The Western Diet = Undiversified and Unhealthy Human Microbiome
Consider this: Many see themselves as a singular organism. Unless they are pregnant, most will sit down for dinner and think, “this is a nice dinner for one”, however; this is far from the truth. In reality, humans are hosts to trillions of bacteria, fungi, viruses and parasites which feed off the food we consume. The bacteria typically coexist peacefully to make up our Human Microbiome, or gut flora, and there are far more of them than there are human cells in our body. “There are approximately 10 times as many microorganisms within the gastro-intestinal tract of humans (approximately 100 trillion) as there are somatic cells within the body” (Bird and Conlon). That’s right: our human cells are outnumbered ten to one by these microscopic bacteria. With this knowledge, we can conclude that the human host has a direct relationship with the trillions of tiny living organisms staking out in the body and ultimately how we feed them determines their ability to function properly. Due to the high consumption of processed foods, carbohydrates, meat and sugar with a low intake of fiber, the standard western diet of the American people has negatively affected the gut flora of everyone consuming it and as a result the microbiome is now undiversified and unhealthy.
This complex ecosystem of bacteria is unique to each individual, meaning that no two microbiomes are the same. These tiny organisms can be found living throughout the body in places such as the skin, uterus, lungs, placenta, mouth and stomach, to name a few. The microbes living in different areas of the body have unique duties to maintain which keep their human host healthy. For example, the largest cluster of microbes can be found inside the digestive tract, which is also known as the gut flora. These specific microbes have the important role of keeping the metabolism functioning properly and maintaining homeostasis throughout the body. Being that the stomach is widely considered the second brain, the job of the gastrointestinal microbiome is very vital to our health and happiness. The high-profile job of the human microbiome is a two way street, as it is also our responsibility as the host, to play a part in providing these bacteria with the optimal nutrition from the foods we eat to create a suitable environment so they can do their job of keeping us healthy. Equipped with this knowledge, wouldn’t it be best that we only consume foods that help our good microbes flourish? After all, they do so much for our health that it is only right we do something for them in return. This is not the case in America.
It doesn’t take Christopher Columbus to discover America has a toxic and scandalous relationship with high processed and fast foods. One quick drive into any local town, in all 50 states, will reveal several fast food restaurants or dessert shops within a mile from one another. People and children around the entire nation are addicted to sugar which you can find hidden insidiously in almost every food group from salad dressings, canned goods, bread, all the way to candy and restaurant meals. America is known for quick convenience, big portions, cheap costs and delicious taste. Although it may be cheap, what is the real cost of this type of diet? You would think that health is a top priority, but we are only human and lets be honest, the food is just too good to turn down. Why would you choose a celery stick over a juicy cheeseburger? A salad over pizza and wings? What about local veggies over pasta and bread? That answer is perfectly clear: it is hard to make these tough decisions.
So, what really happens if we fail to play our role in sustaining a healthy diet for our microbes? If our gut bacteria does not receive the quality of food that is necessary for them to thrive, it starts a war in the lining of our stomach. This war is similar to the ever-familiar spiritual war on human life. It’s the battle of good and bad. “The microbiome consists of microbes that are both helpful and potentially harmful. Most are symbiotic (where both the human body and microbiota benefit) and some, in smaller numbers, are pathogenic (promoting disease) (“The Microbiome” 2019). That’s right, there is a diversity of good microbes and bad microbes that coexist in unison inside every one of us. The good microbes help to enable our health and prosperity and the bad ones aim to burn our health to the ground with diseases and chronic inflammation. Like many of us, there is also a third type of microbe that is neutral and can be persuaded by a sort of “peer pressure” from the bad microbes, which can lead them to the disease-promoting side rather quickly if the host consumes a bad diet. It is optimal to maintain a healthy diversity of good and bad microbes so that there is balance in the body. The only control we have in the war of good versus bad microbes is the human diet, which is responsible for feeding the good bacteria, wiping out the bad and keeping all the bacteria diversified. Researchers from the University of Harvard have spent decades observing the microbiome only to concluded that “diet plays a large role in determining what kinds of microbiota live in the colon (“The Microbiome”). In other words, if we don’t have control over our diets, our diets can very easily have control over us.
To lay the groundwork for this argument, it is important to understand exactly what Americans are consuming before assessing the damage. According to Judith Thalheimer, a Registered Dietitian specializing in community education and author of the article “Undoing the Unhealthful Western Diet: The Typical American Diet May Be Hazardous to Your Health” suggests that:
“Most Americans eat lots of refined grains (like white bread, pasta, cakes, and cookies), red and processed meats, fried foods, sweets, and high-fat dairy products (like ice cream and cheese). On the whole, we drink too many sugar-sweetened beverages, and don’t choose enough fruits, vegetables, fish, whole grains, nuts, seeds, or legumes (beans and lentils).”
We have been conditioned to think choosing food for pleasure over purpose has no consequences, but with technology advancing and knowledge expanding at rapid rates, we are discovering that we may have been misguided all along. While the food is tasty and satisfying, western-style diets are on average, considerably low in fiber, beneficial nutrients like prebiotics, probiotics, dark leafy greens, healthy fats, unprocessed meat, vitamins, minerals, and microbiota-accessible carbohydrates (MACs) which allow the good microbes to live abundantly. At the same time, there is a surplus of industrialized and processed foods containing alarmingly high amounts of sodium, added sugar and saturated fats which feed the bad guys. This combination leads to a very undiversified bacteria profile in our stomach. Due to the lack of diversity, the bad microbes multiply and coerice us into craving the unhealthy foods which allow them to flourish and inturn, we eat more, gain weight, and increase our chances of illness.
Gratefully, there are researchers out there who dedicate their lives to discovering which foods are good for us and which are bad by studying our gut flora. Unfortunately, the western diet has been proven to cause more harm than we were once aware of. In order to study the microbiome, researchers conduct in-depth comparison studies using humans, mice or rats as test subjects. They take fecal samples from the test subjects to get an in depth observation of which bacteria lurk in our system. These studies are effective in determining how the western diet affects the quality of the bacteria in the microbiome, and can help determine how certain diets cause symptoms like obesity.
According to The International Journal of Obesity “obesity prevalence has increased worldwide at an alarming rate, primarily due to reduced physical activity and Westernization of dietary habits” (Bortolin et al.). This journal also concludes that one of the standard archetypes of people in the USA are the 70% of overweight adults according to the National Health and Nutrition Examination Survey. One group of researchers in China have affiliations with the Department of Biochemistry, and the Department of Education in Saúde, sought to confirm that the western diet causes obesity. They conducted a comparative study using a diet-induced obesity model (DIO). They designed a prototype of the Western Diet (WD) which were pellets with high-fat, high-sugar and high-salt with low-fiber and compared it to two other DIO models. The two in comparison were a high-fat diet (HFD) which used various fat sources in different proportions and a cafeteria diet (CAF), which included highly palatable energy-dense foods like cheese, salami, cakes, and cookies. The CAF diet was intended to mimic a different style of western diet that contained substantial amounts of salt, sugar and fat while also including processed foods. The study was conducted on ten week old rats where three groups were assigned different DIO models for 18 weeks. At the end of the study period, the rats fecal samples were taken and the results gave insights on the different diets effects on the microbes. By observing the different study groups excitement for their food, they concluded that the western diet and the cafeteria diet prototypes were the most palatable. It is reasonable to think that the most palatable diets tend to lead to overconsumption because the foods are very delicious and addicting. These types of foods mimicked the western diet of cheeseburgers, fries, milkshakes, pizza, hot dogs and sugary drinks. Overall, the western diet most effectively promoted obesity because it was palatable and the rats developed more fat due to the desire to consume more. From this they discovered “excessive fat accumulation is a hallmark of obesity” (Bortolin et al.). This test is useful because humans and rodents digest foods in a similar fashion.
Obesity isn’t the only concern revolving around the western diet. “Diabetes is one of the fastest-growing diseases in the United States and currently affects about 26 million Americans. Another 67 million Americans are estimated to have prediabetes, of which 60 million are unaware that they have the condition” (How Common Is). It is very common in America to have, or to know someone that has diabetes. This study also confirmed that the WD promoted a pre-diabetic condition. The insulin levels and insulin resistance were three times higher in WD-fed rats than in rats fed other diets. This data shows that the WD also led to a greater impairment in glucose homeostasis than the other diets, meaning that sugar levels were all over the place. Lastly, they noted changes in the type of bacteria living in the gut flora of the WD-fed rats. They discovered an abundance of 4 types of bacteria thriving in the WD-fed rats which are considered to be the best friend of obesity.
If you take a look down every single aisle of your local grocery store outside of the meat and produce sections, you can easily tell that highly processed foods go above and beyond being readily available to the public. Your local food store will showcase dozens of aisles dedicated to chips, cookies, crackers, ice cream, carbohydrates, and candy, while the produce aisle is limited to one small section. We are so desensitized to processed food that it is actually uncommon to visit the produce aisle alone and leave, because if it were common, our guts would have a wide range of diversity from the fresh fruit and vegetables, instead we have quite the opposite.
We can learn a lot about what the microbiome likes by observing the way people eat and their health as a direct result. Profoundly enough, some researchers suggest the paleo diet is the key to restoring our gut bacteria. A 2019 study composed by researchers who affiliate with the Unit of Microbial Ecology of Health in Italy aimed to understand the specifics of the human microbiome makeup based on certain dietary patterns. Their approach was effective as they evaluated extensive meta-analyses of human microbiomes of 15 Italian subjects following a modern paleolithic diet (MPD) where there is high intake of fish, vegetables, fruits, lean meat, nuts, seeds and eggs with no consumption of dairy, grains, refined sugar or salt. Their observative research approach led to the discovery that “increasing the consumption of MACs . . . and minimizing the intake of processed foods . . . could be the key to rewild the Western microbiota, counteracting the loss of GM diversity and thus restoring evolutionarily important functionality to our gut” (Barone). This shrinkage of GM diversity of western cultures depict a “maladaptive microbiome state which may contribute to the rising incidence of chronic non-communicable diseases, such as obesity, diabetes, asthma and inflammatory bowel disease” (Barone et al.).
An article titled “Gut Feeling for Diversity” written by Leslie Beck goes into detail on the specific foods which help the microbiome flourish. A study included in this article conducted in the journal Cell Host & Microbe that concluded that “compared with people who ate a typical American diet, those who followed a lower-calorie, mostly plant-based diet had a far more diverse microbial community in their gut” (Beck). Beck suggests to consume more beans, nuts, raw oats, chickpeas and unripe bananas in order to feed a healthy gut diversity. With that being said, how many times do people in American pull up to the drive thru window and order oats or nuts?
It is because of this that Americans lack diversity in their gut flora. One of the biggest drivers of various illnesses such as obesity, crohn’s disease, atherosclerosis and diabetes, is the lack of diversity in the microbiome. In the study conducted with the DIO model, they also found that gut microbial diversity was drastically decreased in CAF-fed rats, a diet with a western-style influence plus processed foods, suggesting a “microbial community dysbiosis, which is a disruption of gut microbiota composition that is known to participate in the pathogenesis of diverse diseases, including obesity, type 1 diabetes and autism” (Bortolin et al.). The overwhelming rates of these illnesses in America is a direct result in their choice of diet. People often come into the United States with a perfectly normal microbiota and find that their bacteria gets quickly disrupted after only a few weeks of consuming the delicious, high-carbohydrate diet of the American people.
There are more ways to determine how diet impacts the gut by doing actual studies on people, which is what Ed Wong, a scientific journalist, Michael Nuenlist from the Institute of Digestive Disease and Tim Spector, an author and Professor of Genetic Epidemiology did. They are a few of the people who have dedicated their lives studying and observing the microbiota in the body. Together they composed a 2016 documentary titled “It Takes Guts” that revealed a lot of information on scientific studies comparing the microbes in the western populations to those of some of the oldest tribes in the world. In one segment, Tim Spector wanted to see exactly what the Western Diet would do to the microbiome after 10 days of heavy fast-food consumption. He decided to let his son eat burgers and fries for every single meal with the occasional order of chicken nuggets for ten days straight. After this study, he got his results by taking a fecal sample from his son and the results were were than he hypothesized. After just 10 days, the diversity of his sons microbiome plummeted. The fast food consumption wiped out 3,500 of his 6,000 microbiomes and it took two weeks of an intense high-fiber diet to put his gut back on track. Tim Speculates that Americnas aren’t getting enough fiber in their diets and as a result, their diversity in their stomach bacteria is lacking. These types of studies are crucial to understanding how microbes develop and operate in the stomach and to understand which bacteria emerge from which dietary patterns.
In contrast, diet is not the only determining factor in the development of our gut flora. According to and article titled Gut Microbiome Response to a Modern Paleolithic Diet in a Western Lifestyle Context “The reduction of biodiversity have occurred at multiple stages along the recent transition to modern urban societies, and several aspects typical of the urbanization process-such as sanitation, antibiotics, C-section and Western diet-have been pointed out as contributing factors” (Barone et al.). One of the most influential ways to get beneficial bacteria happens at birth. Babies who are born vaginally get their first colony of microbes from the mothers vaginal wall after coming out of a completely sterile environment also known as the womb. This sets the foundation of the newborns health, as these first-contact microbes play a huge part in a well-developed immune system of the infant. After birth, the babies build on to their microbiome by being breastfed, as the milk transfers necessary beneficial bacteria from the mothers microbiome to the babies. There has been a change in the last 10 years in birthing and feeding practices which has had a huge effect on gut health. Women are now getting more cesarean sections and formula feeding and in doing so, the babies are not being exposed to the necessary beneficial bacteria as the babies before them. This is where diet comes into play. Since the odds are against most of us at birth, it is as important as ever to feed our guts with the foods it needs to colonize itself with the proper bacteria, but we are learning that America has failed this quest miserably.
People always say that diets are hard, and that is certainly true because in America we are surrounded by foods that bring us pleasure before they bring us health. Due to the fact that no two microbiomes are alike, it can be hard to conclude that one diet works for all because the complexity of the microbiome function makes for very difficult research. Nonetheless, the help from several professional researchers, we now understand more about these tiny microbes than ever before. With this knowledge we can take measures of adjusting our diets and changing the food system in America so that ourselves and our microbes thrive. While there is still much to learn, it is safe to conclude that our diets can help us manage which type of bacteria grow and flourish as a result and it is one hundred percent our personal responsibility to make the right dietary decisions for our health even though we are tempted to do otherwise. We have become a very ill nation and the time is now to reevaluate our food system and give ourselves the chance to make America healthy again.
Bortolin, R C, et al. “A New Animal Diet Based on Human Western Diet is a Robust Diet-Induced Obesity Model: Comparison to High-Fat and Cafeteria Diets in Terms of Metabolic and Gut Microbiota Disruption.” International Journal of Obesity, vol. 42, no. 3, 2018, p. 525.
“The Microbiome.” The Nutrition Source, 4 Sept. 2019, https://www.hsph.harvard.edu/nutritionsource/microbiome/.
Barone, Monica, et al. “Gut Microbiome Response to a Modern Paleolithic Diet in a Western Lifestyle Context .” PLoS ONE, vol. 14, no. 8, 2019, p. e0220619. Gale Health and Wellness, https://link.gale.com/apps/doc/A595927386/HWRC?u=pcc&sid=HWRC&xid=ce83dda6. Accessed 8 Nov. 2019.
“How Common Is Type 2 Diabetes?: Diabetes Type 2.” Sharecare, https://www.sharecare.com/health/type-2-diabetes/how-common-type-2-diabetes.
Conlon, Michael A, and Anthony R Bird. “The Impact of Diet and Lifestyle on Gut Microbiota and Human Health.” Nutrients, MDPI, 24 Dec. 2014,
Eisen, Leora, director. It Takes Guts. Syndicado, 2016.
Thalheimer, Judith C. “Undoing the Unhealthful Western Diet: The Typical American Diet May Be Hazardous to Your Health. EN Explores Which Dietary Changes Can Have the Biggest Positive Impact.” Environmental Nutrition, vol. 41, no. 5, May 2018, p. 7. EBSCOhost, search.ebscohost.com/login.aspx?direct=true&db=hxh&AN=128955370&site=ehost-live.