Skip to Main Content

++

Introduction

++

High-Yield Terms

  • Beriberi: result of a diet that is carbohydrate rich and thiamin deficient; characterized by difficulty walking, loss of sensation in hands and feet, loss of muscle function of the lower legs, mental confusion/speech difficulties, nystagmus

  • Wernicke encephalopathy: manifests with symptoms similar to those of beriberi but not associated with carbohydrate-rich diet

  • Wernicke-Korsakoff syndrome: extreme consequence of chronic thiamin deficiency, resulting in loss of short-term memory and mild to severe psychosis

  • Pellagra: classically described by the 3 Ds: diarrhea, dermatitis, and dementia, caused by a chronic lack of niacin

  • Pernicious anemia: one of the many types of megaloblastic anemias, caused by loss of secretion of intrinsic factor, which is necessary for absorption of vitamin B12

  • Megaloblastic anemia: a macrocytic anemia resulting from inhibition of DNA synthesis during erythrocyte production

  • Xerophthalmia: pathological dryness of the conjunctiva and cornea due to progressive keratinization of the cornea

  • Rickets: characterized by improper mineralization during the development of the bones resulting in soft bones

  • Osteomalacia: characterized by demineralization of previously formed bone leading to increased softness and susceptibility to fracture

++

High-Yield Concept

As is evident from its role in the activities of 3 TLCFN enzymes, thiamin plays a critical role in overall energy homeostasis and thus, a deficiency of this vitamin will lead to a severely reduced capacity of cells to generate energy (see Clinical Box 8-1).

++

CLINICAL BOX 8-1: THIAMIN DEFICIENCY

The earliest symptoms of thiamin deficiency include constipation, appetite suppression, nausea as well as mental depression, peripheral neuropathy, and fatigue. Chronic thiamin deficiency leads to more severe neurological symptoms including ataxia, mental confusion, and loss of eye coordination resulting in nystagmus. Other clinical symptoms of prolonged thiamin deficiency are related to cardiovascular and musculature defects.

The severe thiamin deficiency disease, known as Beriberi, is the result of a diet that is carbohydrate rich and thiamin deficient. An additional thiamin deficiency–related disease is known as Wernicke encephalopathy. This disease is most commonly found in chronic alcoholics due to their poor diet and has symptoms similar to those of beriberi. Wernicke-Korsakoff syndrome is an extreme manifestation of chronic deficiency of thiamin. It is characterized by acute encephalopathy followed by chronic impairment of short-term memory and mild-to-severe psychosis.

++

Vitamins are organic molecules that function in a wide variety of capacities within the body. The most prominent function of the vitamins is to serve as cofactors (coenzymes) for enzymatic reactions. The distinguishing feature of the vitamins is that they generally cannot be synthesized by mammalian cells and, therefore, must be supplied in the diet. The vitamins are of 2 distinct types, water soluble and fat soluble.

++

The minerals that are considered of dietary significance are those that are necessary to support biochemical reactions by serving both functional and structural roles as well as those serving as electrolytes. The use of the term dietary mineral is considered archaic since the intent of the term mineral...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.