The science-based food intolerance resource since 2013

What to expect with food and digestion

Back in the summer of 2001, I was obsessed with a certain regional brand of diet iced tea, and I would drink a few gallons of it a week. It was so good! That summer I also developed a problem with gas and diarrhea. My flatuence was so bad that I tried to keep people out of my cubicle at work because I was sure that the whole place had to stink. This coincided with a very stressful period in my life, so when I Googled my symptoms and read that irritable bowel syndrome could be caused by stress, I diagnosed myself with IBS. “Great,” I thought, “things are going badly and now I’m sick on top of it. That’s all I need.”

Fortunately, I wasn’t “sick” — I was just drinking too much sucralose sweetener. Sucralose feeds certain types of intestinal bacteria, which in turn produce the smelly gas, and it also pulls water into the intestines, causing diarrhea. The caffeine in the tea probably added to the diarrhea by moving my meals through my large intestine too quickly for even the usual amount of water to be absorbed from the stool. Later I would realize that my summer of embarassment did not constitute a chronic illness like IBS, which needs to be going on for at least 6 months to meet the Rome III diagnostic criteria [1] — I had simply eaten too much of something that would be hard for any body to handle, and the same thing could have happened with fructose if I had been drinking the same, excessive amount of regular cola or juice.

The point of my story is that sometimes a food will just do it to you. We might say that it “disagrees with you,” but if a food disagrees with you, odds are that it disagrees with a lot of other people, too. That’s why it’s important to understand that normal digestion varies, and it’s not always perfect. If you have a healthy gastrointestinal system — which puts you in only a modest majority, since almost a quarter of Americans suffer from digestive disorders [2] — this is good news. When the equipment is in working order, what you get out of it depends on what you put in. Leslie Bonci, MPH, RD, calls this an “investment in intestinal well-being” in the American Dietetic Association Guide to Better Digestion [3]:

“To make an investiment in intestinal well-being, one should consider food choices, portions, and meal timing. Food is one of the few things in life that we can control, and it is important to use food in a positive and intestinally friendly way. Experimenting with food choices as well as eating habits can help achieve a more balanced eating pattern, a healthier lifestyle, and very often, symptom relief.” (p. 4)

Notice that there is no mention here of food intolerance or food sensitivity: better digestion comes down to food choices and eating habits. In other words, no one can eat any amount of any food at any time without opening themselves up to the possibility of constipation, bloating, or gas. In her book, Ms. Bonci does an excellent job explaining the common effects of certain foods and supplements for anyone who wants a better handle on their digestive symptoms.

I am also struck by Ms. Bonci’s idea that “it is important to use food in a positive…way.” We too easily throw around the term “food sensitivity” — which actually isn’t a legitimate medical term — to describe the problems that food has caused. This recent habit doesn’t foster a positive relationship with food: it amounts to making a diagnosis, a claim that you have a disorder — that there is something wrong with you, not with what you have eaten. However, there is a big difference between being ill and making poor food choices.

The infographic

Some foods cause the same problems in everyone when we eat too much of them or in the wrong combination. Maybe for you it’s a pepperoni pizza that will sit like a lead weight in your stomach and then cause diarrhea later on, or maybe your attempts at eating healthier — like adding whole wheat, prebiotics, beans for protein, and lots of fruits and vegetables to your diet — have backfired with gas and bloating. This is not necessarily a sign of food intolerance. Your symptoms might be normal considering what you have eaten. You can see what I mean in my infographic, “What to expect with food and digestion.”

Sources of information for the infographic:

Putting it together

Managing digestive symptoms requires planning, patience, and a lot of information on how different foods can affect digestion. Talking with your doctor is the best place to start so you know that you are not dealing with any serious medical issues. Do not try to diagnose yourself. An accurate diagnosis helps you to know whether you should just change your eating habits or whether you should avoid certain foods because of a food hypersensitivity.

To quote Leslie Bonci again, “it is important to find the correct balance regarding food choices and quantities, so that you can make a meal pleasurable and healthful, not painful.” A registered dietitian can help you restructure your eating so that food can always be a source of enjoyment.


1. Longstreth GF, Thompson WG, Chey WD, Houghton LA, Mearin F, Spiller RC. Functional Bowel Disorders. Gastroenterology. 2006 Apr;130(5):1480–91.

2. National Institutes of Health, U.S. Department of Health and Human Services. Opportunities and Challenges in Digestive Diseases Research: Recommendations of the National Commission on Digestive Diseases. Bethesda, MD: National Institutes of Health; 2009. Report No.: NIH Publication 08–6514. Available from:

3. Bonci L. American Dietetic Association Guide to Better Digestion. John Wiley & Sons; 2003. 259 p.