Iron is a nutrient that plays an important role in transporting oxygen throughout the body.
Since oxygen promotes metabolism, ingesting iron contributes greatly to improving your health in a wide range of areas. In this article, we will introduce foods that are rich in iron, the types of iron, and their functions.

What is Iron?

Iron is a mineral that is necessary for the body.
An adult's body contains approximately 3 to 5 g of iron, of which 70% is "functional iron," which acts as hemoglobin to transport oxygen in red blood cells and myoglobin to store oxygen in muscles.
The remaining 30% is stored as "storage iron" to supplement iron deficiency in the liver, bone marrow, etc.
Iron's role is to carry oxygen throughout the body through the bloodstream.
In addition, sufficient oxygen and iron are required to produce collagen, which creates beautiful skin, so consuming iron also has a significant impact on beauty.

Difference Between Heme Iron and Non-heme Iron

There are two types of iron: "heme iron" and "non-heme iron."
Heme iron is found in abundance in animal foods, such as red meat, liver, and seafood, while non-heme iron is found in abundance in plant foods, such as spinach, komatsuna, and soy milk.
Even though they are all the same type of iron, each has different characteristics, so it is important to understand them before taking them.
We will explain the characteristics of each in detail.

Foods High in Iron

Iron is a mineral that the body cannot produce, so be sure to supplement it through your diet.
Here are some foods that contain both heme and non-heme iron:

● Foods that contain heme iron
Here are some foods that contain heme iron and their iron content.



In particular, dried anchovies can be used to make soup stock or eaten as an ingredient in soups, allowing you to consume vitamins and minerals efficiently.
Fish blood is rich in heme iron, but it also contains a lot of methylmercury, so it is not recommended for women trying to conceive.

● Foods that contain non-heme iron
Here we will introduce foods that contain non-heme iron and their iron content.



Vegetables, beans, seaweed, etc. also contain a lot of iron.
However, because it is non-heme iron, its absorption rate is lower than that of heme iron, so it is important to be mindful of combining it with other foods to increase its absorption rate.

Recommended iron intake

Iron is a mineral that is often recommended for intake.
However, the recommended intake varies widely based on age, gender, and whether or not you menstruate.
The table below shows the difference between the recommended daily intake and the estimated average requirement set by the Ministry of Health, Labour and Welfare.



Source: Ministry of Health, Labor and Welfare "Dietary Reference Intakes for Japanese" 2020 edition
https://www.mhlw.go.jp/content/10904750/000586553.pdf

Tips for taking iron

How can we efficiently absorb the iron we need on a daily basis?
Here we will introduce you to some foods that contain iron, as well as tips on how to efficiently consume iron by using cooking utensils and eating methods.

● Use cast iron cookware
It is said that using iron frying pans and pots allows you to easily consume iron without having to worry too much about what you eat every day.
This is because simply changing your cooking utensils can cause the iron that is easily absorbed in food to dissolve.
In particular, cooking with vinegar or foods with a strong acidic taste will increase the amount of iron dissolved, allowing you to absorb more of it.
In addition, it is recommended to use an iron kettle when boiling water, as this allows you to consume iron from hot water or hot drinks.
There are also "iron balls" on the market that you can add to your pot when cooking, allowing you to consume iron even if you don't have iron utensils.

● Be creative with your eating habits
Even if you eat a lot of iron-containing foods at one meal, the amount of iron you can absorb at one time is limited.
Even if you ingest 10 mg of iron, only about 1 mg of it is absorbed.
Excess iron or iron that is not absorbed is excreted in the stool.
In order to absorb nutrients efficiently, be sure to pay attention to your nutrition, eat three meals a day, and make sure to get your nutrients from a variety of foods rather than just one ingredient.
Another option is to try supplementing your diet with supplements.

Nutrients that increase iron absorption

The iron that is taken into the body is not simply absorbed and functions as it is.
It is very important to increase the absorption rate in the body after ingestion.
Here we will introduce the nutrients that support iron absorption and the foods that hinder it.

● Vitamin C and Citric Acid
The absorption rate of non-heme iron into the body can be increased by taking it together with vitamin C or citric acid.
It is thought that non-heme iron, which is trivalent iron, becomes divalent iron through the reducing action of vitamin C and citric acid, making it easier to absorb.
Vitamin C is found in large amounts in vegetables such as broccoli and radishes, and in fruits such as strawberries and mandarin oranges.
Citric acid is found in many foods that have a strong sour taste, such as pickled plums and lemons.
To increase the absorption of non-heme iron, it is a good idea to eat them in combination.

● protein
Protein is one of the nutrients that makes up hemoglobin.
To increase iron absorption, we recommend eating it with foods rich in protein, such as meat or fish.

For example, simply stir-frying komatsuna, which contains non-heme iron, together with meat, which is high in protein, will increase the absorption rate much more than if you consumed either of them alone.

In particular, liver and clams, which are rich in heme iron and protein, can help you absorb more iron when consumed together with foods that contain non-heme iron.
Additionally, combining it with protein-rich egg dishes and dairy products can also help improve iron absorption.

● Beware of foods that impair absorption
Some foods can reduce the absorption of non-heme iron, so be careful with your food choices.

• Tannins
It is a bitter component found in coffee, black tea, and green tea.
Try to avoid drinking alcohol during, before and after meals, and choose drinks that do not contain tannins, such as water or barley tea.

• Fiber
There are two types of dietary fiber: soluble and insoluble. Soluble dietary fiber is found in large amounts in seaweed and is a nutrient that increases the absorption rate of iron. On the other hand, insoluble dietary fiber is found in burdock, mushrooms, etc. and reduces the absorption rate of non-heme iron.

In addition, sodium phosphate, a food additive, also inhibits iron absorption, so be careful when choosing foods.

summary

Iron, which is essential for maintaining a healthy body, must be ingested daily through the diet.
Prevent anemia by consuming a balanced mix of heme iron, which is easily absorbed, and non-heme iron, which is easily absorbed when combined.

Article supervision

Kondo Chigusa
Chigusa Internal Medicine Clinic Kakuozan

At the age of 33, she aspired to be a doctor and passed the entrance exam for medical school in one year. During her time as a medical student, she worked as a model and a GT race queen, and is a very popular beauty doctor in her 50s who has been featured in various media outlets. Currently, she is involved in community medical care as the director of Chigusa Internal Medicine Clinic Kakuozan, and is also active in the fields of preventive medicine and anti-aging medicine as a specialist in the Japanese Society of Anti-Aging Medicine.
As the representative of Japan in several international beauty pageants, including Mrs. Global Earth, she also works to spread education about environmental protection around the world.

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