BY TAMARA DUKER FREUMAN, MS, RD, CDN, CSDH

It goes by many names. In polite company, it’s referred to as stool, feces, or a bowel movement—and in truly polite company, it’s not referred to at all.

Among friends and family, we may call it by nicknames like doody, poo, poop, or number two. Or we may allude to its taking place using one of hundreds of euphemisms, such as “seeing a man about a horse” or “laying a brick.”

Just as the Inuit have dozens of names for snow as a sign of its centrality to their way of life, humans in many societies have dozens of words to refer to the waste that we pass from our digestive systems—and the act of doing it.

Whether or not we care to admit it, moving our bowels is a pretty central and universal aspect of our human experience—and this is particularly evident when our bowels aren’t behaving themselves.

When everything is working smoothly, we barely think about any of this—but the moment things speed up, slow down, or change in an odd way, “getting regular” suddenly becomes very important. Modern dietary habits, especially high sugar intake, can play a surprising role in these disruptions.

What is Stool?

What, exactly, is this stuff coming out of our digestive tracts?

Stool—or poop, or whatever your preferred term—is a waste product that comes together in the penultimate portion of our digestive tract called the colon—or large intestine. It’s composed of a variety of ingredients.

Water—About 75% of your stool is composed of water, with the remainder composed of various solid matter as described below. The longer a stool spends in your colon, the less water it will contain. This is because, as the waste stream travels through the colon, some fluid and sodium are reabsorbed back into the body.

Leftover residue from your diet—Any portions of your food that were unable to be broken down (digested) and absorbed into the body further upstream in the small intestine will proceed onward to the colon for elimination. Basically, any plant-based fiber that we humans don’t have enzymes to digest will fulfill its destiny as residue that bulks up our stool. It is perfectly normal—and indeed, expected—to see these fibers in your stool.

Dead bacteria—A sizeable percentage of your stool is composed of dead bacteria. Our digestive tract is home to trillions of microorganisms that are collectively known as the gut microbiota—and many of them are concentrated in the colon. Bacterial populations are constantly in flux—with older organisms dying off to be replaced by newly divided ones. The dead ones enter our waste stream and get pooped out.

Because dead bacteria retain their genetic material, scientists can use specific gene tests on stool samples to identify characteristics of each person’s unique gut microbiota—gathering information on a subset of species and strains that live in our colons and in what relative proportions. The composition of a person’s gut microbiota is as individual as their fingerprints.

Pigments from dead red blood cells—We have trillions of red blood cells, and when they die, our body needs to discard their little corpses, so they don’t pile up. Waste products from these dead cells travel to the liver, where they are transformed into a pigment called bilirubin. This pigment is packaged into a digestive fluid called bile and released into the intestines during the digestive process.

Some of the bilirubin pigment from bile remains in the digestive tract and travels to the colon, where the resident gut bacteria act upon it. This process turns the bacteria from their yellowish color to a darker brown—its signature brownish hue.

Other stuff—The cells lining the colon secrete small amounts of other stuff into the stool, including some proteins and mucus. When these cells die and are shed, they become part of the poop. There’s a wee bit of fat in the stool as well—but there shouldn’t be all that much. Finally, there are minute amounts of minerals and electrolytes, such as calcium, sodium, phosphate, iron, potassium, magnesium, and zinc.

What Does it Mean to Be “Regular?”

In the gastroenterology practice where I work, patients often want to know how their pooping patterns compare with those of others. What they’re really asking is—Am I normal? It’s a difficult question to answer because there is a range of elimination habits that would be normal.

In terms of frequency, the range of what’s considered normal can roughly be summed up as anything from four bowel movements per day to three bowel movements per week. Having more than four bowel movements daily is sometimes referred to as hyperdefecation, whereas going less than three times per week would meet one of the clinical definitions of constipation. Very frequent—but formed—stools are not actually necessarily considered diarrhea.

Diarrhea has as much to do with frequency and volume as it does with texture. By the book, it is defined as loose, watery stools at least three times per day or a total stool volume of more than 2,050 milliliters per day—though, realistically, almost none of us are measuring that.

When bowel movements become loose, urgent, or overly frequent, one of the most common—and most overlooked—culprits is undigested sugars and other carbohydrates that your gut simply cannot handle efficiently.

When Sugars Stir Up Your Gut

If you feel like the high of sugary foods brings you into a low, you are not alone; certain sugars can trigger gas, bloating, or diarrhea in people with carbohydrate intolerances such as lactose, fructose, sucrose, or sugar alcohol (polyol) intolerance. Understanding which foods contain these sugars—whether naturally occurring or added—can help you decide what is safe to eat, what is best limited, and when a supplemental digestive enzyme might make a problematic food more tolerable.

You have two main options to manage symptoms of carbohydrate intolerance: avoid foods that contain the sugars that trigger your symptoms, or use a supplemental enzyme if available to help your body digest and absorb the sugar.

If you choose to consume a food you have an intolerance to without using enzymes, you will likely find that your symptoms of gas, bloating, and/or diarrhea will be dose-dependent. In other words, a small amount of the food or drink with the problematic ingredient may provoke only mild symptoms, whereas larger portions may provoke more significant symptoms.

These reactions are medically benign, which means that they are not actually harmful to your health. Rather, they can just be very uncomfortable and unpleasant, lasting anywhere from a few hours to a day or so. I, for one, am somewhat lactose intolerant, and yet I sometimes choose to eat high-lactose, real ice cream anyway.

The consequences of doing so when I stick to a single scoop are minimal, and to me, they are worth putting up with for the pleasure I get from eating ice cream. If I were doubled over in pain from gas, cramps, and diarrhea from that same moderate portion, I would probably make a greater effort to find a lactose-free alternative or carry over-the-counter lactase enzyme supplements so I could take them before partaking of ice cream when out and about.

Low-Lactose and Lactose-Free Diet

This is best for people with lactose intolerance and temporary forms of lactose intolerance caused by active celiac disease or Crohn’s disease affecting the small intestine.

Lactose is a milk sugar that occurs naturally in dairy products. It can also be added to sweets, candy, chocolates, and even medications (such as birth control pills) as an inactive filler ingredient. Vegan or plant-based foods will be naturally lactose-free, as will all meats and eggs.

Contrary to a pervasive belief, eggs are not dairy products and are therefore naturally lactose-free. Another myth about lactose is that goat’s and sheep’s milk are substantially lower in lactose than cow’s milk; they are not. However, hard, aged cheeses made from all three of these milks are typically extremely low in lactose, if not fully lactose-free, because as cheese ages, the lactose seeps out along with the liquid whey.

Lactose intolerance is caused by inadequate production of the digestive enzyme called lactase in your small intestine. Lactase is required to break down lactose into its two component sugars, glucose and galactose, so they can be absorbed individually. When you consume more lactose than your enzyme capacity can digest, the excess goes undigested and unabsorbed and travels to the colon, where it can cause gas, bloating, diarrhea, and/or cramping.

This pattern is called primary lactose intolerance. Some people temporarily lose the ability to digest lactose when there has been damage to the lactase–producing cells of the small intestine—for example, in uncontrolled celiac disease or active stages of Crohn’s disease affecting the small intestine—and this is called secondary lactose intolerance. Typically, secondary lactose intolerance improves or resolves once healing of the affected segments of the small intestine has taken place.

Low-Fructose Diet

This is best for those with dietary fructose intolerance. Fructose does not require enzymes to be digested, and therefore, fructose intolerance does not result from an enzyme deficiency. Instead, fructose requires dedicated sugar transporters lining the small intestine to carry it from the bowel into the body.

Some people naturally express more of these transporters, or have better-functioning transporters, than others. Some may have a normal number of transporters but consume so much fructose in their diets—perhaps from juicing frequently or drinking lots of soda and other soft drinks—that they simply overwhelm their body’s capacity for absorption.

Once you max out your individual ability to absorb fructose, any excess goes undigested and unabsorbed and travels to the colon, where it can cause gas, bloating, diarrhea, and/ or cramping. When fructose and glucose are consumed in equal balance, the fructose may actually be absorbed by the same pathways as sucrose (table sugar). But when a food contains relatively more fructose than glucose, the potential for fructose malabsorption increases.

Because tolerance varies by person and by portion size, working with a knowledgeable clinician or dietitian can help you identify which high-fructose foods you tolerate well and which are best limited.

Low-Sucrose Diet (Sucrase-Isomaltase Deficiency / CSID)

This diet will benefit those with sucrose intolerance, or congenital sucrase-isomaltase deficiency (CSID), as well as those with temporary forms of sucrose intolerance caused by active celiac disease or Crohn’s disease affecting the small intestine.

Sucrose is a sugar that occurs naturally in certain fruits, vegetables, and sweeteners such as maple syrup and molasses. It can also be extracted from beets and sugar cane to produce isolated sugar, which can be used as a sweetener. On a food label, it might also be listed as “cane juice” or “evaporated cane juice,” but it’s the same white stuff as plain old table sugar. Contrary to what you may have heard, brown-colored raw sugar or even brown sugar itself is not substantively different from white, more refined sugar, either digestively or metabolically—sugar is sugar is sugar.

When you consume more sucrose than your digestive enzymes can break down, the excess travels to the colon, where it can cause gas, bloating, diarrhea, and cramping. Congenital sucrase-isomaltase deficiency (CSID) was once thought to be quite rare, especially among adults, since it is typically diagnosed in early childhood when a baby develops chronic diarrhea and fails to gain weight (failure to thrive).

We now understand that there are many variants of sucrase-isomaltase-related genes, and some that result in lower enzyme levels may be more prevalent among people with a diagnosis of Irritable Bowel Syndrome (IBS) than in the general population. Relatedly, sucrose intolerance can often be misdiagnosed as IBS.

A low-sucrose diet is for people with sucrose intolerance who do not have access to supplemental enzymes that aid in sucrose digestion. On a low-sucrose diet, you can consume all animal proteins so long as they are not prepared with condiments, marinades, or other sugar-containing ingredients. Unsweetened dairy products are also fine, so long as you’re not lactose intolerant. Nuts, seeds, butter, and vegetable oils are also fine.

Some, but not all, people with sucrase-isomaltase deficiency have a hard time digesting starchy foods, especially in larger portions. These include grains and starches such as bread, pasta, flour-based baked goods, crackers, cereal, potatoes, rice, oatmeal, corn-based products, and chips or pretzels. If your symptoms are improved but not resolved on a low-sucrose diet, a one- to two-week elimination trial of grains and starches will tell you whether these foods give you trouble as well.

If the elimination trial resolves your symptoms, gradual reintroduction with small amounts at a time will help you determine which portions you can comfortably consume. Chewing starchy foods thoroughly can improve their digestibility by prolonging exposure to saliva-digesting enzymes.

Low-Sugar Alcohol / Polyol Diets

This diet is best for people who have chronic diarrhea from many causes that is not well controlled using fiber therapy or other interventions. It is also suitable for IBS-D and inflammatory bowel disease (IBD).

Sugar alcohols, also known as polyols, are naturally occurring molecules that are similar enough in structure to sugar that they taste sweet, but not similar enough to be absorbed into our bodies in the same way. All human beings malabsorb sugar alcohols to some degree, and they will provoke diarrhea in anyone if a high enough dose is consumed.

Tolerance to sugar alcohols varies a lot by person; some people can consume a substantial amount and feel fine, whereas more sensitive individuals can experience digestive upset—gas, bloating, and/or diarrhea—after consuming even tiny amounts.

Because sugar alcohols are not well absorbed, they barely affect blood sugar levels—if at all—and they contain fewer calories per gram than sugar. This makes sugar alcohols one of the more common sweeteners among keto products and other sugar-free or no-sugar-added products marketed to people with type 2 diabetes.

Some packaged foods may list out the grams of sugar alcohols they contain as a separate line item on the “Nutrition Facts” label; if not, you’ll need to scan the ingredient list to alert you to their presence. Ingredients that end in “-ol” are sugar alcohols, including sorbitol, mannitol, maltitol, xylitol, erythritol, and lactitol.

If you consume many packaged, processed, low-carb or keto foods, your cumulative intake of sugar alcohols could become quite high, and this alone could provoke diarrhea. Among the sugar alcohols, erythritol may be somewhat better tolerated for some people, but this varies by individual.

In people already experiencing diarrhea from another cause, even modest intakes of sugar alcohols can worsen symptoms. Celery juice is another dietary fad that can pile on sugar alcohols (mannitol) and aggravate diarrhea in susceptible people. For these reasons, I tend to steer my patients with chronic diarrhea away from sugar alcohols, recognizing that tolerance is often dose-dependent, meaning that some people can get away with eating small amounts of these foods.

Sugar-Restricted Diets for Multiple Carbohydrate Intolerances

If you have been diagnosed with multiple carbohydrate intolerances, or are struggling with sensitivity to several sugars as a result of another condition—such as SIBO, celiac disease, or Crohn’s disease—the fruits and vegetables you are most likely to tolerate will be those in which glucose is the predominant form of sugar. In practice, that means choosing foods that contain little or no lactose, fructose, sucrose, or sugar alcohols, while favoring those with more balanced or more glucose-forward sugar profiles.

Because tolerance can vary widely from person to person, working with a knowledgeable clinician or registered dietitian can help you identify which fruits and vegetables are most likely to be safe starting points and which are best introduced more cautiously.

Keeping a Food Journal

As a clinician, I really need to see the timing of any symptoms my patients are experiencing in the context of the times they are eating various foods, and I need to see records for several days to connect, say, morning diarrhea with what might have been consumed the prior afternoon or evening.

For me, this is easiest to visualize as a very low-tech data table—with columns for time of day, foods and drinks consumed, and any symptoms noted—filled in over the course of a week or two.

Looking at the sample food and symptom journal, I can quickly begin developing hypotheses about what might be triggering my patient’s symptoms.

In this sample case, there are a few possibilities that came to mind: Is he lactose intolerant, and could the undigested lactose be from milk products consumed earlier that day? One day’s worth of records will not answer that question, but with a week or two of consistent tracking, I can test my hypothesis.

In other situations, people are hoping to pin their symptoms on a single food or ingredient when the problem is more global—such as simply eating too much fiber overall when they already struggle to empty their bowels adequately. All this is to say that a well-seasoned GI-focused registered dietitian (or GI RD, as we like to call ourselves) can help you make sense of the data you gather, and it is worth staying open to explanations for your symptoms that may not match the narrative you have developed in your mind.

When you understand what “regular” really looks like and how different sugars can quietly throw your bowels off balance, your symptoms become a little less mysterious and a lot more manageable. Small, targeted changes—whether that means tweaking lactose, fructose, sucrose, or sugar alcohols, or working with a GI-savvy dietitian—can turn chronic gas, bloating, or diarrhea from something you endure into something you can influence, one meal and one bowel movement at a time.

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Tamara Duker Freuman, MS, RD, CDN, CSDH, is a nationally-known expert in digestive health and medical nutrition therapy for gastrointestinal diseases. In addition to her clinical work, Tamara is a high-profile nutrition writer.

Her first book, The Bloated Belly Whisperer, was published in 2018, and her advice is read by hundreds of thousands of readers each month through online publications including U.S. News & Health Report’s “Eat + Run” blog, its syndicates, and EatingWell.com. She lives in New York with her husband and twin children.

Well Being Journal adapted the above excerpt from REGULAR by Tamara Duker Freuman, MS, RD, CDN, CSDH. Copyright © 2023 by Tamara Duker Freuman. Featured with permission of Balance Publishing, an imprint of Hachette Book Group. All rights reserved.