Chapter 6 – Immune System in Undernourished Host: Probiotics as Strategy to Improve Immunity

Malnutrition includes both undernutrition and obesity, and is one of the leading causes of death worldwide. Undernutrition is a systemic alteration, caused by imbalance between the nutrient intake and energy requirements. Protein-energy malnutrition (PEM) causes loss of weight and delay in growth. PEM brings consequences such as atrophy of lymphoid tissues; the thymus is one of the most affected organs. Reports suggest that PEM is one of the most common causes of immunodeficiency, which could lead to death from infection. Obesity is a chronic disease with a multifactorial origin, which predisposes individuals to diseases such as diabetes and dyslipidemia, among others. Probiotics have been proposed as a potential immune system adjuvant. It has been demonstrated that probiotic fermented milk (PFM) administration recovered the intestinal barrier, histological alterations, and mucosal and systemic immune functions in a PEM model. Also, it has been reported that probiotics could induce a positive balance in the microbiota and stimulate the intestinal immune system in obese hosts.