Signs of Iron Deficiency and Causes of Lack of Iron in the Body

Of all the different types of nutritional deficiencies that can occur in humans, iron deficiency is the most common. Although iron is used by various cells and tissues for different functions, the most well known purpose of iron in the human body is in the production of hemoglobin, a vital component of red blood cells. Hemoglobin is the component that allows blood to carry oxygen. Therefore the most common signs of iron deficiency relate to problems with the ability of red blood cells to carry hemoglobin.

What Causes Iron Deficiency?

The causes of iron deficieny are linked to the sourcing of this mineral, its utilization within the body and any loss. The human body cannot produce iron. Therefore it must be sourced from food. This iron from the food must then be absorbed into the body where it can be processed to be used in various ways, one of the most important which is to form hemoglobin in red blood cells.


Contrary to popular belief, iron deficiency is not only caused by a lack of dietary iron. The human body sources iron from food and some foods have more iron than others. For example, meat is abundant in heme iron which the body absorbs more readily than nonheme iron that is found in plant foods. Therefore vegetarians and particularly vegans may be at a higher risk of iron, especially if they do not maintain a balanced diet that is abundant in iron-rich foods.

Blood Loss

The other common cause of iron deficiency is blood loss. Massive blood loss can cause iron deficiency but there will be recovery a short while thereafter. The problem often lies with frequent heavy bleeding and even prolonged slow bleeds where iron is lost on a continuous basis. Sometimes this bleeding is obvious while at other times it may be undetectable and the first indication of a slow bleed arises when an iron test shows a deficiency.

Menstruating girls and women who have heavy periods, prolonged periods or very short menstrual cycles with frequent periods are at a greater risk of iron deficiency. However, men are not entirely impervious to iron deficiency. A bleeding peptic ulcer and even bleeding hemorrhoids (piles) can lead to slow blood loss over a period of time which may result in iron deficiency.

Read more on causes of low iron in men.


Even when sufficient iron-rich foods are consumed, there can be various problems with the digestion of these foods, absorption and assimilation of iron that can result in deficiencies. Some of these problems are genetic and may be present from birth but this is usually rare. Instead the problems usually lie with digestion (less common) or absorption (more common) of iron-rich foods and iron, respectively.

When the stomach acid levels are low (achlorhydria) then the iron from food may not be released fully. Any problems with the bowels, and specifically the small intestine, where the bowel wall is inflamed can hamper iron absorption. The same may occur with bowel surgery. Furthermore, certain substances like starch and clay can block iron absorption in the gut although these are not common substances that people ingest.

Signs of Lack of Iron in the Body

The signs and symptoms of iron deficiency are a consquence of the conditions it causes. Iron deficiency anemia is one of the main outcomes of low iron levels in the body. The term anemia means that the oxygen-carrying capacity of blood is reduced. In other words, the blood holds less oxygen which means that less oxygen is distributed throughout the body. Therefore the signs and symptoms discussed below are primarily due to iron deficiency anemia.

Read more on signs of low iron levels.

Persistent Fatigue and Exhaustion

Every person feels tired after a prolonged period of physical and mental exertion, or with poor nutition or insufficient sleep. Rest and a balanced diet usually allows the body to recuperate. However, with iron deficieny anemia there is exhaustion that seems unrelated to the level of phsyical and mental activity. Even rest and a nourishing meal does not help with recovery in severe cases of iron deficiency or there is just short term recovery. Sometimes this unexplained fatigue and exhaustion is the only sign of iron deficiency.

Pale and “Sickly” Appearance

The red color of blood is due to red blood cells. When the oxygen levels are low the red blood cells may not have the same red hue as normal. Furthermore there may also be some narrowing of the superficial blood vessels to direct more blood and oxygen to vital inner organs. This causes a pale appearance to the skin since blood flow contributes to normal skin complexion. Sometimes this may be described as a “sickly” look.

Easily Short of Breath

Since the blood has a lower oxygen-carrying capacity, even slight exertion can result in an increased need for oxygen. This may present as shortness of breath. As a result breathing rate and depth increases. A person may find themselves panting and gasping for breath with physical exertion that would otherwise cause a slight increase in breathing rate. In severe cases of iron deficiency anemia, there is shortness of breath even at rest.

Pounding Heart Feeling

The heart has to work harder to push blood at a faster rate in an attempt to oxygenate it quicker. Therefore the heart rate is often elevated in iron deficiency anemia. This may at times be felt as a pounding in the chest which is known as palpitations. For some people with severe deficiencies, the pounding can even be felt while sedentary whereas others may only feel it after physical exertion.

Constantly Lightheaded

With less oxygen reaching the brain, a person may feel lightheaded and sometimes even dizzy. This lightheaded feeling may be present all the time or only arises with physical activity. It often coincides with shortness of breath and a rapid heart rate which may be felt as palpitations. Dizziness may also arise with a sudden change in position, like standing up suddenly after sitting or lying down.

Difficulty Concentrating and Anxiety

Brain activity is affected in various ways with the low oxygen levels. One of these effects on the central nervous system is difficult concentrating which worsens with physical and mental exertion. Depending on the severity, there may also be an impact on decision making. The lack of oxygen is also deciphered as distress by the body and this may activate the sympathetic nervous system. One of the consequences is anxiety for no reason.

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