Would you be surprised to learn that more than half of your body isn’t human? According to Germany’s Max Plank Institutes, only 43% of the body consists of human cells. The remainder is a community of microbial settlers known as the microbiome.
You’ve probably heard the phrase “all disease begins in the gut.” Microbes reside all over your body but those dwelling in your gut — your esophagus, stomach and intestines —rule the roost in determining your health. The state of your microbiome can be linked to a wide variety of conditions, from obesity and diabetes to autism and even depression.
What Determines a Healthy Gut?
Your body hosts trillions of different microbes, both helpful and pathogenic. To keep your system humming you need to restrain the bad guys and support the good guys. Studies haven’t identified ideal combinations of “good” and “bad” bacteria but they have concluded that it’s better to have many different species, with a majority of beneficial types.
Why Does Gut Health Matter?
When “bad” bacteria run the show, a disease state is likely lurking. Planting beneficial bacteria provides a potential fix. Fecal microbiota transplants are a fairly dramatic treatment, which has been used for conditions like recurrent infections, obesity, autism and ulcerative colitis.
Most researchers have been adopting a more tempered approach. About 15 years ago, microbiologist Liping Zhao conducted an experiment on his overweight self. For two years he consumed a diet of fermented foods and whole grains. Not only did he lose 45 pounds, his blood pressure, heart rate and cholesterol declined to healthy levels. He thanks his fiber-rich diet, which accelerated the growth of beneficial gut bacteria.
Diet Improves Gut Health
Numerous factors like your genome and lifestyle influence the kinds of bacteria that reside in your gut. A healthy diet is a proven strategy for improving your microbiome. Numerous edibles, including omega-3 fatty acids and fermented foods help to build diversity. But for bulking up the ratio of “good guy” bacteria, plant foods win first prize.
Plant Foods are All-Stars
Over the years, the American Gut Project has collected many thousands of samples from people around the world. Their conclusion: Consuming 30 different plant-based foods every week is the surest way to encourage bacterial diversity. This figure aligns with long-standing healthy eating guidelines recommending “5 a day,” advice confirmed in a 2021 study published in Circulation. It linked increased longevity (and lower risk of cancer, respiratory disease and cardiovascular disease) with consuming 3 servings of vegetables and 2 servings of fruit every day.
After decades of research, one consistent message is emerging: What’s good for your health is good for your gut and vice-versa. Your gut is central to a continuous feedback loop linking many different bodily processes.
Why Plant Foods
Plant foods are rich in microbiota-accessible carbohydrates (MACs), the technical term for substances that include fiber, oligosaccharides (also provided by human breast milk), and some phytochemicals. Studies show that a MAC-rich diet supports microbial health and can reshape a sickly microbiota.
Fiber Leads the Way
Fiber is by far the most prevalent MAC. Studies show that the more fiber you consume, the more robust your microbiome because fiber-rich foods like whole grains and legumes feed the beneficial bacteria in your gut. Humans don’t digest fiber. It reaches your large intestine intact, providing a nourishing meal for your microbial friends, encouraging them to flourish, reproducing and expanding their territory. This helps to keep you healthy.
It’s More Than Fiber
Other components of plant foods also promote wellbeing. These include phytonutrients, chemicals produced by plants. One of these substances, polyphenols, is emerging as a major player in microbial health.
Although polyphenols are potent antioxidants, your body usually doesn’t make good use of them. Now we’re learning that your microbiota may be involved. Without an adequate stockpile of certain types of bacteria your body will be challenged to extract the beneficial compounds polyphenols provide.
Increasing your consumption of polyphenol-rich foods like fruits, vegetables, nuts, seeds herbs and spices, encourages “good-guy” intensification while creating a hostile environment for the “bad-guys.” Researchers are currently exploring the possibility that these improvements may also boost the antioxidant benefits of consuming polyphenols.
Beneficial Bacteria Keep You Well
Beneficial bacteria also support wellness by generating health-promoting substances. These include vitamins like folate, B12 and vitamin K2. In addition, they produce short-chain fatty acids, substances with numerous health benefits like regulating your metabolism, supporting your immune system and fighting inflammation.
Additionally, good bacteria keep the mucous layer of your intestinal lining strong. You’ve probably heard of “leaky gut,” a condition linked with inflammation, food sensitivities and numerous autoimmune diseases. Intestinal permeability develops when the walls of your gut spring leaks, allowing substances like toxins and unhealthy bacteria to escape into your bloodstream. We don’t know what causes junctions to loosen but we do know that certain types of friendly bacteria feast on parts of your intestinal lining, producing substances that help to strengthen its’ barrier. That means that instead of creeping into your bloodstream, potential pathogens are properly excreted.
These days you can find a link between the microbiome and most diseases. So it’s worth remembering that the term microbiome didn’t enter public consciousness until 2001 when Nobel-prize-winning microbiologist Joshua Lederberg mentioned it in an article. Since then, more and more research is showing that we — and our health — are not self-sufficient entities. We are part of a community. Supporting our microbial friends by eating a plant-focused diet is one way to keep this complex ecosystem humming.
Judith Finlayson is the author of You Are What Your Grandparents Ate: What You Need to Know About Nutrition, Experience, Epigenetics, and the Origins of Chronic Disease. Visit her at www.judithfinlayson.com.
Wen, Li et al. Factors Influencing the Gut Microbiota, Inflammation and Type 2 diabetes. The Journal of Nutrition 2017.
Wang, Dong D. et al. Fruit and Vegetable Intake and Mortality: Results from 2 Prospective Cohort Studies and US men and Women and a Meta-Analysis of 26 cohort Studies. Circulation 2021.
Menni, C. et al. Omega-3 fatty acids correlate with gut microbiome diversity and production of N-arbamylglutamate in middle aged and elderly women. Scientific Reports 2017
Anhe, F. et al. Triggering Akkermansia with dietary polyphenols: A new weapon to combat the metabolic syndrome? Gut microbes 2016.