IBS: The nutrition prescription

I said on Monday I would talk more about irritable bowel  IBS and the FODMAP diet. True to my word, I’m going to give the quick-and-dirty rundown.
FODMAPs are Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. They are specific types of sugars and dietary fiber that while perfectly healthy, generally, are poorly absorbed in the small intestine by many people with IBS. They are then passed along to the large intestine where they act as “fast food” for the bacteria that inhabit it, causing excessive gas and bloating. The FODMAPs can also mess with the fluid balance in the large intestine, causing diarrhea or constipation (often alternating).
The irony is that oligosaccharides, are considered prebiotics, aka good food for our good bacteria. So, what’s good for one person is not so good for the next!
So, a low-FODMAP diet starts with a two-week FODMAP elimination diet, which includes only foods known to be low in FODMAPs, with a few moderate-FODMAP foods allowed in limited portions.
High-FODMAP foods are avoided completely. These include:
  • Milk, yogurt and a few soft cheeses (high lactose)
  • Wheat, rye and barley (but NOT because of the gluten…it’s because of the types of carbs in these grains)
  • Fruits that have a higher fructose-to-glucose ratio (including apples and pears)
  • Other foods and condiments high in fructose
  • Foods high in sugar alcohols (such as xylitol and sorbitol)
  • Beans and lentils
  • Certain vegetables (including the cruciferous veggies and the onion family)
If FODMAPs are to blame, then the patient usually notices symptom relief fairly quickly, but the elimination diet is followed for two weeks to get a clean slate before the challenge portion of the diet. Then, each FODMAP group is “challenged” in a controlled manner.

This seems sort of simple, but it can actually be complicated in ways you don’t anticipate (as I discovered during my “test” of the elimination diet). It’s best done with the help of a registered dietitian who has experience working with IBS patients and FODMAPs.

The ultimate goal of the elimination and the challenge portions of the diet is to find out specifically which foods, in which amounts, cause symptoms. This allows patients to have the most varied diet possible, while still avoiding IBS symptoms…or at least know what they’re getting into if they choose to eat a food they know gives them trouble! Things have come a long way since the days when people with IBS were told that to give up dairy, eat more fiber or to try to reduce their stress level.

If you want to learn more, Kate Scarlata, RD has some great FODMAP information on her blog. So does IBSfree, the website of Patsy Catsos, RD, author of IBS: Free at Last.