In the summer of 2008, a 26-year-old man from Shanxi Province walked into a lab at Shanghai Jiao Tong University, and 23 weeks later walked out 113 pounds lighter. He had not participated in a clinical trial of some new secret weight loss pill, or signed up for a punishing Biggest Loser-style exercise program, nor had he been fussed over by behavioral scientists who made his plates and drinking cups smaller with each passing week. The researchers, who were microbiologists, had simply put the man’s gut microbes on a diet.
One of the huge mysteries in studies of diet and exercise is the difference between people who get the same treatment but have remarkably different outcomes. Inevitably, some people in a study show little improvement despite weeks or even months of following what might seem like draconian changes in their normal diet and lifestyle. Other people apparently drop weight just by getting out of bed in the morning, and also improve their circulating triglycerides, total cholesterol, and biomarkers of inflammation with apparent ease. We all know someone like this in our daily life.
But why are there such extreme differences between people?
Is our DNA to blame? Our human genes may be involved in some cases but we generally share more than 99% genetic similarity with other people; more interestingly, the huge differences in peoples weight gain/loss may be driven more by the different bacteria in our intestines, which can be more than 90% different between one person and the next.
In addition to the familiar human genome that we inherit from our moms and dads, each of us also has hundreds of trillions of microbial symbionts, each with their own genomes. Research programs such as the Human Microbiome Project have revolutionized our understanding of our microbial bodies, which outnumber our human cells ten to one, and account for more than 2 pounds of our body weight. We know microbes can change profoundly in each of us throughout life, and that we can change them through diet, medications we take, hygiene, etc. We know that how we enter this world – C-section versus vaginal birth – can impact your initial “seeding” of microbes, which further change during breast- or formula-feeding, and what you eat later in life also affects your gut microbes and even how healthy you are as a senior citizen. We know that people in more traditional societies have different microbes than those in more Westernized populations, and that diet can play a role in these differences. You can also change the health prospects of a mouse overnight by changing its diet and thus its microbes.
Advances in bioinformatics (fancy word for data analysis) and refinements of DNA techniques – not too mention a significant increase in computing power – is changing everything. The evidence that life events and diet can shape our gut microbes is increasing, but which direction should we nudge them? What is a healthy or optimal mix of gut microbes? The honest answer is nobody knows (yet), but projects are underway – that you can participate in – to help us to better understand the role bacteria play in our health and lifestyle.
In the meantime, as you contemplate your New Years resolution to join the gym (again), lose weight, improve your diet, or to purchase the latest gizmo to track your every move, you might want to consider whether your microbes will support your decision. After all, they’re in control. Take that you anthrocentric ape!
Below are five suggestions on how you might improve the health of your gut microbes (and some other microbes in your life) in 2013.
No. 5. Antibiotics. It’s a familiar story by now: over zealous use of antibiotics are driving antibiotic resistance among microbes at an alarming rate. But it gets worse: the average child in the developed world will likely receive 10-20 courses of antibiotics before his or her 18th birthday. This, coupled with the low therapeutic doses in animal feed – and ipso fact our feed, may be shifting our gut microbes into an unhealthy state and possibly contributing to the metabolic disease of obesity. It’s also well documented that following a course of broad-spectrum antibiotics, it could take weeks, months or even years for your gut microbial community to bounce back – or at all. During this period of imbalance, opportunistic pathogens can set up shop. Or worse. While antibiotics are clearly needed in some (probably most) scenarios, ask more questions in 2013 before downing them without a care.
No. 4. Open a window. For 99.99% of human history the outside was always part of the inside, and at no moment during our day were we ever really separated from nature. Today, a National Activity Survey found that between enclosed buildings and vehicles, modern humans spend a whopping 90% of their lives indoors. Though keeping the outside out does have its advantages – protection from the elements and decreasing your chances of being eaten by a zombie – it has also changed the microbiome of our home. Studies show that maybe opening window and increasing natural airflow will improve the diversity and health of the microbes in your home, which in turn benefit the inhabitants. In the not-so-distant future, building codes will likely reflect the biological benefits of rewilding our living and workspaces. Never hurts to get a head start.
No. 3. Adopt an ecological perspective. In 2013 familiarize yourself with the writings of Aldo Leopold, John Muir, and other important and interesting – past and present – naturalists and ecologists. The human-microbial superorganism is a vast ecological system, subject to the same rules of resistance, resilience, and balance as any ecosystem on the planet. The sooner you learn to tend your microbial garden, the sooner you will understand how human ecology and your health is nothing more than understanding our history and place in the larger biosphere.
No. 2. Eat more plants. This is not a hard one. I don’t mean to give up meat, but I mean to eat a greater diversity and quantity of whole plants. This is the single most important (in my opinion) dietary strategy for improving the diversity and health of your gut microbiome. In short, your gut microbes thrive on a diversity of fermentable substrates (aka dietary fiber). But not all fiber is the same (physically or chemically), so consuming a diversity of whole plants will assure a steady flow of substrates for your resident microbes. And make 2013 the year you eat more of the whole plant, not just the soft and tasty parts. Consume the entire asparagus, not just the tip; consume the trunk of the broccoli, not just the crown; consume all of the greens at the top of the leek, not just the bulb. By doing so, you will guarantee that the harder-to-digest portions of the plant will extend the metabolic activity of your microbiome deep into your bowels. Also track how many species of plants you eat in a week – shoot for 30-40, or more.
No. 1. Get your hands dirty. More to the point: start a garden. Getting your hands dirty and covering more of your body (and food) with mother nature’s blanket will help you not only connect with the natural world we have tried so hard to remove ourselves, but will reacquaint your immune system with the trillions of microorganisms on the plants and in the soil. The loss of this interface with the terra firma of our evolutionary past – body to soil, body to nature – is where the wheels came off the wagon. As people of the world move from poverty to middle class, they also move from the gritty reality of our ancestral life to the promise of modern development and its triple-washed produce and squeaky-clean surroundings. Reconnecting with ecosystems, through gardening or some other ‘outside’ means, will allow you to understand and manage your inner-ecosystem. There is no better way.
*Joining the American Gut project might not be a bad idea either. Education and understanding does a body (and microbiome) good.