You’ve probably been there at some point.
You feel more tired than usual. Not sick. Not burned out. Just… less energy than you usually have.
It’s one of those feelings that’s hard to put your finger on.
Maybe you’ve even thought: Why do I actually feel this tired?
You might take a blood test.
The results come back and everything looks normal.
The blood value is good. Nothing stands out.
But you still can’t quite shake the feeling that something isn’t right.
And sometimes your gut feeling can actually be completely right.
Because it can be about the iron stores.
What that blood test doesn’t always reveal
When testing iron in healthcare, they often first look at hemoglobin (Hb).
It’s the protein in red blood cells that transports oxygen in the body. And it’s important.
But the body also has a store.
That store is called ferritin and functions as the body’s iron reserve. A kind of stockpile that can be used when the need increases.
Ferritin is sometimes measured at the same time as Hb, but not always.
That means iron stores can be low long before the blood value changes.
The ferritin value many never hear about
In many labs, ferritin is considered normal already from about 15–30 µg/L.
But in practice, many women experience symptoms long before levels drop that low.
That’s why levels around 50 µg/L or higher are sometimes discussed when talking about energy, hair growth, and physical endurance.
How different levels of iron stores affect the body can of course vary individually. But many start to notice a difference in energy only when ferritin is somewhere around that level.
That’s also why you can feel tired even though your blood test shows everything looks normal.
How much iron is actually in food?
To give a little perspective.
If you eat 100 grams of beef, you get about 2–3 mg of iron.
If you eat 100 grams of cooked lentils, you get about 3 mg of iron.
That sounds like quite a lot. But the recommended daily intake for women of childbearing age is around 15 mg per day according to the Nordic nutrition recommendations.
Besides, the body doesn’t absorb all the iron we eat.
And iron from plants is absorbed significantly less well than iron from animal foods.
That means the amount of iron on the plate is not always the same as the amount the body can actually use.
The detail that can determine how much iron the body absorbs
How much iron you eat is one thing. How much the body actually manages to absorb is another.
Here comes vitamin C.
Vitamin C helps the body convert iron into a form that is easier to absorb in the intestines.
That means the same meal can provide different amounts of iron depending on what you eat with it.
For example:
lentils + lemon beans + bell pepper or a iron supplements together with vitamin C, can improve absorption.
At the same time, there are things that do the opposite.
Coffee and tea contain substances that can reduce iron absorption if consumed directly with a meal.
That’s why the stomach reacts differently to iron supplements
If iron stores are already low, it can sometimes be difficult to replenish them through diet alone.
Some then choose to supplement with iron in supplement form for a period.
What many notice then is that iron can sometimes affect the stomach.
Constipation, nausea, or discomfort are quite common with certain forms.
That’s why the form of iron plays a big role.
For example, often used iron bisglycinate, where the iron is bound to the amino acid glycine. That form is usually gentler on the stomach and absorbed effectively.
Even the quality of the raw material and how the supplement is made can affect how well the body tolerates it.
Small signals the body sometimes tries to give
Low iron stores don’t always just show up as tiredness.
Many also describe things like cold hands and feet, getting easily out of breath, or hair feeling thinner than usual.
None of that, nor the tiredness, is something you should have to get used to.
Or think “that’s just how life is.” Or that there’s something wrong with you.
Getting more iron can be an easy way to experiment and see if it makes a difference for you.
Iron affects not only everyday energy. It can also be noticed in things like exercise, recovery, and how stable your energy feels throughout the menstrual cycle.
Sources
EFSA – Dietary Reference Values for Iron
NIH Office of Dietary Supplements – Iron Fact Sheet
Nordic Nutrition Recommendations (NNR)
