Chia seeds

Can anyone tell me if it is OK to eat Chia seeds after RNY? At what stage would it be OK to start eating them. Also why have I been advised not to eat green leafy vegetables like baby spinach and kale - before my gastric bypass I was drinking green juice everyday.

Thanks

I was told to avoid strawberries, anything with small seeds, and any greens for the first three months.  No seeds was to avoid the risk of having a small seed catch in the still healing staple lines.  Lack of green vegetables and other roughage was just to keep the healing insides from being irritated. 

Some doctors have different plans.  That was mine.  After three months, no food was off limits to me.