How are typical Western diets and lifestyles influencing people’s health? What is microbial diversity and what happens when it’s compromised?
Science journalist Ed Yong writes about the health implications of living a Western lifestyle in his book I Contain Multitudes, which debunks common myths about microbes and how they impact our lives. Yong argues that a typical Western diet is just one factor that leads to decreased microbial diversity.
Read on to learn about the health risks of following a typical Western diet and lifestyle, according to Yong.
The Consequences of a Typical Western Diet & Lifestyle
According to science journalist Ed Yong, typical Western diets and lifestyles are drastically changing the gut microbiomes of people living in wealthier, developed countries. In his book I Contain Multitudes, Yong cites other contributing factors like our lower exposure to microbes in our environment and the use of antibiotics. As a result of these factors, many species of microbes that were once ubiquitous in humans are going extinct, leading to a decrease in microbiome diversity. Although scientists don’t agree on the implications of this pattern, Yong suggests it may be responsible for the rise in inflammatory conditions (like allergies, asthma, and inflammatory bowel disease) in Western countries.
(Shortform note: This idea that being too clean is increasing the prevalence of inflammatory conditions in the West is called the “Hygiene Hypothesis.” Researchers have also made this observation in populations in high-income, urban areas within poorer countries. A contributing factor to this phenomenon is the fact that children today spend less time outside (and therefore encounter fewer microbes) than previous generations. Some groups are trying to reverse this trend by increasing access to outdoor learning at school and encouraging unstructured outdoor play.)
#1: Diets Alter the Microbiome
Yong claims that those who live in wealthier, developed countries tend to follow a typical Western diet, eating less fiber than people in less developed countries, and they also eat more processed foods. A plant-based diet (which is higher in fiber) requires more diverse microbes. Processed foods and saturated fats, on the other hand, nourish less diverse microbes, and Yong writes that these foods also tend to nourish inflammatory microbes—microbes that are associated with the immune system’s overactivity, in conditions like asthma and allergies. Chlorinated water, which kills microbes, is another potential contributing factor to our decreased microbial diversity.
(Shortform: Based on this idea that certain foods disrupt the balance of the microbiome, Gundry’s The Plant Paradox recommends eliminating the following foods from your diet: grains, legumes, corn, soybeans, whole grain foods and other saturated fats, sugars, and artificial sweeteners. He also recommends eating more leafy greens, vegetables, tubers, and omega-3 fats like fish oil and olive oil. Given the challenges of eliminating many common staple foods, others recommend simply eating non-processed foods.)
#2: Our Environments Alter the Microbiome
Aside from the typical Western diet, living a Western lifestyle can also compromise our microbiome, according to Yong. He suggests that people in wealthier countries are simply exposed to fewer microbes because they generally spend less time outside and less time around livestock. Yong points to research indicating that even having a dog or cat in the house helps bring in more diverse microbe species that suppress allergies in humans.
(Shortform note: Even among scientists who support the Hygiene Hypothesis, there’s a consensus that some types of bacteria and viruses can actually cause allergies and asthma. So while lifestyle is an important factor, especially during childhood, it also doesn’t explain all cases of inflammatory illness.)
#3: Antibiotics Impact the Microbiome
The third factor Yong describes is the use (or overuse, as he suggests) of antibiotics in Western nations. At the same time that the typical Western diet contributes to people eating food that nourishes less diverse microbes and exposing themselves to fewer wild microbes in the environment, they’re also killing the gut microbes they do have when they take antibiotics.
Like antibacterial cleaning products, antibiotics get rid of microbes indiscriminately. A downside of this is evident in Yong’s example of an intestinal infection called C. difficile (also known as C. diff). This bacterial infection is difficult to get rid of and often occurs as a result of taking antibiotics. (Shortform note: Since the book was published, the US Food and Drug Administration approved the first fecal microbiota therapy for recurring cases of C. diff. The drug is manufactured from human stool samples with microbes that restore balance to the gut microbiome.)
Similar to conflicting opinions on sanitizing our environment, Yong admits that there’s no consensus on how to balance the sometimes life-saving effects of antibiotics with their potentially detrimental effects on the microbiome.
(Shortform note: In addition to the impact of antibiotics on beneficial microbes, Gundry’s The Plant Paradox explains the health risks of ingesting antibiotics by eating meat. He writes that antibiotics in meat can make us resistant to similar antibiotics that we may need to treat diseases, and they also increase our fat storage by disrupting our microbiome.)
#4: Sanitized Environments Decrease Microbial Diversity
In addition to the microbial changes that a typical Western diet can cause, Yong also describes the ways that human hygiene habits alter microbial diversity indoors. Although modern sanitation practices have largely eliminated diseases like cholera and typhoid in wealthy countries, Yong explains that our tendency to sanitize things to get rid of germs has led to less diverse microbial communities. This occurs because anti-bacterial cleaning products kill all microbes, even if they’re harmless or beneficial.
Scientists don’t agree on the implications of this phenomenon. Some argue that the benefits of disinfection outweigh the downside of decreased microbial diversity, though Yong points out that there are some contexts where it’s clearly detrimental. For example, despite rigorous cleaning and constant disinfection of surfaces, 5-10% of people who are admitted to the hospital in the US get an infection during their stay. Furthermore, research shows that hospital rooms contain fewer pathogens if windows are open to allow outside air to flow in. Otherwise, the hospital is too sterile with no beneficial microbes to compete with pathogens.
|Environments Might Be Too Clean or Not Clean Enough|
The study discussed in this section was conducted in Oregon, and the same principle may not apply in other settings with more air pollution. For example, a three-year study in California showed almost 30,000 hospitalizations and ER visits as a result of air pollution. These cases included conditions like asthma and other cardiovascular and respiratory illnesses linked to high levels of particulate matter in the air and high ozone levels. More research is needed in diverse geographic locations and during different seasons to determine if the benefits of outdoor ventilation apply in other contexts.
In addition, Bill Bryson’s The Body points out that inadequate hand-washing in hospital settings leads to over a million infections every year. Therefore, we may be going overboard with sanitation in some ways while still needing improvement in other types of personal hygiene and environmental cleanliness.