By Paige Jarreau and Signe Asberg

Freedom of thought. Food and shelter for all. These are universal human rights. Should we add the right to healthy gut microbes to this list? A new PLOS Biology paper argues that access to healthy gut microbes, for example via access to fiber-rich fresh fruits and vegetables, should be a human right. This is based upon mounting evidence that our gut microbes are critical to our health and longevity. Learn more in this blog post about microbiome inequality and how it compounds income inequality, how you can feed your healthy gut microbes on a budget, and what we can do to make fresh foods more broadly accessible. Give to your local food bank today!

Many aspects of your life affect the types and diversity of microbes in your gut. Your early life conditions, current diet, stress levels, living environment and many other factors help determine the types of bacteria and other microbes that are living in your intestines. 

The collection of microbes living in a person’s gut is known as their microbiome. Each person’s microbiome looks a bit different – sometimes very different – than the next person’s. But in general, a more diverse collection of microbes in the gut is a signal of a healthier gut. A diverse collection of gut microbes protects a person against infection and inflammation. There are also certain species of gut bacteria that are known to have positive health benefits. These include species of bacteria that eat and thrive on plant fibers that we humans couldn’t otherwise digest.

Your gut contains a multitude of microbes.

“Daily, we encounter millions of particles of bacteria, fungi, and viruses, as well as archaea and protozoa, and trillions more live on and in our bodies.” – Sue Ishaq et al., 2019

Your gut microbes can impact your health in many ways. There are an increasing number of research studies that link the microbiome to metabolic health, inflammation, allergies, cognitive health, mental health and more. Your gut microbes might even impact how you age

While a healthy gut microbiome protects you from disease, a gut microbiome that is disturbed, lacks diversity or contains too many “bad” microbes and too few “good” ones may put you at risk for obesity, diabetes, anxiety, depression and brain aging. We know this from many animal studies and some human studies. Mice raised in a lab such that they don’t have any bacteria in their guts (called germ-free mice) have health, psychological and cognitive problems. These mice even make fewer important brain chemicals called neurotransmitters (like GABA and serotonin) that are important for brain cells to communicate with one another. This is because gut microbes help create many of these neurotransmitters, as well as many other chemicals and hormones important to health. 

Gut microbes actually produce chemicals that affect your brain.

However you look at it, a healthy gut microbiome is essential to your overall health and longevity. But how do you get a healthy gut microbiome? There are many factors that affect your gut microbiome or the number and types of microbes living in your gut. Some of these factors you don’t have any control over, such as how you were born (a vaginal birth provides a baby with a very different set of microbes than a cesarean birth does) and what types of microbes you are exposed to in your living environment. On the other hand, you most likely have control over other factors that affect your gut microbiome in important ways, particularly your diet

“Diet is the biggest driver of your gut microbiome, and the fiber content in your diet is a huge driver,” says Dr. Sue Ishaq, a microbiologist (a researcher who studies microbes) and an assistant professor at the University of Maine. “Out of all the gut-related information that you could possibly find on the internet, getting enough fiber is the one thing that is always correct in terms of your gut microbiome! This is well-established in the scientific literature. If you do nothing else, try to get good fiber and a variety of fibers, from grains but also from green leafy vegetables and other plants.”

For example, high fiber foods like whole grains, legumes (think beans and peas) and bananas feed Clostridium, Eubacterium and Butyrivibrio bacteria that in turn make an important short chain fatty acid called butyrate. Butyrate has been shown to protect the brain from injury and to help it learn and adapt to its environment. Butyrate created by fiber-munching bacteria may even change what genes are turned on and off in your brain, turning on genes that protect your brain cells from stress, death and damage. Butyrate is also a source of energy for your brain cells and can boost the function of your brain cells’ energy powerhouses – their mitochondria. When your brain is protected from stress and when it can produce and use energy more efficiently, it can simply work better. So when you are on a high fiber diet, your brain probably works better

In one study, children on a higher fiber diet had better memory and were better at multitasking and staying focused on a task.

“High fiber diets have numerous reported health benefits in reducing risk of type 2 diabetes, colon cancer, obesity, stroke and cardiovascular disease, making it a widely recommended healthy diet. Many of the reported effects have been associated with the microbiome and its ability to produce SCFA, like butyrate.” – Bourassa et al., 2016

But despite the power of a high fiber diet to help people recruit healthy gut microbes, there is one big downside to it. It isn’t available to everyone.

Many people do not have easy access to a grocery store with fresh foods. They may only have access to groceries available at gas stations, for example.

The problem with a high fiber diet is… access.

Today there is an exploding amount of online information and advice about fiber, probiotics and other microbiome-boosting foods and supplements. But much of this content sets up a false narrative of control over one’s own gut microbes and thus health. 

Many people today are turning to probiotic supplements in hopes of building a more diverse and healthy collection of microbes in their guts. Some of these people might turn to probiotics as an alternative to fresh fruits and vegetables, particularly if they are picky eaters. But probiotic supplements have yet to show widespread positive impact on people’s guts. Most probiotic supplements contain only a few species of bacteria that may or may not help diversity a given person’s collection of gut bacteria. Probiotics also cater primarily to people with money to spend on health foods.

Fresh foods – and a rich variety of them – are a far better source of healthy gut bacteria than any single probiotic supplement is. But here also exists a problem of access. A huge number of people don’t in fact have much to any control over the types of foods they can buy and eat. Many people, including people close to you or perhaps even yourself, don’t have access for one reason or another to fresh fiber-rich foods like fruits and vegetables that can feed and help grow healthy gut microbes.

“Variation in diet has been linked to variation in the gut microbiota of humans, with low food diversity and fiber-poor diets (e.g., the Western diet) reducing gut microbial diversity and functionality.” – Sue Ishaq et al., 2019

Many bacteria, one microbiome: Is a diverse microbiome a human right?

In an essay published in PLOS Biology last week, Dr. Sue Ishaq and colleagues – including students who took a special topics microbiology course taught by Ishaq at the University of Oregon – argue that access to healthy gut microbes should be a basic human right given how important these gut microbes are to our health. 

Diet is a very important in determining what kinds of microbes live in our gut. Part of its importance comes from the fact that we can control and modify it – theoretically. In reality, many people can’t afford or don’t have easy access to the foods that recruit health-promoting gut microbes.

“Diet, as well as medications and other things that you are putting into your body, is really important in driving your gut microbiome,” Ishaq said. “Whatever it is that you are eating is going to recruit [your gut microbes]. If you don’t have access to fiber especially but also fresh foods in general then you can’t recruit [the healthy microbes that thrive on these foods]. There are people who are suffering the effects of a microbiota they’ve recruited because they don’t have a choice [over what they eat], because they don’t have access to healthy, fiber-rich foods.”

There are areas in all major U.S. cities where people would have to walk many miles to find anything other than fast food. These areas are known as food deserts. They are areas in which access to fresh fruits and vegetables is limited or even nonexistent. When and where people in these areas can find fresh fruits and vegetables, they may not be able to afford them or may not choose to purchase them for a variety of reasons.

People living in low income communities may not buy fruits and vegetables because they spoil quickly and they are heavy and awkward to carry on the often long walk home from the grocery store, says UK food scholar Dr. Megan Blake

Vegetables are heavy to carry home and can spoil quickly. This makes it more difficult for people in low income communities to purchase them.

“People just aren’t as enthusiastic about [fruits and vegetables] as they are about other foods, and it can be difficult to get their children to eat them,” Blake said.

A poor diet, especially if it is low in fiber, can have significant negative impacts on a person’s health, including their physical but also mental health. A diet low in fiber doesn’t recruit healthy gut microbes that eat this fiber. Especially when added to other stresses, such as financial and food insecurity, a poor diet can lead to an unhealthy gut microbiome and health issues including obesity, chronic inflammation and chronic disease.

“Lower-income communities have a higher prevalence of high-fat, high-sugar, or highly processed diets, with fewer dietary options, as this food is often cheaper and more accessible.” – Sue Ishaq et al., 2019

To recruit healthy gut microbes, a person also has to eat high fiber foods like fresh fruits and vegetables regularly, not just once in a while. This can be particularly difficult for people living in urban, food desert environments.

“Your gut microbiome is really reactive [to what you eat] – a consistent diet is the best way to stabilize your gut microbiome,” Ishaq said. “As humans, we tend to have strong food preferences and routine – we mostly eat a lot of the same foods every day. If you eat fast food every day, then an occasional salad probably won’t meaningfully improve your gut microbiome. But as long as you aren’t eating fast food every day, you can enjoy a Big Mac today and your normal [healthy] diet will still be able to re-recruit the bacteria that are normally in your gut.”

(Hopefully your “normal” gut bacteria are fiber-munching ones!)

It doesn’t take long for your gut microbiome to change, but it takes time for it to stay changed,” Ishaq continued. “If you were to eat a salad, your gut microbiome would start changing immediately. But if you want that microbiome to stay and you want to recruit good microbes that are able to break down fiber and make a lot of the good byproducts that your body needs like short chain fatty acids, you need to eat that salad on a regular basis. Because if you don’t feed your healthy gut microbes [that thrive on fiber], they die out.”

Fresh foods are an important source of healthy gut microbes.

When living in a food desert, buying fresh fruits and vegetables can be risky.

Dr. Megan Blake spends her time thinking and investigating ways to get more fruits and vegetables to people living in low income communities. This doesn’t just mean bringing more fruits and vegetables into food deserts, through food bank programs for example, but actually making sure that people in these communities are empowered to make healthy choices.

”People in their daily lives tend to think within a constrained set of foods – this is what is available to me – and within that constrained set they choose what they think is best within a given context,” Blake said.

Often, that context isn’t about making better health decisions. It may be about celebrating with family (over cake). It may be about what is easiest to carry home from the grocery store. It may be about getting the most food (and calories) that one can for a given amount of money. For example, even though most people enjoy fruit, people in low income communities often don’t buy fresh fruit because they see it as a luxury, not a need. While most people in low income communities seem to be concerned about eating better, they often aren’t able to make better food decisions due to financial constraints, knowledge gaps and other issues, including even fear. 

“When you are on a very tight income, you may have a lot of fear about trying new things because if you don’t like them, if you don’t know how to cook them, if you don’t cook them well or your belly doesn’t like them, it wastes an important portion of your food budget for the week. It is a middle class affordance that if you try something and you don’t like it, you can call in a pizza and cook something different tomorrow. But we find that people are very conservative and risk averse around the foods that they choose when they have to pay for them [with a limited budget].”

Blake works with a food redistribution charity program that delivers surplus fresh foods to people in areas that could be described as food deserts. According to Blake, most people (75%) who have participated in the program have said that they were able to get more fruits and veggies into their diet as a result of this program. Thanks to the program, participants were able to try new foods without the risk of not like the food and wasting some of their limited weekly food budgets.

“Today, things like parsnips and avocados are foods that many people in poor income communities have never seen or tried before,” Blake said. If people don’t recognize these items as food they would like or don’t know what to do with them once they get them home, they certainly aren’t going to buy them. But Blake finds that when you remove financial barriers, most people are willing to try new foods. 

On the other hand, it’s normal to have to try a new food several times before you begin to enjoy it. Fruits and vegetables in particular can be an acquired taste. It can even take some time for a person’s gut to adapt to the higher fiber content of a diet rich in fruits and vegetables. This poses a problem for people in food deserts who may only rarely have the opportunity to try a new fruit or vegetable item. If they decide they don’t like it or find that the item upsets their stomach (which fiber can do for people who don’t normally eat much fiber), they are likely to decide not to run the (financial) risk of ever purchasing that food in the future.

“There are people who, if they have gotten an upset stomach with certain fruits or vegetables, will decide that they can’t eat those foods,” Blake said. “I think that there are a lot of people who assume that they have a physical disorder that prevents that from eating certain foods, as opposed to a temporary intolerance.”

Blake also described instances, in the case of school programs aimed at providing more fruits and vegetables to children, where parents complained that the food was making their children sick. This may be because the children were getting more fruits and vegetables in their diet than they were accustomed to, which can speed up the passage of food through the gut.

Educational efforts aimed at adults as well as kids can help people understand that the body needs time to adapt to higher fresh food and fiber content and that this adaptation process is normal and healthy. Without educational efforts, people may decide that they are intolerant to certain types of foods after trying them just once or a few times, even though their guts would adapt over time if they continued to eat these foods on a regular basis.

“If we aren’t providing healthy, fiber-rich foods in our schools, then we may also not be teaching kids healthy eating habits, and thus we are reinforcing poor diets and insufficient gut microbiota in certain communities,” Ishaq said.

We need to broaden access to gut microbes via fresh foods – starting with access for children and low income communities.

We need to broaden access to healthy gut microbes – starting with mothers and children.

Health inequality is a global problem, yet it is a problem that every country and state must deal with itself. For most countries, overcoming inequality in health requires systemic changes in far more places than just health services. Child care, education, housing and working conditions, income and social networks all influence our diet and therefore our microbiomes.

Microbiome inequality begins as early as in the womb and continues through infancy, childhood and into adulthood. A child’s living conditions and their parents’ behavior in regards to diet, lifestyle and health impact the child throughout their life. The good news is that when society invests in childhood health, the rewards are larger than if investments are made later in life. This goes for our health in general, but also for our microbiomes.

An excellent place to start in creating more microbiome equality is in maternal healthcare and child care. For instance, studies from several countries have shown that mothers with fewer socioeconomic resources are less likely to breastfeed. Breastfeeding is important for its nutritional value, positive impact on the baby’s immune system and social development. But it is also important for the baby’s microbiome. Through nursing, a baby receives microbes from his/her mother and is therefore “colonized” by his/her mother’s microbes. Several factors influence a mother’s ability to breastfeed, including access to support, help and coaching from family or healthcare workers, access to parental leave or a working situation that allows for breastfeeding.

Quality child care is also an effective way to build healthy microbiomes. Child care facilities and schools that offer healthy meals of fruit and vegetables do an important job of building healthy habits (and microbiomes). 

Higher education levels are also associated with better health (and healthier microbiomes) later in life. This is an important incentive for governments to invest in high-quality schooling for all children, which makes it more likely that they will complete higher education.

Overall, to broaden access to healthy gut microbes, countries as well as local communities will need to focus on removing systemic barriers as opposed to simply calling people to engage in healthier habits. Healthy diet or other healthy habit campaigns aimed at individuals such as mothers without acknowledging their challenges, structural and financial barriers can be stigmatizing, expensive and ineffective.

Diversify your gut microbes on a budget.

Are you on a tight budget but still want to support a healthy collection of microbes in your gut? As long as you have access to a modern grocery store, it’s fairly simple to feed your fiber-munching healthy gut microbes on a budget.

“While I was a graduate student, my income was fairly limited for a little while,” Ishaq said. “A friend of mine who was under similar circumstances was actually researching cookbooks – he sent me a book called Good and Cheap [PDF here]. The ingredients list for every meal is fairly short, the preparation time is short and the book does a good job of explaining cooking instructions in simple terms.”

A cheaper way to make meals that call for fruits or vegetables is to substitute frozen or canned items for fresh ones. Frozen and canned fruits and vegetables also last longer and won’t spoil, lowering the risk that you’ll waste a tight budget on a food item that spoils before you have the chance to cook or eat it. Just look for frozen and canned fruits and veggies that don’t have any salt or sugar added. 

Check out this resource for how to cook veggies easily in a microwave

Most studies have investigated the impact of fiber-containing whole foods (fresh fruits and vegetables) on the gut microbiome and health. That being said, canned and frozen vegetables are still vegetables, Ishaq says, and still contain fiber. 

There are many different types of fiber. The gold standard is to get a variety of fibers into your diet. But any fiber is better that no fiber, Ishaq says. Fiber is a structural carbohydrate of plants – it is what gives foods like apples and peas their structure or shape. Fiber typically doesn’t get destroyed in cooking, canning or freezing these plants. So canned and frozen vegetables are good, budget-friendly sources of fiber if you can’t afford, don’t have access to or are uncomfortable preparing fresh vegetables.

On the other hand, processed plant foods often lose the fiber content that the original plants contained. This includes foods made from white flour, such as break and pasta. White flour is ground, bleached and radically transformed from its original structure (grains of wheat), which destroys its fiber content. So try to purchase plant foods you can recognize when possible, such as frozen green beans or spinach.

Are you buying fresh fruits and vegetables on a tight budget? Does your living situation prevent you from buying fresh fruits and vegetables on a weekly basis. You can buy fruits and veggies that last several weeks and that don’t spoil and waste your money. 

Produce that stays good for a longer time (on the range of 1-2 weeks or longer) includes apples, pears, melons, raisins, bell peppers, cabbage, citrus fruits, oranges, potatoes, onions, carrots, celery, beets, pumpkin and squash (lasts between 2 and 6 months in a dark cabinet!

Carrots are a budget-friendly veggie that stay fresh for a long time.

Remember that it is OK to try something and not like it. If you are buying a fruit or vegetable item for the first time, buy a small amount of it at first. If you don’t like it, you won’t be out a lot of money. If you think it’s ok or if you like it, you can buy more of it in the future and prepare a larger meal with it!

What can you do to help broaden access to healthy gut microbes?

Support local farmers’ markets and ask your local farmers’ markets to work with your local food assistance programs, Ishaq recommends. Support or help start a community or neighborhood farm. Ask your local government officials to mandate or assist local stores in carrying fresh fruits and veggies. 

You could donate money today to help local food banks deliver fresh fruits and vegetables to communities in need. You can donate to Feeding America or a local food bank in your state/country.