The nutrient essential for the production of red blood cells is iron. Iron is a critical component of hemoglobin, the protein in red blood cells that transports oxygen from the lungs to the rest of the body. A deficiency in iron can lead to anemia, resulting in fatigue, weakness, and pale skin. It is crucial to include iron-rich foods such as red meat, legumes, and leafy greens in the diet. Proper intake of vitamin C can also enhance iron absorption, playing a key role in maintaining overall health and vitality.