Table 1. Factors That Influence Iron Absorption
Physical State (bioavailability) heme > Fe2+ > Fe3+
Inhibitors phytates, tannins, soil clay, laundry starch, iron overload, antacids
Competitors lead, cobalt, strontium, manganese, zinc
Facilitators ascorbate, citrate, amino acids, iron deficiency
Ok, so to understand about the best iron supplement, you need to understand about how iron is absorbed. Heme iron (in blood) is transported totally separate from iron by by itself.
According to the table above, heme iron is the best. But drinking blood and eating a lot of red meat isnt kosher. Actually the real practice that Paul was warning against was people strangling animals and drinking the blood to get a high off the catacholamines. Anyways, if your not into meat, ferrous (Fe2+) is absorbed by a metal ion transporter. Vitamin C and citrate help as well as a low pH. Low PH and ascorbate and citrate stabilizes the Fe in a soluble form.
Really, the best and cheapest way to take iron is FeSo4 iron sulfate between meals with a glass of citrus juice or a vitamin C tab. Don't take it with Antacids, milk, soy, other minerals, tea, coffee, or with wheat-containing foods as other metals, tannins and phytates inhibit absorption.
If the iron upsets your stomach than take it with meals. If iron causes constipation, than take a stool softener colace.
Don't be fooled into taking expensive iron supplements that claim they are necessarily better absorbed. FeSO4 is dirt cheap and does very well. Taking your iron along with vitamin A, beta-carotene and riboflavin can increase absorption, but I would only do this of you also were deficient in these vitamins. Iron with amino acids are also well absorbed. But again, the gains may not be worth the price.
Iron Supplement Tablet Size Elemental Iron
Ferrous fumarate 325 mg 108 mg
Ferrous sulfate 325 mg 65 mg
Ferrous gluconate 325 mg 35 mg
Ferrous fumarate has the highest elemental iron per 325mg tab. The max dose of iron per day should not exceed 200mg/day unless a hematologist says its okay. Due to deminishing returns, taking multiple small iron tabs per day is better than taking a large dose of iron all at one time.
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