You can increase your hemoglobin by eating more iron-rich foods, improving how your body absorbs that iron, and making sure you’re getting enough of the vitamins that support red blood cell production. Healthy hemoglobin ranges are 13.2 to 16.6 g/dL for men and 11.6 to 15 g/dL for women. If your levels fall below those ranges, dietary changes are usually the first step, with supplements and medical treatment reserved for more significant drops.
Why Hemoglobin Drops in the First Place
Hemoglobin is the protein inside red blood cells that carries oxygen to your tissues. When levels fall, it’s almost always because your body is either losing red blood cells faster than it can make them or it’s missing a key ingredient it needs to build them. The most common missing ingredient is iron, but deficiencies in folate (vitamin B9) and vitamin B12 can also tank your levels. Blood loss from heavy periods, surgery, or gastrointestinal bleeding is another frequent cause. Chronic conditions like kidney disease, inflammatory disorders, and certain infections can suppress red blood cell production too.
Iron-Rich Foods That Make the Biggest Difference
Iron is the central building block of hemoglobin, and the type of iron you eat matters. Your body absorbs heme iron (from animal sources) much more efficiently than non-heme iron (from plants). That doesn’t mean plant iron is useless, but you’ll need to eat more of it and pair it strategically to get the same benefit.
Best Heme Iron Sources
- Oysters: 6.9 mg per 3 oysters
- Mussels: 5.7 mg per 3 ounces
- Organ meats: 1.8 to 19 mg per 3 ounces, depending on the type
- Duck breast: 3.8 mg per 3 ounces
- Bison: 2.9 mg per 3 ounces
- Beef: 2.5 mg per 3 ounces
- Sardines: 2.5 mg per 3 ounces
- Lamb: 2.0 mg per 3 ounces
Best Non-Heme Iron Sources
- Fortified cereals: 8 to 16 mg per serving (check the label, as brands vary widely)
- Cooked spinach: 6.4 mg per cup
- Cooked lima beans: 4.9 mg per cup
- Soybeans: 4.4 mg per half cup
- Cooked Swiss chard: 4.0 mg per cup
- Lentils: 3.3 mg per half cup
- White beans: 3.3 mg per half cup
- Chickpeas: 2.4 mg per half cup
- Kidney beans: 2.0 mg per half cup
The daily iron recommendation from the NIH is 8 mg for adult men and 18 mg for adult women of reproductive age. Pregnant women need 27 mg. After age 51, both men and women need 8 mg. These numbers give you a target to aim for as you look at the food values above.
How to Absorb More of the Iron You Eat
Eating iron-rich food is only half the equation. What you eat alongside it can dramatically change how much iron actually reaches your bloodstream.
Vitamin C is the single best absorption booster. It converts iron into a form your gut can absorb more easily, and it continues to help shuttle iron into cells even after it’s in your blood. Practical pairings look like squeezing lemon over cooked spinach, eating strawberries with fortified cereal, or adding bell peppers to a bean stew. This pairing matters most for plant-based iron, since non-heme iron is harder to absorb on its own.
Calcium works in the opposite direction. It reduces iron absorption by roughly 18 to 27%, depending on the amount. You don’t need to eliminate dairy or calcium-rich foods, but try not to eat them at the same meal where you’re focusing on iron intake. Coffee, tea, and other drinks high in tannins (a type of plant compound) also interfere with iron absorption. Spacing your coffee or tea at least an hour away from iron-heavy meals is a simple fix.
Folate and Vitamin B12 Matter Too
Iron gets most of the attention, but your body can’t build functional red blood cells without folate and vitamin B12. When either is missing, your bone marrow produces oversized, malformed cells called megaloblasts. These abnormal cells don’t divide properly, can’t always exit the bone marrow into your bloodstream, and die earlier than healthy red blood cells. The result is fewer circulating red blood cells and lower hemoglobin.
B12 deficiency can also cause neurological problems over time, including memory loss, balance issues, and tingling or prickling in the hands and feet. Good sources of B12 include meat, fish, eggs, and dairy. Folate is found in dark leafy greens, legumes, and fortified grains. If you eat a varied diet, you’re likely covered, but vegans and older adults are at higher risk for B12 deficiency specifically and may need a supplement.
When to Consider Iron Supplements
If dietary changes aren’t enough, or your hemoglobin is significantly low, iron supplements can help. The three common forms differ in how much usable iron they deliver per tablet:
- Ferrous fumarate (325 mg tablet): 108 mg of elemental iron
- Ferrous sulfate (325 mg tablet): 65 mg of elemental iron
- Ferrous gluconate (325 mg tablet): 35 mg of elemental iron
The “elemental iron” number is what your body can actually use. A 325 mg ferrous sulfate tablet doesn’t give you 325 mg of iron; it gives you 65 mg. This is worth knowing because it explains why your provider might choose one form over another depending on how much iron you need and how well you tolerate it.
Managing Supplement Side Effects
Iron supplements are notorious for causing stomach cramps, nausea, constipation, and diarrhea. These side effects are real and common enough that many people stop taking their supplements too early. A few strategies help:
Taking iron with a small amount of food reduces nausea and cramping, though a full meal (especially one with calcium or coffee) can blunt absorption. A few crackers or a piece of fruit works well. If constipation becomes a problem, an over-the-counter stool softener can help. If nausea and vomiting persist, taking smaller doses spread through the day often makes a difference. Switching to a different form of iron (say, from ferrous sulfate to ferrous gluconate, which has less elemental iron per dose) is another option to discuss with your provider rather than simply stopping.
Exercise and Altitude
Your body naturally adjusts hemoglobin production in response to oxygen demand. Living at or spending extended time at high altitude triggers your kidneys to release a hormone that tells your bone marrow to produce more red blood cells. Research on altitude acclimatization shows that hemoglobin mass increases measurably within about two weeks of living at higher elevations. This is why elite athletes sometimes train at altitude before competitions.
Regular exercise, particularly aerobic activity like running, cycling, or swimming, increases your body’s demand for oxygen and can stimulate red blood cell production over time. However, exercise alone won’t correct a clinically low hemoglobin level caused by iron deficiency or another underlying condition. Think of it as a supporting factor, not a fix.
How Long It Takes to See Results
If you start eating more iron-rich foods or taking supplements, don’t expect overnight changes. Your body needs time to absorb iron, incorporate it into new hemoglobin molecules, and release those red blood cells into circulation. Most people begin to feel less fatigued within a few weeks, but it typically takes two to three months of consistent iron intake to fully replenish depleted stores. A follow-up blood test around that time will show whether your levels have responded.
If your hemoglobin hasn’t budged after a few months of dietary changes and supplementation, the cause may not be simple iron deficiency. Chronic blood loss, absorption disorders like celiac disease, vitamin B12 or folate deficiency, or chronic illness can all keep hemoglobin stubbornly low and require different treatment approaches.