This is Your Brain on Food Chapter 5. ADHD Gluten, Milk Caseins, and Polyphenols
Author: Uma Naidoo Publisher: New York, NY: Little Brown Spark. Publish Date: 2020 Review Date: 2023-5-4 Status:📚
Annotations
- Curatolo P, D’Agati E, Moavero R. The neurobiological basis of ADHD. Italian Journal of Pediatrics. 2010;36(1):79. doi:10.1186/1824-7288-36-79.
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what role does your gut play? Larger molecules such as dopamine and noradrenaline cannot cross the blood-brain barrier, which means that they are confined solely to your brain. But they are made of precursor molecules—building blocks—that can. And where are these precursor molecules made? You guessed it: the gut.
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Gut bacteria play an important role in ADHD, synthesizing many of these chemical precursors.7 Different bacterial species in the gut produce different chemicals, which means that if gut bacteria change, the brain’s chemical stability can be upset.8 And as we’ve seen with other conditions, a reduction in the diversity of gut bacteria can be particularly problematic.9
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- Lyte M. Microbial endocrinology in the microbiome-gut-brain axis: how bacterial production and utilization of neurochemicals influence behavior. Miller V, ed. PLoS Pathogens. 2013;9(11):e1003726. doi:10.1371/journal.ppat.1003726.
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- Desbonnet L, Garrett L, Clarke G, Bienenstock J, Dinan TG. The probiotic Bifidobacteria infantis: An assessment of potential antidepressant properties in the rat. Journal of Psychiatric Research. 2008;43(2):164–74. doi:10.1016/j.jpsychires.2008.03.009; Clayton TA. Metabolic differences underlying two distinct rat urinary phenotypes, a suggested role for gut microbial metabolism of phenylalanine and a possible connection to autism. FEBS Letters. 2012;586(7):956–61. doi:10.1016/j.febslet.2012.01.049; Gertsman I, Gangoiti JA, Nyhan WL, Barshop BA. Perturbations of tyrosine metabolism promote the indolepyruvate pathway via tryptophan in host and microbiome. Molecular Genetics and Metabolism. 2015;114(3):431–37. doi:10.1016/j.ymgme.2015.01.005.
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- Sandgren AM, Brummer RJM. ADHD-originating in the gut? The emergence of a new explanatory model. Medical Hypotheses. 2018;120:135–45. doi:10.1016/j.mehy.2018.08.022.
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In 2017, Esther Aarts and her colleagues examined the differences in the microbiome between patients with ADHD and healthy individuals.10 Compared to controls, people with ADHD had more bacteria that made phenylalanine, a building block necessary for dopamine and noradrenaline synthesis.
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- Aarts E, Ederveen THA, Naaijen J, et al. Gut microbiome in ADHD and its relation to neural reward anticipation. Hashimoto K, ed. PLoS One. 2017;12(9):e0183509. doi:10.1371/journal.pone.0183509.
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The investigators then looked at how the brains of each group responded to reward. Decreased anticipation of brain reward is a hallmark of ADHD—in other words, studies show that people with ADHD aren’t motivated as strongly by incentives to behave in a certain way.11 Sure enough, the researchers found that the ADHD subjects showed less brain activation in response to being rewarded. Furthermore, the less their brains responded to the reward, the more phenylalanine-producing bacteria were present in their guts. The researchers concluded that ADHD subjects had to make more bacteria that produce phenylalanine to compensate for how their brains responded.
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- Volkow ND, Wang G-J, Newcorn JH, et al. Motivation deficit in ADHD is associated with dysfunction of the dopamine reward pathway. Molecular Psychiatry. 2010;16(11):1147–54. doi:10.1038/mp.2010.97.
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The exact reason that gluten sensitivity and brain dysfunction are connected is not fully understood. In 2005, Päivi A. Pynnönen and her colleagues assessed adolescents with celiac disease and behavioral problems.16 They found that adolescent celiac disease patients had significantly lower tryptophan concentrations in their blood.
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- Pynnönen PA, Isometsä ET, Verkasalo MA, et al. Gluten-free diet may alleviate depressive and behavioural symptoms in adolescents with coeliac disease: a prospective follow-up case-series study. BMC Psychiatry. 2005;5(1). doi:10.1186/1471-244x-5-14.
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Three months after patients started a gluten-free diet, the researchers found a significant decrease in patients’ psychiatric symptoms compared to their baseline condition, coinciding with significantly decreased celiac disease activity and prolactin levels and with a significant increase in L-tyrosine, L-tryptophan, and other amino acids known to be precursors of brain chemicals such as serotonin. The authors concluded that it was possible that behavioral problems, such as those that occur with ADHD, may in part be due to certain important precursor amino acids not being available until people stopped eating gluten. In certain individuals, gluten-free diets can help the body increase levels of the precursors to make serotonin, which is one neurotransmitter involved in ADHD.
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Eating a lot of dairy means you eat a lot of casein, which may worsen ADHD.17 Casein is the main protein found in dairy products such as milk, cheese, yogurt, and ice cream, but it can be a factor even in foods that are thought of as dairy substitutes, like nondairy creamer and margarine. Not all casein is the same. The main form is called beta-casein, of which there are two major types, A1 and A2. Most regular milk contains both types, but research suggests that A1 proteins may be harmful to the gut in ways that A2 proteins are not. In 2016, a team led by Sun Jianqin studied forty-five participants who consumed milk containing both A1 and A2 milk proteins, and then milk containing only A2 protein.18 The researchers found that when subjects drank milk containing A1 protein, they had more gastrointestinal inflammation, their thinking was slower, and they made more errors on an information-processing test. It was as if the A1 protein muddied their thinking, something that ADHD patients can ill afford. The study even suggested that lactose intolerance may be caused by sensitivity to A1 caseins rather than lactose itself. Although more research is under way about whether A1 milk causes any adverse effects except occasional digestive problems, it’s clear that sufferers of ADHD should be cautious about the kind of casein they consume.19
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- Ly V, Bottelier M, Hoekstra PJ, Arias Vasquez A, Buitelaar JK, Rommelse NN. Elimination diets’ efficacy and mechanisms in attention deficit hyperactivity disorder and autism spectrum disorder. European Child and Adolescent Psychiatry. 2017;26(9):1067–79. doi:10.1007/s00787-017-0959-1.
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- Jianqin S, Leiming X, Lu X, Yelland GW, Ni J, Clarke AJ. Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows’ milk. Nutrition Journal. 2015;15(1). doi:10.1186/s12937-016-0147-z.
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- Küllenberg de Gaudry D, Lohner S, Schmucker C, et al. Milk A1 β-casein and health-related outcomes in humans: a systematic review. Nutrition Reviews. 2019;77(5):278–306. doi:10.1093/nutrit/nuy063.
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Luckily there is milk available that only has A2 proteins. Milk from breeds of cows that originated in Northern Europe is generally high in A1 protein. These breeds include Holstein, Friesian, Ayrshire, and British shorthorn. Milk that is high in A2 protein is mainly found in breeds that originated in the Channel Islands and southern France. These include Guernsey, Jersey, Charolais, and Limousin cows.20
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- Truswell AS. The A2 milk case: a critical review. European Journal of Clinical Nutrition. 2005;59(5):623–631. doi:10.1038/sj.ejcn.1602104; Farrell HM Jr, Jimenez-Flores R, Bleck GT, et al. Nomenclature of the proteins of cows’ milk—sixth revision. Journal of Dairy Science. 2004;87(6):1641–74. doi:10.3168/jds.s0022-0302(04)73319-6.
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It’s worth noting that sheep’s and goats’ milk is generally A2 milk, which makes cheese and yogurt choices a bit easier. You can also try nut milks and milk nut yogurts as a way to avoid casein.
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One crucial type of antioxidant is polyphenols. Polyphenols are chemical weight lifters for the body’s immune response. They act as low-dose toxins that train the body to mount an immune response in a process called hormesis. Polyphenols can also exert other biological effects that are helpful to the brain; for example, they influence the survival and regeneration of neurons. The richest sources of polyphenols are berries, cherries, eggplant, onions, kale, coffee, and green tea.
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Some animal and human studies have indicated that when there is a deficiency of zinc, hyperactivity may occur.39 Indeed, zinc deficiencies are associated with ADHD in children, in part because its absence reduces the activity of reward pathways that rely on dopamine.40 Other studies have shown that children with ADHD have lower levels of iron and magnesium than controls, both of which are involved in dopamine synthesis.41 In 2017, Jin Young Kim and her colleagues studied 318 healthy children to see if their diets impacted their cognition. They used the Symbol Digit Modalities Test (SDMT), a test of speed of information processing, to see which dietary elements were beneficial.42 They found that the consumption of vitamin C, potassium, vitamin B1, and nuts all increased performance on the SDMT. In addition, the more mushrooms people ate, the better they were able to reason, while noodles and fast food decreased SDMT scores.
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- Golub MS, Takeuchi PT, Keen CL, Hendrick AG, Gershwin ME. Activity and attention in zinc-deprived adolescent monkeys. American Journal of Clinical Nutrition. 1996;64(6):908–15. doi:10.1093/ajcn/64.6.908.
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- Gao Q, Liu L, Qian Q, Wang Y. Advances in molecular genetic studies of attention deficit hyperactivity disorder in China. Shanghai Archives of Psychiatry. 2014;26(4):194–206; Lepping P, Huber M. Role of zinc in the pathogenesis of attention-deficit hyperactivity disorder: implications for research and treatment. CNS Drugs. 2010;24(9):721–28.
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- Cortese S, Angriman M, Lecendreux M, Konofal E. Iron and attention deficit/hyperactivity disorder: what is the empirical evidence so far? A systematic review of the literature. Expert Review of Neurotherapeutics. 2012;12(10):1227–40; Curtis LT, Patel K. Nutritional and environmental approaches to preventing and treating autism and attention deficit hyperactivity disorder (ADHD): a review. Journal of Alternative and Complementary Medicine. 2008;14(1):79–85.
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- Kim JY, Kang HL, Kim DK, Kang SW, Park YK. Eating habits and food additive intakes are associated with emotional states based on EEG and HRV in healthy Korean children and adolescents. Journal of the American College of Nutrition. 2017;36(5):335–41.