RDA of Iron

My Supplement Has 100% of the RDA of Iron but My Iron is Still Low?

If you find yourself wondering why you are taking enough iron but you are still iron deficient, you may be taking the wrong type of iron. There are two types of iron. One is ionic iron which is manufactured in a laboratory from chemicals and the other is Heme Iron which is derived from bovine red blood cells. Heme Iron absorbs far better than does ionic iron. All Proferrin® products are Heme based iron supplements, ensuring that you are taking the only supplement you need to support healthy iron levels.

How does this relate to your iron supplement? The USDA publishes RDA’s based on the amount of a vitamin or mineral that you should ingest daily in order to maintain healthy levels. According to the Institutes of Medicine version the RDA of Iron includes a very important footnote (click on Elements Table .pdf file at bottom of page). That footnote says that the RDA “assumes” that you are getting 75% of that daily Iron intake amount from Heme Iron sources. So, if the iron in your supplement is ionic iron (virtually all of them are) the RDA really doesn’t mean anything relative to the iron supplement you are taking. Thus, it is very easy to be taking an iron supplement that supposedly meets the RDA, but still be low in iron, because not enough of the ionic iron is absorbing into the bloodstream to meet your body’s demand for iron. The only sure way to ingest enough absorbable iron is to take a Heme Iron supplement such as Proferrin®*. Furthermore you need to make sure that in your supplement the total number of milligrams of elemental iron in the form of Heme Iron is high enough to meet at least 75% of the RDA of Iron. There is only one supplement that contains 100% of its iron in the form of Heme Iron. That iron supplement is Proferrin®, and it contains a proprietary Heme Iron called Heme Iron Polypeptide. You will easily obtain the remaining 25% in the form of inorganic iron found in other foods such as enriched flours or grains used to make breads and cereals.[1]

Below is a table, which lists the recommended daily allowance of iron, with an adjoining column that showing the RDA recommendation when 75% of that intake comes from a Heme Iron source. The Institute of Medicine recommends that 75% of your iron intake comes from a Heme Iron source (e.g. lean meat, eggs, and seafood). Most iron supplements do not contain Heme Iron, which means if you are supplementing your iron, but not taking Proferrin®, you may not meet your recommended iron intake*.

GenderUSDA – RDA75% of RDA (Heme Iron)
Males8 – 11 mg. (age dependent)6 – 8.25 mg.
Females8 – 18 mg. (age dependent)6 – 13.5 mg.
Pregnancy27 mg.20.25 mg.

* This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.


  1. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc : a Report of the Panel on Micronutrients. Washington, DC: National Academy Press; 2001.

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