Now that i've expressed myself about the foolhardiness of taking some abstract researcher's advice to not take iron if you think you might need it....
Iron is a very important component of MANY of the enzymes your body uses to catalyze reactions, without which you will DIE. Certainly, a mere shortage will only reduce your well-being. ONLY (ha!).... Our bodies are "intelligent" and will funnel resources to the functions it considers most urgent. Since iron's #1 mission seems to be oxygenating our tissues via the blood, all those "housekeeping" functions of the iron-containing enzymes will suffer first, if there is a relative shortage of iron in your system. By the time you're certifiably anemic, you are SERIOUSLY deficient.
And how could a red-meat-eater like me be at all likely to have a shortage of iron? EASY. I'm a life-long hypothyroid.
One of the first things a doctor will ask, if s/he suspects hypothyroidism is, "how is your digestion?" We hypos tend to have low stomach acid. Low stomach acid leads to bad nutrient absorption, among many other things. (And with the very high numbers of hypothyroid people around these days, most of the people suffering from GERD probably owe it to LOW rather than to elevated stomach acid.)
When we eat a meal, or even a single food, all of the components compete for absorption throughout our bodies, and whatever is in larger proportions usually ends up "winning." This is why sugar-eaters need more vitaminC -- they compete for the same receptor. Different amino acids also compete with each other. Ditto, with the metals.
This is why most of the supplements i take are NOT taken WITH a meal. I take my systemic enzymes in the morning, half an hour or more before anything else. (Since i started taking my coffee black, i don't worry about when in the sequence i start drinking it.) Next i take the tyrosine, so it doesn't have anything to compete with at all; if i haven't had oysters or liver in a long time, i sometimes take copper with it. A half-hour or more later, i take T-100, iodine, vitamin D, and my first dose of carnitine, and afterward i eat when i get hungry. Some four or more hours later, i have the iron, B12, C and selenium, and after a bit i eat another meal. The second dose of carnitine (which is not an amino acid as it was originally described, but actually closer to a B-vitamin) needs to come by 2:00 in the afternoon, because it has been known to delay sleep. Before bed, i take another thyroid glandular with my magnesium, zinc and manganese. I rarely need melatonin, but if i'm wound up for some reason, or if i have something special to get up for the next morning, i find it valuable.
Not eating grains, or an excess of unsoaked nuts, WILL help you absorb iron and other minerals better. Some of us must still make special efforts to get the nutrients we need. Not wasting our "powers" on nutrients we DON'T need -- most carbohydrates -- allows us to make the most of our calories and "aging bodily resources."