Complex carbohydrates have an appreciable amount of fiber or roughage that is essential for the proper elimination of waste. There are no recommended dietary allowances for dietary fiber but it is suggested that an intake of 25% dietary fiber a day is desirable.

Since we do not need complex carbohydrates, how much and from where should we get it?

Yes, we do need complex carbohydrates. It's essential to our diet and nutrition. How much of it is needed depends entirely on your goals.