Diseases of malnutrition

• Macronutrients


  Protein, carbohydrate, and fat
• Metabolically active substrates


  Amino acids, glucose, and free fatty acids or glycerol
• Potential fates of macronutrient substrates


  • Replacement of lean tissue proteins, adipose tissue triglycerides, and glycogen catabolised during post-ingestive periods
  • Provision of the necessary energy to fuel these processes and other biochemical reactions, including those producing the energy needed for physical activities

  
• The energy-producing reactions consume oxygen and release carbon dioxide, water, and heat.
• Not all ingested macronutrient energy is available for metabolic processes.

  
• Average net digestive losses on mixed diets


  • 8% for protein
  • 5% for fat
  • 2% for carbohydrate
• Urea and other nitrogenous end-products of protein metabolism excreted in urine account for an additional 1.25 kcal per gram of protein.
• Wilbur Olin Atwater


  American chemist who constructed an adiabatic calorimeter for studying humans and established the currently used metabolizable energy values
• Epidemiological approach


  Includes the study of three separate but interacting factors: the disease-producing agent, the victim on whom the destructive agent acts, and the environment
• Environmental factors encompass the conditions of life, climatic and geographic, economic, social and educational, religious and cultural factors.
• During the famine catastrophes in Africa during the 1960s, WHO brought attention to the medical aspects of starvation.
• The increasingly successful control of some of the major communicable diseases did not result in a general improvement in health as expected. Their disappearance had, in fact, revealed the devastating effect of the interaction of agent, victim and environment in the production of various forms of malnutrition.
• Agents of malnutrition


  • Inadequate total food intake
  • Deficiency of one or more specific nutrients
• Victims of malnutrition


  • Unborn child
  • Infant
  • Pre-school-child
  • Schoolchild
  • Woman, particularly when pregnant or lactating
  • Wage-earner
  • Lonely old man
• It is not difficult to understand why, in any environment which provides no safe water, no sanitary method of sewage disposal and often inadequate shelter from extremes of climate, many babies and young children die from the diarrhoeal diseases or from respiratory infections.
• The concepts of kwashiorkor and marasmus were presented to the scientific community in the second half of the 20th century.
• Since depletion is usually a combined deficiency and loss of protein and energy, the general term of PEM became widely accepted.
• According to ESPEN, malnutrition is the synonym of undernutrition.
• Nutritional disorders and nutrition related conditions, as defined by ESPEN, will be discussed in module Dietetics/Nutritional Therapy and Research III (BNFH19) of the fourth semester.
• Types of malnutrition


  • undernutrition
  • micronutrient-related malnutrition
  • overweight, obesity, diet-related NCDs
• According to the WHO, undernutrition includes wasting, stunting, and underweight.
• Wasting


  Low weight-for-height, often indicating recent and severe weight loss, can also persist for a long time, usually occurs when a person has not had food of adequate quality/quantity or had frequent/prolonged illnesses
• Treatment of wasting is possible.
• Stunting


  Low height-for-age, the result of chronic or recurrent undernutrition, usually associated with poverty, poor maternal health and nutrition, frequent illness, inappropriate feeding and care in early life, prevents children from reaching physical and cognitive potential
• Treatment of stunting is not always possible.
• Underweight


  Low weight-for-age, a child who is underweight may be stunted, wasted or both
• Severe protein-energy malnutrition


  • Kwashiorkor
  • Marasmus
• Kwashiorkor


  A form of malnutrition due to the lack of protein in the diet of the weaned child, characterized by oedematous swelling, skin changes, and apathy
• Treatment of kwashiorkor is possible.
• Cicely Delphine Williams, a Jamaican physician, described kwashiorkor in 1933 and proved it to be curable by giving the children milk.
• Bilateral oedema and depigmented hair in kwashiorkor
• Children affected by kwashiorkor


  • Nearly always small for their age, with hair and skin of a pale colour
  • Exhibit feet and legs swollen from an accumulation of excess fluid
  • Appetites are capricious, and they are easily liable to digestive upsets
• Children more severely ill with kwashiorkor

  • May have hair of any colour to greyish-white, very pale skins, and swellings of the legs and thighs, hands and face
  • In the most advanced state, the hair is so loosely embedded that it can be pulled out in tufts without causing pain
  • Eyes may be closed with the swelling, which occurs in nearly every part of the body, and the skin may break down as though it had been burnt
  • At this stage, the child appears to be desperately unhappy or sunk in apathy, will not stand or walk and will not willingly move in his bed except to pull the covers over his head, resists any interference, even feeding
• Once the stage of gross swelling, severe skin lesions and apathy has been reached, kwashiorkor is fatal unless it is skilfully treated, and even where the best care and attention can be given the mortality may be as high as 30%
• Pathogenesis of oedema in kwashiorkor


  May have more to do with albumin's redistribution into the interstitium than an absolute deficiency
• Oedema in kwashiorkor


  • Often the result of increased microvascular permeability to protein macromolecules, including albumin
  • Plasma proteins are normally retained within the vascular space by the endothelial glycocalyx, a negatively charged sieve like structure that lines the luminal surface of blood vessels
  • Endothelial glycocalyx damage allows plasma proteins to escape from the microvasculature into the interstitium
  • The subsequent levelling of protein concentration gradients between the intravascular and interstitial environments permits fluid to flow from the vascular space into the interstitium
• Marasmus


  • A form of starvation that is less specifically related to a shortage of protein
  • Can be caused by the almost complete absence of food but, except in times of famine, this is rare
  • Much more frequently it develops when breast-feeding fails for one reason or another, or when the child suffers from some disease that prevents the utilization of the food eaten or renders the diet inadequate for the maintenance of health
• Marasmic child


  • Wasted, not swollen
  • Hair is dull and dry, but not discoloured
  • Skin is thin and wrinkled and has lost its elasticity, but it does not break down
  • Does not refuse food and does not show the same resentful apathy as in kwashiorkor
  • Terrible wasting makes the eyes look enormous and staring, and there may be, in some cases, a stiffness in the limbs, due to muscle spasm
• Why marasmus develops, rather than kwashiorkor, is not understood but it seems that in kwashiorkor something happens that starts a series of changes in the chemistry of the body-perhaps in the complex process of the constant renewal of proteins that causes the characteristic signs to appear
• Marasmus


  • Child is much less likely to be depleted of proteins, and dies chiefly because his diarrhoea and vomiting, or the other causes of his condition, have brought about great losses of body fluids, and such gross wasting of all the tissues fat, muscles, intestinal walls, and others that they can no longer perform their various biological functions