What is iron and why is it important?
Iron is a mineral that is essential for many functions in the human body. It helps transport oxygen through the blood to cells and tissues. It is also important for energy production, immune system function, brain development, and muscle function. Not having enough iron can lead to iron deficiency anemia, fatigue, decreased immune function, and impaired brain function.
Getting enough iron in your diet is important, but you also need to be able to absorb the iron you consume. Even if you eat foods that are high in iron, if your body cannot properly absorb it, you may still end up with an iron deficiency. There are several factors that can affect iron absorption and steps you can take to increase absorption from foods.
What affects iron absorption?
There are a few key factors that impact how much iron your body can absorb from foods:
Type of iron
There are two types of iron found in foods – heme iron and non-heme iron. Heme iron comes from animal sources like red meat, poultry, and seafood. It is more readily absorbed by the body compared to non-heme iron. Non-heme iron comes from plant sources like lentils, beans, spinach, and fortified cereals. This type of iron is not as easily absorbed. On average, the body absorbs about 15-35% of heme iron from food but only 2-20% of non-heme iron.
Other compounds in food
Certain compounds can either enhance or inhibit iron absorption depending on what foods they are found in:
– Vitamin C enhances iron absorption when eaten with iron-rich foods. Foods high in vitamin C like citrus fruits, tomatoes, and broccoli can boost absorption.
– Polyphenols found in tea, coffee, and plant foods can inhibit iron absorption. Drinking tea and coffee with meals can limit iron absorbed from foods.
– Phytates found in whole grains, legumes, nuts and seeds can also inhibit iron absorption because they bind to iron.
– Calcium supplements can decrease iron absorption if taken with iron-rich foods.
Iron status
People who have lower iron stores or are iron deficient absorb more iron from food. When the body is low or depleted of iron, more absorption mechanisms kick in to try to replenish stores. Those with adequate iron status do not absorb as much from food sources.
Stomach acid levels
Stomach acid helps convert iron into a form that allows it to be absorbed. Conditions that reduce stomach acid like acid reflux disease can decrease iron absorption. Getting older also typically results in lower stomach acid which can inhibit iron absorption.
Tips to increase iron absorption
Here are some evidence-based tips to help increase your absorption of iron from foods:
1. Combine iron-rich foods with vitamin C sources
Eating iron-containing foods alongside vitamin C-rich foods enhances absorption. Try combining:
– Iron-fortified cereal with strawberries or orange juice
– Spinach salad with red bell peppers
– Black bean soup with tomatoes
– Lentils with red cabbage slaw
– Steak with broccoli
Having a food source of vitamin C with each iron-containing meal can optimize absorption.
2. Avoid tea, coffee, and calcium supplements with meals
The polyphenols in tea and coffee can significantly decrease iron absorption if consumed with iron-rich foods. Try to avoid having these drinks during meals.
Calcium supplements also impair iron absorption. Take calcium supplements between meals rather than with food to sidestep this issue.
3. Increase heme iron sources
Heme iron sources like red meat, poultry, and fish are more readily absorbed than plant-based sources of iron. Including some heme iron sources in your diet can help boost absorption.
Some good options are:
– Lean red meat – aim for 1-2 servings per week. Choose cuts with “loin” or “round” in the name which are leaner.
– Skinless poultry – chicken, turkey, duck all provide heme iron. Remove the skin to reduce saturated fat intake.
– Oily fish – such as salmon, mackerel, sardines, and tuna
– Cooked clams, mussels, and oysters
4. Enhance non-heme iron absorption with vitamin C
For vegetarian and vegan diets, getting enough iron means relying on non-heme sources. Absorption of plant-based iron can be enhanced by combining foods high in vitamin C. Some good meal ideas include:
– Chili made with tomatoes, bell peppers, kidney beans, and spinach.
– Lentil soup with tomatoes and kale.
– Tofu vegetable stir fry with broccoli and red bell pepper.
– Chickpea and avocado salad with red cabbage slaw.
– Overnight oats made with soy milk, spinach, and strawberries.
Pairing two or more vitamin C-rich foods with plant-based iron sources at each meal can significantly boost absorption.
5. Consider removing phytates
Phytates in whole grains, legumes, nuts and seeds bind to iron and inhibit absorption. Sprouting and soaking can help reduce phytates and increase absorption.
– Choose sprouted grain breads and sprouted brown rice.
– Soak beans overnight and rinse well before cooking.
– Soak and rinse nuts and seeds to lower phytate content.
– Consider phytase enzymes that help break down phytates to improve iron absorption.
Phytates also provide beneficial antioxidants and fiber. Don’t avoid these foods entirely, just take steps like soaking to reduce the phytate content.
6. Add iron-absorption boosters
Certain spices and ingredients are thought to potentially increase non-heme iron absorption including:
– Garlic
– Onions
– Pepper
– Turmeric
– Meat proteins and extracts
Adding these to meals may help boost iron absorption, though the evidence is limited. Additionally, taking ginger, probiotics, or enzymes like phytase with meals could aid absorption.
7. Limit antacid use
Antacids like Tums that reduce stomach acid can potentially lower iron absorption, especially if taken with meals.
If using antacids for reflux or heartburn, try taking them between meals only to avoid interfering with iron absorption at mealtimes. Talk to your doctor if reflux persists.
8. Optimize stomach acid if needed
Boosting stomach acid can help absorption of non-heme iron for those with low levels. Strategies include:
– Taking vitamin C supplements with meals – enhances acidity.
– Consuming fermented foods like sauerkraut and yogurt – contain probiotics that may stimulate acid production.
– Trying Swedish bitters or herbal combinations with gentian, dandelion, fennel etc.
– Discussing betaine HCL supplements with your healthcare provider.
Increasing stomach acid should only be done under medical supervision to avoid complications like ulcers.
9. Get adequate vitamin A, copper and protein
These nutrients support the proteins that transport iron in the body. Deficiencies can potentially reduce iron absorption and status.
Vitamin A – found in orange vegetables, eggs, liver
Copper – found in shellfish, nuts, avocados
Protein – found in fish, poultry, meat, dairy, beans, lentils
Balanced intake of these nutrients ensures your body can properly transport iron.
10. Treat underlying conditions that may cause malabsorption
Certain medical conditions can also lead to impaired iron absorption:
– Celiac disease
– Atrophic gastritis
– H. pylori infection
– Gastric bypass surgery
– Inflammatory bowel diseases
See your doctor if you have digestive issues or ongoing low iron with poor dietary absorption. Treating any underlying conditions can help resolve iron malabsorption.
Supplements to increase iron absorption
If your iron status remains persistently low despite following an iron-rich diet and absorption-enhancing strategies, you may need supplemental iron. Common forms include:
Ferrous sulfate
This is one of the most common oral iron supplements. Ferrous sulfate contains ferrous iron, which your body more readily absorbs compared to ferric iron.
Typical dosage = 150-300 mg of elemental iron daily between meals. Take with vitamin C to enhance absorption and avoid calcium supplements at the same time.
Potential side effects include nausea, constipation, abdominal discomfort and black stools. Starting at a lower dose and taking with food can help minimize side effects.
Ferrous fumarate
Similar to ferrous sulfate, this supplement also provides highly absorbable ferrous iron.
Typical dosage = 90-200 mg of elemental iron daily between meals and with vitamin C sources.
Has a lower risk of intestinal side effects compared to ferrous sulfate for some individuals. Still may cause temporary side effects.
Ferrous gluconate
Another form of ferrous iron salt that has good absorption.
Typical dosage = 240-300 mg of elemental iron daily between meals with vitamin C.
Usually causes less gastrointestinal side effects than ferrous sulfate, but is not absorbed quite as well. Still an effective option.
Iron polysaccharide complex
Consists of ferric iron bound with a polysaccharide that helps improve absorption.
Typical dosage = 150 mg of elemental iron daily.
May cause less side effects than traditional ferrous salts. But absorption can vary depending on the complex used.
Heme iron polypeptide
Made up of heme iron sources for high bioavailability.
Typical dosage = 15-30 mg of elemental iron daily.
Absorbed 2-3 times better than traditional iron supplements but more expensive. Upper limit is still recommended to avoid adverse effects.
Carbonyl iron
Special form of elemental iron that does not dissolve in the intestines.
Typical dosage = 50-100 mg elemental iron 2-3 times per day.
Minimal side effects but absorption can be low and inconsistent. Needs stomach acid to help absorb.
Key takeaways
There are several effective ways to increase your absorption of iron from foods and supplements:
– Combine iron-rich foods with vitamin C sources
– Limit tea, coffee, antacids and calcium supplements with meals
– Include heme sources like red meat, poultry and fish
– Enhance plant-based iron absorption with vitamin C
– Soak, sprout and ferment foods to reduce iron-binding phytates
– Boost stomach acid and treat underlying conditions if needed
– Take supplements with vitamin C away from meals if diet is not sufficient
Increasing iron absorption and status takes consistency with diet and supplementation. Work with a healthcare provider and registered dietitian if iron deficiency or anemia persists. With time and consistency, you can optimize your body’s ability to absorb iron from vegetarian and non-vegetarian food sources.