Guide to a low-FODMAP diet

Patients perceive food as a trigger for many digestive issues. The link between foods and digestive disorders is well recognized, and there’s a chance that restricting certain foods can dramatically improve symptoms in sensitive people.
As a registered dietitian nutritionist (RDN), I’ve seen how a low-FODMAP diet can be helpful for people with irritable bowel syndrome (IBS) with symptoms such as recurrent bloating, gas, cramps, diarrhea or constipation.
This diet is something that I may recommend to clients who suffer from IBS. While most diets can be done without the help of a RDN, I’d recommend consulting with a RDN before, during and after starting this one.  
What is a FODMAP?
FODMAP stands for fermentable oligo-, di, mono-saccharides and polyols. 
In simpler terms, FODMAPs are a group of carbohydrates that are commonly malabsorbed in the small intestine and seem to trigger digestive symptoms in some individuals. 
Those saccharides and polyols are short-chain carbohydrates that, if poorly digested, ferment in the lower part of your large intestine (bowel) and produce carbon dioxide, hydrogen and/or methane gas that causes the intestine to stretch and expand. These poorly digested carbohydrates can also pull water into the bowel and lead to diarrhea. The result is strong pain, bloating, visible abdominal distension and related symptoms.
FODMAPs are common in the diet and can be found in everyday foods such as: wheat, barley, rye, apples, pears, mango, onion, garlic, honey, kidney beans, cashews and some medicines, to name a few. Research has shown that the low FODMAP diet can improve gastrointestinal symptoms related to IBS.  Learn more about IBS
What is the low FODMAP diet?
The low FODMAP diet is a two-to-six week elimination diet that involves removing high FODMAP foods from your diet to assess whether or not these foods are triggering your gastrointestinal symptoms. This diet should be treated as a learning diet, rather than one you’d stay on forever. 
The goal of this diet is to help you determine your personal dietary triggers. After the low FODMAP elimination phase, a dietitian can help guide you on how to strategically re-introduce FODMAPS to your diet. 
For example, these foods are rich in FODMAPs and would be eliminated during this diet:
  • Lactose: milk, custard, ice cream, yogurt, milk powder, ricotta cheese, cottage cheese
  • Excess fructose: apples, figs, mango, pears, watermelon, asparagus, artichoke, snap peas, honey, agave
  • Fructans: dried fruit, nectarine, persimmon, garlic, onion, wheat/barley/rye, insulin additives 
  • Gos: legumes, pistachios, cashews
  • Polyols: apricots, blackberries, peach, pears, cauliflower, mushrooms, sugar alcohol additives like isomalt, mannitol, sorbitol, maltitol
Who should follow a low-FODMAP diet?
A low-FODMAP diet isn’t for everyone. Unless you’ve been diagnosed with IBS, you should consult with a RDN prior to starting this diet. FODMAPs are generally found in healthy foods that function as prebiotics. Prebiotics support the growth of beneficial bacteria in your gut. It’s unknown what the effect of a low-FODMAP diet is on the bacteria in the gut and, therefore, we practice caution with its long-term use in gastroenterology.
If you suffer from gastrointestinal symptoms, be sure to consult with your doctor or a RDN; don’t self-diagnose your condition. While there’s a lot of advice online, it’s all generalized - a health professional can help you figure out what works for you and rule out a more serious intestinal condition. 

Olivia Vaughn is a registered dietitian nutritionist at The Ohio State University Wexner Medical Center.