Women breastfeed around the world, and they have varied diets. There are no foods that you absolutely need to avoid while breastfeeding unless you have a family history of food allergies and have been advised to avoid those foods by your healthcare provider.
If you begin to notice that your baby is unhappy (including gassiness or crankiness) when you give certain foods, you can try to find the culprit by eliminating those items from your diet one at a time to try to find the cause of the baby's discomfort. For instance, into his or her second month, your baby may start to show sensitivities to certain foods that you are eating. One of the biggest culprits to show up as a food sensitivity for breastfed babies is mother's consumption of cow's milk/dairy products. Because it takes a few weeks to eliminate dairy from your system, you will need to stop consuming dairy that includes cow's milk for a few weeks to really tell if it is the cause.
Some babies show sensitivities to other foods besides dairy products including caffeine. Again, unless your doctor recommends avoiding certain foods, there is no reason to limit your diet while breastfeeding.