producing short-chain fatty acids that protect the gut lining and support broader metabolic and immune function (Fernandes et al., 2023).
Food, Fiber, and Gut Microbiota
Figure 2. The relationship among food, fiber, and gut microbiota.
The connection between diet and immune functioning is well studied. Micronutrients such as vitamins A, C, D, and E, zinc, selenium, and iron are vital in the formation of immune barriers and the overall operation of cellular immune system cells. Lack of these nutrients undermines the body's ability to mount effective responses to infection and maintain tolerance to self-tissues (Lungu et al., 2022).
The regular inclusion of a wide variety of whole foods ensures the body receives micronutrients in their most bioavailable forms, supporting immune barriers and cell function (Mitra et al., 2022). By contrast, ultra-processed, energy-dense diets are consistently poor in this regard.
Inflammation is an innate defensive biological process. In the acute setting, it helps the body react to injury and infection. However, low-grade, long-term inflammation without a specific trigger contributes to the development of major chronic conditions such as cardiovascular and cerebrovascular disease.
Dietary preferences influence chronic inflammation levels. Diets high in saturated fat and ultra-processed foods are linked with elevated systemic inflammation. Conversely, whole-food, plant-based diets rich in fiber are associated with fewer inflammatory markers and reduced risk of inflammation-related disease (NCCIH, 2021; NCCIH, 2022).
Health outcomes do not arise from singular symptoms or isolated factors. A holistic view is essential to understanding food as medicine. The gut, immune system, and inflammatory regulation are dynamic, interconnected systems in which diet plays a critical role.
Food as medicine is best understood as a pattern of nourishment rather than a targeted therapeutic agent. The cumulative, systemic effects of consistent dietary quality on gut health, immunity, and inflammation represent one of the most compelling mechanisms through which food protects and promotes health across a lifetime (NCCIH, 2021; ODPHP, 2025).