There is many myths surrounding breastfeeding and what you eat.
Breastmilk is made from plasma (blood) so officially speaking the only things that you consume that effect your baby would be things that carry through the blood such as drugs, chemicals and alcohol etc. Many midwives say it is all just coinsidence that your baby has a bad night once in a while when you have eated something like coke, garlic etc. Physiologically there should be no way that something that goes into your stomach can end up in your breast milk.
Then again, many other midwives say there are things that upset the little ones. I personally don't take too much notice but then it's a personal choice thing. Some women are convinced that certain things upset their baby but then when you look at it logically, how can it??
My advice would be keep an eye on it and if you do see a pattern it will do you no harm to avoid things if it works for you. Remember babies will always have the odd rough night, it doesn't have to be something you have eaten. It could just be a growth spurt when they are very hard to settle - these come at around ten days and six weeks.
Much love
