In theory, a well-planned diet rich in whole foods can provide many essential nutrients. However, modern agriculture, food processing, and busy lifestyles make achieving optimal levels of all nutrients challenging. Certain nutrients like vitamin D, vitamin B12 (especially for plant-based diets), and selenium are difficult to obtain in sufficient quantities from food alone. Additionally, individual absorption varies based on gut health, age, and lifestyle factors. Supplementation fills nutritional gaps and ensures a consistent intake of key nutrients that support overall wellness. A combined approach of nutrient-dense eating plus strategic supplementation is often most effective.