Abstract
This chapter presents a case scenario of lactose intolerance. Lactose intolerance is the inability to digest and absorb lactose, which is the sugar in milk, due to deficiency of the enzyme lactase. This condition commonly occurs after weaning, and it results in various gastrointestinal symptoms such as diarrhea. In addition, it may result in nutritional deficiencies. Management of lactose intolerance requires diet manipulations. This case study provides the needed information to implement the appropriate intervention such as patient's details and case history. Moreover, the case analysis section discusses in detail the disease pathophysiology and the medical nutrition therapy goals. This comprehensive analysis will allow the dietetic professional to follow the nutrition care process (NCP) framework (assessment, diagnosis, intervention, and monitoring and evaluation) to properly intervene and deal with the case. This case study will show the importance of the medical nutrition therapy for the management of lactose intolerance.
TopEtiology And Pathophysiology
There are three types of lactose intolerance: primary, secondary, and congenital. Figure 1 is a mind map that shows the etiology, pathophysiology, symptoms and medical nutrition therapy (MNT) of lactose intolerance. Primary lactose intolerance, also called adult hypolactasia, is the most common, and it is the decline of lactase or LPH synthesis after infancy (Deng, Misselwitz, Dai, & Fox, 2015; Mahan & Raymond, 2017; Swagerty, Walling, & Klein, 2002). This type is closely related to ethnicity and increasing age (Mayo Clinic Organization, 2020). In other words, the activity of LPH is known to be low before 24 weeks of gestation, and then it increases during the third trimester to reach levels that are comparable to infants’ levels who are at the age of two to eleven months. After this phase, the genetic makeup determines what happens next. In most of the cases, the activity of this enzyme starts to decrease at ages around five years, and this is categorized as lactase non-persistence phenotype. This type of lactose intolerance is characterized by low levels of lactase activity in the jejunum as well as poor proximal digestion of lactose. A minority of individuals with non-persistent lactase have been reported to have defects in the intracellular processing of the produced lactase protein. On the other hand, the pathophysiology that occurs mostly relies on the LCT gene (also called lactase-glycosylceramidase) regulation; it is the gene that provides information for the synthesis of the enzyme lactase. In fact, adult hypolactasia is inherited in an autosomal recessive pattern which means these subjects must have two of the recessive alleles to show symptoms (Genetics Home Reference, 2020; Pray, 2000; Robayo-Torres & Nichols, 2007).
Key Terms in this Chapter
Hydrogen Breath Test: It is a diagnostic test that is specific and sensitive to diagnose carbohydrate malabsorption or small intestine bacterial overgrowth.
Lactase: It is the enzyme responsible to digest and hydrolyze lactose, the sugar in milk, into glucose and galactose.
Short Chain Fatty Acids (SCFA’s): They are produced by the intestinal microbiota in the fermentation process (e.g., acetic, butyric, and propionic acids).
Preterm Infant: It is an infant born before the completion of 37 weeks of gestation.
Diarrhea: It is defined by the World Health Organization as the passage of loose or liquid stool for three or more times per day (or more frequent than what is normal for the individual).
Gene Mutation: It is an alteration in the sequence of the deoxyribonucleic acid (DNA) that makes up a gene.
Lactose Tolerance Test: It is a diagnostic test that reveals the body’s ability to break down lactose; that if lactose is digested and absorbed, this will result in rise of blood sugar.
Oral Rehydration Solution (ORS): It is a fluid that contains glucose and salts used to replace fluid losses and correct dehydration as in the case of diarrhea.