What is the best form of iron?

5 forms compared by what actually reaches your bloodstream. Absorption ranges from 20% to 90% — a difference that matters more than the milligrams on the label.

0 forms

0 best absorption %

0 average %

Ranked by absorption

Higher means more of the dose reaches you

Iron Bisglycinate 90 Iron for Energy 85 Heme Iron 85 Iron Fumarate 25 Iron Sulfate 20

Short answer

Iron Bisglycinate absorbs best — 90%.

Gentle high-absorption iron. Typical dose 18-65 mg elemental, about $30 a month. The cheapest option is Iron Sulfate at $8, but it only absorbs at 20%.

See Iron Bisglycinate

Every form side by side

Form	Absorbed	Safety	Per month	Dose	Evidence
Iron Bisglycinate	90%	7/10	$30	18-65 mg elemental	A
Iron for Energy	85%	7/10	$15	18-200 mg elemental iron	A
Heme Iron	85%	10/10	$120	18-30 mg	A
Iron Fumarate	25%	8/10	$18	65-130 mg	A
Iron Sulfate	20%	6/10	$8	65-200 mg	A

Head to head

10 comparisons

Iron Fumarate vs Iron Sulfate 25% · 20% Iron for Energy vs Iron Sulfate 85% · 20% Iron Bisglycinate vs Iron Sulfate 90% · 20% Heme Iron vs Iron Sulfate 85% · 20% Iron for Energy vs Iron Fumarate 85% · 25% Iron Bisglycinate vs Iron Fumarate 90% · 25% Heme Iron vs Iron Fumarate 85% · 25% Iron Bisglycinate vs Iron for Energy 90% · 85% Heme Iron vs Iron for Energy 85% · 85% Heme Iron vs Iron Bisglycinate 85% · 90%

How to read this

Absorption is the share of the dose that reaches your bloodstream — the number that decides whether the milligrams on the label mean anything.
A cheaper form at half the absorption is not cheaper per unit delivered.
Safety here reflects tolerance at normal doses, not toxicity risk.
Evidence A means the form itself was studied, not just the parent compound.

Common questions

What is the best form of iron?

Iron Bisglycinate — it absorbs at 90%, the highest of the 5 forms here. Gentle high-absorption iron. Typical dose 18-65 mg elemental.

Which form of iron is worst absorbed?

Iron Sulfate at 20%. It is usually the cheapest option, which is exactly why it ends up in budget products.

Is the expensive form of iron worth it?

Compare per unit delivered, not per bottle. Iron Sulfate costs $8 a month at 20% absorption, Iron Bisglycinate costs $30 at 90%.

How much iron should you take?

Doses differ by form: Iron Bisglycinate 18-65 mg elemental; Iron for Energy 18-200 mg elemental iron; Heme Iron 18-30 mg; Iron Fumarate 65-130 mg.