11.3: Problems from Malnutrition
- Page ID
- 84069
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Diversity of Problems
A person who does not maintain nutritional homeostasis is said to have malnutrition. This condition can cause a constellation of problems whose nature and severity depend on the specific nutrients or combinations of nutrients that are above or below the normal range; the amount of deviation from the normal range; and the frequency of the deviation or the length of time it exists. Sometimes malnutrition for one nutrient may directly affect only one body function (e.g., vitamin K and blood clot formation). In many other cases malnutrition for one nutrient (e.g., protein deficiency) may affect many or all cells in the body. However, since body cells and systems are interdependent, malnutrition that directly affects one or a few functions ultimately has widespread effects. For example, vitamin K deficiency leading to poor blood clotting can result in slow but steady blood loss, anemia, and therefore a reduced oxygen supply to all body cells.
Onset of Problems
In some cases of malnutrition problems develop quickly. For example, water deprivation on a hot day can result in overheating within a few hours. In many other cases problems develop gradually. In some of these cases, the diet may provide certain nutrients at low levels and body cells may function at only a slightly reduced or slowly diminishing capacity. For example, a slight deficiency in B vitamins may result in a barely noticeable decline in strength. In other cases of nutrient deficiency, the body may be able to compensate partially by drawing on its reserves. For example, calcium deficiency may not become apparent for many years because blood calcium levels can be maintained by withdrawing calcium from the bones. Finally, in cases of nutrient excess the body may be able to convert or store large quantities of the excess nutrient and thus protect body cells from injury. For example, the liver can store much vitamin A and reduce or delay the toxic effects of an excessive dietary intake of that vitamin.
Nature of Problems
Besides developing gradually, manifestations of malnutrition often begin as vague and nonspecific abnormalities such as weakness, nausea, headache, and changes in personality. In other cases, the effects of malnutrition may seem to result from a specific disease that is often not associated with malnutrition (e.g., dementia). In both situations, determining that the problem is caused by malnutrition is difficult and malnutrition is often overlooked as a cause.
Consequences
Since malnutrition is a deviation from homeostasis, body cells do not have optimum conditions and function less effectively. This decline in cell function leads to a decline in the ability of the body to adapt to other changes in internal or external conditions and therefore may result in further decrements in homeostasis. For example, calcium deficiency can lead to weaker bones that provide less support, and then fractures from traumatic injury or ordinary activities may occur. Similarly, protein deficiency can reduce the ability of white blood cells to combat bacteria, and infections may occur. Finally, in cases of excess fat and carbohydrate intakes, the obesity that may develop can inhibit the quick movements needed to avoid an accident such as a fall.
Besides reducing adaptive responses that maintain homeostasis, the malfunctions caused by malnutrition can substantially reduce the enjoyment derived from activities. As examples, obesity from an excess food intake often leads to an earlier onset of fatigue and discomfort from recreational activities, and a zinc deficiency can lead to reductions in taste sensations and decrease the pleasure derived from foods.
A third consequence of malnutrition is disease. Some types of malnutrition are known to cause specific diseases. For example, iron deficiency causes anemia, and high blood alcohol levels cause cirrhosis. Other types of malnutrition are only risk factors or contributing factors to disease; recall the dietary risk factors for osteoporosis and colorectal cancer (Chaps. 9 and 10).