For April you get a chance to be inside my head and see how my free association logic runs sometimes. I was thinking about a topic for this month and with April, April Fool's Day popped into my head. That doesn't have much to do with health (although we have discussed the very healthy habit of laughing). But next up popped Fool's Gold - also not a lot to do with health - but its "real" name is Iron pyrite and that led to thinking about just plain old iron which DOES have something to do with health! At last! Our "Of the Month" topic for April is iron!
Iron is one of the most abundant elements on earth, although it is rarely found in a pure form there. A little over 5% of the earth's crust is iron and nearly all of its core is iron. It is found in the sun and stars and is a major component of a type of meteorite called a siderite. In fact, the picture here is of a meteorite made primarily of iron. We commonly know iron mostly as a hard metal in steel and other alloys and in our cast iron skillets.
That same iron, element number 26 on the periodic chart, is also a critical piece of human health. Iron was first recognized as a constituent of the body in 1713 and then as a dietary essential in the 1860s. There are only two oxidation states of iron that are stable in the body - the ferric (Fe3+) and ferrous (Fe2+) forms - which only matters to the chemistry buffs out there. It comes in as Fe3+, but is quickly changed to Fe2+ for absorption. There are between 2 and 4 grams of iron in us at any given time and in a healthy person, over 65% of the iron is traveling through the bloodstream in hemoglobin.
Functions of Iron. The biochemistry of iron usage in the body is incredibly complex! The biggest use of iron is in the bone marrow in the production of heme. Iron in the central atom in this structure which is responsible for oxygen delivery to tissues (as hemoglobin), storage of oxygen in muscle (as myoglobin), and also the electron transfer in the cytochrome production of energy.
Additionally, iron is a component of several enzymes in the body that are responsible for a variety of functions including synthesis of amino acids, conversion of Vitamins A and B3, liver function and functioning of the immune system.
Sources & Availability of Iron. Dietary iron is found in one of two forms - heme and non-heme. Meat, fish and poultry contain a little over 50% of the heme form. Plants only contain the non-heme form. some of the higher vegetable iron levels are found in tofu, Swiss chard, lentils and amaranth. And black strap molasses! Dairy also has the non-heme form and is not a good source of iron. Both forms of iron are poorly absorbed, but the non-heme form is even less well absorbed. This is partly because it is attached to other compounds and must be broken down further to become available. In general, only 10-20% of dietary iron is absorbed by the body. The rest you just flush away. It is interesting that the absorption of iron is inversely related to the amount of iron stores in the body. In other words, the more iron we have stored, the less iron will be absorbed - and vice versa. All the intricacies of this feedback loop are not fully understood, but it is surely a protective mechanism. Excess iron in the body is detrimental, sometimes life-threatening, so it makes sense that if we already have enough, we wouldn't want to take in any more! However, it is IMPORTANT to know that excessive flooding the body with iron CAN overcome the resistance to absorption and result in very real problems. More on that to come....
Enhancing absorption. Absorption of non-heme iron can be increased by being eaten with vitamin C. Studies indicate that eating non-heme iron plain will result in 2-3% absorption. If taken with 75mg of vitamin C (ascorbic acid), the rate goes up to about 8% in a person with adequate iron stores already. In general, iron is better absorbed in a higher acidity environment. This means that people taking over-the- counter or prescription acid-blockers for heartburn are reducing their ability to absorb iron. Eating protein at the same time also appears to help.
Copper doesn't affect the absorption of iron, but it is essential for the release of iron from storage. Iron will get absorbed and stay in storage forever without copper and that doesn't do us much good!
Inhibiting absorption. There are many more known dietary inhibitors of iron absorption than enhancers. Various compounds found in tea, coffee, spinach, chard, chocolate, some berries, some grains and egg yolks may interfere to some degree. The phenolic compounds in tea and coffee are the biggest culprits, reducing absorption 40-60% when consumed with or just after a meal. Other minerals also interfere, including calcium, magnesium, zinc, manganese and nickel. Multi-vitamins that contain a combination of these are, therefore, not likely to be adding any appreciable iron to your stores.
Iron Deficiency. Iron deficiency may be caused by lack of dietary intake and/or poor absorption. Since most of the iron is being carried around in the bloodstream, a deficiency can also be caused by excessive blood loss. Symptoms of iron deficiency include a certain kind of anemia, weakness, fatigue, lack of concentration, decreased immune system function, pale skin and possibly behavioral disturbances and learning difficulties in children. Most cases of deficiency respond well to supplementation.
Iron Toxicity. It is possible to have a toxic dose of iron all at once. This has been recorded in children who take large amounts of adult iron supplements.
PLEASE KEEP THESE AND ALL SUPPLEMENTS AND MEDICATIONS OUT OF THE REACH OF CHILDREN!!! There is also a genetic condition called hemochromatosis where iron absorption is heightened and perhaps misregulated. Excess iron is stored in the heart, liver, pancreas and maybe other organs as well, causing permanent tissue damage. The full-blown form of hemochromatosis is rare, but it's estimated that 8-15% of U.S. Caucasians may have a milder form called hemosiderosis which still absorbs and stores excess iron, but without the tissue damage. Genetic testing is available to determine what form a person has.
Iron in Lab Tests. Testing for iron in the blood isn't necessarily as simple as all that. If you and your doctor suspect iron deficiency or overload, there will be a number of tests to give the most complete picture. We can test for total iron, for total stored iron, for iron binding capacity and percent saturation. Looking at the nature of the red blood cells - their size, shape, color and volume - is important. And remember that other things may impact the state of iron in the blood including lowered levels from current menses, current infection, pregnancy, liver dysfunction, low stomach acid, low vitamin C status and increased levels from lead poisoning, some drugs and alcohol, and spleen dysfunction.
So How Much Iron Do You Need? We certainly need to replace as much iron as we lose each day. Calculating the normal lifespan of a red blood cell carrying around iron in hemoglobin, men and post-menopausal women lose between 0.7-1.0 mg of iron per day largely due to death of a certain number of those red blood cells. In the RDA recommendations of 1989, an assumption was made of 10% dietary iron absorption and so set the goals at 10 mg/day. The amount was higher, 15 mg/day, for pre-menopausal women. A later Committee suggests 15 mg/day for men and women maintains stores at 300 mg, a level at which there is no evidence of deficiency.
That is certainly a good place to begin, but individual considerations may be necessary. As we've seen, the assumption of 10% absorption may be generous, particularly in vegetarians. In vegetarians who feel they may have problems with iron levels, having bloodwork done before supplementing is the safest route to go. Healthy meat-eaters, in general, are probably getting all they need in their diet and should not have to supplement at all.
If you do decide to supplement with iron, be aware that some forms of iron can be very constipating. It can also make your stools very dark, so don't be alarmed. Some believe that supplementing with citrate, malate or fumerate forms of iron are best absorbed and have the least number of side effects. You might need to experiment to find what works best for you. You might also consider cooking in cast iron, which does provide small amounts of iron as well. And for those with iron excess problems,
avoid cooking in cast iron!
Remember, with iron we need to be like Goldilocks - not too little, not too much, just the right amount!
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