If you have spent any time in the grocery store in the last year, you have no doubt noticed an explosion in products claiming “good source of fiber” or “50% of your daily fiber needs in one serving.” In fact, “contains fiber” appears to be slowly nudging aside the nutritional constants of “low fat” and “reduced calorie.” So what’s all the fuss about?
The rapid movement of fiber to the front of the nutritional line is being driven by a number of market and scientific forces, including important changes in how we define health and well being. For decades now, dietary fat has been the nutritional whipping boy, blamed for everything from obesity to heart disease and everything in between. A steady flow of clinical research, however, is showing us that not all fats are bad and that fat may not make us fat or even cause heart disease. As research mounts and marketing departments in food companies take notice, “low fat” as a lead health claim on many of our favorite products will slowly fade – or at least the font will get smaller. Though “fewer calories” will remain the titan of health claims for marketers, it, too, will be knocked down the what-makes-us-healthy ladder a notch or two.
The nutritional shuffling of key health claims in the grocery isle is part of a larger shift driven by ongoing scientific research behind the scenes that is repositioning fiber as a key nutrient to preventing disease – but not for reasons that most people think.
Much of what we have been taught about the health benefits of fiber – and much of what we read in popular diet books – is based on research from the 1970s through the early 1990s: fiber is nature’s broom, bulks the diet so we feel fuller, “moves things along” as they say, and so on. These mechanical aspects of the benefits of fiber then lead into the claims that fiber reduces your risk of heart disease, diabetes, some cancers, and if you eat judicious amounts, help you maintain a healthy weight…all true.
However, advances in medical science and our understanding of human biology has researchers rethinking the role of fiber in human health, moving it beyond a nutrient that once made the public and scientists alike yawn, to one that is front and center in some of the most exciting research into human health and disease. With all science, it will take years to trickle down to the general public. However, as the ever more frequent “eat more fiber” labels in your local grocery store reveal, food marketers are getting out in front of this fiber revolution as they are following the science and medical research very closely – always looking for an edge.
To understand the reemerging role of fiber in achieving optimal health and preventing or relief from diseases as diverse as cancer, heart disease, irritable bowel disease, obesity, osteoporosis, diabetes, and autism, we need to go back in time just far enough to remove the cultural noise of our so-called “modern society” to see the simple biological rules of nature that scientists are realizing form the foundation of human health.
Us, once upon a time
It’s a cool, damp morning. A young mother tosses back and forth on the ground of her family hut, experiencing familiar cramping indicating that her second child will soon be born. With contractions easing for the moment, she steps into the morning sun to tend a small fire and the morning needs of her family. After everyone has been taken care of, she unceremoniously slips out of her village of 20 or so huts scattered along the shore of the shallow lake and into the green trees and shrubs that mark the edge of her village.
With contractions coming closer together and shortened breath she squats and grasps the slender, but sturdy trunk of a tree for balance. Gritting her teeth and sweating profusely, she does not make a sound, not wanting to draw attention to her location. With a push the baby’s head appears, the face turned towards her rectum. All is going well. The pressure of the baby moving through the birth canal has forced the passing of several small bowel movements. With one final push the baby falls to the ground, the mother slightly breaking the fall with her one free hand. After catching her breath, she reaches down and turns over her new baby, who has landed face down in the dirt, excrement, and fluids from the birth. Everything went perfectly. It’s a girl.
In the sterile womb, the fetus was completely protected from the world she was about to enter – but not for long. While passing through the birth canal, this newest member of our species received the time-honored mouthful of lactobacillus bacteria from her mother in the same way that she had received them from her mother; the first of many inoculations from the microbial-dominated world she was about to enter. Once she is freed from the birth canal and gasping for air, millions of natures’ tiny little microbes clinging to the dust particles in the air fill her mouth and nostrils, and once she officially makes landfall on this earth, she is welcomed to the biosphere by billions of additional soil microbes as her moist body quickly sops up the parched soil and its microbial residents. This also includes a healthy dose of bacteria in the mother’s feces the baby landed on, as nearly 50 percent or more (dry weight) of her mother’s fecal matter is made up of bacteria that originated from the diverse ecosystem of her mother’s gut.
Within moments of birth, the child begins to nurse, thus receiving additional sources of bacteria, or at least their byproducts. In the weeks leading up to birth, microbes started appearing around the nipples of the swollen breasts. These bifidobacterium grew deep in the oxygen-poor chambers of the milk ducts during late pregnancy and moved to the surface as the first invisible drops of colostrum (first milk or immune milk) began appearing. While all bifidobacterium are anaerobic, meaning they are unable to survive in air, they live just long enough on or near the surface to secrete lactic acid and other antibiotic chemicals that help clear, in a “nature’s wet-wipe” sort of way, the soon-to-be suckled nipple of potentially nasty microbes such asStaphylococcus aureus.
Once the newborn begins to suckle, the lactic acid deposited on the nipple by the sacrificed bifidobacterium from the milk ducts meet up with the lactobacillus acquired from the mother’s birth canal in the mouth of the child. Together, they help select the hundreds of bacterial species that will soon inhabit the mouth of the child over the coming days and months. The growing colony of oral bacteria is further bolstered by the nursing infant as she probes her mother’s mouth with wandering fingers, returning the moist results to her own.
As mother and child rest under the small tree, shaded from the sun that has now risen to its late morning position overhead, they have successfully survived not just the complications of child birth through an ancient ritual that seems almost unimaginable to us today, but have completed a set of initial biological imperatives that have given the child a reasonable chance of living a healthy, long life. Without the evolutionary passing of microbes from mother to child our species would not resemble anything like us today. In fact, without them the baby would die within days.
This vaginal birth on the dirt floor of natures’ delivery room assures some organic control of the species of bacteria that will soon inhabit the baby’s body. In this natural setting, a first-come first-gets-to-stay rule applies. During the first few days, these bacteria will begin to populate every imaginable part of the baby – from her skin, hair, nasal passages, fluids around her eyes, vagina, and most importantly, her gastrointestinal tract, from mouth to anus. While this invisible alien invasion of microbes may appear horrifying, it’s all part of a fine-tuned, organic relationship that humans have worked out deep in our evolutionary past with the microbial world. Within a few weeks, there will be more microbial cells in her tiny body than human cells. According to nature’s plan, she will be more microbe than mammal.
As mother and child spend the next few hours getting know one another, the suckling baby enters the next phase in her development as a super-organism – a human hybrid of trillions of microbial genomes to her one.
Food for us and them
Previously germ free, her tiny gut is rapidly colonized by the initial inoculation of microbes from mother and nature. In the early hours and days following birth, different species of bacteria will compete for their place along the wall of her intestines, forming tightly held colonies called microfilms. But like the baby herself, they will soon need nutrients to survive and grow.
Almost immediately after being scooped into her mother’s arms, she begins to suckle. While nearly 90 percent of breast milk is water, the remaining 10 percent of solids is rich in life-giving protein, fat, vitamins, lactose, and some minerals – all the baby needs for normal growth and development. But for all its nutritional wonder, these are all more or less nutrients for the baby – quickly digested and absorbed in the upper intestines. What about nutrients for her new microbial hitchhikers, the vast majority of which have settled in the far reaches of her intestinal tract in the colon?
In order for nutrients to reach the very end of the intestinal tract and be available for the bacteria, they must escape digestion and absorption in the upper intestine. In other words, the baby’s gut is designed to capture and utilize as much of the nutrients passing through her stomach and small intestine as possible and it pays to be stingy, digesting and absorbing as much as possible. But some foods, due either to their physical or molecular structure, cannot be digested and absorbed, so move along the line to the colon. These undigested fractions of foods are known as fiber. And fiber, once it reaches the colon, is broken down and utilized by the resident bacteria for maintenance and growth. Simply stated: fiber is food for bacteria, and mother’s milk is loaded with it.
For our newborn girl, that first swallow of mother’s milk contained special oligosacchrides. “Oligo-,” derived from the Greek oligos, means “a few” and “sacchride” is of course sugar. Because of a special chemical structure, oligosacchrides cannot be digested and absorbed in the upper intestines, and are therefore not utilized by the baby for nutrition. Passed along the pipeline, these fibers end up in the colon, where billions – soon to be trillions – of bacteria break them down with special enzymes and utilize them as an energy source. Roughly translated, our newborn baby will consume between 5 to 10 grams a day of the special oligosacchride fiber, depending on how much she feeds.
So, through some ingenious human biology, breast milk not only delivers the necessary nutrient package for the development and growth of our newborn girl, but also provides the necessary fiber for the growth and maintenance of the trillions of bacteria that make up the other half of her human hybrid. This symbiotic relationship between host (baby girl) and bacteria is often referred to as commensal, literally meaning “at the table together.” The steady flow of fiber from the first sip of breast milk will result in the rapid growth of bifidobacterium within her developing gut. You may recognize this group of bacteria if you eat yogurt, as they are often added as probiotics to many popular foods. As the bifidobacterium grow in numbers, they will nudge out or suppress the growth of less desirable species.
The symbiotic relationship our newborn baby develops with her “first encounter” bacteria in the coming days and months will play a critical role in the development of her immune system and the actual development of the gut. What she does or does not do with and for her human hybrid over the coming weeks, months, and first years of her life will strongly influence her ability to fight infection and disease throughout life. But first, its time for the proud mother to introduce the village’s newest member to its hundred or so members and the thousands of species of bacteria that call it home as well.
A bugs life
As mother and baby settle into a weekly routine in the first few months, the day-to-day care of the new baby is mostly that of the mother, with some wet-nursing assistance from other young mothers. During those days when the new baby is not strapped to her mother’s back on gathering forays to dig for roots and tubers, or to gather berries, greens, and spear fish from the shallow waters of the lake, the baby is fussed-over by an aging grandmother whose main concern seems to be limiting the number of times the brother lifts and then drops the new baby while exploring the small village.
With each new encounter, the baby is exposed to the diversity of bacteria on and within the village and its inhabitants. Throughout her entire day, the baby ingests a steady stream of microbes as her curious fingers probe every corner of the village, from its dirt and rocks, to its people and pets, to the foreign objects her curious brother tries to get her to chew in a never ending “let’s see if my baby sister will eat this” game. And with each new encounter, her well-fed intestinal bacteria, which are by now dominated by bifidobacterium and other lactic acid bacteria, sort through the billions, often trillions, of foreign bacteria flowing through her system every day.
A majority of these foreign invaders are harmless and will pass through her system. Ever vigilant and protective of the warm, nutrient-rich environment deep within our new baby’s gut, her commensal bacteria continuously engage the mass of invaders as they move through her intestines down to the colon, looking for pathogens that might be interested in setting up shop and causing some harm. Through chemical communications between each other and the cells of her delicate intestinal wall, her commensal bacteria lower the pH (more acidic) of the intestinal environment, making life a little more difficult for invaders. Through sheer numbers, her natural defenders outcompete invaders for food and attachment sites on the wall of the intestines. As long as the pathogens stay in the center of the intestines (the lumen) and cannot attach to the delicate wall, they stand a pretty good chance of being swept from the system with any one of numerous bowel movements per day. If the acidic environment and the lack of nutrients and fleshy real estate aren’t enough of a deterrent, her commensal bacteria also excrete antimicrobial substances that make life a living hell for the invaders. This invisible germ warfare is played out every minute of every day from the moment she is born and will continue for the rest of her life. If her human hybrid is well nourished and functioning, she will remain happy and healthy.
Throughout the first year of life, much of her development as a human is hard-wired in her genes. However, because of the long history developed between her ancestors and the ancestors of the commensal bacteria in her gut, not everything is genetically preordained and aspects of her intestinal development require direct interaction with her microbial friends. In fact, so intertwined is our relationship with these microbial friends that they are collectively considered a metabolic organ, meaning an impact on them will have a direct impact on health and well-being in the same way impacting any other organ, such as the liver, heart, or pancreas will have undesired effects.
When you realize humans are biological organisms, like our microbial friends, trying to survive and thrive in an ever-changing and dynamic environment, it’s not hard to imagine that forming symbiotic relationships with other organisms is a successful strategy for survival. Even though our newborn girl was born with a complete immune system and gut, it is small and underdeveloped. Through some clever chemical signals, the commensal bacteria that attached to the wall of her intestines during the first few days following birth work with her immune system to develop some key systems that will teach her body to fight off unwanted pathogens, how and when to react to other invaders, and to develop the delicate mucosal layer lining the inside of her gastrointestinal tract. It is not an understatement to suggest she would not achieve the wonders of a fully functioning human body without experiencing this host-microbial interaction early in her development. However, as she moves from mother’s milk and the nutrients it provides to her human hybrid to regular food, she will have to continue her end of the bargain in this symbiotic relationship.
Species gone wild
About halfway between her first and second birthday, our fast growing baby girl starts dabbling in soft foods. While full weaning is still one to two years away, she’s slowly introduced to soft cakes of mashed foods of plants, animal meat, and fish, all gathered and hunted within the valley her family settled near the lakeshore. She will begin accompanying her mother on more and more foraging trips, sampling and tasting all the gathered berries, nuts, roots, tubers, insects, fruits, and leafy greens along the way. Everything she will eat will be minimally processed – raw in many cases – and as with everything else in her life up until this point, literally covered in dust, dirt and microbes. Even if prewashed in the shallow waters of the lakeshore, nature’s microbes will be clinging tightly to the leaves, skins, and roots of everything she eats.
While the slow weaning process has started to reduce the amount of important nutrients (fiber) to the commensal microbes in her gut, her gut bugs have hardly missed a meal as she starts consuming an increasing amount of fiber-rich plants. Like the fiber-like oligosacharides in breast milk, oligosacchrides are present in thousands of plants in nature. Onions, for example, contain large amounts of oligosacchrides. But in nature, fiber is as diverse as the plants they come from. While the physical and chemical diversity of plants and fiber in her valley is impressive, the fiber across all these plants share one basic characteristic: they cannot be broken down and digested in the stomach and small intestine, so they end up in the colon where waiting bacteria break them down to extract energy not only for themselves, but much-needed energy (calories) for their human host.
Like so many in her valley, our growing little human hybrid enjoys a rich diversity of plants and animals in her diet – foraged and hunted from a nutritional landscape that literally changed at a glacial pace. Though her valley will someday cultivate seeds and raise animals, these hallmarks of modern civilization are generations in the future. Archaeological research around the world suggests that she consumed an extraordinary diversity and quantity of plants and therefore maintained a well-fed population of commensal bacteria. One such glimpse into the diet of our ancient human hybrid ancestors can be found along the shores of the Sea of Galilee in modern-day Israel.
At this location, archaeologists have uncovered a remarkably well-preserved collection of plant remains from the archaeological site of Ohalo II. Buried in the oxygen-poor sediments for 23,000 years, a window into our nutritional past reveals a broad-spectrum diet that yielded a collection of >90,000 plant remains representing small grass seeds, cereals (emmer wheat, barley), acorns, almonds, raspberries, grapes, wild figs, pistachios, and various other fruits and berries. A stunning 142 different species of plants was identified, revealing the rich diversity of fiber sources that was consumed by the site inhabitants.
An ethnographic example of the diversity of plants and fiber consumed by pre-agricultural societies such as the one our baby girl was born into comes from Australia. Early travelers and missionaries in Australia noted in detailed records that Aborigines ate some 300 different species of fruit, 150 varieties of roots and tubers, and a dizzying number of nuts, seeds, and vegetables. A recent analysis by researchers at the University of Sydney of over 800 of these plant foods suggest the fiber intake was estimated between 80 to 130 grams a day – possibly more – depending on the contribution of plants to daily energy needs. Today, the average American consumes around 15 grams a day, from a very limited number of plants.
As time swept over her valley, our baby girl would become a mother herself, passing microbes to her offspring as her mother did with her. Carrying in their guts the key to our success as a species, our ancestors handed down to us one of the greatest symbiotic relationships the natural world has ever nurtured. As foraging gave way to the rise of domesticated crops and creation of massive politically controlled civilizations steeped in culture that punctuated the landscape, we slowly changed the rules between us and them. Today we find ourselves in a modern medical and nutritional world that seems hell bent on extracting ourselves from the natural world from which we, and our microbial friends, came. The culture and technology that pushes humanity forward has evolved so rapidly, that our genome and the delicate balance within our human hybrid cannot keep up or adapt. So freakish is our modern food supply, our commensal microbes barely recognize or realize the food for them in our daily meals.
This article is about our discordance between nature’s plan for the health and well being of not just us, but our entire human hybrid. We don’t need another diet book about us, we need a plan for “all” of us. This blog is about “repositioning” and “reclaiming” fibers’ role in human health. It’s about what fiber is: food for our human hybrid. Continuing to neglect the health and nutritional requirements of our entire human hybrid will only assure our inflamed and leaky guts will continue to play an active role in the major diseases of our time – if not cause most of them directly.
To see where we have gotten off track and how we can restore balance and optimal health for our entire human hybrid, we need to visit another delivery room. But this time, circa 2009.
livNAKED friends. Please tell others.