Common nutritional deficiencies among athletes often include iron, calcium, vitamin D, and omega-3 fatty acids. Iron is crucial for oxygen transport and energy production, making its deficiency problematic for endurance athletes. Additionally, many athletes may not consume adequate dairy or plant-based calcium sources, leading to weakened bones. Vitamin D is essential for bone health and muscle function, and its deficiency is prevalent, particularly in those training indoors or in lower sunlight areas. Omega-3s, found in fatty fish, are vital for inflammation reduction and recovery but may be lacking in certain diets, especially vegetarian or vegan ones.