Understanding Iron Deficiency: What Causes It? Iron deficiency is one of the most common nutritional deficiencies in the world. It occurs when the body doesn't have enough iron to produce adequate levels of heamoglobin —a protein in red blood cells responsible for carrying oxygen throughout the body. While the effects of iron deficiency are well-documented—fatigue, weakness, pale skin, and shortness of breath—many people don't fully understand what causes it. In this article, we'll explore the main reasons why iron levels might drop and how to recognize risk factors. 1 . Inadequate Iron Intake - The most straightforward cause of iron deficiency is simply not getting enough iron in your diet. This is especially common among: Vegetarians and vegans who may lack sufficient heam iron (the type found in animal products). People with unbalanced diets or those who skip meals regularly. Children and teenagers who are growing rapidly and need more iron than adults. ...