Less sugars, carbs, and highly glycemic foods such as wheat, rice, and corn will probably make the most difference. Basically avoid the sorts of things in a Little Debbie snack. It'll improve your skin a lot too!
> On the level of tissue, glutamine plays a role in maintaining the normal integrity of the intestinal mucosa.,[12] but randomised trials provide no evidence of any benefit of nutritional supplementation.[12]
It's cheap to buy and try if it changes anything for you.