How to increase the absorption of iron from foods

Iron is an essential mineral your body needs to function correctly.

Thus, it’s vital to consume adequate amounts of it in your daily diet.

Interestingly, the foods you eat influence how much iron you consume and how well it is absorbed into your body.

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Once your body absorbs it, it’s used as a building block for hemoglobin, a protein found in red blood cells that helps shuttle oxygen around your body.

Iron is also a component of myoglobin, an oxygen storage protein in your muscles. This oxygen is used when you use your muscles.

The recommended intake range is 7–18 mg per day for the general population and up to 27 grams for pregnant women.

Which foods contain iron?

You may have heard that you can get iron from red meat, but many other foods naturally contain iron.

In foods, iron is present in two forms: heme and non-heme.

Sources of heme iron

Heme iron is found in animal foods that contain hemoglobin, such as meat, fish, and poultry.

Heme iron is the best form of iron, as your body readily absorbs up to 40% of it.

Good food sources of heme iron include:

Beef
Pork
Chicken
Veal
Fish such as halibut, haddock, perch, salmon, or tuna
Shellfish such as clams, oysters, and mussels

Red meats and organ meats like liver are particularly good sources.

Sources of non-heme iron

Non-heme iron primarily comes from plant sources and is present in grains, vegetables, and fortified foods.

This is the form added to foods enriched or fortified with iron and many supplements.

It’s estimated that 85–90% of total iron intake comes from the non-heme form, while 10–15% comes from the heme form.

Regarding its bioavailability, non-heme iron is absorbed much less efficiently than heme iron.

Good sources of non-heme iron include:

Fortified cereals, rice, wheat, and oats
Dark green leafy vegetables like spinach and kale
Dried fruits like raisins and apricots
Beans like lentils and soybeans

Summary: Heme iron is found in animal foods, while non-heme iron comes from plant sources. Your body better absorbs the heme iron than the non-heme iron.

Certain populations may be at risk of iron deficiency

Iron deficiency is the most common cause of anemia, affecting millions worldwide.

An iron deficient person may have various symptoms, including fatigue, dizziness, headaches, sensitivity to cold, and shortness of breath when doing simple tasks.

Moreover, iron deficiency can result in poorer attention span and mental function. Being deficient during early childhood has been linked to lower IQs.

Children, adolescents, and women of reproductive age, particularly during pregnancy, are most at risk of iron deficiency. This is because their intake doesn’t meet their body’s high demand for it.

Additionally, it’s commonly thought that vegetarians and vegans are more prone to iron deficiency. But interestingly, studies have shown that vegetarian and vegan diets contain just as much iron, if not more, than diets containing meat.

However, although vegetarians may consume as much iron as non-vegetarians, a review found that they are still at greater risk of deficiency.

This is because they consume mainly non-heme iron, which is not absorbed as well as the heme form in animal products.

It’s generally recommended that vegetarians multiply their recommended iron intake by 1.8 times to compensate for the reduced absorption.

Summary: Iron deficiency is very common. Those most at risk include children, adolescents, women of reproductive age, pregnant women, vegetarians, and vegans.

Foods that aid in iron absorption

While not all dietary iron is absorbed equally, some foods can enhance your body’s ability to absorb it.

Foods rich in vitamin C

Vitamin C has been shown to enhance iron absorption. It captures non-heme iron and stores it in a form that’s more easily absorbed by your body.

Suggested read: 7 common nutrient deficiencies

Foods high in vitamin C include citrus fruits, dark green leafy vegetables, bell peppers, melons, and strawberries.

In one study, taking 100 mg of vitamin C with a meal increased iron absorption by 67%.

Hence, drinking citrus juice or eating other foods rich in vitamin C while eating high-iron foods can increase your body’s absorption.

In vegetarian and vegan diets, iron absorption may be optimized by including vitamin C-containing vegetables during meals.

Foods containing vitamin A and beta-carotene

Vitamin A is critical in maintaining healthy vision, bone growth, and your immune system.

Beta-carotene is a red-orange pigment found in plants and fruits. It can be turned into vitamin A in your body.

Good food sources of beta-carotene and vitamin A include carrots, sweet potatoes, spinach, kale, squash, red peppers, cantaloupe, apricots, oranges, and peaches.

One study of 100 people given cereal-based meals found that the presence of vitamin A increased iron absorption by up to 200% for rice, 80% for wheat, and 140% for corn.

In the same study, adding beta-carotene to the meals increased absorption by more than 300% for rice and 180% for wheat and corn.

Meat, fish, and poultry

Meat, fish, and poultry not only provide well-absorbed heme iron, but they can also stimulate the absorption of the non-heme form.

Several studies have reported that adding beef, chicken, or fish to a cereal-based meal resulted in about 2–3 times greater non-heme iron absorption.

Research has also shown that adding 75 grams of meat to a meal increased the absorption of non-heme iron by about 2.5 times compared to a meal without it.

Based on study findings, it was estimated that 1 gram of meat, fish, or poultry provided an enhancing effect similar to that of 1 mg of vitamin C.

Summary: You can enhance iron absorption from meals by eating foods high in vitamin C, vitamin A or beta-carotene. Eating meat, fish, or poultry with other foods can also help.

Foods that may hinder iron absorption

Just as some foods can improve iron absorption, others can hinder it.

Foods containing phytate

Phytate, or phytic acid, is found in foods like whole grains, cereals, soy, nuts, and legumes.

Even a tiny amount of phytate can significantly decrease iron absorption.

In one study, as little as 2 mg of phytate in foods inhibited iron absorption by 18% when added to wheat rolls. And when 250 mg of phytate was eaten, up to 82% was not absorbed.

Nonetheless, the negative effect of phytate can be counteracted by consuming foods that enhance non-heme iron absorption, such as vitamin C or meat.

Calcium-rich foods

Calcium is an essential mineral for bone health.

However, some evidence shows that it hinders iron absorption, regardless of whether the source is a dairy product or calcium supplement.

Studies have shown that 165 mg of calcium from milk, cheese, or a supplement reduced iron absorption by 50–60%.

This is worrisome as increased calcium intake is commonly recommended for children and women, the same populations at risk of iron deficiency.

However, most studies were short-term and conducted in single meals. A thorough review of long-term studies found that calcium and milk products had no adverse effects on absorption.

To maximize absorption, calcium-rich foods should not be eaten with meals that provide most of your dietary iron.

In the case of supplements, calcium and iron supplements should be taken at different times of the day, if possible.

Foods containing polyphenols

Polyphenols are found in various amounts in plant foods and beverages, including vegetables, fruits, cereals and legumes, tea, coffee, and wine.

Coffee and tea, which are widely consumed around meals, have a high polyphenols content, and they have been shown to inhibit the absorption of non-heme iron.

In one review, drinking a cup of black tea with a meal reduced iron absorption by 60–70%, regardless of whether the tea was weak, normal, or strong.

However, when participants drank tea between meals, the reduction in absorption was only about 20%.

To counteract the negative effect of polyphenols, leave a couple of hours between your iron-rich meal and your afternoon tea or coffee.

Summary: Foods containing phytates, calcium, and polyphenols can significantly reduce iron absorption.

Health risks of excessive iron levels

Iron toxicity from food sources is rare. Once consumed, your body has its own balancing system to ensure that it gets just enough.

Nevertheless, one report showed that deadly overdoses were possible with excessive intakes of iron supplements.

Excessive iron levels can also occur in some people with hemochromatosis. This is usually caused by a gene that enhances absorption.

Other causes of iron overload include repeated blood transfusions, massive doses from the diet, and rare metabolic disorders.

Additionally, consuming too much iron over time may cause large deposits in the liver and other tissues.

Consequently, it may lead to diabetes, heart disease, and liver damage.

You should probably never take an iron supplement unless recommended by a health professional.

Summary: Consuming too much iron can have health risks. Because of this, supplements are not recommended for most people.

Tips to get enough iron

The tips below can help you maximize your dietary iron intake:

Eat lean red meat: This is the best source of easily absorbed heme iron. Eating it several times per week can help if you are deficient.
Eat chicken and fish: These are also good sources of heme iron. Eat a variety of them.
Consume vitamin C-rich foods: Eat vitamin C-rich foods during meals to increase the absorption of non-heme iron. For example, some lemon juice drizzled over leafy greens will increase the amount you absorb.
Avoid coffee, tea, or milk near meals: Avoid these during meals that contain iron-rich foods. Have your coffee or tea between meals instead.
Choose foods rich in non-heme iron: If you don’t eat meat and fish, include plenty of iron-rich plant foods in your diet.

Summary: To maximize your iron intake, include meat, fish, poultry, beans, and lentils in your diet and vitamin C-rich foods during your meals. Also, spread out your tea, coffee, and dairy intakes between meals.

Summary

Iron is a vital mineral essential for your body’s function. Two types of it are found in food — heme and non-heme.

Meat, fish, and poultry contain the heme form, which is easily absorbed by your body.

Non-heme iron is mainly found in plant foods, but this form is more challenging for your body to absorb. You can improve your body’s absorption by eating foods containing vitamin C, vitamin A, meat, fish, and poultry during your meals.

On the other hand, foods containing phytates (cereals and grains), calcium (milk and dairy), and polyphenols (tea and coffee) can hinder iron absorption.

By carefully selecting your foods and knowing how certain foods can enhance or inhibit absorption, you can ensure you’re getting the iron you need.