WHAT IS IRON?
Iron (Fe) is a metallic chemical element and has the atomic number 26.
Iron proteins are found in all living organisms including humans. It is iron that gives our blood its red colouring.
Iron has the longest history of discovery and exploration of all the micronutrients,
The heme proteins hemoglobin, myoglobin and cytochrome P450 are inorganic compounds using iron.
Free iron is highly toxic in the body and can lead to excessive cell damage because of iron’s catalytic effect on the formation of free radicals.
Ferritin is a protein that binds iron and releases it in a controlled way.
In our cells iron storage is carefully regulated by transferrin a blood plasma glycoprotein. Transferrin absorbs iron from our upper intestine and also collects it from macrophages (our bodies’ garbage collectors) . Transferrin binds iron and carries it in the blood delivering it to tissues throughout our bodies.
Iron uptake is highly regulated in our bodies because our bodies have no way of excreting iron although we do lose a small amount through mucous expulsion and skin sloughing.
WHAT DOES IRON DO FOR US?
Iron is key to our metabolism and is an essential part of hundreds of proteins including enzymes.
Heme (iron containing compound) is an essential component of:
1. Cytochromes – Electron Transport and Energy Metabolism
Cytochromes are one of the compounds that are critical to our cells for energy transport in the mitochondria. The mitochondria are responsible for converting nutrients into energy through the electron transport chain. The electron transport chain transports electrons in a sequence that generates ATP (adenosine triphosphate) which is the storage unit for energy in our cells.
2. Hemoglobin (an iron containing oxygen carrier protein) is responsible for Oxygen Transport that makes up about two thirds of our bodies iron content. It is the most important protein in red blood cells and is used to transport oxygen from the lungs to the rest of the body. It has the unique ability to get oxygen quickly from the lungs and then deposit it as needed as it circulates through the tissues.
Myoglobin stores oxygen for short periods of time and transports it to the cells in our muscles as they demand it.
3. Antioxidant and Pro-Oxidant Function
a.Catalase and peroxidases set into motion a reaction that converts hydrogen peroxide to water and oxygen. Hydrogen peroxide can accumulate in our cells. Reactive oxygen species (ROS) are oxygen containing chemicals that react with other molecules and change them in ways that are very damaging to our cells. Peroxide is an ROS. When Catalase and peroxidases convert peroxide they protect the cells from damage.
b. Myeloperoxidase is a heme containing enzyme that catalyzes things called neutrophils. Neutrophils create an ROS called hypochlorous acid which is used by white blood cells, as part of the immune system, to engulf bad bacteria in order to kill them, positive use for ROS.
Non-heme iron proteins:
1. Prolyl Hydroxylase – Oxygen Sensing Enzyme
When we are in a situation where we are not getting enough oxygen such as asthma or being at high altitudes something called hypoxia happens. Hypoxia simply means a lack of oxygen.
Hypoxia creates a response through factors known as ‘hypoxia inducible factors’ (HIF) which alter genetic coding so that various proteins are created that will compensate for the lack of oxygen by increasing red blood cell production and blood vessel production. Increased blood vessel growth is called angiogenesis. Angiogenesis is important in fetal development and a problem in cancer growth.
HIF is an important factor in human growth and for life itself but for obvious reasons needs to be controlled. This is where the iron dependent enzyme prolyl hydroxylase comes in. Prolyl hydroxylase plays a critical role in regulating HIF
2. Ribonucleotide reductase is an iron dependent enzyme that is needed to create DNA. Iron therefore is needed for vital functions such as growth, reproduction, healing and immune function.
WHAT HAPPENS WHEN WE DON’T GET ENOUGH IRON?
Iron deficiency is the most common nutrient deficiency in the world.
Lack of foods containing iron in the diet and eating foods that are high in zinc contribute to this deficiency. Zinc found in oysters, dark chocolate and some seeds such as pumpkin seeds can decrease iron uptake levels.
There are three levels of iron deficiency:
The first is when stored iron is depleted but there is still enough iron in circulation to function.
The second is when the level of functional iron is so low that it impairs the production of red blood cells but not enough to show the signs of anemia.
The third level brings impaired red blood cell production full cycle resulting in anemia. Anemia brings fatigue, heart problems and rapid breathing when the body is exerted. There is reduced oxygen delivery to the tissues and decreased oxygen levels to the muscles.
Iron deficiency in children can produce poor cognitive development and behaviour problems and has been linked to an increased susceptibility to lead poisoning.
Low birth weight, premature births and death of the mother at birth are all associated with severe iron deficiency during pregnancy.
WHAT HAPPENS WHEN WE GET TOO MUCH IRON?
Iron overload disorders:
Genetic defects – hemochromatosis
Iron accumulates in the hippocampus of the brain of those with Alzheimer’s disease and in the substantia nigra (mid brain) of those with Parkinson’s disease. Although iron is required for normal brain development too much of it can result in high levels of oxidative stress. Because the brain is so susceptible to oxidative stress and the damage it does excess iron can lead to neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Large amounts of ingested iron can damage DNA, proteins, fat and other cells in our bodies. Free iron reacts with peroxides to produce free radicals.
Iron toxicity occurs when there is free iron in our cells and this happens when there is more iron than there is transferrin to bind the iron.
The cells that are damaged by iron are usually the heart and the liver along with cells elsewhere in the body. The damage to these cells can lead to respiratory distress, long term organ damage, shock liver failure, coma and death.
Excess iron intake from iron supplements (usually meant for adults) is the leading cause of death in children under six years of age.
WHERE DO WE GET IRON?