VitalMatrix
MineralsStrong

Iron

Also known as Ferrous bisglycinate, Ferrous sulfate

Iron is the core of hemoglobin, which carries oxygen through the blood. Deficiency causes fatigue and is especially common in menstruating women, vegetarians, and endurance athletes, but iron should only be supplemented when low.

EnergyBlood health
By the Vital Matrix Editorial TeamReviewed by the Vital Matrix Research TeamLast updated June 25, 2026Strong2 citations
Where to buy(affiliate links — we may earn a commission, which never changes our ratings)Nootropics DepotiHerb

Benefits

Corrects iron-deficiency fatigue

Strong

Restoring iron stores resolves the tiredness of deficiency anemia.

Supports exercise capacity

Moderate

Adequate iron is needed for oxygen delivery during exertion.

Pros & cons

Pros

  • Resolves a very common deficiency
  • Dramatic energy improvement when deficient

Cons

  • Constipating for many people
  • Dangerous if taken without deficiency

Side effects

Constipation and GI upset

A very common reason people stop iron; gentler forms or alternate-day dosing help.

Moderate

Toxic in overload

Excess iron is harmful; never supplement without confirmed need.

Serious

How to take it

Typical dose

Only when deficient; commonly 18–65 mg elemental iron

Timing

With vitamin C; away from calcium, coffee, and tea

Tip: Alternate-day dosing can improve absorption and reduce side effects.

Forms: which one to choose

The main forms of Iron compared by absorption, tolerability, and best use.

Iron Bisglycinate

Most popularHigh absorption

Best for: Sensitive stomachs · Chelated and easy on digestion

Read about Iron Bisglycinate

Ferrous Sulfate

Moderate absorption

Best for: Standard, low-cost repletion · The classic, most-studied iron salt

Read about Ferrous Sulfate

Ferrous Fumarate

Moderate absorption

Best for: More elemental iron per pill · Higher elemental iron by weight

Read about Ferrous Fumarate

Ferrous Gluconate

Moderate absorption

Best for: A gentler salt option · Lower elemental iron per pill

Read about Ferrous Gluconate

What the research says

  1. [1]Iron and fatigue in deficiency

    Strong

    Supplementation improves fatigue and work capacity in iron-deficient individuals, even without full anemia.

    Clinical trials · 2016PubMed

  2. [2]Alternate-day iron dosing

    Moderate

    Spacing doses may increase fractional absorption by reducing hepcidin spikes.

    Absorption studies · 2017PubMed

How Iron interacts

Synergies, absorption effects, and cautions between Iron and other supplements in the matrix.

Iron and its direct connections · click a node to open its guide

Boosts absorption
Vitamin C

Vitamin C strongly increases absorption of plant-based iron when taken together.

Compare the pairing
Synergy
Folate (B9)

Both folate and iron are needed for healthy red blood cell production. Deficiency in either causes anaemia.

Compare the pairing
Cofactor
Vitamin B12 (Cobalamin)

Both are required for healthy red blood cell production; deficiency of either causes anaemia.

Compare the pairing
Use with care
Calcium

Calcium taken at the same time inhibits iron absorption; separate them by at least two hours.

Compare the pairing
Use with care
Psyllium Husk

Soluble fiber can bind minerals such as iron and reduce their absorption, so separate the two by a couple of hours.

Compare the pairing
See it on the matrix

Frequently asked questions

What is Iron used for?

Iron is most commonly used for energy and blood health. Restoring iron stores resolves the tiredness of deficiency anemia.

How much Iron should I take?

A typical dose is Only when deficient; commonly 18–65 mg elemental iron. Alternate-day dosing can improve absorption and reduce side effects. Start at the lower end and confirm the right dose for you with a healthcare professional.

When is the best time to take Iron?

Recommended timing: With vitamin C; away from calcium, coffee, and tea.

What are the side effects of Iron?

Reported side effects include constipation and gi upset and toxic in overload. A very common reason people stop iron; gentler forms or alternate-day dosing help.

Who should be careful with Iron?

Do not supplement iron without a blood test confirming deficiency. Keep away from children; overdose is dangerous. Speak with a healthcare professional if any of these apply to you.

Important cautions

  • Do not supplement iron without a blood test confirming deficiency. Keep away from children; overdose is dangerous.

More Minerals

Boron

A trace mineral for bone, hormones, and mineral metabolism.

MineralsModerate
4 connectionsBone health · Hormones

Calcium

The primary structural mineral of bones and teeth.

MineralsModerate
5 connectionsBone health

Copper

The trace mineral that balances zinc.

MineralsModerate
2 connectionsMineral balance · Antioxidant