Vitamin marginal

Of the water-soluble vitamins, intakes of nicotinic acid [59-67-6] on the order of 10 to 30 times the recommended daily allowance (RE)A) have been shown to cause flushing, headache, nausea, and moderate lowering of semm cholesterol with concurrent increases in semm glucose. Toxic levels of foHc acid [59-30-3] are ca 20 mg/d in infants, and probably approach 400 mg/d in adults. The body seems able to tolerate very large intakes of ascorbic acid [50-81-7] (vitamin C) without iH effect, but levels in excess of 9 g/d have been reported to cause increases in urinary oxaHc acid excretion. Urinary and blood uric acid also rise as a result of high intakes of ascorbic acid, and these factors may increase the tendency for formation of kidney or bladder stones. AH other water-soluble vitamins possess an even wider margin of safety and present no practical problem (82). 

Although clinical deficiency disease is rare, there is evidence that a significant proportion of the population have marginal vitamin Bg status. Moderate deficiency results in abnormalities of tryptophan and methionine metabolism. Increased sensitivity to steroid hormone action may be important in the development of hormone-dependent cancer of the breast, uterus, and prostate, and vitamin Bg status may affect the prognosis. 

The balance between excess and insufficient zinc is important. Zinc deficiency occurs in many species of plants and animals, with severe adverse effects on all stages of growth, development, reproduction, and survival. In humans, zinc deficiency is associated with delayed sexual maturation in adolescent males poor growth in children impaired growth of hair, skin, and bones disrupted Vitamin A metabolism and abnormal taste acuity, hormone metabolism, and immune function. Severe zinc deficiency effects in mammals are usually prevented by diets containing >30 mg Zn/kg DW ration. Zinc deficiency effects are reported in aquatic organisms at nominal concentrations between 0.65 and 6.5 pg Zn/L of medium, and in piscine diets at <15 mg Zn/kg FW ration. Avian diets should contain >25 mg Zn/kg DW ration for prevention of zinc deficiency effects, and <178 mg Zn/kg DW for prevention of marginal sublethal effects. 

A number of nutrients affect bone integrity early in life. While the role of certain minerals and vitamins bearing on skeletal integrity is well established, that of protein remains controversial, especially when consumed in excessive amounts. Protein-included calciuric effect as observed in adult man and animals may also occur early in life and thus conceivably affect peak bone mass adversely, particularly when calcium intakes may be marginal. In studies reported here (test model young female rats), it was found that a diet approaching adequacy in protein and based equally on plant and animal sources would favor some parameters which bear on skeletal mass at maturity more than other combinations of protein consumed. 

A survey about the dietary habits within the scope of the "National Health and Nutritional Examination Survey" showed that an inverse correlation (Morabia et al., 1989) exists between COPD and vitamin A supply as the only one of 12 examined dietary components. If a diminished supply of vitamin A increases the appearance of obstructive respiratory diseases, a marginal or local vitamin A deficit could be responsible for the observed changes of the respiratory mucosa. Such a deficit results in a loss of cilia, an increase of secreting cells and finally the formation of squamous metaplasia (Biesalski et al., 1985 Chytil, 1985 Shah and Rajalekshmi, 1984). 

The mean initial serum retinol concentration derived from the 161 children was 0.74 0.46 pmol/liter. Fourteen children (8.7%) exhibited a vitamin A deficiency defined by extremely low serum retinol concentration <0.35 pmol/liter and 78 children (48%) revealed marginal deficiency as indicated by low serum concentrations (<0.70 pmol/liter). Serum retinol concentration was not different in the study- and control group prior to inhalation (Fig. 5.3). 

An impairment of the mucociliary clearance increases the susceptibility against respiratory infectious diseases frequently associated with marginal vitamin A deficiency (Sommer et ah, 1984). Interestingly vitamin A status following supplementation with 15-mg RP monthly for 2.5 months (Rahman et ah, 1996) was not improved in the presence of respiratory tract infections (Sommer et ah, 1986). 

Medical personnel who work in affluent areas are unlikely to see large numbers of people with vitamin deficiency diseases. However, certain groups of the population are particularly at risk, such as low-income families and chronically ill patients. The classic symptoms of any vitamin deficiency disease as observed in laboratory animals are often blurred in humans. The clinical picture is often complicated by deficiencies of other vitamins, minerals, calories, and protein and by infections and parasite infestations, which usually accompany longstanding malnutrition. Biochemical, physiological, and behavioral changes can occur in the marginal deficiency state without or before the appearance of more specific symptoms. Since the nonspecificity of these changes makes them difficult to detail, this section focuses on the symptoms associated with individual vitamin deficiency diseases. 

The symptoms of pantothenic acid deficiency have not been clinically described. Since pantothenic acid is a ubiquitous vitamin, isolated deficiency is unlikely. However, marginal deficiency may exist in persons with general malnutrition. 

Folic acid deficiency, unlike vitamin B12 deficiency, is often caused by inadequate dietary intake of folates. Patients with alcohol dependence and patients with liver disease can develop folic acid deficiency because of poor diet and diminished hepatic storage of folates. Pregnant women and patients with hemolytic anemia have increased folate requirements and may become folic acid-deficient, especially if their diets are marginal. Evidence implicates maternal folic acid deficiency in the occurrence of fetal neural tube defects, eg, spina bifida. (See Folic Acid Supplementation A Public Health Dilemma.) Patients with malabsorption syndromes also frequently develop folic acid deficiency. Patients who require renal dialysis develop folic acid deficiency because folates are removed from the plasma during the dialysis procedure. 

Technologists should become aware of possible reduction of available vitamins due to such processing as some vitamins can be considered marginally deficient in American diets. This concern is especially important in those modified protein foodstuffs that can contribute a sizable portion of our daily calories. 

Deficiency of vitamin K A true vitamin K deficiency is unusual because adequate amounts are generally produced by intestinal bacteria or obtained from the diet. If the bacterial population in Ihe gut is decreased, for example by antibiotics, the amount of endogenously formed vitamin is depressed, and can lead to hypoprothrombinemia in the marginally malnourished individual (for example, a debilitated geriatric patient). This condition rcaj require supplementation with vitamin K to correct the bleeding tendency. In addition, certain second generation cephalosporins (for example, cefoperazone, cefamandole, and moxalactam) cause hypoprothrombinemia, apparently by a warfarin-like mechanism. Consequently, their use in treatment is usually supplemented with vitamin K. 

These products aim primarily to provide a boost to mental energy or buzz . They are marketed as pick-me-ups , and command a high profit margin. An impressive list of ingredients is essential for credibility and typical components include caffeine, taurine, glucuronolactone, inositol, maltodextrin, vitamins and herbal extracts such as guarana, ginseng and schizandra. 

Table XII shows some margins of safety calculated by Dr. Sheldon Wagner of Oregon State University, for a set of common prescription medicines. These include caffeine when prescribed at the dose level for which it is prescribed as a medicine, antibiotics, tranquilizers, vitamins, and other drugs. Notice that the margins of safety range from 1/2 through 100, 200, and up to 1000.

Table VI summarizes total GSH-Px activity toward LHP and 15-HPETE in tissues from rats fed on vitamin E and/or Se deficient diets. GSH-Px activity toward fatty acid hydroperoxides was reduced markedly in liver and lung under Se-deficient states whereas kidney enzyme levels were only marginally affected. It should be noted that these total enzyme activities were contributed by both Se-GSH-Px and non-Se GSH-Px in crude cytosols of Se supplemented animals. However, in Se-deficient...

Cyclization of enynones to methylenecyclopentenones. This cyclization can be effected under thermal conditions, particularly in the case of activated (Z)-enynones, but in only moderate yield. Some acceleration is observed with reagents known to promote enolization (LiCl and collidine p-toluenesulfonate), but dramatic effects can be obtained with phenols such as 1. Vitamin E is marginally more... 

E. coli does not synthesize vitamin Bi2 and grows well without this nutrient. However, in certain circumstances there is a marginal benefit to the cell to be able to manufacture methionine by a pathway involving the vitamin. For this purpose the required apoprotein is synthesized, and the receptor protein is inserted in the membrane in anticipation of finding Bi2 in the environment (70). Phages BF23 and the E colicins have somehow managed to adapt to the Bi2 receptor (71). Besides the surface receptor, a second protein component in the periplasmic space may be necessary for further transport of the vitamin. 

Thurnham, D. I. (1981) Red cell enzyme tests of vitamin status do marginal deficiencies have any physiological signifi-... 

Tolerable Upper Levels of Intake A number of the vitamins are known to be toxic in excess. For most, there is a considerable difference between reference intakes that are more than adequate to meet requirements and the intake at which there may he adverse effects, although for vitamins A (Section 2.5.1) and D (Section 3.6.1) there is only a relatively small margin of safety. 

A mild infection, such as measles, commonly triggers the development of xerophthalmia in children whose vitamin A status is marginal. In addition to functional deficiency as a result of impaired synthesis of RBP (Section 2.2.3) and transthyretin in response to infection, there may be a considerable urinary loss of vitamin A because of increased renal epithelial permeability and proteinuria, permitting loss of retinol bound to RBP-transthyretin. The American Academy of Pediatrics Committee on Infectious Diseases (1993) recommended vitamin A supplements for aU children who have been hospitalized with measles. 

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