Talk to your doctor or specialist about any deficiencies you might have as having Crohn's disease can mean you stop getting important minerals and vitamins, here are some common deficiencies and what to take for them:
Many people suffer from a lack of energy due to their Crohn's so I recommend taking sublingual b12 supplements to keep up your energy levels. It is important to get the sublingual version of b12 which dissolves under the tongue. This is because many people with Crohn's disease struggle to dissolve b12 through food and tablets due to damage to the gut.
Avoiding dairy has been recommended to me by many dieticians so it makes it very difficult to keep recommended calcium levels in your diet. I recommend taking a daily calcium supplement (it's in fact the only supplement I take) along with introducing Edemame beans and Sesame seeds to your diet which are the safest way to get Calcium.