Iron plays a vital role in many metabolic functions in the human body. As such, a deficiency in iron can lead to a wide range of physical symptoms and impairments, such as:
- Cracked corners of the mouth
- Susceptibility to infections
- Pale skin
- Fatigue
- Forgetfulness, memory problems
- Brittle fingernails
- Smooth tongue
- Itching (pruritus)
- Decreased sexual desire
- ADHD
- Depression and anxiety
- Reduced physical performance
- Rapid heartbeat, shortness of breath during exertion
- Headaches, dizziness
- Fatigability
- Restlessness and sleep disorders
- Hair loss
Iron has numerous functions within the complex metabolic system of the body. Some of the key functions of iron include:
Blood Formation
Iron is the binding site for oxygen in hemoglobin, the protein in red blood cells. Without sufficient iron, the body's capacity to transport oxygen decreases, resulting in shortness of breath, reduced performance, palpitations, irregular heartbeat, and fatigue. Interestingly, since blood formation is so crucial, symptoms of iron deficiency tend to manifest in other iron-dependent processes before appearing in blood production.
Immune System
Many immune system processes, such as the function of T-cells and macrophages, depend on adequate iron levels. Iron deficiency is often associated with increased susceptibility to infections.
Sexual Health
A decrease in sexual desire has been linked to iron deficiency.
Energy Production
In the mitochondria—the "powerhouses" of cells—many chemical reactions take place to convert fats and carbohydrates into ATP, the cell's energy currency. These reactions depend on enzymes that require iron to function properly.
Hormone Production
Iron is involved in the production of various hormones. For instance, thyroid hormone, essential for weight regulation and metabolism, and dopamine, which plays a role in ADHD, are both dependent on iron.
Connective Tissue
Iron is crucial for the production of collagen fibers, particularly in tendons, skin, hair, mucous membranes, and nails.
Muscle Function
In muscle cells, oxygen also needs to be transported for cellular respiration. Myoglobin, the oxygen-binding protein in muscles, is dependent on iron, which explains why iron deficiency can lead to rapid muscle fatigue.
Central Nervous System
Weakness, dizziness, fatigue, and even symptoms of dementia and depression are typical signs of iron deficiency.
Iron deficiency is the most common nutritional deficiency in the Western world. Exhaustion, fatigue, poor performance, hair loss, and concentration difficulties are typical symptoms, especially in women.
It’s well-known that iron from animal-based foods, bound to amino acids, is absorbed much more efficiently than iron from plant sources. For example, a steak has a far greater impact on iron absorption than oatmeal, even though oats contain nearly twice as much iron per serving.
Because of this, pharmacies and supplement manufacturers often create iron supplements with higher amounts of iron (100 mg) and add Vitamin C (200 mg) or piperine (pepper extract) to enhance absorption. However, these can sometimes cause side effects like constipation, nausea, or stomach pain.
Daily Iron Needs
- For men: about 10 mg/day
- For women: at least 15 mg/day
Women of childbearing age need more iron due to menstrual blood loss, while pregnant and breastfeeding women require higher amounts to support the developing child. Athletes also need more iron, as red blood cells can be destroyed during strenuous activities, increasing the need for new blood formation.
Iron is absorbed as a two-valent cation (Fe2+) in the small intestine.
Iron Needs for Adolescents and Adults
| Age Group | Men | Women |
|---|---|---|
| 15 to under 19 years | 12 mg | 15 mg |
| 19 to under 25 years | 10 mg | 15 mg |
| 25 to under 51 years | 10 mg | 15 mg |
| 51 to under 65 years | 10 mg | 10 mg |
| 65 and older | 10 mg | 10 mg |
| Pregnant | - | 30 mg |
| Breastfeeding | - | 20 mg |
There’s a vast number of iron supplements on the market, many of which can be overwhelming to understand.
Despite the many available options, only a few proven compounds are found in over-the-counter and prescription iron supplements. Excluding ferric maltol and ferric polymaltose, all other commonly used supplements contain ferrous iron (Fe2+). Prescription iron infusions always use ferric iron (Fe3+). Legally approved iron forms for use in dietary supplements include ferrous aspartate, ferrous taurine, and others, although these are rarely found in commercial products.
Ferrous vs. Ferric Iron
There’s a lot of discussion around the "valency" of iron, which isn’t always easy to grasp without a background in chemistry. Simply put, ferrous iron (Fe2+) is better absorbed after being dissolved in the small intestine, whereas ferric iron (Fe3+) is less readily absorbed because it must first be reduced to ferrous iron. This is where Vitamin C in some iron tablets can be helpful.
The Role of Valency in Iron
Iron atoms have different valence states, meaning they can gain or lose electrons. Ferrous iron (Fe2+) is missing two electrons, while ferric iron (Fe3+) is missing three. Hemoglobin in red blood cells can only bind oxygen when it contains ferrous iron (Fe2+). Ferric iron (Fe3+) forms methemoglobin, which cannot bind oxygen.
Apart from hemoglobin, ferrous iron also binds to myoglobin (the muscle’s oxygen storage protein) and iron-dependent enzymes like cytochromes, which play a key role in the energy production process in cells.
When iron isn’t bound to hemoglobin, it’s stored as ferric iron (Fe3+) in proteins like ferritin or transported through the body by transferrin.
Iron Tablets/Iron Capsules can be used to treat iron deficiency. There is now a wide range of products and iron compounds available. The most commonly used iron compounds include:
- Ferrous sulfate
- Ferrous bisglycinate
- Ferrous glycine-sulfate complex
- Ferrous gluconate
- Ferrous fumarate
A relatively new product is ferric maltol, which has been shown to be effective primarily in patients with chronic inflammatory bowel diseases but is much more expensive than other supplements.
Selecting the Best Iron Products
With so many options, here are a few things to consider when choosing iron supplements:
- Dosage: Given that iron is generally poorly absorbed in the digestive tract, an adequate dosage is essential for treating iron deficiency.
- Absorption Rate: The better a substance is absorbed, the more effective it is. Many factors influence absorption, including medications, food intake, and the severity of the deficiency being treated.
- Quick vs. Slow Release: Quick-release iron supplements are absorbed better but may cause more side effects. Slow-release forms are better tolerated but may be less effective.
- Tolerance: Iron that dissolves quickly in the digestive tract often causes more side effects, while slow-release products are generally easier on the stomach.
- Cost: The cheapest option isn’t always the most effective. Comparing dosage and package size helps determine the best value for money.
The Correct Use of Iron Supplements
There are two main types of iron supplements: quick-release and slow-release. Quick-release iron dissolves in the stomach and is absorbed more effectively but often causes more side effects. Slow-release capsules are gentler on the stomach but are absorbed less efficiently.
Amino Acid Chelates/Iron Bisglycinate—An Alternative for Iron Supplementation
Iron can be substituted more effectively and with fewer side effects through amino acid chelates. Due to the poor tolerance and absorption issues of traditional iron supplements like ferrous sulfate, gluconate, and fumarate, many people are turning to alternatives like iron bisglycinate. Studies have shown that bisglycinate iron supplements are more bioavailable and can be effective at a much lower dose, leading to fewer side effects.
