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The Fine Balance of Supplementing with Calcium and Iron

Mind Your Minerals

Everywhere you look in both natural and mainstream media, women are bombarded by consistent nutritional requirement messages - get more calcium and iron. The logic behind this bombardment is sound. Yes, women need other nutrients but they are at greater risk than men to be nutritionally deficient in these two minerals and ongoing deficiency leads to some rather nasty results.


Calcium is the most abundant mineral in the body and has multiple biological roles. Most know it as providing rigidity, structure and strength to bones and teeth. What is lesser known is that calcium plays a role in many if not most metabolic processes.

In healthy people, calcium is consumed and excreted thought the day. Your bones act as a calcium 'bank' for your body. When intake absorption exceeds what is used for metabolic requirements and what is excreted, the surplus is deposited into your bones. Conversely, when intake absorption falls below your metabolic requirements and excretions, your body draws calcium from your bones. This ensures the calcium level in your blood remains constant (for use in metabolic processes) regardless of your intake level. If your body pulls from your bones often enough, it leads to Osteoporosis (brittle fragile bones).

Every day we lose calcium through our bodily fluids. Combined losses from sweat, urine and feces can easily account for over 1000mg daily. This is why, in addition to a healthy diet, all women should be supplementing with 'good quality' calcium.

There are many low quality supplements available, which use inexpensive and poorly absorbed forms of calcium. Taking poorly absorbed sources (calcium carbonate, calcium citrate, and coral calcium to name a few) are a waste of money, as your body does not retain any meaningful amount. Your best bet is to look for supplements using better-absorbed forms of calcium (calcium potassium phosphate-citrate, calcium gluconate lactate, and calcium fructoborate), which actually deliver the calcium your body, needs.


Iron, although not as abundant in the body as calcium, is no less vital. Healthy adult bodies have between 3.5 and 5 grams of iron. About two thirds of your iron resides in hemoglobin (the red part of blood cells). A very small amount is used in enzymatic reactions and the remaining majority is stored in various places (liver, spleen, muscles).

Iron has several vital functions but primarily it’s the component of hemoglobin that carries oxygen throughout your body. Simply put, without sufficient iron our cells don’t receive the oxygen they need to function properly.

Like calcium, we lose iron each and every day. Most of our iron loss is internal (from within intestines, urinary tract, and airways). In women, it equates to between 1 to 2mg each day. Having the right amount of iron is vital. Too little iron and you may develop iron deficiency anemia, which makes you feel tired, weak, cold and irritable. Unlike calcium, excess iron is not excreted and too much iron is toxic.

Most healthy men get enough iron from their diet and rarely develop an iron deficiency. Most women's diets are not as meat heavy and therefore contain less iron. Additionally, women can lose large amounts of iron because of menstrual bleeding, pregnancy, and breast-feeding.

Thus women (even healthy ones) have an increased risk of iron deficiency.

Many people find supplementing with iron quite difficult. Iron is naturally a stomach irritant, which can result in stomach upset, constipation and heartburn. The irritation is reduced when taken with food but iron is best absorbed on an empty stomach. To mitigate the irritation and improve the taste, some supplements (mainly liquids) include juices in their iron product. Some forms of iron are well absorbed and tolerated (no stomach irritation), so look for products containing micronized iron pyrophosphate.


A Fine Balance

Getting enough of both iron and calcium becomes a nutritional balancing act. Calcium inhibits the iron absorption; in some cases absorption is reduced by as much as 62%! Despite this fact, some multiproducts contain both calcium and iron. Unfortunately people who need to supplement believe they are getting their requirements when in fact the reaction in the gut inhibits absorption of both.

The solution is quite simple. First off, find out from the National Institutes of Health website (http://ods.od.nih.gov) or from your doctor, how much elemental calcium and iron you should be getting daily. Subtract from that number the amount you obtain from your diet. The resulting number is the amount you need to supplement with each day. Go to your local store, and buy separate supplements (one for calcium and one for iron) that each have absorbable forms, such as those listed above, and take them at separate times of the day. Separate them by at least an hour to ensure you have no overlap in your gut.

By taking the time (about 10 minutes) to research and calculate your actual needs then planning ahead and taking high quality supplements at the right times, you can allow your body to absorb the calcium and iron it needs.


Joel Thuna, MH, is a master herbalist with over 30 years of experience. Dr Claude Gallant holds a PhD in Microbiology.