The United States Department of Agriculture states that a 180 g serving of boiled spinach contains 6.43 mg of iron.
The reason you should you always use a stainless steel knife to cut your spinach is intriguing and is a major stumbling block to the fortification of food with iron.
Remember that a lack of iron is the world’s most prevalent nutritional deficiency.
Both iron blade and spinach will become discolored because of the reaction between the polyphenols in the spinach and the iron blade.
If you want to see a dramatic illustration of this, make yourself a cup of tea and add a few crystals of a soluble iron salt such as ferrous sulfate.
Don’t drink it.
The black discoloration you see is caused by the reaction between polyphenols, called tannins, in the tea, and the iron.
The resulting black compound is highly insoluble.
The implications for iron absorption in the body are huge because iron in this form is virtually unavailable for absorption. So whatever the source of strength in Popeye’s spinach, it is not the iron.
Polyphenols are found in many vegetables and, together with phytates, are the reason why many people who subsist on cereal and vegetable diets have an iron deficiency.
Fortifying such diets with iron salts creates two problems.
First, the iron is not absorbed; and second, the colored ironpolyphenols make the food look unattractive.
The best way to get enough iron is to have a balanced diet.
Get enough protein because dietary iron is best absorbed as part of a protein such as heme protein.
To all the vegetarians out there, if you don’t eat your meat, you can’t have any pudding.