Maximum safe dose of iron from food & supplements

The maximum safe dose of iron from dietary supplements is 45 mg for adults. Higher dosages can cause side effects. However, eating foods high in iron doesn’t cause iron toxicity.

Health benefits of iron

Iron is an essential trace element. We have to get it food. The body can’t synthesize it.

Iron is an essential component of hemoglobin. This protein is found in red blood cells. It transfers oxygen from the lungs to the tissues.

Also, iron supports muscle metabolism and healthy connective tissue. It’s also crucial for energy metabolism, cellular functioning, physical growth, neurological development, and the synthesis of neurotransmitters, hormones, amino acids, and collagen.[1,2]

However, iron deficiency is the most common nutritional deficiency worldwide.

Iron deficiency may cause gastrointestinal disturbances, impaired cognition, weakened immune function, fatigue, and low body temperature. In addition, iron deficiency may cause manganese toxicity. Too much manganese may cause adverse effects. Furthermore, iron deficiency during pregnancy increases the risk of premature delivery, and miscarriage.[3]

The human body recycles iron. But, we lose a certain amount of iron every day, which we have to replenish. We lose only small amounts of iron in urine, feces, the gastrointestinal tract, and the skin every day. Women lose more iron during menstruation period, due to blood loss.

The recommended daily intake of iron is 8 mg and 18 mg for men and women, respectively. Pregnant women need even higher dosages of 27 mg of iron a day!

Hence, many women should benefit from taking iron supplements. You’ll find a wide variety of iron supplements on iHerb.

What’s ferritin?

Most iron in the body is found in hemoglobin. A high percentage of remaining iron is stored in the form of ferritin in the liver, spleen, and bone marrow. Also, it’s located in myoglobin in the muscle tissue.

In fact, ferritin is a blood protein that contains iron. Thus, serum ferritin concentration is a measure of the body’s iron stores. It’s a common test for diagnosing iron deficiency.

What’s the maximum safe dosage of iron from supplements?

The maximum safe dosage of iron is 45 mg a day, both for women and men. Too much iron from supplements for a long time may cause side effects. Extremely high dosages can be dangerous for health.

However, there are iron supplements with more than 65 mg of iron per tablet. This dose is 360% of the recommended daily intake and 140% of the maximum safe dose!

Only people with health problems, or people who need to replenish their iron stores, may need higher amounts of iron than the maximum safe dose. In any case, you should consult your healthcare provider before taking iron supplements.

Side effects of high iron dosages

Higher iron dosages than the recommended daily intake can lead to gastric upset, constipation, diarrhea, nausea, abdominal pain, and vomiting.

Furthermore, extremely high doses of iron from supplements may reduce zinc absorption, leading to zinc deficiency!

In addition, excess iron can form free radicals, leading to oxidative stress and tissue damage. Also, too much iron may stimulate the growth of pathogens.[4]

Iron toxicity may occur due to high doses of iron from supplements. Foods are unlikely to cause iron toxicity. The body can control iron absorption rates from dietary sources.

Do I need iron supplements?

Actually, iron deficiency is pretty common. Young children, women of reproductive age, and pregnant women have higher risk of iron deficiency.

Poor diet is the main reason of iron deficiency, though. Hence, most healthy people could increase their iron levels by following a well-balanced diet. Only people with health problems may need iron supplements.

It’s estimated that between 14% to 18% of Americans take a supplement containing iron. Many of them could get the recommended daily intake of iron from food. They don’t need iron supplements.

Certainly, you should consult your physician before taking any supplement or changing your diet.

Can I get more iron from food than the maximum safe dose?

Actually, it’s rather unlikely to get more iron than the maximum safe dose from food.

Animal-based foods

Only beef liver and oysters are particularly rich in iron, though. Big servings could contain more iron than the maximum dose. But, people don’t eat these two foods regularly. Moreover, you should avoid eating beef liver, due to the increased risk of vitamin A toxicity.

Animal-based food high in iron are meat, poultry, fish, and eggs. In addition, they have much higher bioavailability of iron, as compared to plant-based foods.

But, avoid consuming cheese and other dairy products with iron-rich foods. Not only are they poor dietary sources of iron, but also calcium in dairy may inhibit iron absorption.

Vegan foods

Actually, we can’t possibly exceed the maximum safe dose of iron by following a plant-based diet. In fact, vegans and vegetarians should get 1.8 times more iron from food than meat-eaters! Iron in vegan foods is less bioavailable.

Vegan foods high in iron are whole grains, pseudocereals (e.g. quinoa), legumes, fruits, vegetables, potatoes, and dark chocolate. Also, you could boost your daily iron intake by drinking certain fruit juices!

How could I increase iron absorption?

Consuming a wide variety of foods rich in iron is good for increasing your iron intake. But, you should avoid certain foods in order to increase iron absorption!

First, you shouldn’t drink coffee, tea, or red wine when consuming foods high in iron. These beverages contain polyphenols. These compounds bind to iron in the intestine, inhibiting its absorption.

Certain animal proteins such as milk proteins (casein, whey), and egg proteins may inhibit iron absorption as well.

On the contrary, meat, and fish contain a peptide known as MFP Factor, which enhances the absorption of iron. In fact, combining beef, chicken, or fish with plant-based foods rich in iron can increase iron absorption by 2-3 fold!

Additionally, vitamin C significantly enhances iron absorption. Thus, you could benefit from eating foods high in vitamin C with foods high in iron!

Last, but not least, honey might increase iron levels by 20%, although it has negligible amounts of iron! More about the benefits of honey in health and weight loss here.


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