Do potatoes worsen Crohn's symptoms?

Potentially.  Here is the evidence I've found in support of eliminating potatoes to ameliorate Crohn's symptoms.  But what I've really learned, is that they should not be a part of any wellness diet, regardless of the specific underlying pathology.

Potatoes are polysaccharides.  Elaine Getschell, (Specific Carbohydrate Diet) among others, theorized that polysaccharides (starches) feed undesirable bacteria in the small bowel and large intestine causing IBD symptoms.  Since potatoes are predominantly starch (polysaccharide), digestion occurs in the large bowel.  Eliminating potatoes removes what is potentially a very significant source of polysaccharides, cutting off nourishment for harmful bacterias in a vulnerable gut.  See my post "What is the Specific Carbohydrate Diet?"

Potatoes are nightshades (solanaceae) containing  alkaloids, which are toxins, which may affect nerves, muscles, and joints in susceptible people.  Patients in the arthritis community commonly eliminate nightshades from their diets for symptom relief. See Dr. Childer's Arthritis Nightshades Research Foundation.  See my post entitled "Do foods from the nightshade family worsen the symptoms of CD?"

Potatoes contain glycoalkaloids (alpha-solanine and alpha-chaconine), natural defense mechanism, which makes the intestine even more permeable.  Peeling and high heat cooking does not eliminate glycoalkaloids.   To make matters worse, frying potatoes intensifies these molecules.  Diarrhea is among the effects of glycoalkaloid intake. Those with gut integrity issues are best to avoid worsening permeability.  See  my post entitled "Do glycoalkaloids worsen Crohn's symptoms?"  

Potatoes are a mainstay of the high carb SAD diet, which is associated with a plethora of negative health effects including inflammation, cancers, and metabolic syndrome. As a general rule, reducing or eliminating high carbohydrate foods is health-promoting.  

There is great interest in carbohydrate reduction in many wellness communities.  In the paleo community, see, for example, Mark's Daily Apple and Robb Wolf.  For an alternative wellness plans by medical doctors, see, for example, Dr. Mercola at Mercola.com and Drs. Eades and Eades at DrsEades.com.  For low glycemic foods see Atkins, South Beach Diet, and  Low Glycemic diets.

I cannot identify any downside to eliminating potatoes, other than dealing with the shock of others who find it astonishing that we are able to go on living without potatoes.  My kids don't miss them and neither do I.  We roast carrots and mash squash, and with all the other yummy food we're eating, we've never looked back.