What you eat can
Breast milk won't make babies gassy usually, and most tolerate straight breast milk very well.
However, there are certain foods that are famous for causing gas and bloating if mom eats them, then breastfeeds: cabbage, spicy foods
, pepper, onions, garlic, caffeine
, broccoli, cauliflower, carrots. I've had parents figure out almonds, tomatoes, and such. Scout recent meals and take notes.