It may be easy for a patient to understand that an unhealthy diet negatively impacts their health and can lead to outcomes such as gastrointestinal dysfunction, metabolic syndrome, cardiovascular disease, and obesity. However, its less likely for patients to associate their mood, cognition, and neurological function to the food they eat. Perhaps, part of this is due to lack of awareness of the body or the disconnected relationship to food altogether. Unfortunately, this disconnection is only made worse by our culture's tendency to rush through meals and eat on the go. In fact, Americans spend the LEAST amount of time eating and drinking compared to other developed countries.
This brings me to a quote by Thích Nhất Hạnh, "Haste is a form of violence."
You might be wondering, how does this quote relate to food & mood? Well, when we hurry, we mindlessly speed through the present moment. Violence is intentionally or unintentionally causing harm. When we eat quickly, without care or concern for the food we are ingesting, it's possible that we are harming our body by feeding it with food devoid of nutrients and without even noticing the reaction our body has to that food! Slowing down and truly tasting the food on our plate, can help us digest and assimilate properly and notice the body's response to individual foods.
Now, back to the biology. Gut dysbiosis (or imbalance of bacteria in your gastrointestinal tract) and inflammation, commonly attributed to a diet filled with processed, sugary, and refined foods, may directly influence brain function and behavior by disrupting the bidirectional gut-brain axis. Gut function is almost entirely influenced by the nervous system, including the vagal and spinal afferents, sympathetic and parasympathetic efferents, and the ENS (deemed the gut’s brain)—all this is to say, a dysfunctional gut impairs our brain function (Daulatzai, 2014). Since the gut microbiota modulates excitatory and inhibitory neurotransmitters such as serotonin, an altered pathogenic microbiota can directly effect the production and release of these neurotransmitters. For example, 95% of serotonin production occurs in the intestines; however, with stress and increased intestinal permeability, a patient may begin to produce less serotonin because of systemic inflammation. This was made clear in athletes subjected to chronic exercise stress, ultimately impacting their gut and brain (Clark & Mach, 2016).
Other factors besides diet also play a role in decreased serotonin synthesis, one being continuous exercise-induced stress as seen in athletes. This gut-brain axis dysfunction provoked by gastrointestinal inflammation and altered microbiota may possibly explain depression or loss of motivation in athletes.
The takeaway from this post is this: Patients may not be aware of the "mind-body" connection or how food affects their mood. Creating more awareness around food and its effect on mood is important. The gut plays a major role in the formation of neurotransmitters and neurotransmitter transmission; thus, eating a healthy diet and maintaining a healthy gut lining is crucial to proper psychological functioning.
References:
Clark, A., & Mach, N. (2016). Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes. Journal Of The International Society Of Sports Nutrition, 131-21
Daulatzai, M. A. (2014). Chronic functional bowel syndrome enhances gut-brain axis dysfunction, neuroinflammation, cognitive impairment, and vulnerability to dementia. Neurochemical Research, 39(4), 624-644. doi:10.1007/s11064-014-1266-6