Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues and form.
Malnutrition is a category of diseases that includes undernutrition and overnutrition. Undernutrition is a lack of nutrients, which can result in stunted growth, wasting, and being underweight. A surplus of nutrients causes overnutrition, which can result in obesity or toxic levels of micronutrients. In some developing countries, overnutrition in the form of obesity is beginning to appear within the same communities as undernutrition. Malnutrition is reported to occur in US healthcare and worldwide up to 40% of hospitalized patients are estimated to be affected by disease-related malnutrition.
Most clinical studies use the term 'malnutrition' to refer to undernutrition. However, the use of 'malnutrition' instead of 'undernutrition' makes it impossible to distinguish between undernutrition and overnutrition, a less acknowledged form of malnutrition.Ngaruiya, C., Hayward, A., Post, L. and Mowafi, H., 2017. "Obesity as a form of malnutrition: over-nutrition on the Uganda 'malnutrition' agenda". Pan African Medical Journal, 28, p. 49. Accordingly, a 2019 report by The Lancet Commission suggested expanding the definition of malnutrition to include "all its forms, including obesity, undernutrition, and other dietary risks."Swinburn, B., Kraak, V., Allender, S., et al., 2019. "The Global Syndemic of Obesity, Undernutrition, and Climate Change: The Lancet Commission report." The Lancet, 393(10173), pp. 791–846. The World Health OrganizationReferences Min, J., Zhao, Y., Slivka, L. and Wang, Y., 2017. "Double burden of diseases worldwide: coexistence of undernutrition and overnutrition-related non-communicable chronic diseases". Obesity Reviews, 19(1), pp. 49–61. and The Lancet Commission have also identified "[t]he double burden of malnutrition", which occurs from "the coexistence of overnutrition (overweight and obesity) alongside undernutrition (stunted growth and wasting)".Ghattas, H., Acharya, Y., Jamaluddine, Z., Assi, M., El Asmar, K. and Jones, A., 2020. The child-level double burden of malnutrition in the MENA and LAC regions: Prevalence and social determinants. Maternal & Child Nutrition, 16(2).
Type
Undernutrition
Undernutrition can occur either due to protein-energy wasting or as a result of micronutrient deficiencies.Morley, J., 2012. Undernutrition in older adults. Family Practice, 29(suppl 1), pp.i89-i93. It adversely affects physical and mental functioning, and causes changes in body composition and body cell mass.Cederholm, T., Bosaeus, I., Barazzoni, R., Bauer, J., Van Gossum, A., Klek, S., Muscaritoli, M., Nyulasi, I., Ockenga, J., Schneider, S., de van der Schueren, M. and Singer, P., 2015. Diagnostic criteria for malnutrition – An ESPEN Consensus Statement. Clinical Nutrition, 34(3), pp. 335–340.Sobotka, L., 2012. Basics in clinical nutrition. 4th ed. Prague: Galen. Undernutrition is a major health problem, causing the highest mortality rate in children, particularly in those under 5 years, and is responsible for long-lasting physiologic effects.Martins, V., Toledo Florêncio, T., Grillo, L., Do Carmo P. Franco, M., Martins, P., Clemente, A., Santos, C., Vieira, M. and Sawaya, A., 2011. Long-Lasting Effects of Undernutrition. International Journal of Environmental Research and Public Health, 8(6), pp. 1817–1846. It is a barrier to the complete physical and mental development of children.
Undernutrition can manifest as stunting, wasting, and being underweight. If undernutrition occurs during pregnancy, or before two years of age, it may result in permanent problems with physical and mental development. Extreme undernutrition can cause starvation, chronic hunger, Severe Acute Malnutrition (SAM), or Moderate Acute Malnutrition (MAM).
The signs and symptoms of micronutrient deficiencies depend on which micronutrient is lacking. However, undernourished people are often thin and short, with very poor energy levels; and swelling in the legs and abdomen is also common. People who are undernourished often get infections and frequently feel cold.
Micronutrient undernutrition Micronutrient undernutrition results from insufficient intake of vitamins and minerals. Worldwide, deficiencies in iodine, Vitamin A, and iron are the most common. Children and pregnant women in low-income countries are at especially high risk for micronutrient deficiencies.
Anemia is most commonly caused by iron deficiency, but can also result from other micronutrient deficiencies and diseases. Vitamin B12 deficiency may cause anemia, but not in all cases, in which may result in changes in consciousness or thinking, or even irreversible neurological damage. This condition can have major health consequences.
It is possible to have overnutrition simultaneously with micronutrient deficiencies; this condition is termed the double burden of malnutrition.
Protein-energy malnutrition 'Undernutrition' sometimes refers specifically to protein–energy malnutrition (PEM). This condition involves both micronutrient deficiencies and an imbalance of protein intake and energy expenditure. It differs from calorie restriction in that calorie restriction may not result in negative health effects. Hypoalimentation (underfeeding) is one cause of undernutrition.
Two forms of PEM are kwashiorkor and marasmus; both commonly coexist.
Kwashiorkor is primarily caused by inadequate protein intake. Its symptoms include edema, wasting, liver enlargement, hypoalbuminaemia, and steatosis; the condition may also cause depigmentation of skin and hair. The disorder is further identified by a characteristic swelling of the belly, and extremities which disguises the patient's undernourished condition. 'Kwashiorkor' means 'displaced child' and is derived from the Ga language of coastal Ghana in West Africa. It means "the sickness the baby gets when the next baby is born," as it often occurs when the older child is deprived of breastfeeding and weaned to a diet composed largely of carbohydrates.
Marasmus (meaning 'to waste away') can result from a sustained diet that is deficient in both protein and energy. This causes their metabolism to adapt to prolong survival. The primary symptoms are severe wasting, leaving little or no edema; minimal subcutaneous fat; and abnormal serum albumin levels. It is traditionally seen in cases of famine, significant food restriction, or severe anorexia. Conditions are characterized by extreme wasting of the muscles and a gaunt expression.
Overnutrition Excessive consumption of energy-dense foods and drinks and limited physical activity causes overnutrition. It causes overweight, defined as a body mass index (BMI) of 25 or more, and can lead to obesity (a BMI of 30 or more). Obesity has become a major health issue worldwide.The GBD. 2015 Obesity Collaborators. Health Effects of Overweight and Obesity in 195 Countries over 25 Years. N. Engl J Med. 2017;377:13–27. Overnutrition is linked to chronic non-communicable diseases like diabetes, certain cancers, and cardiovascular diseases. Hence identifying and addressing the immediate risk factors has become a major health priority.Nicolaidis S. Environment and obesity. Metabolism. 2019;100s:153942. The recent evidence on the impact of diet-induced obesity in fathers and mothers around the time of conception is identified to negatively program the health outcomes of multiple generations.Billah, M., Khatiwada, S., Morris, M., & Maloney, C. (2022). Effects of paternal overnutrition and interventions on future generations. International Journal Of Obesity, 46(5), 901–917. doi: 10.1038/s41366-021-01042-7
According to UNICEF, at least 1 in every 10 children under five is overweight in 33 countries.
Effects
Undernutrition weakens every part of the immune system. Protein and energy undernutrition increases susceptibility to infection; so do deficiencies of specific micronutrients (including iron, zinc, and vitamins). In communities or areas that lack access to safe drinking water, these additional health risks present a critical problem.
Undernutrition plays a major role in the onset of active tuberculosis. It also raises the risk of HIV transmission from mother to child, and increases replication of the virus. Undernutrition can cause vitamin-deficiency-related diseases like scurvy and rickets. As undernutrition worsens, those affected have less energy and experience impairment in brain functions.
Undernutrition can also cause acute problems, like hypoglycemia (low blood sugar). This condition can cause lethargy, limpness, seizures, and loss of consciousness. Children are particularly at risk and can become hypoglycemic after 4 to 6 hours without food. Dehydration can also occur in malnourished people, and can be life-threatening, especially in babies and small children.
Signs There are many different signs of dehydration in undernourished people. These can include sunken eyes; a very dry mouth; decreased urine output or dark urine; increased heart rate with decreasing blood pressure; and altered mental status.
Site Sign Face Moon face (in kwashiorkor); shrunken, monkey-like face (in marasmus) Eye Dry eyes; pale conjunctiva; periorbital edema; Bitot's spots (in vitamin A deficiency) Mouth Angular stomatitis; cheilitis; glossitis; parotid enlargement; spongy, bleeding gums (in vitamin C and B12 deficiencies) Teeth Enamel mottling; delayed eruption Hair Dull, sparse, brittle hair, with thinning of the hair follicles; hypopigmentation; flag sign (alternating bands of light and normal color); broomstick eyelashes; alopecia Skin Dry skin; follicular hyperkeratosis; patchy hyper- and hypopigmentation; erosions; poor wound healing; loose and wrinkled skin (in marasmus); shiny and edematous skin (in kwashiorkor) Nail Koilonychia; thin and soft nail plates; fissures or ridges Musculature Muscle wasting, particularly in the buttocks and thighs Skeletal Deformities, usually resulting from deficiencies in calcium, vitamin D, or vitamin C Abdomen Distended; hepatomegaly with fatty liver; possible ascites Cardiovascular Bradycardia; hypotension; reduced cardiac output; small vessel vasculopathy Neurologic Global developmental delay; loss of knee and ankle reflexes; poor memory, often resulting from deficiencies in vitamin B12 and other B vitamins Hematological Pallor; petechiae; bleeding diathesis Behavior Lethargic; apathetic; anxiousSource: "Protein Energy Malnutrition"
Cognitive development Protein-calorie malnutrition can cause cognitive impairments. This most commonly occurs in people who were malnourished during a "critical period ... from the final third of gestation to the first 2 years of life". For example, in children under two years of age, iron deficiency anemia is likely to affect brain function acutely, and probably also chronically. Similarly, folate deficiency has been linked to neural tube defects.
Iodine deficiency is "the most common preventable cause of mental impairment worldwide." "Even moderate [iodine] deficiency, especially in pregnant women and infants, lowers intelligence by 10 to 15 I.Q. points, shaving incalculable potential off a nation's development." Among those affected, very few people experience the most visible and severe effects: disabling goiters, cretinism and dwarfism. These effects occur most commonly in mountain villages. However, 16 percent of the world's people have at least mild goiter (a swollen thyroid gland in the neck)."
Causes
Social and political