Heme Iron | Functional foods

What is heme iron

Hemoglobin is present in red blood cells and composed of “heme iron” (iron porphyrin complex) and globin (a type of protein).
Heme iron plays an important role in transporting oxygen throughout the body, and is abundant in animal foods such as meats and fishes.

Heme iron and non-heme iron

1：Amount of iron in foods

There are two different kinds of dietary iron. One of them is heme iron, which is found in abundance in animal foods such as meat and fish. The other one is non-heme iron, which is found mainly in vegetables and cereals (Fig. 1).
Heme iron is known to have a higher iron absorption rate than non-heme iron (Figure 2). However, more than 85% of iron consumed by Japanese people is non-heme iron, through eating vegetables, even though it has a low absorption rate.
In order to prevent iron deficiency effectively, we would like to recommend to you a well-balanced diet containing heme iron-rich foods.

Figure 2: Iron absorption rate in various foods

2：Literature and reports on heme iron and non-heme iron

There are several research reports on the absorption of heme iron in the body. In many cases, heme iron is reported as better absorbed than non-heme iron and its absorption rate is indicated 5 to 6 times higher than non-heme iron.

Comparison of the absorption rates of heme iron and non-heme iron

3： Various literature reports on heme iron and non-heme iron

The absorption of non-heme iron could be inhibited by dietary fiber or tannin during their absorption from the intestinal tract. In addition, iron ion itself could cause damage to the stomach wall or intestinal tract.
On the other hand, heme iron is a polyhedral compound in which iron ions are surrounded by porphyrin rings, and therefore, it is less likely to damage the stomach wall and intestine, and less susceptible to absorption inhibition from dietary fiber and tannins. Because of these physical characteristics, heme iron is more easily absorbed in the body than non-heme iron. Furthermore, since the amount of iron absorbed is regulated by an active enzyme called heme oxygenase, there is less likelihood of iron overdose. Yes, heme iron is a body-friendly supplement.

4：Comparison of the absorption of heme iron and non-heme iron into the blood vessels

In 2008, we conducted a comparative study of the absorbability of heme iron and non-heme iron in iron-deficient subjects (humans) using crossover blind method.

Transition of serum iron amount changed after ingestion

Regarding the change in serum iron concentration, 1 hour after intake, the "heme iron intake group" showed approximately 5 times more serum iron concentration compared to the “non-heme iron intake group,” and the high rate of absorption was maintained thereafter. It indicates that oral intake of heme iron is more effective than that of non-heme iron in helping iron absorption.

Current iron deficiency situation

Iron deficiency is regarded as one of the world's three major nutrient deficiencies, alongside vitamin A and iodine deficiencies. Iron is one of the minerals whose intake deficiency is manifested in Japan as well.
Particularly, iron deficiency among women due to menstrual blood loss, and insufficient intake of iron during pregnancy and lactation (when iron requirements increase), is very serious.
In addition, ferritin deficiency (stored iron deficiency), which is called as hidden anemia, has recently attracted much attention.

Reffrence

Shuichi Kimura, Micronutrient Deficiency and Food Nutrition Enhancement, Food Nutrition Enhancement, 15th International Congress of Dietetics, 2008
"Iron" in Information system on safety and effectiveness for health foods, National Institute of Health and Nutrition

Functions of iron in the body

There are some reasons why iron deficiency occurs. The first reason is that there are not that many foods containing high concentrations of iron; the second reason is that only very tiny amount of iron can be absorbed in the small intestine, and most of the iron intake is discharged in the stool. Additionally, the changes in diet and lifestyle are also responsible.

Iron and oxygen

Since generally iron can be easily associated with "oxygen," it plays an important role in carrying oxygen throughout the body. Such iron is called functional iron. Our body comprises approximately 60 trillion cells, and iron supplies oxygen to all of the cells, helping produce energy in cells. Yes, iron helps us live a healthy life.

Hemoglobin level and serum ferritin level

The value of hemoglobin is used as an index for measuring anemia through blood tests in hospitals or during medical checkups. However, as the body tries to maintain a balanced hemoglobin count, hemoglobin levels tend to be maintained in the initial stages of iron deficiency. Before this hemoglobin value changes, "serum ferritin level" drops. Ferritin helps with iron storage, and prevents the ferritin stored in the liver and spleen from being lost and causing iron deficiency and anemia. Since "serum ferritin levels" cannot be measured by routine tests, the stored iron deficiency is overlooked. As storage iron normally serves as a reserve, a slight decrease in its amount does not register as a symptom of anemia in the body. However, in recent years, there have been reports on the mental effects of decrease in ferritin or "storage iron," such as indefinite complaints and depression tendency.

If storage iron runs out, hemoglobin starts decreasing, followed by a decrease in red blood cells, and eventually some serious symptoms specific to anemia could appear such as dizziness, shortness of breath, palpitation, fatigue due to muscle deficiency, etc. Various other symptoms such as fatigue and weakness also appear.
Iron is an important nutrient and we would like to recommend sufficient iron intake to prevent these symptoms.

Iron is an essential element in the production of red blood cells (hemoglobin)

Necessity of regular/sufficient intake of iron

Reticulocytes are produced in approximately 5 days in the bone marrow, and they become red blood cells in 1 to 2 days in peripheral blood. Red blood cells normally have a lifespan of about 120 days, and are then destroyed in the spleen. Aged erythrocytes are normally phagocytosed by macrophages. Globin proteins are broken down into amino acids and used for protein synthesis. Heme is freed from iron, which is recycled and used in hemoglobin synthesis.

Although iron absorption and excretion is as low as approximately 1 mg a day for an individual, we could be faced with iron deficiency due to an imbalance in iron supply and demand conditions. This occurs because there are not that many iron-rich foods, and we could lose much iron through menstruation, pregnancy, lactation, sports, and other activities. Iron cannot be easily recovered by the body even if we try to get it temporarily replenished with a single shot or in a short period of time. In addition, it is not sufficient to consume only iron, because vitamin A, vitamin B12, folic acid, protein, copper, vitamin E and other minerals are also required to make red blood cells. Furthermore, copper transports iron to facilitate hemoglobin production, and zinc affects its metabolism. Therefore, the intake of other essential nutrients besides iron is important as well.

Intake of iron from foods is very important, but sometimes it is difficult to maintain daily intake requirements. Therefore, we recommend our heme iron, which does not affect the stomach wall much and is suitable for regular intake.