. “The Effect of Aspartame on Rat Brain Xenobiotic-Metabolizing Enzymes.” Philosophy of the Social Sciences, 2006, journals.sagepub.com/doi/abs/10.1191/0960327106het646oa.