Apologies to anyone who is squeamish about the topic, but in this post, I'm calling nonsense on the idea that women are prone to iron anemia because of menstruation.
This story starts with dietary guidelines -- and the recommendation that men consume about 10 mg dietary iron per day, and women about 18 mg. Less than that 18mg for women, the narrative goes, leads to anemia, and to your doctor chiding you to eat more spinach and chug iron supplements.
Those darn red blood cells and their iron needs...
Anemia is an important health topic.
According to the WHO/CDC, mild iron anemia in adult women is commonplace. That's interesting and useful information, because it brings up the all sorts of great questions that need answering, such as why it happens and how best to treat it.
The problem is that these great questions are, for the most part, being ignored. Instead, doctors, textbooks, and reputable websites continue to repeat the same tired old notion:
- WebMD: "Women in the childbearing years are particularly susceptible to iron-deficiency anemia because of the blood loss from menstruation."
- ZocDoc: "Young women are unique because they lose a significant amount of blood every month through their period (menses), which is obviously not something that affects men or children."
- MedicineNet: "Women are more likely than men to have anemia because of the loss of blood from menstruation."
- Livestrong.com: "Adult women need to increase iron intake once menstruation begins. Menstruation means a loss of blood every month, which can affect overall iron content of the body. Women must compensate by increasing iron intake."
Yep, supposedly it's that darn period, the bane of the weaker sex and medieval society's favorite scapegoat for all things female. Women, so the logic goes, bleed. Replacing lost blood takes iron. So, women need more iron. Q.E.D., case closed.
Except that that makes absolutely no sense.
Let's look at it pragmatically.
An average human has 1-1/4 gallons of blood circulating through their veins at any given moment in time. The entirety of the red blood cells those 1-1/4 gallons of blood are replaced every 100 to 120 days, or about a little over a quart a month. This means that men, with their 10 mg of dietary iron a day, manage to restock more than a quart's worth each month.
By saying that women's higher iron needs are due to menstruation, mathematically, what we are saying is that while it takes 10 mg of dietary iron per day (the amount recommended for men) to restock a quart of blood, it takes 18mg per day (almost double -- the amount recommended for women) to restock a quart plus three tablespoons. See? It doesn't make sense.
But, the naysayers cry -- there's more to the female cycle than blood loss, so isn't possible that more iron is lost during menstruation than that accounted for by blood alone? Welp, let's look at the numbers again. As suggested by this Australian website:
"Women need more iron than men to make up for the amount of iron they lose in their menstrual period. Around 1 mg of iron is lost for every day of bleeding."
Sounds reasonable. But let's do the math.
One mg of iron per day of bleeding. Let's err on the generous side, and say five days of bleeding per period. That's 5 mg of additional iron needs per menstrual cycle. But remember -- the guidelines state that women need 8 mg more per day than men, 18 mg compared to 10mg. That's 200 mg more per full menstrual cycle (25 days), which is a whole lot more than 5 mg.
But what about heavier-than-normal menstrual bleeding?
Granted, some doctors/books/websites qualify their whole menstruation-leads-to-anemia by qualifying that it's heavier than normal menstruation that's the real culprit, and of course very excessive bleeding could be problematic. But here, the numbers get in the way again. To diagnose menorrhagia, doctors look for blood loss of about 80 ml, or 5.4 tablespoons. But remember, to account for the additional iron recommendations a woman would have to lose nearly a quart of blood in one period. That's enough to saturate 63 overnight sanitary pads.
I don't know about you, but if I experienced that, I'd be headed to my nearest emergency room, not wondering if I need to eat more spinach.
So. Can we please move past the whole concept of menstruation as some sort of nutritional iron black hole, and start looking for what is probably a really interesting reason why women do need lots more dietary iron? Because inquiring minds want to know, and I have yet to come across a sensible answer. (Know of one? Leave a comment -- I'd love to hear about it.)
And in the meantime, here are my favorite not-well-known solutions for those of us who -- whatever the actual cause -- find ourselves being handed iron supplements by our doctors:
- Eat more spices. Lots more spices. (Read more on this here.) One tablespoon of cumin has 22% of daily iron, as much as 1 1/2 cups of raisins, or 4 1/2 cups of spinach.
- Replace some of the grains in your diet with pseudograins, such as amaranth and quinoa. Both are awesome almost anywhere you'd use brown rice, and both are iron powerhouses. Per cooked cup, amaranth delivers 28% daily iron, quinoa 15% per cooked cup, and brown rice a mere 4%.
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