Why Is Iron So Important to Vegetarians?

Why Is Iron So Important to Vegetarians?

Iron is one of the essential micronutrients. The human body contains about 3-4 grams of iron, and most of it is present in the form of hemoglobin or in the red blood cells. Thus, its main role in the body is oxygen supply. However, it also plays a vital role in physical growth, neurological development, and the formation of some hormones.

Though in minute amounts, iron is found in many foods. Nevertheless, iron deficiency is not rare, particularly among females.

Managing iron deficiency is not simple. Many people fail to manage iron deficiency even by increasing their dietary intake or taking supplements. It is because not all iron sources are equally good. Important is not how much iron you consume but how much is absorbed by the body. Consuming foods and supplements with low-bioavailable iron is not going to help.

What are different sources of dietary iron?

If iron intake is low, it mainly affects the formation of hemoglobin. This leads to hypochromic anemia. Iron deficiency anemia leads to fatigue, impaired cognition, difficulty concentrating, low exercise performance, and poor body temperature regulation.

In the human diet, iron may come from animal sources and vegetables. Or it is divided into heme and non-heme iron. Heme iron is in red meat, organ meat, and so on. In contrast, non-heme iron is found in seafood, vegetables, grains, nuts, and fortified cereals.

Studies show that the western diet gets only about 10-15% of the iron in the form of heme iron and the rest in non-heme form. However, studies show that non-heme iron present in vegetables, fortified cereals, and even many health supplements is very poorly absorbed by the body. It is because non-heme iron readily binds with other dietary components like oxalates, carbonates, and so on. Thus, interestingly enough, in non-vegetarians, heme iron may constitute close to half of the dietary iron supply.

It means that non-heme iron in vegetables, seafood, and poultry products has much lower bioavailability than heme iron. Hence, those who do not consume much meat must increase their iron intake or supplement it.

How does iron benefit for vegetarians?

As already explained that heme iron has excellent bioavailability, unlike non-heme iron found in various vegetarian foods like tofu, seeds, nuts, grains, legumes, green vegetables, and so on.

Since non-heme iron is so poorly absorbed, increasing the intake of iron-rich foods by vegetarians often fails to help them manage iron deficiency.

Regretfully, many people even fail to benefit from a high dietary intake of iron-rich foods due to the low availability of iron and thus the need to supplement. It means that supplementing iron is the better way of managing iron deficiency.

Thus, if a person has low anemia, fatigue, or a problem concentrating, it could be due to low iron levels in the blood. However, in many cases, iron deficiency may be subclinical, meaning that hemoglobin may be close to normal, and yet a person may feel fatigued and have reduced mental abilities.

When it comes to the daily iron requirement, about 8 mg of iron is sufficient for an adult male. However, females of childbearing age need 18 mg or more. This requirement increases to 27 mg in pregnancy.

It appears that non-heme iron like that in seafood, legumes, is only about 5-15% bioavailable. For example, a cup of spinach or lentils may contain 3 mg of iron. As one can see that just about 10% of it will be absorbed by the body. Thus, even vegetarian men may struggle to meet their daily iron requirement through iron-rich vegetables.

On the contrary, one-third or more of iron in supplements is readily absorbed by the body. It means that those at risk must consider at least intermittent iron supplementation. However, females living with low hemoglobin may benefit from more frequent iron supplementation.


Although iron is needed just in minute amounts by the body, people still struggle to get enough of it via the diet due to the low bioavailability of non-heme iron. In addition, consuming foods rich in iron like legumes, nuts, and cereals and even using certain supplements may also fail to help due to the low bioavailability of iron compounds in these foods or supplements.

Thus, one of the options for preventing iron deficiency in those living on a predominantly vegetarian diet could be iron supplementation. In addition, it may help quickly relieve iron deficiency due to its excellent bioavailability. Moreover, most supplements also contain other vitamins that promote iron absorption.

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