Because my patient population involves primarily women of child-bearing age, I see iron deficiency A LOT.
We've been told for many years that we should be avoiding red meat and opting for more plant-based food options to be "healthier". Naturally, health-conscious women begin reducing or completely eliminating red meat from their diets. Depending on what their levels were before the diet change, it may take a couple years for iron to get so low that they start exhibiting symptoms.
Depending on the age this diet change was made, a woman may have no clue that this may be impacting her menstrual cycle. I can tell you from my own experience (and I see this reflected in my patients) that period cramps were extremely painful when I was iron deficient. I was vegetarian from the time I was in high school all the way through college, I was both extremely tired AND had heavy and painful periods. Oddly enough, the female body tends to lose more blood when a woman is iron deficient, further worsening the cycle.
Technically, a woman is not considered iron deficient unless her Ferritin is at 15 ng/mL or below. I can tell you from personal and clinical experience that every patient that I've had who had a Ferritin below 20 ng/mL really struggled to stay awake during the day.
This is one of the reasons why men typically do far better on a plant-based diet because their iron needs are much lower. Women often crave burgers and steaks as they are about 5 years into a vegan/vegetarian diet. Why? Because the body knows best! These cravings point our bodies in the direction of nutrient density.
It took me about two years to increase my iron stores from 32 ng/mL in 2013 to 56 in 2015. And that was while eating liver and red meat regularly (just not enough)!
So why do we need iron?
Iron's main role in the body is to carry oxygen on red blood cells. You've all heard of Lance Armstrong blood doping with EPO to increase his red blood cells right? Well, the reason why he benefited from more blood cells is because he had more oxygen carrying capacity! So think of it like this: If you become iron sufficient, how much better would you be able to perform in athletics, at work, or in school?!
If you've been exhausted and requiring caffeine and/or a nap to make it through the day, consider seeing me in my office so I can help determine what might be causing your fatigue. There are too many good things in life to go through it with sub-optimal energy!