We’ve all been inflamed before, and we know exactly what this looks like. Think of the time where you’ve got a papercut on your finger, and the skin around it turns pink and becomes swollen. Or when you rolled your ankle in gym class and it swelled up immediately. This is inflammation, and it’s the body’s natural defense mechanism against foreign invaders. It’s what keeps us protected against viruses, pathogens, and basically anything we don’t want in our body. Inflammation keeps us healthy, as long as it’s kept in check. However, today’s society is becoming increasingly inflamed, and chronic inflammation (inflammation that lasts beyond a few days or weeks) is beginning to get a (well deserved) bad rep. Chronic inflammation is implicated in many non-communicable diseases such as diabetes, cardiovascular disease, arthritis, and Chronic Obstructive Pulmonary Disease (Pahwa, Goyal, Bansal et al., 2021). Not only that, but chronic inflammation is starting to be correlated to many mental diseases such as depression, anxiety, schizophrenia (Effendy, 2018) and even Parkinson’s Disease and Alzheimer’s (Cenit, Sanz, & Codoner-French, 2017), and mental performance as a whole (Beilharz, Maniam, & Morris, 2015, Leigh & Morris, 2020). How does this work? Let’s look at the mechanisms behind chronic inflammation.
What Causes Chronic Inflammation
When the immune system senses that something is off, it turns “on” and starts to secrete it’s messenger cells called cytokines that go around and let the rest of the body know that basically it’s under attack. In order to help the body start to fight off whatever it’s up against, it starts to produce inflammation (remember, the body’s defense mechanism). What causes the body to think something is “off”? There are a few potential processes.
Gut Permeability: When the intestinal lining is impaired, and particles that otherwise would have been kept in the gut start to make their way into circulation, your body believes it is under attack and cytokines start to be produced, leading to widespread inflammation (Oriach et al., 2016). See last week’s blog post for more info.
Increased Fat Cells: As adipose tissues (fat tissues) increase in size, they start to secrete their own cytokines, telling the body to start producing inflammation (Leigh & Morris, 2020). In one study, simply transplanting white adipose tissue from obese was shown to promote inflammation in lean mice, and reduce inflammation in the obese mice as a result of the removal of adipose tissue from the donor (Leigh & Morris, 2020).
Oxidative Stress: reactive oxygen species (ROS) are a normal byproduct of mitochondrial metabolism (basically your body creating energy and doing normal stuff like breathing), and are important in several functions throughout the body. However, when there is an overproduction of ROS, and a limited amount of antioxidants, we are in a state of oxidative stress. Oxidative stress has been shown to result in chronic inflammation (Hussain et al., 2016).
Inflammation and Cognition
When there is inflammation throughout the body, the cytokines that are produced can make their way into the Central Nervous System (CNS…aka the brain), which then modulates inflammation processes in the brain itself. This can lead to both neurodegenerative diseases such as Alzheimer’s, and impairment of cognitive functioning (Marsland et al., 2015).
Chronic inflammation has been linked to several cognitive deficits including memory, reasoning, global cognition, executive function, alertness, and learning (Leigh & Morris, 2020, Marsland et al., 2015). The hippocampus is a part of the brain that is essential for processes involving learning and memory. This brain region is also highly susceptible to inflammation, and when inflamed can cause deficits in these cognitive processes. For example, in mice, hippocampal inflammation was negatively associated with their performance on a spontaneous alternation task, and they showed impaired spatial recognition memory (meaning, impaired ability to both learn and remember) (Leigh & Morris, 2020). In addition, human studies that have experimentally induced inflammation have shown impaired global memory in otherwise healthy subjects (Beilharz, Maniam, & Morris, 2015). Are you familiar with the experience of “brain fog,” where your brain feels fuzzy and it’s hard to think or concentrate? This may also be due to inflammation. A new study found that after injecting healthy young men with a vaccine that causes temporary inflammation, the part of the brain that is responsible for “alertness” (reaching or maintaining an alert state) was particularly affected by inflammation, which may be the cause of what we know to be “brain fog” (Balter et al., 2019).
Not only does chronic inflammation impact your mental performance at work, but for those of you who are trying to lose weight, inflammation may be your antagonist. The hippocampus is the region of the brain that modulates food consumption. When watching TV late at night and all of the sudden a Taco Bell commercial comes on, this part of the brain is responsible for either allowing you to look the other way and forget about the Crunchwrap supreme, or compelling you to get in your car and head straight to the drive thru. When the function of the hippocampus is altered (for example, due to chronic inflammation…) it may impair your ability to make decisions around eating (“no, I’m not going to eat that donut, instead I’ll have an apple..”) (Leigh & Morris, 2020). This can further exacerbate the obesity problem, creating a vicious cycle.
How Does Diet Impact Inflammation & Cognition?
I’m glad you asked. Studies are showing that diet can have a major impact on the development of chronic inflammation, and thus our cognitive processes. An obesogenic diet can rapidly produce chronic inflammation (Leigh & Morris, 2020). What’s an obesogenic diet? Unfortunately for all the Americans reading this, (and others who live in a country that is starting to, or already has, adopted our “Western Style Diet”) this type of diet is where we get on average 60% of our energy from. This Western Style Diet is high in processed fat, simple sugars, and food additives, and low in vitamins, minerals, and fiber. Think: Big Macs, breakfast cereals, “energy bars,” pastries, white bread, hot dogs…you get the point. Walk down any grocery store aisle and you’ll see several examples of our Western Style Diet. And we don’t have to be consuming this type of diet consistently to reap its consequences. Research has shown that as little as 1 to 3 days on a “high fat” diet was enough to change the expression of inflammatory markers in the brain of rodents (Beilharz, Maniam & Morris, 2015).
Not only is inflammation quickly produced, but its effects on cognition work just as fast. In healthy males, a high fat diet impaired attention, speed of retrieval, and depressed mood after only 5 days (Holloway et al., 2011) and another study found that this same diet followed for 7 days was enough to decrease reaction times and attention (Edwards et al., 2011). 4 days of consuming only a high fat and high sugar BREAKFAST (something we as Americans probably consume daily..) was enough to worsen performance on verbal learning and logical memory in undergraduate students (Attuquayefio et al., 2017).
And remember what we talked about earlier about the impaired hippocampal activity resulting in an inability to modulate food choices? Healthy undergraduate students who reported consuming more fat and refined sugar had reduced sensitivity to their own internal hunger and fullness cues, having to eat more to feel “full” (Francis & Stevenson, 2011). These deficits can all be linked to increased inflammation markers in the subjects’ bodies.
Cool Off Inflammation and Boost Your Brain
So now you get it. An unhealthy diet creates inflammation, which impairs our ability to think, learn, remember, pay attention, reason, even exhibit self-restraint when it comes to food cravings (or experience food cravings in general, but that’s a topic for another day). If you’re like most people, you want to get the most out of your brain on any given day, and you can’t afford to be off your game even in the slightest! I hear you. I’ve been working on reducing my own inflammation to improve my own mental performance over the past year, and I’ve noticed tremendous differences. Here are a few simple nutrition tips that you can use to reduce inflammation, thus improving your own overall mental performance!
Support gut health: in last week’s blog we discussed some ways to decrease your risk of intestinal permeability, which will help to reduce your inflammation. Adding things like fermented food with probiotics (think: yogurt, Kefir, Tempeh, sauerkraut, etc.) and fiber (vegetables, berries, nuts and seeds) to your diet will help to feed your beneficial gut bacteria the nutrients they need to stay strong!
Increase intake of antioxidants: as we discussed, oxidative stress can drive inflammation. What helps to reduce the risk of oxidative stress? Well, antioxidants (sometimes the English language makes sense…sometimes). Antioxidants are found in foods such as berries (buy organic when possible!), dark chocolate, Extra Virgin Olive Oil, green tea (again, buy organic when possible), nuts and seeds, and dark leafy greens.
Reduce intake of inflammatory foods: certain foods are known to cause inflammation in the body, such as the typical Western style diet of processed foods, fried foods, red and processed meats, sugars, and certain oils (see my Brain Boosting Shopping Guide for more information about oils to avoid).
Chronic inflammation has severe consequences to our health and our brain power. Cooling off inflammation will not only help you to feel better and reduce your risk of disease, but it will also help you to think more clearly, learn, remember, and focus more easily, and may even lower your risk of obesity. The impact that inflammation has on our cognitive processes is what makes it one of my 5 Pillars of Brain Power**. If you want help optimizing your nutrition to reach your brain potential, click here to schedule your free 30 minute initial consultation with me. Together, we’ll help you reach your peak.
References
Attuquayefio T, Stevenson RJ, Oaten MJ, Francis HM (2017) A four-day Western-style dietary intervention causes reductions in hippocampal-dependent learning and memory and interoceptive sensitivity. PLoS ONE 12(2): e0172645. https://doi.org/10.1371/journal.pone.0172645
Balter, L. J., Bosch, J. A., Aldred, S., Drayson, M. T., Veldhuijzen Van Zanten, J. J., Higgs, S., Raymond, J. E., & Mazaheri, A. (2019). Selective effects of acute low-grade inflammation on human visual attention. NeuroImage, 202, 116098. https://doi.org/10.1016/j.neuroimage.2019.116098
Beilharz, J., Maniam, J., & Morris, M. (2015). Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions. Nutrients, 7(8), 6719–6738. https://doi.org/10.3390/nu7085307
Cenit, M. C., Sanz, Y., & Codoñer-Franch, P. (2017). Influence of gut microbiota on neuropsychiatric disorders. World Journal of Gastroenterology, 23(30), 5486. https://doi.org/10.3748/wjg.v23.i30.5486
Edwards, L. M., Murray, A. J., Holloway, C. J., Carter, E. E., Kemp, G. J., Codreanu, I., Brooker, H., Tyler, D. J., Robbins, P. A., & Clarke, K. (2011). Short-term consumption of a high-fat diet impairs whole-body efficiency and cognitive function in sedentary men. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 25(3), 1088–1096. https://doi.org/10.1096/fj.10-171983
Effendy, E. (2018). Exploring the link between inflammation and mental disorders. IOP Conference Series: Earth and Environmental Science, 125, 012187. https://doi.org/10.1088/1755-1315/125/1/012187
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Francis, H. M., & Stevenson, R. J. (2011). Higher reported saturated fat and refined sugar intake is associated with reduced hippocampal-dependent memory and sensitivity to interoceptive signals. Behavioral neuroscience, 125(6), 943–955. https://doi.org/10.1037/a0025998
Holloway, C. J., Cochlin, L. E., Emmanuel, Y., Murray, A., Codreanu, I., Edwards, L. M., Szmigielski, C., Tyler, D. J., Knight, N. S., Saxby, B. K., Lambert, B., Thompson, C., Neubauer, S., & Clarke, K. (2011). A high-fat diet impairs cardiac high-energy phosphate metabolism and cognitive function in healthy human subjects. The American journal of clinical nutrition, 93(4), 748–755. https://doi.org/10.3945/ajcn.110.002758
Hussain, T., Tan, B., Yin, Y., Blachier, F., Tossou, M. C. B., & Rahu, N. (2016). Oxidative Stress and Inflammation: What Polyphenols Can Do for Us? Oxidative Medicine and Cellular Longevity, 2016, 1–9. https://doi.org/10.1155/2016/7432797
Leigh, S. J., & Morris, M. J. (2020). Diet, inflammation and the gut microbiome: Mechanisms for obesity-associated cognitive impairment. Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease, 1866(6), 165767. https://doi.org/10.1016/j.bbadis.2020.165767
Marsland, A. L., Gianaros, P. J., Kuan, D. C. H., Sheu, L. K., Krajina, K., & Manuck, S. B. (2015). Brain morphology links systemic inflammation to cognitive function in midlife adults. Brain, Behavior, and Immunity, 48, 195–204. https://doi.org/10.1016/j.bbi.2015.03.015
Oriach, C. S., Robertson, R. C., Stanton, C., Cryan, J. F., & Dinan, T. G. (2016). Food for thought: The role of nutrition in the microbiota-gut–brain axis. Clinical Nutrition Experimental, 6, 25–38. https://doi.org/10.1016/j.yclnex.2016.01.003
Pahwa, R., Goyal, A., Bansal, P., & Jialal, I. (2021). Chronic Inflammation. StatPearls Publishing.