Only a fraction of ingested iron is absorbed by the body. The amount may range from only 5% to 35% according to a journal in the National Center for Biotechnology Information. So, even if you’re consuming enough iron, chances are you’re not absorbing all of it.
The amount of iron absorbed can depend on the circumstances and the type of iron. Here, we’ve taken a look at some of the different types of iron and how they are absorbed.
Ferrous iron, is quickly oxidized to the insoluble ferric (Fe+3) form at the human body’s pH.
When Fe+3 enters the first section of the small intestine, gastric acid lowers the pH allowing the transport of Fe+2 across the intestinal absorptive cells.
This lowering of the pH by gastric acid, which in turn allows the transport of Fe+2, is called ferric reductases. This process “enhances the solubility and uptake of ferric iron”, according to the Review on iron and its importance for human health.
However, if gastric acid production is impaired then iron absorption will be reduced substantially.
Dietary heme is also transported across the intestinal absorptive cells, however, the process that allows this is unknown.
Following this yet unknown process, dietary heme is then metabolized by heme oxygenase 1 (HO-1) to free (Fe+2) for absorption.
This process is more efficient that the absorption of inorganic iron according to the Review on iron and its importance for human health. This process also does not depend on gastric acid for absorption.
Red meats that are high in hemoglobin are known to be excellent nutrient sources of iron. They provide Fe+2 directly which can be transported across the intestinal absorptive cells and then exported to the bloodstream through the Fe+2 transporter ferroportin.
The flow of Fe+2 is sped up by several other mechanisms until it is picked up by transferrin, which delivers it into tissues.
The Review on iron and its importance for human health states that this process can be carried out up to 10 times daily in an attempt to deliver the iron that the body needs. The total iron content of transferrin corresponds to less that 0.1% of body iron.
Another process is thought to exist for the absorption of plant ferritins which are mostly present in legumes. However, most ferritin appears to be degraded during digestion.
Active Iron was developed with scientists at Trinity College Dublin. The new technology uses a unique iron-whey protein complex to ensure iron is released in the small intestine, where it is most readily absorbed.
If iron reaches the stomach it is known to cause oxidative stress and trigger gastric side-effects.
Studies confirm that the new Active Iron formulation doubles the amount of iron absorbed while being so gentle that it can be taken on an empty stomach. In our trial 9 out of 10 experienced no side effects. Active Iron only uses denatured whey-protein and encapsulated ferrous sulfate.