We love our green smoothies (my version is similar to this) but we were recently warned that consuming raw spinach wasn't very good for our health.I did some google research and found that raw spinach contains large amounts of oxalic acid which can apparently inhibit the absorbtion of iron and calcium in the body. Oxalic acid can also combine with calcium in the kidneys and form kidney stones. Cooking spinach breaks down the oxalates which enables the body to absorb the high levels of calcium and iron present in the spinach and also prevents these unabsorbable "stones" from forming.We have been having silverbeet in our smoothies lately so I am now off to check if silverbeet contains oxalix acid also! It probably wouldn't be a worry to most people, but I just thought I would post a warning incase people are making these regularly.