Daily iron need: How much Spirulina must I eat? – Iron content in Spirulina platensis

Daily iron need: How much Spirulina must I eat? – Iron content in Spirulina platensis

This article will give you some data from the scientific literature on how much Spirulina platensis you need to eat to fill your daily need of iron. It will first go through why you need iron and what your daily need is. Then it will give you the scientific data on the iron content of Spirulina and what you can find in Spirulina grown with HealthAlgae’s Spirulina grow medium. It will also lift other benefits Spirulina has for iron absorption. 

What this article will go through about iron in Spirulina

Why iron is important to eat

Iron has an important function inside the heme group in hemoglobin. Hemoglobin sits packed in your red blood cells and is the protein complex that binds oxygen in your lungs and releases it into your tissue, and then transport the CO2 out of your tissue and releases it in the lungs. Iron also sits in the myoglobin in your muscles cells and works as a cofactor in many enzymes. 

You also have iron stores in the form of ferritin within many cells, especially in some immune cells and in your liver. If you lack iron your body will produce less hemoglobin and red blood cells. You will more easily feel tired and less work will exhaust you. For women who plan to become pregnant or who are pregnant iron is even more important since the child needs a lot of iron to grow properly. Under the nine months of pregnancy, the child will absorb about 1200 mg of the mothers circa 3000 to 4000 mg of iron (1 – 3). 

How much iron is absorbed from the food?

The iron absorbed from the food depends on the type of iron it has. Iron comes in two forms in food. Either as Fe3+ in the form of salts within plants or as Fe2+ (heme iron) which partly is found in meat and blood products. The non-heme iron has an absorption in the intestine of between 1 to 10% while the heme iron, found in 5 to 10% in meat and blood products, has an absorption level of 20 to 30% (4).

How much iron do I need to absorb every day?

There are different directions on how much iron you should get per day. Women in the menstruating age and especially women who plan to get pregnant or who are pregnant need twice or several times what men do (5, 6). The needs (absorption) are as follows:

– Men: circa 1.5 mg per day (5)

– Women: circa 3.5 mg per day (5)

– Pregnant or who plant to get pregnant women: 4 to 5 mg per day (6)

Today’s western diet contains about 7 mg iron per 1000 kcal food and a total of 1 to 2 mg of this is said to absorbed (7). Other sources say that the average iron absorption or uptake per person and day in the western world is 2.1 mg (4).

Other studies claim that a pregnant woman needs even higher iron uptake per day in the following proportions (8):

– 4 mg per day for the first trimester

– 5 mg per day for the second trimester

– 6 mg per day during the third trimester

This may be due to the extra need for iron that the baby and mother need. The same research study claims that the iron stores need to be above 300 mg iron (full stores are about 1000 mg) to reduce the risk of iron deficiency during pregnancy. As an example in the country of Denmark, it has been shown that 42% of the women go into a pregnancy with too low iron reserves and risk anemia during pregnancy (8). It is in fact so that the child drains the mother of 1200 mg of iron during the pregnancy (1). A pregnancy is 280 days and an absorption of 5 mg per day of a total 1400 mg would barely cover the child’s and mother’s need here.  

How much iron do I need to eat every day to fill my absorption needs?

There are different recommendations to what your daily need of iron should be. Based on the above need of at least 5 mg per day and an absorption level for iron of 10% a daily dietary need for a woman who plans to be pregnant, or is pregnant should be at least 50 mg iron. 

However, the recommended need of iron for women age 19 to 50 according to the different responsible agencies was in 2014 as follows (4):

– 18 mg/day (New Zealand, Australia, Canada and USA

– 14.8 mg/day (Great Britain)

– 19.6 mg/day (FAO)

– 29.4 mg/day (WHO)

The WHO level is sat at its level since many women in developing countries only have vegetable sources of iron, which has a lower uptake, and hence need a greater intake of iron per day. 

To be noted here is that not a single western country in 2014 could reach over Great Britain’s recommended daily intake of iron of 14 mg per day (4).

Does Spirulina have iron?

Yes, Spirulina contains a lot of iron. Beneath we will go through how much it has and how much you need to eat every day to fill your daily need.

How much Spirulina do I need to eat every day to fill my iron need?

For you to determine how much Spirulina you need to eat to reach your daily iron need,  three different levels of 10 mg, 30 mg (WHO recommended need evened out), and 50 mg (for pregnant women) has been sat. Three different scientific sources of the iron concentration of Spirulina platensis has been used. 

Table 1. Scientific data on iron content in Spirulina platensis and how many gram you need to eat per day to reach different iron contents. 

Spirulina data source

Iron content (mg/100g)

Weight (g) to give 10 mg iron

Weight (g) to give 30 mg iron (recommended by WHO)

Weight (g) to give 50 mg iron (pregnant)

Spirulina platensis (9)

83.3

12

36

60

Spirulina platensis (10)

180.0

5.5

16.5

27.5

Spirulina platensis (11)

273.2 – 787.0

1.3 – 3.7

3.9 – 11.1

6.5 – 18.5

To get 50 mg iron every day as a pregnant woman, depending on the source of the Spirulina, you need to eat in between 6.5 to 60 gram dry Spirulina per day. 

When it comes to growing and eating your Spirulina in its fresh form you have to calculate in the weight of the water. That will make your Spirulina circa 5 times heavier than its dry weight. So to fill your daily iron need (50 mg) with fresh Spirulina you need to eat between 32.5 to 300 gram Spirulina per day. 

This may seem much but compared to Spinach, which has 3.18 mg iron per 100 gram (need to eat 1.57 kg to reach 50 mg iron) and pastry meat, which has 2.01 mg iron per 100 gram (need to eat 2.49 kg to reach 50 mg iron) it is much less (12, 13). 

The best option to compete with Spirulina is blood pudding with 17 mg iron per 100 gram (need to eat 294 gram to reach 50 mg iron) (14).

The difference in iron content between the different sources of Spirulina used in these scientific studies is most likely due to how and in what condition the Spirulina has been grown. Spirulina nutrient grow mediums with more iron will also give a Spirulina product containing more iron. 

The Spirulina grow mediums we at HealthAlgae sell are developed to be complete and high yielding sources of nutrition. Depending on your yield (which will vary depending on how good your growing conditions are) you can expect circa 163 to 325 mg per 100 gram dry Spirulina. See the table beneath for more details. 

Table 2. Expected iron content in dry and fresh or wet Spirulina platensis grown with HealthAlgae’s Spirulina grow medium. The values vary since growing conditions can give different harvest yields per liter culture. But expect to be somewhere within the given range. 

HealthAlgae Spirulina type

Iron content (mg/100g)

Weight (g) to give 10 mg iron

Weight (g) to give 30 mg iron (recommended by WHO)

Weight (g) to give 50 mg iron (pregnant)

Dry Spirulina

163 – 325 

3.1 – 6.1

9.2 – 18.4

15.4 – 30.7

Wet/fresh Spirulina

32.6 – 65.2

15.4 – 30.7

46.2 – 92.0

77.0 – 153.5

How Spirulina can improve iron absorption from the food

For you to determine how much Spirulina you need to eat to reach your daily iron need,  three different levels of 10 mg, 30 mg (WHO recommended need evened out), and 50 mg (for pregnant women) has been sat. Three different scientific sources of the iron concentration of Spirulina platensis has been used. Besides containing very high levels of iron, there are also other ways Spirulina can improve iron absorption:

– Spirulina lowers inflammation

– Spirulina is high in C-vitamin which improves iron absorption in the intestine (4, 6). 

– Spirulina hinders C-vitamin oxidation through its high antioxidant properties 

– Spirulina has anti-obesity effects

To much iron and or Inflammation makes hepatocyte cells in the liver produce hepcidin which limits iron absorption from the intestines (3). The body’s response to limit iron in the blood during inflammations is thought as a protective measure against growing bacteria that need iron to thrive (3).

There are some studies with supplementation of Spirulina that shows that Spirulina lowers inflammation, by amongst many mechanisms, decrease the release of histamine from mast cells and lowering interleukin 4 release (15). This lesser inflammation may improve the transport of iron in the blood and body. 

Vitamin C is known to increase the iron absorption by chelating iron and thus make it more soluble in the intestine (6). It also reduces it from its Fe3+ form to Fe2+ which improves uptake in the intestine (6). Spirulina can also function as a protector and source of vitamin C. This partly since it has been shown to limit the oxidation of vitamin C due to its high antioxidant properties and that Spirulina also contains vitamin C (10.1 mg per 100 gram – 10 to 20% of Recommended Daily Intake of vitamin C – RDA) (16 – 18). 

Obesity is both caused by and the cause of inflammation, which also limits iron absorption (6). Spirulina has in some studies, proven to be good at reducing glucose levels and blood fat levels (19, 20). This reduction in obesity may improve iron absorption.

If you like to test your serum iron content or blood values there are today also self home health test kits you can take in your home and send for analysis. Two sites that list home health tests are for English readers www.alyzme.com and for Swedish readers www.alyzme.se.

Spirulina grow kit 500 ml + 10L

With this starter kit with 500 ml Spirulina culture and 10 liter dry complete Spirulina grow medium you can start your own culture and grow your own Spirulina. In the kit, there is also a grow manual (47 pages) which will give you information on all aspects of growing Spirulina, how to make your own growing medium and plots to help you follow and measure your culture. 

Eating Spirulina and supplementing with vitamin B12

Dried Spirulina is known to contain analogs of vitamin B12 and not the real vitamin B12 (22). These analogs hinder the limited uptake and transport of vitamin B12 by the intrinsic factor in the gut and intestine (23). 

Many people already have a too low intake of vitamin B12. Even if you do not supplement your food with vitamin B12 today or eat Spirulina it is recommended that you start (24). 

Vitamin B12 is essential for its part in the synthesis of DNA and myelination of nerves and neurons (24). Too little can, among others, cause anemia, depression, dementia and Alzheimer’s (24, 25). Hence we strongly recommend you to supplement vitamin B12 alongside eating Spirulina.  

Conclusion about iron content in Spirulina

For you to determine how much Spirulina you need to eat to reach your daily iron need,  three different levels of 10 mg, 30 mg (WHO recommended need evened out), and 50 mg (for pregnant women) has been sat. 

Three different scientific sources of the iron concentration in Spirulina platensis has been used. Men need to absorb circa 2 mg iron per day, menstrual woman 4 mg per day and pregnant up and possibly above 6 mg per day. Since absorption in the gut is low, you need to get at least 10 mg and best 50 mg iron per day through your food. Especially the later if you are or plan to be pregnant. 

To meet that need you need to eat circa 6.5 to 60 gram dry Spirulina or 32.5 to 300 gram wet/fresh Spirulina every day,  Spirulina has some benefits so that it improves iron absorption but can also hinder vitamin B12 absorption. Because of this, and in general, due to low vitamin B12 content in today’s food, you need to supplement with extra B12. If you want to grow and eat your own much more tasty Spirulina, HealthAlgae also sells Spirulina cultures, grow medium and photobioreactors that you can use at home. 

Spirulina grow kit 500 ml + 10L

With this start kit with 500 ml Spirulina culture and 10 liter dry complete Spirulina grow medium you can start your own culture and grow your own Spirulina. In the kit there is also a grow manual (47 pages) which will give you information on all aspects of growing Spirulina, how to make your own grow medium and plots to help you follow and measure your culture. 

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3685880/
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2730642/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3048577/
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4179187/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4214798/
6. https://www.ncbi.nlm.nih.gov/books/NBK222309/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3105608/
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918713/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6373937/
10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257696/
11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5274660/
12. https://fdc.nal.usda.gov/fdc-app.html#/food-details/380642/nutrients
13. https://fdc.nal.usda.gov/fdc-app.html#/food-details/340988/nutrients
14. http://www7.slv.se/SokNaringsinnehall/Home/FoodDetails/1430
15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136577/
16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5274660/
17. https://fdc.nal.usda.gov/fdc-app.html#/food-details/170495/nutrients
18. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
19. https://www.ncbi.nlm.nih.gov/pubmed/12639401
20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2788188/
21. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4259868
22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257642/
23. https://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12312
24. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3874776/
25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1123448/

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