Nutritional supplements are products used to complement the diet by providing essential vitamins, minerals, amino acids, and other nutrients that may be lacking from food intake. Common supplements include multivitamins, fish oil, calcium, and vitamin D, often used to support bone health, boost immunity, or improve overall well-being. Research in this area evaluates the efficacy of these supplements in promoting health and preventing nutrient deficiencies, especially for those with specific needs, such as pregnant women, the elderly, or athletes. However, overuse or unnecessary supplementation can lead to harmful side effects, such as nutrient imbalances or toxicity. Ongoing studies aim to better understand the optimal dosages, safety profiles, and long-term effects of these supplements on health, offering evidence-based recommendations for their appropriate use.