In honor of Mental Health Day on October 10th, this weeks post will discuss the impact one’s microbiome can have on mental health.
Nearly one in five adults (18 years or older) live with a mental illness in the U.S (SAMHSA, 2019). Moreover, the WHO ranks depression as the leading cause of disability worldwide with suicide positioned as number two in leading causes of death for individuals aged 10-34 (NIMH, 2021). A variety of social, psychological, and biological factors contribute to ones overall mental mental health. In the last decade, an emerging body of research has been alluding to ones microbiome (namely the gut’s microbiome) as another influential factor; otherwise known as the brain-gut axis (Sandhu et al.,2017).
The gut-brain axis consists of a bidirectional communicative pathway between the brain and the gut, mediating neural, endocrine, immunological and metabolic signaling. Many of the microorganisms that reside within the gut’s microbiome synthesize metabolites, hormones, and neurotransmitters that play apart of a variety of cognitive functions (see table below for specifics). Upon dysbiosis (defined as the imbalance of the microbiome’s composition), a handful of diseases can come about including irritable bowl syndrome, diabetes, obesity and central nervous system disorders (Gao et al., 2020). In prior posts I have discussed in depth of how one’s microbiome composition is heavily influenced by ones diet (POST) amongst other factors including genetics and medication, particularly antibiotics (POST). In summary, diets high in energy-dense, processed, sugar and saturated fat content (characterized as the Western Diet) encourage dysbiosis as it minimizes growth of beneficial bacteria such as Bifidobacteria and Lactobacillus sp. and their respective metabolite and neurotransmitter production whilst encouraging inflammatory inducing pathogenic species such as those belonging to the Enterobacteriaceae family. Thus, it is no mere coincidence that lower levels of Bifidobacteria and Lactobacillus sp. are seen in individuals suffering from depression (Sandhu et al.,2017). Moreover, research has shown administration of Lactobacillus strains as supplements have actually decreased depression and anxiety symptoms thereby adding conformational evidence to their funtions in the body (Bravo et al., 2011). Such goes to show that the food we choose to eat dictates the species composition within one’s microbiome as it not only feed ourselves but the 1014 of microorganisms within.
With this in mind, the diet industry has pushed forth use of artificial sweeteners (AS) as a “healthy” alternative to reduce chronic conditions such as obesity and diabetes. Examples of AS include sucralose, aspartame, neotame, monk fruit extract, and sterviol glycosides. AS mimic the sweetness of sugar in a more concentrated, low/non-caloric form, enabling lower quantities to be used. Yet, what they fail to mention is how such sweeteners directly also interact with gut microbiota as they cannot be metabolized and further disrupt its composition (primarily a reduction in beneficial species). Studies using rodent models report how AS contribute to glucose intolerances and increased appetite stimulation leading to greater food intake, weight gain, and alterations in blood glucose. The studies saw these effects even at FDA approved quantities (Abou-Donia et al., 2008, Cabral et al., 2018, Martinez-Carrillo et al., 2019). The species of the bacteria that are less sensitive to AS are often gram negative bacteria that which carry endotoxins (LPS) on their outer membrane. At systemic high levels, studies have shown their inducing inflammatory effects that which result in depression like symptoms including reduced social behavior, lack of appetite, poor memory, and decreased motor activity along with anxiety (Dantzer et al.,2008, Sandhu et al.,2017 ).
I encourage you to look on ingredient lists of food products in your own pantry or even at the grocery store and you may be surprised the frequency such AS are used. Two foods that I instantly came across was my mom’s favorite Light & Fit yogurt and an untouched box of Quaker oatmeal that likely has been sitting in my pantry for months, both containing sucralose.
Photo credits: https://www.realmomnutrition.com/products-with-artificial-sweeteners/, https://www.runnershighnutrition.com/
Furthermore, a Nature article published a study demonstrating correlational data between lifestyle factors and the composition of ones microbiome (specifically at the ratio between Firmicutes to Bacteriodetes, two major phylums of bacteria that make up ones microbiome in the gut). Ideally, a respective ratio of about 15% to 80% between Firmicutes to Bacteriodetes represents a healthy heterogeneity amongst one’s gut microbiota. Shockingly, of the study’s 3,400 participants, Firmicutes abundance ranged from about 6% to 100% and Bacteriodetes abundance ranged from about 0% to 90%. Those with lower levels of Bacteriodetes and higher levels of Firmicutes concurrently had a smaller diversity within their gut’s microbiota flora. When comparing diversity with lifestyle factors, consumption of raw vegetables throughout the week and vigorous activity were associated with greater variance in microbiota. On the other hand, their data showed a negative correlation with diversity within one’s microbiome with activities such frequent consumption of ice cream, potatoes, rice, pasta, and sedentary behavior (2020). Thus, the study demonstrates that in by partaking in physical activity throughout the week, whilst implementing a variety of healthy greens into their diet will benefit one’s microbiome diversity greatly. In by doing so, one can lesson their risk for chronic conditions that ails both their physical and mental health.
If you are going to take anything from this post take this: Food feeds the mind and the body. Taking shortcuts by substituting artificial sweeteners is not the answer as it has been shown to exasperate the very problems one is trying to address. And if you are in need of an inspirational role model just turn to the one only, Popeye!
A MicroByte 