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Nutritional Neuroscience Lab


Nutritional Neuroscience Lab

Dr. Kathleen Holton

Nutritional Neuroscience Lab
4400 Massachusetts Avenue NW
Washington, DC 20016

The main focus of the Nutritional Neuroscience Lab is studying how food additives negatively influence neurotransmission, and how dietary nutrients may help prevent excitotoxicity. We are especially interested in how exposure to dietary excitotoxins can lead to neurological symptoms, including pain, cognitive dysfunction, parasthesias, gastrointestinal disorders, memory loss, inattention, impulsivity and centrally mediated fatigue. 

What is an Excitotoxin? Excitotoxins are amino acids in the diet which also function as excitatory neurotransmitters in the nervous system. These amino acids have the ability to over-excite a neuron to the point that it dies, when present in high enough amounts. Even in smaller amounts, exposure to excitotoxins may lead to abnormal excitatory neurotransmission. Excitotoxicity also leads to increased production of reactive oxygen species and oxidative stress in cells, which in turn, increases the demand for dietary antioxidants.

The most common exposure to dietary excitotoxins comes from the use of free amino acids as food additives. The most well-known food additives in this class are monosodium glutamate (MSG) and aspartame (which is a dipeptide of phenylalanine and aspartate), though there are many others hidden under various names on food labels. Any food which contains free forms of glutamate, aspartate or L-cysteine has the potential to elicit symptoms in sensitive individuals; however, there are also foods like soy sauce and parmesan cheese which naturally contain higher levels of these amino acids. Extremely potent glutamate analogs also exist in the environment, but exposure to these chemicals is much less frequent.

In prior research, we have demonstrated that individuals with fibromyalgia and irritable bowel syndrome experience symptom improvement when excitotoxins are removed from the diet, and that symptoms return upon double-blind challenge with MSG as compared to placebo. We are now working to understand the mechanism behind why these individuals may be more susceptible to these food additives than the general population. This research is also being expanded internationally to Meru, Kenya this summer, where we will be beginning pilot testing of the Excitotoxin Elimination Diet in patients with chronic widespread pain. 

Our lab is also studying the effects of diet on ADHD. We are interested in understanding whether children and adolescents/young adults consume diets lower in micronutrients than controls of a similar age. The effects of breakfast consumption on cognitive function are also being tested in college-age students with and without ADHD. Additionally, we are exploring the potential contribution of food additives to the symptoms of ADHD in children, including the potential role of dietary excitotoxins, as well as glycine, a dietary amino acid which serves dual roles as both a co-agonist of the NMDA glutamate receptor, and as an inhibitory neurotransmitter at the spinal cord. 

Disordered glutamatergic neurotransmission has been implicated in many other disorders as well, including: Alzheimer’s, epilepsy, migraine, depression, obsessive compulsive disorder, and others. Thus, it is essential to understand the potential negative role of dietary excitotoxins, as well as the positive protective effects of micronutrients. Our lab is striving to advance this understanding of the interaction of diet and excitotoxicity.