Raising your iron levels comes down to three things: eating more iron-rich foods, helping your body absorb the iron you already consume, and avoiding the common habits that block absorption. Most people can improve their iron status through diet alone, but some situations call for supplements or medical treatment.
How much iron you need depends on who you are. Adult men need 8 mg per day. Pre-menopausal women need 18 mg, more than double, primarily because of menstrual blood loss. Pregnant women need 27 mg. These numbers sound small, but your body only absorbs a fraction of the iron you eat, which is why strategy matters as much as quantity.
Heme vs. Non-Heme Iron
Iron in food comes in two forms. Heme iron, found in meat, poultry, and seafood, is absorbed at a rate of 15 to 35%. Non-heme iron, found in plants, eggs, and fortified foods, is absorbed far less efficiently. For people eating mixed diets, overall iron bioavailability lands around 14 to 18%. For vegetarians, it drops to 5 to 12%.
Here’s what makes this gap so significant: heme iron contributes only 10 to 15% of total iron intake in meat-eating populations, yet because of its superior absorption, it can account for over 40% of the iron your body actually takes in. A small serving of red meat or shellfish punches well above its weight compared to an equivalent amount of spinach or lentils.
That said, non-heme iron still matters. It makes up the majority of dietary iron for almost everyone, and it’s found in a wide range of affordable, accessible foods: beans, lentils, tofu, fortified cereals, dark leafy greens, and whole grains. The key is pairing these foods with absorption boosters and keeping them away from absorption blockers.
What Helps Your Body Absorb More Iron
Vitamin C is the single most effective way to increase non-heme iron absorption. It converts iron into a chemical form your gut can take up more easily. Practical pairings look like this: squeeze lemon over lentil soup, eat strawberries with your fortified cereal, add bell peppers to a bean stir-fry, or drink a small glass of orange juice alongside an iron-rich meal.
Eating heme and non-heme iron together also helps. Adding even a small amount of meat or fish to a plant-based meal boosts absorption of the non-heme iron in that same meal. This is sometimes called the “meat factor,” and it works independently of vitamin C.
What Blocks Iron Absorption
Some of the most common drinks and foods actively interfere with iron absorption, and the effects are surprisingly large.
- Tea and coffee: The polyphenols in tea reduced iron absorption from a test meal by 56 to 72% in one study, and by more than 85% in women with iron deficiency anemia. Coffee has a similar, slightly weaker effect. If you drink either regularly, keep them at least an hour away from iron-rich meals.
- Calcium: Whether from dairy or supplements, calcium reduces iron absorption by roughly 18 to 27%. One study found it cut absorption from 10.2% down to 4.8% in a single meal. If you take a calcium supplement, take it at a different time of day than your iron-rich meals or iron supplements.
Phytates, found in whole grains and legumes, also reduce absorption. Soaking, sprouting, or fermenting these foods (think sourdough bread instead of regular bread) breaks down some of the phytates and frees up more iron.
How to Take Iron Supplements Effectively
If diet changes aren’t enough, iron supplements are the standard next step. The most common forms are ferrous sulfate (20% elemental iron), ferrous fumarate (33% elemental iron), and ferrous gluconate (12% elemental iron). A typical 325 mg ferrous sulfate tablet delivers about 65 mg of actual iron. A 200 mg ferrous fumarate tablet delivers about 66 mg. A 300 mg ferrous gluconate tablet delivers only 36 mg. The label on your supplement should list the elemental iron content, which is the number that actually matters.
Timing makes a real difference. Research published in The Lancet found that taking iron supplements on alternate days rather than every day increased absorption per dose by 35 to 50%. This happens because a dose of iron triggers your body to produce a hormone called hepcidin, which temporarily blocks further absorption. By the next day, hepcidin levels are still elevated. Skipping a day lets them fall, so your gut is primed to absorb more from the next dose.
In a randomized trial, alternate-day dosing also triggered significantly fewer gastrointestinal side effects like nausea, constipation, and stomach pain. However, there’s a tradeoff: because you’re taking half as many doses per week, total iron absorbed over time is somewhat lower than daily dosing. For people who struggle with side effects, alternate-day dosing offers a practical compromise. For those who tolerate daily dosing, it still delivers more total iron over the same period. Taking supplements on an empty stomach improves absorption, though taking them with a small amount of food can reduce stomach upset if needed.
How to Know If It’s Working
A blood test measuring serum ferritin is the most useful way to track your iron stores. Ferritin below 15 micrograms per liter is diagnostic of iron deficiency. Levels between 15 and 30 indicate probable deficiency. Above 30 makes deficiency unlikely, but the target for healthy, replete iron stores is above 100.
If you’ve started supplements or made significant dietary changes, expect to recheck your levels after about three months. Hemoglobin often starts improving within a few weeks, but fully rebuilding your iron stores takes longer, sometimes four to six months or more depending on how depleted you were.
When Diet and Supplements Aren’t Enough
Some people don’t respond well to oral iron. This includes people with inflammatory bowel disease, chronic kidney disease, or a history of bariatric surgery, all conditions where gut absorption is impaired. It also includes anyone who can’t tolerate the side effects of oral supplements despite trying different formulations and alternate-day dosing.
In these cases, intravenous iron is the alternative. It bypasses the gut entirely and delivers iron directly into the bloodstream. IV iron is also preferred when there’s a time-sensitive need, like correcting anemia before surgery with less than six weeks of lead time. The number of infusions depends on how depleted your stores are: someone who is iron-deficient but not anemic may need only one or two sessions, while someone with severe anemia may need several sessions spread over weeks.
For most people, though, the combination of iron-rich foods, vitamin C at meals, smart timing around tea, coffee, and calcium, and properly dosed supplements will steadily bring iron levels back up. The tolerable upper intake level for supplemental iron in adults is 45 mg of elemental iron per day unless a healthcare provider has recommended a higher therapeutic dose for confirmed deficiency.