Dietary micronutrient deficiencies

Dietary micronutrient deficiencies, such as the lack of vitamin A, iodine, iron or zinc, are a major source of morbidity (increased susceptibility to disease) and mortality... 

The risk of colon cancer appears to be inversely related to calcium and folate intake. Calciums protective effect may be related to a reduction in mucosal cell proliferation rates or through its binding to bile salts in the intestine, whereas dietary folate helps in maintaining normal bowel mucosa. Additional micronutrient deficiencies have been demonstrated through several studies to increase colorectal cancer risk and include selenium, vitamin C, vitamin D, vitamin E, and 3-carotene however, the benefit of dietary supplementation does not appear to be substantial.11... 

Kwashiorkor is a type of malnutrition associated with insufficient protein intake, usually affecting children aged 1-4 years, although it can also occur in older children and adults. It is likely caused by a combination of factors (protein deficiency, energy and micronutrient deficiency). The absence of lysine in low-grade cereal proteins (used as a dietary mainstay in many underdeveloped countries) can lead to kwashiorkor. 

The optimal dietary requirements of vitamin E for humans are not yet known, especially with the emergence of new paradigms regarding adequate levels of dietary micronutrients (Chalem, 1999). Recommendations in the United States and Canada have been reevaluated, and a new concept of Dietary Reference Intake (DRI, 2000) was issued for vitamin E and other antioxidants. The DRI recommendation should prevent specific deficiency disorders, support health in general ways and minimize the risk of toxicity, which carries more tasks than the previous recommendations (DRI, 2000). Accordingly, the recommendations for intakes were set to higher levels than previously. Estimated Average Requirements (EAR) for adults, both men and women, were set to 12 mg a-tocopherol/day, RDA to 15 mg/day and Tolerable Upper Intake Level (UL) to 1000 mg/day. Moreover, the EAR and RDA are based only on the 2R-stereoisomeric forms of a-tocopherol, because the other vitamers... 

Description. Every cell in the body requires iron for a variety of functions. This versatile mineral is involved in oxygen transport (hemoglobin) and storage (myoglobin), is required by enzymes that produce energy for the cell, and it plays an important role in the function of the immune and central nervous systems. Iron is required in relatively high doses to maintain proper nutrition. Of aU the nutrients, the allowance for iron is the most difficult to obtain from dietary sources, aud therefore is the most common single micronutrient deficiency in the world. ... 

When dealing with starvation, individual nutritional factors tend not to be assessed. Yet lack of specific micronutrients could very well affect cognition. Certainly, dietary iodine deficiency is implicated in endemic cretinism with marked, often irreversible, mental retardation, deaf-mutism, and motor defects. While endemic goiter afflicts 200 million people worldwide, only in regions of severe deficiency are infants born cretinous. 

Nickel is an essential micronutrient for maintaining health in certain species of plants and animals. Its deficiency effects from dietary deprivation have been induced experimentally in many species of birds and mammals. To prevent nickel deficiency in rats and chickens, diets should contain at least 50 pg Ni/kg ration, while cows and goats require more than 100 pg Ni/kg rations, perhaps reflecting the increased use by rumen bacteria. Nickel deficiency is not a public health concern for humans because daily oral intake is sufficient to prevent deficiency effects. 

Malabsorption is defined as an inadequate assimilation of dietary substances due to defects in digestion, absorption or transport. Malabsorption can affect macronutrients (proteins, carbohydrates, fats), micronutrients (vitamins, minerals) or both, causing excessive faecal excretion and producing nutritional deficiencies and GI symptoms. Digestion and absorption occur in three phases, namely (i) the intra-lumen hydrolysis of fats, proteins and carbohydrates by enzymes, and emulsification by bile salts, (ii) digestion by brush-border enzymes and uptake of end-products and (iii) lymphatic transport of nutrients. Malabsorption can occur when any of these phases is impaired. 

Selenium is known to be an essential micronutrient for humans and other animals both inadequate and excessive selenium intake can cause adverse health effects. However, most people in the United States are unlikely to suffer from selenium deficiency. The current recommended dietary allowance (RDA) for selenium established by the Food and Nutrition Board of the National Research Council is 55 pg/day for adults. Adverse health effects due to selenium are generally observed at doses at least 5 times greater than the RDA. 

Cyanide-nutrient interactions are reported for alanine, which appears to exacerbate cyanide toxicity, and for cystine, which seems to alleviate toxicity. Dietary cyanide - at levels that do not cause growth depression -alleviates selenium toxicity in chickens, but not the reverse. For example, dietary selenium, as selenite, at lO.Omg/kg for 24 days, reduced growth, food intake, and food utilization efficiency, and produced increased liver size and elevated selenium residues the addition of 45.0 mg CN/kg diet (100.0 mg sodium nitroprusside/kg) eliminated all effects except elevated selenium residues in liver. The mechanism of alleviation is unknown and may involve a reduction of tissue selenium through selenocyanate formation, or increased elimination of excess selenium by increasing the amount of dimethyl selenide exhaled. At dietary levels of 135.0 mg CN/kg plus 10.0 mg selenium/kg chick growth was significantly decreased. This interaction can be lost if there is a deficiency of certain micronutrients or an excess of vitamin K. 

Nickel is an essential micronutrient for maintaining health in certain species of plants and animals. Nickel deficiency effects from dietary deprivation of nickel has been induced experimentally in many species of birds... 

Vitamins have been added to food products for a long time as a strategy to improve dietary intake of these micronutrients and to prevent nutritional deficiencies. Generally, supplementation is performed in foods that are easily available and in those that are habitually used by the population... 

Micronutrients are different from macronutrients (Uke carbohydrates, protein, and fat) because they are necessary only in very small quantities. Nevertheless, micronutrients are essential for good health and their deficiency can cause serious health problans. Micronutrients include dietary minerals, which are important for the smooth operation of aU biological functions and cellular activity. Therefore, their consumption is associated with the reduction of the risk of certain types of diseases. The most important micronutrients are the following ... 

Trace nutrients, micronutrients a general term for any essential dietary component required in small quantities, like TVace elements (see) and Vitamins (see). Deficiency of T.n. leads to deficiency symptoms, e.g. vitamin deficiency diseases. T.n. act catalytically or are precursors of catalytically active substances in the organism. Essential amino acids therefore have an equivocal status in this classification. Flavoring principles are definitely not T. n. 

The term vitamin was derived from vitamine a word made up by the Polish scientist Casimir Funk from vital and amine , with the meaning amine of life . It was suggested in 1912 that the organic micronutrient food factors that prevent beriberi and perhaps other similar dietary-deficiency diseases might be chemical amines. This proved incorrect for the micronutrient class and the word was shortened to vitamin. Vitamins have been produced as commodity chemicals since the middle of the 20th century and are widely available as inexpensive synthetic multivitamin dietary supplements. They are classified by... 

In people with low body stores of Fe the absorption of Cd is higher than in subjects with normal Fe stores [44], which has been also observed in experimental animals [45]. Interestingly, dietary Cd absorption tends to be higher in females than in males [46] because of increased incidence of low Fe stores or overt Fe deficiency in women at fertile age [47,48]. Women with low body Fe stores, as refiected by low serum ferritin levels, have on average twice (about 10% but up to 20%) the normal rate of oral Cd absorption [49]. This may be explained by the close correlation between Cd absorption and the expression of DMTl, whose expression is induced by Fe deficiency and transports Fe and Cd into the mucosa cell equally well [34,50]. This situation is exacerbated during pregnancy when enterocytes have an increased DMT-1 density at the apical surface to optimize micronutrients absorption [46,48]. 

As for most other micronutrients, the requirement of niacin to prevent or reverse the cHnical deficiency signs is not known very precisely, and probably depends on ancillary dietary deficiencies or other insults occurring in natural human populations. For the purpose of estimating niacin requirements... 

The realization that selenium (Se) may be an essential micronutrient for human diets has arisen only recently, in the second half of the twentieth century. Selenium deficiency, attributable to low soil selenium levels in farm animals, especially sheep that are afflicted by selenium-responsive white muscle disease, has been recognized for at least half a century. However, the more recent identification of Keshan and Kashin-Beck diseases as endemic selenium-responsive conditions, occurring in a central 4000-1— km-wide belt of central China and in areas of Russia, demonstrated conclusively that not only is selenium an essential element for man but also deficiencies occur naturally and require public health measures to alleviate them. Selenium incorporation into plants is affected by the acidity of the soil and by the concentrations of iron and aluminum present so that selenium content of human diets is modulated by these components of the environment. The very recent discovery that these diseases probably arise through the interaction of selenium deficiency with enhanced viral virulence has added a further layer of complexity, but it does not alter the fact that selenium is an essential dietary component that cannot be substituted by any other element. Another complicating factor is that moderately increased soil selenium concentrations result in the opposite condition of seleno-sis, or selenium overload, with equally debilitating consequences. Of all elements, selenium has a very narrow safe intake range, and unlike some other potentially toxic elements, it is absorbed efficiently by the intestine over a wide range of concentrations and across a variety of different molecular forms. 

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