The iron in plants and seaweed is not the same as that in meat. Part of the iron in meat is haem iron, that of plants is non-haem iron, and its absorption depends a great deal on what you eat alongside it. This is something I wish I had known much earlier in my living food journey.
At Biovie, we have been working with seaweed for 18 years. Aurélie and I are often asked the same question: where do you find iron when you eat little or no meat? That is the subject of this article.
In this article, I share what we have learned about plant-based iron and edible sea vegetables, with practical guidelines for your meals.
Vitamin C and iron: a duo to know
The iron in plants is better absorbed when eaten with vitamin C: vitamin C increases iron absorption. That is why it is worthwhile to combine plant-based iron sources with fresh fruit and vegetables, preferably raw.
The mechanism is simple to understand: vitamin C reduces ferric iron to ferrous iron, the form that the intestinal wall absorbs best. A squeeze of lemon, a few orange or kiwi segments, fresh parsley or raw pepper on the plate are enough.
Absorption inhibitors: the detail that ruins everything else
Let's say it plainly: you can eat the best plant-based iron source and absorb only a fraction of it, simply because of what you drink alongside.
- Tannins in tea and coffee can reduce absorption by up to 60% when taken during the meal. This is by far the main brake.
- Phytates in whole grains and unsoaked legumes - hence the value of soaking, and even more of sprouting.
- Calcium in large quantities, notably through dairy products taken at the same time.
- Certain treatments, in particular antacids and proton pump inhibitors.
The fix comes down to one sentence: move your tea or coffee to thirty minutes to an hour after the meal, and avoid combining your iron source with a meal very rich in dairy products.
Iron deficiency: 25% of French women affected
Let's start with the figures, because they are telling. According to Santé Publique France (ESTEBAN study, 2023), 25% of women of childbearing age have an iron deficit. One woman in four. And that is only the visible part: many people live with low ferritin without knowing it, attributing their tiredness to stress or lack of sleep.
The 7 symptoms that reveal a lack of iron
How do you know if you are lacking iron? Here are the most commonly cited signs:
- Persistent tiredness : You wake up tired, even after a good night's sleep
- Unusual breathlessness : Climbing a staircase leaves you more out of breath than before
- Excessive sensitivity to cold : You are always cold, especially in the extremities
- Pale complexion : Your skin lacks radiance, your mucous membranes are pale
- Brittle nails and dull hair : Your skin appendages suffer first
- Difficulty concentrating : "Brain fog" sets in
- Palpitations : Your heart beats faster to compensate
If you recognise yourself in several of these signs, talk to your doctor: only a blood test can tell you where you stand.
Why women are 3 times more affected than men
The answer is physiological: menstruation. Each month, a woman loses between 15 and 30 mg of iron. The daily needs of a woman of childbearing age are 16 mg a day, compared with only 9 mg for a man.
And during pregnancy, it is even more marked. ANSES indicates that iron needs increase by 50% during this period. The INCA3 study reveals that 77% of pregnant women have insufficient intakes. That is considerable. To find out more aboutliving food and pregnancy, see our dedicated guide.
The three stages of iron deficiency
A deficiency does not set in overnight, and it is useful to know where you stand: you can be short of iron well before being anaemic.
- Stage 1 - depletion of stores. Ferritin falls, but nothing is felt yet. A blood test that measures only haemoglobin can appear perfectly normal. Yet this is the moment when it would be easiest to act.
- Stage 2 - deficient erythropoiesis. Iron begins to run short for properly making red blood cells. Tiredness sets in, often put down to lifestyle.
- Stage 3 - iron deficiency anaemia. Here, symptoms become hard to ignore: breathlessness, pallor, exhaustion at the slightest effort.
The practical point to remember: if you recognise yourself in the symptoms, ask for a ferritin measurement, not just haemoglobin. It is the only way to spot stage 1.
Haem iron and non-haem iron
You often hear that iron of animal origin (haem) is better absorbed than plant iron (non-haem). In reality, the absorption of non-haem iron depends a great deal on the rest of the meal.
Haem iron, found in meat and fish, is absorbed at about 15 to 25% depending on sources. The non-haem iron in plants is absorbed in very variable proportions, depending on the food and on what accompanies it.
Bioavailability, what are we talking about?
Bioavailability is the share of the iron consumed that is actually absorbed by the body. For non-haem iron, it varies by food and by meal: this is why raw contents do not tell the whole story.
Seaweed and iron: guidelines
At Biovie, we have offered seaweed since our beginnings. For a complete overview, see our guide on seaweed and micro-algae.
Spirulina
Spirulina is a micro-algae that we offer as a food supplement. Its iron content varies greatly according to studies and growing conditions: the composition of our spirulina is given on its product page.
The spirulina mixes easily into a juice or a smoothie. Recommended daily dose: 3 g. Do not exceed the recommended daily dose. A food supplement is not a substitute for a varied and balanced diet and a healthy lifestyle. Keep out of the reach of young children.
You can explore all the products in this category in our Spirulina.
The spirulina also naturally contains phycocyanin, the blue pigment that gives it its colour, and chlorophyll.
