Diet has an impact on practically every bodily function. Diet is important in sustaining optimum immunological function, among other things. Numerous studies have shown that certain foods have immunomodulatory qualities; nevertheless, the mechanisms behind these effects are often unknown. All cells, including immune cells, require sufficient nutrients as part of a diversified diet for health and function. Certain dietary patterns may help the body better prepare for microbial attacks and inflammation, but individual items are unlikely to provide more protection. Many micronutrients are required for each stage of the immunological response in the body. A single dietary deficiency can change the immunological response of the organism. Deficits in these nutrients can be avoided by eating a high-quality diet. The elderly are an especially vulnerable demographic. As the quantity and quality of immune cells decreases with age, the immune response generally deteriorates. If the elderly suffers chronic or acute disorders, this increases the chance of bad outcomes. Furthermore, one-third of the elderly in developed countries suffer from vitamin inadequacies.