Low Ferritin: Why Your Iron Levels Look Fine But You Feel Anything But

I see this in clinic more than almost anything else. Someone comes in exhausted. Not just tired — the kind of tired that sleep doesn’t fix. Their hair is coming out in the shower, they’re cold all the time, they can’t hold a thought. And they’ve already been to their GP, had bloods done, and been told everything is normal.

In a significant number of those cases, when I actually look at the numbers, ferritin — iron storage — is sitting at the very bottom of the reference range. It’s technically normal, but nowhere near sufficient for a body to work well. This is extremely common, particularly in women, and it is consistently missed.

Iron and ferritin are not the same thing

This is where most of the confusion starts, and it matters.

When your GP runs a standard blood test, they may check iron — the amount circulating in your blood right now. Ferritin is different. Ferritin is the protein that stores iron in your tissues. It’s your body’s reserve supply, what your cells draw on when they need it.

The important thing to understand is this: your body will protect circulating iron for as long as it possibly can. It will pull from stores to keep blood levels looking normal. So by the time iron itself drops on a blood test, ferritin has often been depleted for months, sometimes longer. You can feel terrible and still have iron levels that look completely fine.

What it actually feels like

The symptom picture is wide, which is part of why it gets missed and why women are so often told they’re fine.

The most common things I hear:

Tiredness that doesn’t shift no matter how much you sleep. Iron is essential for getting oxygen into every cell in your body. When stores are low, everything is running on less than it needs. That bone-deep tiredness is one of the most consistent signs.

Hair coming out. The hair follicle is one of the most demanding tissues in the body. It’s also one of the first things the body doesn’t prioritise when resources are low. Hair shedding — more on the brush, more in the shower — is an early sign of low ferritin, sometimes showing up long before anything else.

Being cold all the time, especially hands and feet. Iron plays a role in how well the thyroid converts its hormones into the active form. Low ferritin can impair that process, which affects your metabolism and your ability to regulate temperature.

Brain fog and difficulty concentrating. Iron is needed to make dopamine and other neurotransmitters. When stores drop, cognitive function goes with it.

Getting breathless doing ordinary things. Climbing stairs, carrying bags, walking faster than usual. If your body doesn’t have enough iron to carry oxygen efficiently, you feel it.

Restless legs at night. Low ferritin is one of the most common and most correctable causes of restless leg syndrome.

Why this affects women so disproportionately

Men can have low ferritin too, but women are far more likely to, and the reasons are worth understanding properly.

Monthly blood loss is the most obvious one. Even a textbook normal period involves a meaningful iron loss every single month. That loss needs to be replaced through diet, consistently, for years. Heavy periods — which are far more common than people realise, and far too often normalised rather than investigated — can make it almost impossible to make up for what you’re losing each month, no matter how well you’re eating.

Pregnancy and breastfeeding deplete ferritin significantly. The demands are high, the recovery is slow, and many women come out the other side of those years running on empty.

Perimenopause adds another layer. Cycles often become heavier and more erratic in the years before menopause, increasing losses at exactly the time when sleep, stress, and energy are already stretched.

And then there’s the way women are often told their results are fine when they’re not. The reference ranges were built on populations that included men. The threshold for “normal” ferritin doesn’t reflect what women actually need to function well.

Eating well isn’t always enough

This is the part that frustrates a lot of my clients, because they’re already doing the right things.

You can be eating red meat, lentils, leafy greens — all the right foods — and still have low ferritin if your body isn’t absorbing iron properly. Absorption is often the missing piece.

Low stomach acid is one of the most common factors. Stomach acid is needed to convert dietary iron into the form your gut can actually absorb. Chronic stress, long-term use of antacids or proton pump inhibitors, and the natural decline of stomach acid with age can all reduce your absorption capacity.

Tea and coffee close to meals also significantly reduce iron absorption. This is one of those small daily habits that adds up considerably over time. A cup of tea half an hour after lunch, every day, for years, is a meaningful factor for someone who is already borderline.

Calcium competes with iron for absorption. Taking a calcium supplement with an iron-rich meal, or eating a high-calcium meal at the same time as your main iron source, reduces how much of it you actually take in.

Gut inflammation — including coeliac disease, which is not uncommon and often undiagnosed — reduces absorption capacity across the small intestine. If there are longstanding gut symptoms in the picture alongside fatigue and hair loss, that’s worth looking at properly.

Vitamin C does the opposite — it actively improves absorption of plant-based iron. Something as simple as squeezing lemon over lentils, or having some red pepper alongside spinach, makes a big difference.

On supplements

If ferritin is depleted, diet alone will usually not rebuild it quickly enough, especially if there’s ongoing loss through heavy periods. Supplementation is often necessary.

The standard prescription — high-dose ferrous sulphate — is effective but can be hard on the gut. Constipation, nausea, and cramping are common enough that many people stop taking it. Lower-dose, more absorbable forms, particularly ferrous bisglycinate, tend to be much better tolerated and are often the more sensible starting point.

What I look at in clinic

When someone comes in with this picture — fatigue, hair loss, cold intolerance, brain fog — ferritin is one of the first things I want to see. Ideally alongside a full iron panel, a full blood count, B12, folate, and thyroid function, because these interact and can look very similar.

If ferritin is low, the work goes in two directions: understanding why, and building it back up.

On the dietary side, that usually means going through what they’re eating and identifying the absorption factors that are working against them — stomach acid, gut health, the timing of tea and coffee, calcium and iron clashing.

If heavy periods are part of the picture, that has to be addressed too — because supplementing iron while losing it heavily every month is like filling a bath with the stopper out. I work on the hormonal side through nutrition, and for some clients, acupuncture alongside it. There’s more on how I approach cycle-related symptoms on the women’s health page.

It takes time. Most people start to feel a difference around the two to three month mark, and rebuilding stores properly is usually a four to six month process. But the shift when it happens — in energy, in how the hair feels, in being able to think clearly again — is often one of the most significant changes clients experience.

Practical steps worth taking

A note on getting help

If you’re exhausted, losing hair, and been told your bloods are fine, it’s worth getting a second look at the actual numbers — not just whether something was flagged. This is something I see and work with regularly in clinic.

If you’re based in Dublin and want to look at this properly, I offer nutritional therapy consultations in person in Whitehall and online across Ireland and the UK. Get in touch here.