How to increase ferritin

Ferritin rises when iron absorption exceeds iron loss. The levers below are ranked by the size of effect in the studies cited.

• Oral iron. In fatigued non-anemic women, 80 mg of iron a day for 12 weeks raised ferritin by 11.4 ng/mL more than placebo [6]. Alternate-day dosing absorbs more per dose [2].
• Keeping tea and coffee away from meals. One cup of tea cut absorption from a meal by 64%, one of coffee by 39%. Coffee one hour before a meal had no effect, but coffee one hour after inhibited absorption as much as coffee with the meal [4].
• Reducing phytate or adding vitamin C. Phytate in grains and legumes cut absorption in a dose-dependent way, and ascorbic acid significantly counteracted it [7].
• Choosing heme iron. Mixed diets deliver iron with about 14% to 18% bioavailability versus 5% to 12% for vegetarian diets [8].
• Intravenous iron. Used when tablets fail, are not tolerated or cannot be absorbed; it replaces stores quickly [9].

Your own iron status changes absorption more than diet does: the body absorbs more when stores are low [8].

Food iron comes in two forms:

• Heme iron in meat, poultry and fish. It uses a separate absorption route, and tea does not inhibit iron from cooked hemoglobin the way it inhibits plant iron [10]. Meat in a meal is also linked with better absorption of the nonheme iron eaten alongside it [5].
• Nonheme iron in legumes, greens, nuts, seeds and fortified grains. Its absorption depends strongly on the rest of the meal: phytate lowers it and vitamin C raises it [7].

Eggs contain iron, but searches such as "do eggs have ferritin" mix up two things: foods contain iron, and your body makes ferritin to store it.

On a whole-food plant-based diet, the practical pattern is beans or lentils with a vitamin C source such as peppers or citrus, and tea or coffee between meals instead of with them. On a carnivore diet, heme iron intake is high, so low ferritin is less likely to be dietary and worth investigating.

In single-meal isotope studies, ascorbic acid significantly counteracted the inhibition of iron absorption by phytate [7]. But when researchers changed vitamin C intake across a complete diet for five days, from 51 to 247 mg a day, mean iron absorption did not change significantly [5]. The authors concluded the effect in a full diet is far less pronounced than in single meals.

That fits the broader picture: in varied diets with many enhancers and inhibitors, single components have modest effects [8]. Vitamin C is a sensible habit with plant iron, not a substitute for treating deficiency.

Each oral dose of 60 mg or more raises hepcidin for about 24 hours, which cuts absorption from the next day's dose by 35% to 45%. A sixfold increase in dose, from 40 to 240 mg, only tripled the iron absorbed, from 6.7 to 18.1 mg [11].

• Alternate days. 60 mg on alternate days was absorbed at 21.8% versus 16.3% with consecutive daily doses, and twice-daily splitting gave no gain [2].
• Fewer side effects. In a 2023 double-blind trial of 150 women with ferritin of 30 µg/L or lower, alternate-day dosing gave the same ferritin at equal total doses, daily dosing caused gut side effects on 1.56 times as many dosing days, and alternate-day dosing left less iron deficiency at 6 months (3.0% versus 11.4%) [3].
• Side effects are common. Ferrous sulfate more than doubled the odds of gut side effects compared with placebo across 43 trials [12].
• Guideline default. BSG recommends one tablet a day of ferrous sulphate, fumarate or gluconate, and every other day if not tolerated [1].

"Ferritin supplements" are a search term, not a product class: supplements contain iron salts, and ferritin is what your body builds from them. The right dose and schedule depend on how low ferritin is, the cause, and other conditions.

Hepcidin raised by inflammation limits oral iron absorption, and modern parenteral formulations allow rapid, safe replacement of the full iron deficit [9]. BSG lists parenteral iron among the options for people who cannot tolerate oral iron [1], and one clinical review argues it is underused, with full replacement doses given in minutes to a few hours [13]. In restless legs syndrome, intravenous ferric carboxymaltose is rated effective when ferritin is below 300 µg/L [14].

Intravenous iron is a medical treatment given in a clinic; the choice of product and dose belongs to the treating clinician.

In the fatigue trial, ferritin was measured at 6 and 12 weeks, and the authors suggested checking response after six weeks [6]. After a blood donation, low-ferritin donors taking 37.5 mg of iron daily recovered baseline ferritin in a median of 21 days, while most donors not taking iron had not recovered by 168 days [15].

If ferritin does not rise as expected, that is a signal to look again for ongoing blood loss, poor absorption or inflammation, not simply to take more.