Raising hemoglobin comes down to giving your body the raw materials it needs to build red blood cells, then removing the obstacles that get in the way. For most people, that means more iron, the right supporting nutrients, and a few simple timing strategies around meals. Normal hemoglobin runs about 14 to 15 g/dL for adult men and around 13 g/dL for adult women. If yours is low, the approach depends on how far below normal you are and what’s causing the drop.
Iron Is the Starting Point
Iron is the core building block of hemoglobin, the protein in red blood cells that carries oxygen. When iron is low, your body simply can’t produce enough functional hemoglobin, no matter how well everything else is working.
Not all dietary iron is created equal. Heme iron, found in animal foods, is absorbed significantly better than non-heme iron from plants. The richest heme sources include oysters, clams, and mussels, followed by beef and chicken liver, sardines, beef, poultry, and canned light tuna. For non-heme iron, the top sources are fortified breakfast cereals, lentils, beans, spinach, potatoes with the skin on, nuts, seeds, dark chocolate (at least 45% cacao), and enriched rice or bread.
If you eat a plant-based diet, you can absolutely get enough iron. You just need to be more strategic about absorption, which is where the next two sections come in.
Pair Iron With Vitamin C
Vitamin C is the single most effective way to boost absorption of non-heme iron. It works by converting iron into a form your intestinal cells can actually take up. Without that conversion step, much of the iron in plant foods passes through you unused.
The effect is dramatic and dose-dependent. Research published in ACS Omega found that adding vitamin C to a meal containing about 4 mg of non-heme iron increased absorption from 0.8% to 7.1% as the dose of vitamin C rose from 25 mg to 1,000 mg. That’s nearly a ninefold improvement. In practical terms, squeezing lemon over lentils, eating strawberries with your fortified cereal, or adding bell peppers to a bean stir-fry can make a real difference. A single medium orange provides about 70 mg of vitamin C, enough to meaningfully shift absorption.
Avoid Blockers at Mealtime
Coffee and tea contain polyphenols that bind to non-heme iron and prevent it from being absorbed. The key detail: this only happens when you drink them at the same time as an iron-rich meal. A cup of coffee two hours before or after eating won’t interfere. Calcium can also compete with iron for absorption, so if you take a calcium supplement, space it away from your iron-rich meals or iron supplements.
If you’re not iron deficient, none of this matters much. But if you’re actively trying to raise your hemoglobin, skipping coffee and tea with meals is one of the easiest adjustments you can make.
B12 and Folate Matter Too
Iron gets the spotlight, but your body also needs vitamin B12 and folate to produce healthy red blood cells. Both vitamins are essential for DNA synthesis during the rapid cell division that happens when new red blood cells form in your bone marrow. A deficiency in either one leads to a type of anemia where the body produces fewer, abnormally large red blood cells that don’t function well.
B12 comes almost exclusively from animal products: meat, fish, eggs, and dairy. If you’re vegan or over 50 (when absorption from food naturally declines), a supplement or fortified foods like nutritional yeast and plant milks can fill the gap. Folate is abundant in leafy greens, legumes, citrus fruits, and fortified grains. Importantly, a B12 deficiency can’t be fixed by taking folate, and vice versa. Each plays a distinct role, and your body needs both.
What to Expect From Supplements
If your hemoglobin is genuinely low from iron deficiency, dietary changes alone may not be enough. Oral iron supplements are the standard first step. The tolerable upper intake level for iron from food and supplements is 45 mg per day for adults, though doctors sometimes prescribe higher therapeutic doses to replenish depleted stores.
The timeline for improvement is faster than most people expect. With consistent oral supplementation, your body starts producing new red blood cells within four to five days, and hemoglobin typically begins rising by the second week. Full recovery is a longer process. Replenishing your iron stores (measured by a protein called ferritin) usually takes three to six months of continued supplementation, sometimes longer if you have ongoing blood loss or a severe deficiency.
Iron supplements are notorious for causing constipation, nausea, and stomach upset. Taking them with a small amount of food and a source of vitamin C can help with both tolerance and absorption. Some people do better with every-other-day dosing, which newer research suggests may actually improve absorption compared to daily doses.
When IV Iron Makes Sense
For people who can’t tolerate oral iron or who need a faster response, intravenous iron is an option. Guidelines from the European Crohn’s and Colitis Organization note that IV iron is more effective, produces a faster hemoglobin response, and is better tolerated than oral iron. A meta-analysis found that IV iron was about 57% more likely to produce a hemoglobin rise of 2 g/dL or more compared to oral supplements. This route is typically reserved for people with inflammatory bowel disease, chronic kidney disease, heavy menstrual bleeding that outpaces oral supplementation, or severe anemia that needs rapid correction.
Altitude and Exercise
Your body naturally adjusts hemoglobin production based on oxygen availability. At higher altitudes, where oxygen is thinner, your kidneys release more of a hormone called erythropoietin (EPO), which signals your bone marrow to produce more red blood cells. Research in Frontiers in Sports and Active Living found a strong positive correlation between the amount of time spent in low-oxygen conditions and the percentage increase in hemoglobin concentration.
This is why athletes sometimes train at altitude. For most people, though, altitude isn’t a practical tool for raising hemoglobin. It’s more useful to understand that if you’ve recently moved to a higher elevation, your body will naturally adapt over weeks by producing more red blood cells.
Don’t Overdo It
More iron is not always better. Excess iron accumulates in organs and can cause serious damage. Hemochromatosis, a condition of iron overload, causes fatigue, joint pain (especially in the knees and hands), abdominal pain, loss of sex drive, and a characteristic darkening of the skin to a gray or bronze tone. In severe cases, it leads to cirrhosis, diabetes, or heart failure.
Some people carry genetic variants that make them absorb too much iron from food. If your hemoglobin is already normal and you don’t have a diagnosed deficiency, taking iron supplements is unnecessary and potentially harmful. Always get your levels tested before supplementing. A simple blood test measuring hemoglobin, ferritin, and iron saturation gives a clear picture of whether you actually need more iron or whether the cause of your low hemoglobin is something else entirely.