The Role of Oat Nutrients in the Immune System: A Narrative Review

Abstract

Optimal nutrition is the foundation for the development and maintenance of a healthy immune system. An optimal supply of nutrients is required for biosynthesis of immune factors and immune cell proliferation. Nutrient deficiency/inadequacy and hidden hunger, which manifests as depleted nutrients reserves, increase the risk of infectious diseases and aggravate disease severity. Therefore, an adequate and balanced diet containing an abundant diversity of foods, nutrients, and non-nutrient chemicals is paramount for an optimal immune defense against infectious diseases, including cold/flu and non-communicable diseases. Some nutrients and foods play a larger role than others in the support of the immune system. Oats are a nutritious whole grain and contain several immunomodulating nutrients. In this narrative review, we discuss the contribution of oat nutrients, including dietary fiber (β-glucans), copper, iron, selenium, and zinc, polyphenolics (ferulic acid and avenanthramides), and proteins (glutamine) in optimizing the innate and adaptive immune system's response to infections directly by modulating the innate and adaptive immunity and indirectly by eliciting changes in the gut microbiota and related metabolites.

Keywords: fiber; human; minerals; polyphenols; protein.

Figure 1

Overview of the immune response. The human immune system is comprised of both the innate and adaptive defenses. The innate immunity acts rapidly as the first line of protection to abate the establishment of overt infection with a goal for rapid elimination of infectious agents. The recognition of the presence of pathogens is mediated via the expression of nonspecific pattern-recognition receptors and not influenced by prior exposure and annihilation of invading pathogens occurs through direct destruction (complement system) and phagocytosis (immune cells). Although slow at first when encountering a microorganism for the first time, the adaptive immunity response is faster and stronger than the initial response when the microorganism is encountered again (i.e., re-infection) as it draws from its immunological memory from prior exposure to the antigenic components of the microorganism. Oats contain several nutrients that participate in both the innate and adaptive immune systems including fiber, micronutrients (e.g., zinc, iron, copper, and selenium), polyphenols, and proteins.