Undernutrition Diseases
This follows What is a Balanced Diet ?, Dietary needs at different stages of life and What is Malnutrition ?
Definition of Undernutrition :
Definition of Undernutrition :
Undernutrition is a state of nutrition in which there is a deficiency of one or more of the essential parts of a healthy diet. Put simply, the person affected is not eating (or fully digesting and absorbing) enough of all of the types of substances that his or her body needs to extract from food in order to both survive and thrive.
Undernutrition can lead to several different diseases depending on the component of the diet that is lacking and the extent of the deficiency, e.g. if the person is consuming some, but just not enough, of the dietary component that is lacking - or none at all and has no reserves stored in his or body. Undernutrition diseases generally have adverse effects on the tissues of the body (e.g. re. shape, size, composition), on bodily functions, and hence on overall medical health.
Undernutrition can be either:
- General, i.e. due to insufficient amounts of food of any or all types, hence insufficient energy for general activity and resources for the maintenance of the cells, tissues and processes of the body. This leads to starvation.
or
- Specific, i.e. lack of sufficient amounts of a single nutrient e.g. a single vitamin or mineral. The result depends on the nutrient that is lacking and the severity of the deficiency. Different medical conditions - hence different symptoms and risks follow from different deficiencies. There are many examples of medical conditions du to dietary deficiencies. The prevalence and typical severity of cases vary at different locations around the world.
Note: The undernutrition diseases mentioned below do not form a complete list. They are some of the most common undernutrition diseases found around the world and typically included in first-level courses in human biology (e.g. A-Level), diet and nutrition, and similar.
Condition (due to deficiency): |
Marasmus A form of Protein Energy Malnutrition
Marasmus is a condition that affects babies and very young children, typically aged 9-12 months. It is due to dietary deficiencies of both energy (kcal or kJ) and protein.
There are several possible causes and contributory factors, including those listed below.
Causes: |
- malabsorption
- feeding difficulties
- metabolic disorders
- persistent vomiting
- diarrhea
- severe disease of heart, lungs, kidneys or urinary tract
- chronic bacterial disease
- chronic parasitic disease (esp. in tropical regions)
- maternal rejection - if results in under-eating
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Symptoms can include:
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- severe wasting, i.e. very underweight (body weight may be below 75% of that expected)
- infant looks 'old' due to lack of skin fat
- muscles e.g. of arms & legs very thin; also lacks body fat
- appearance pallid
- generally apathetic
- temperature below normal
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Biochemical changes are minimal because the child adapts. However, such "adaptation" might hinder or prevent recovery because it can include atrophy of the pancreas and intestinal mucosa, in turn preventing production of the digestive enzymes and dramatically reducing the area over which absorption of nutrients could occur (i.e. in the gastrointestinal tract).
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Kwashiorkor A form of Protein Energy Malnutrition
Kwashiorkor affects infants just weaning off breast milk, often at approx 1-3 years, typically in relatively poor / developing countries. The word 'kwashiorkor' is derived from an expression meaning "the rejected one", a common situation being that of the child being displaced from its mother's breast (after an extended period of breast-feeding) following the birth of a younger sibling.
Causes: |
Diet deficient in protein and energy-producing foods, e.g. when breast milk replaced with inadequate family diet. |
Symptoms can include:
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- underweight
- oedema
- thin muscles, but fat present
- hair loss, and loss of colour (pigmentation) of hair
- 'moon' face, i.e. unusually/excessively round
- loss of appetite
- diarrhea
- gastrointestinal infection
- general discomfort and apathy
- child fails to thrive
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Biochemical changes can include accumulation of fat in the liver (leading to risk of cirrhosis of the liver) and severe reduction in blood albumin. Albumin is the most abundant protein in blood plasma and its presence keeps fluid from leaking out of blood vessels, so a severe reduction can lead to oedema.
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Note: the two conditions mentioned above, Marasmus and Kwashiorkor, are examples of extreme cases of protein energy malnutrition (also called 'protein energy deficiency' or PEM). There are also intermediate cases in which insufficient protein in a young child's diet causes damage to the child's physical health but not all of the above indications apply.
More about protein energy malnutrition in general:
PEM is sometimes fatal. Recovery may be limited because normal human development includes growth of the brain to approx. 80% of its adult size within the first three years of life. This requires intake of sufficient protein in the early years of life because a normal healthy is composed of approx 50% protein by 'dry weight' i.e. excluding the water content of the brain. Consequently, survivors may never fully achieve the usually expected brain size and development and may therefore experience some intellectual limitations as a result. (Some older sources warn that survivors of PEM conditions may be 'retarded', though that word is not as widely used today.) |
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Anaemia (insufficient iron and/or vitamin B12 and associated nutrients)
Pernicious Anaemia is a form of anaemia (i.e. a reduction in the quantity of the oxygen-carrying pigment haemoglobin in the blood), due to deficiency of vitamin B12. Deficiency can be due to either insufficient dietary intake of vitamin B12, or failure to absorb ingested and digested vitamin B12 through the gastrointestinal tract.
It is characterized by defective production of red blood cells (i.e. erythrocytes) and the presence of megaloblasts in the bone marrow. In severe cases the nervous system is affected.
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Ariboflavinosis (insufficient riboflavin vitamin B2)
Ariboflavinosis is typically found in association with protein energy malnutrition (PEM) and was originally known as pellagra sin pellagra (pellagra without pellagra), due to similarities to the niacin deficiency pellagra - see below.
Symptoms of ariboflavinosis can include sore throat with redness and swelling of the mouth and throat mucosa, cracking of the lips and corners of the mouth, glossitis (magenta tongue with atrophy), seborrheic dermatitis, and a decreased red blood cell count with normal cell size and hemoglobin content (normochromic normocytic anemia).
Deficiency of riboflavin is often found to be accompanied by deficiencies of the other water-soluble vitamins. Although the most common cause of ariboflavinosis is dietary deficiency of riboflavin, it can also occur due to impaired liver function preventing sufficient take-up of ingested riboflavin by the body.
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Beriberi (sometimes written beri beri) is common in countries in which rice forms a substantial part of the diet and polished rice, i.e. rice from which the seed coat (which is rich in thiamin) has been removed, is popular. There are two forms of beriberi:
- Wet Beriberi: involves the accumulation of tissue fluid (i.e. oedema, also known as 'dropsy')
- Dry Beriberi: in which there is extreme emaciation.
Nervous degeneration occurs in both forms of beriberi. Death by heart failure may follow.
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Goitre (insufficient iodine)
Goitre is characterized by swelling of the thyroid gland which is located in the neck.
Goitre in pregancy is particular cause for concern because it can lead to cretinism in the developing foetus. The word 'cretin' is no-longer used to refer to people affected by this condition because common usage in the past resulted in negative connotations i.e. as a general derogatory term directed at people said to be stupid. However, the medical consequences of iodine deficiency in pregancy are still described as 'cretinism', i.e. severely stunted physical and mental development of the foetus due to deficiency of thyroid hormones, e.g. due to maternal hypothyroidism.
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Pellagra results from a diet that includes insufficient niacin and insufficient tryptophan (the amino acid from which niacin can be synthesized in the body).
It is common in maize-eating communities. Symptoms include scaly dermatitis on exposed surfaces of skin, diarrhea and depression.
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Rickets (insufficient calcium or vitamin D)
Rickets is among the most common childhood diseases in some developing countries and is widespread in some parts of Africa and Asia. It is involves softening of bones in children due to dietary deficiency or impaired metabolism of vitamin D and the associated minerals magnesium, phosphorus or calcium. Possible consequences include bone deformity and bone fractures.
'Rickets' in adults is known as osteomalacia (soft bones).
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Scurvy (insufficient vitamin C, also known as 'ascorbic acid')
Scurvy results from deficiency of vitamin C, which cannot be produced in the human body (although many other animals synthesize their own vitamin C).
Symptoms of scurvy typically include a general feeling of unease and lethargy, followed by spots on the skin, spongy gums that can be red and sore, and bleeding from mucous membranes. Spots over the skin are esp. concentrated on legs / thighs. People affected by scurvy tend to look pale, seem depressed, and experience restricted movement. As the disease progresses, open wounds releasing pus (i.e. suppurating wounds), loss of teeth, jaundice, fever, and neuropathy may follow.
Scurvy is now much less common than in the past, e.g. when it was prevalent among seafarers who were restricted to eating only cured and salted meats and dried grains due to extended periods at sea so separated from (perishable) fruits and vegetables. Untreated scurvy can be fatal but, although common in the past, death from scurvy is now rare. Scurvy in infants is sometimes called Barlow's disease, Moeller's disease or Cheadle's disease.
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Xerophthalmia (insufficient retinol, i.e. vitamin A)
Xerophthalmia is also known as 'Dry Eye' and results from insufficient vitamin A obtained from the diet incl. from beta-carotene an important precursor of vitamin A (found in e.g. carrots). Xerophthalmia occurs because vitamin A is necessary for the production of rhodopsin (also known as 'visual purple') without which the rods, one of the types of photo-detector cells in the retina of the eye, do not function.
Symptoms include the cornea and conjunctiva becoming extremely dry, thickened, and wrinkled. Prolonged deficiency of vitamin A can cause blindness.
In general, a good diet that includes sufficient nourishment enables the liver to store enough vitamin A for several years. Nevertheless, xerophthalmia can result from the low quantities of vitamin A and its precursors in diets some developing countries. Xerophthalmia occurs mostly in developing countries such as in Africa and Southern Asia where it usually affects children up to 9 years old.
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Note: The numbers in this table are for ease of reference to and discussion of this table only. There are many conditions and disorders due to, or exacerbated by, nutritional deficiencies. This list includes some common examples but is not complete.
See also carbohydrates, types of sugar, dietary fibre (roughage), fatty acids, fats and proteins.
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