Iron is how oxygen moves. Every red blood cell you make needs it, and those cells are what carry oxygen to your muscles, your heart and your brain. Run short and the whole body is working on less air than it needs.
It is the most common nutrient shortage in the world, and women lose iron every single month, which is why so many of us are quietly running low.
Low iron does not announce itself. It creeps. You are tired in a way that sleep does not touch. Stairs leave you breathless when they never used to. Your heart races over nothing. You are pale, cold-handed, foggy, irritable. Your hair comes out in the shower. Your nails break. Some people crave ice, or the smell of soil, a strange sign, and a real one.
Most women put all of that down to being busy, being a mother, being over thirty.
But here is the part that matters, and it is the reason this is on my shelf with a warning rather than a pitch.
You cannot feel your iron level, and you must not guess it. Ask your doctor for a full blood count and a ferritin test. Ferritin is the one that shows your stores, and you can be running on empty while the standard test still looks normal.
Two reasons I am firm about this. Iron you do not need is not harmless, your body has no way to get rid of the extra, and it builds up. And low iron in a man, or in a woman past menopause, is a signal that something needs finding, not just filling.
If your test comes back low, this is a good one. Ferrous bis-glycinate is a gentler form than the old iron tablets that leave people constipated and nauseous, and it comes with the B12, folate and copper your body needs to actually build blood with it.
Take it with something high in vitamin C, and away from tea, coffee and dairy, which all block absorption. And keep it out of reach of children, iron tablets are one of the most common causes of serious poisoning in small children.
Test first. Then treat. In that order.