if you sort through this, you'll see just how much of a difference there really is in oxalates. it's not some minor difference; spinach is off the chart. even a little bit is likely to block minerals, and you just don't get much iron from it.
the actual reason i bought the spinach was for the betaine & the k, as the eggs were low on both; i took the lutein as a bonus. that's not going to work out - a comparable amount of kale is better for the last two, and i'm better off sticking with the beets, just less, for the betaine, considering i'm likely going to need the potassium, anyways.
but, the other way to get betaine is via quinoa. let me look into that more seriously.