Inflammatory bowel disease: Ulcerative colitis and Crohn's

Both types of inflammatory bowel disease (IBD), ulcerative colitis and Crohn's disease, result from an abnormal reaction by the body's immune system.

Your immune system is the body's defense against foreign invaders like bacteria and viruses. When the body senses these intruders, your immune system sends out white blood cells to fight them. This army of cells triggers a response called inflammation, which fights the attacker and protects the body from infection. Once the invader is destroyed, inflammation usually goes away.

However, in people with IBD, the immune system mistakes food and the normal bacteria in the gut for invading substances and attacks the digestive tract. This can expose your entire gastrointestinal system to a barrage of constant inflammation.

This chronic inflammation can ignite a series of digestive problems. It can make digestion more difficult, leading to abdominal pain, cramping, diarrhea, more-urgent bowel movements, and bloody stools.

Diet and IBD

There is no single diet that works best for managing inflammatory bowel disease. In fact, no studies have shown that any specific diet improves symptoms or that any specific foods cause IBD flare-ups. There is no strong evidence that following any specialized diet — such as low-carb, vegetarian, or paleo — has any effect on keeping IBD in remission.

The best approach for managing IBD is to avoid or reduce the foods that aggravate your symptoms. Having a nutritionist design a specialized diet plan for you may be helpful. The nutritionist will first want to identify foods that may trigger flare-ups or make your symptoms worse.

Some people with IBD also have symptoms of irritable bowel syndrome (IBS), a non-inflammatory disorder of the intestines. In these cases, a low-FODMAP diet may be helpful.

FODMAP stands for the short-chain carbohydrates known as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Some people who eat high-FODMAP foods have an increased risk of problems like diarrhea, bloating, abdominal pain, and flatulence. FODMAPs include the following:

• disaccharides, such as lactose (in milk and other dairy products)
• monosaccharides, such as fructose (for example, in apples and honey)
• oligosaccharides, such as fructans (in wheat, onions, and garlic, for example) and galactans (commonly found in beans, lentils, and soybeans)
• polyols, such as sorbitol and mannitol (in some fruits, vegetables, and artificial sweeteners).

For more information on treating inflammatory bowel disease, check out Ulcerative colitis and Crohn's disease, an online guide from Harvard Medical School.

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