So I must clarify something I said earlier. I made it sound like Selenium was REQUIRED for the liver to process Iron; when more clearly put, Selenium is essential for overall liver function. Selenium protects the liver tissues against oxidative damage and when the liver is overburdoned or stressed the first two functions to slow are fat metabolisation and iron distribution (the liver will retain the iron).
I wanted to add that vitamin E and supplemental Calcium both block Iron absorption. Vitamin B6 and B12 dificiencies can lead to anemia...B12 has been a concern for strict vegans...things to consider?
"Spinach, Swiss chard, beet greens and rhubarb contain a substance known as oxalic acid that may bind iron and lessen its absorption, thus these may not be the best iron providers, despite their iron contents." From "Becoming Vegan" by Dr.'s Davis and Melina
Spinach contains a lot of iron but the iron's bioavailability is actually quite low. That is, our bodies have a difficult time absorbing it. I haven't noticed this information to be included in the Thrive books. Iron absorption is enhanced by the presence of citric acid (present in citrus fruits) so it's always a good idea to eat some kind of citrus fruit (I usually have half an orange) when enjoying spinach.
"Becoming Vegan", I have found, is an outstanding vegan nutrition guide and I recommend it to everyone.