Vitamin status assessment

Vitamin Be requirements have been estimated both by isotopic tracer studies to determine turnover of the body pool (Section 9.6.1) and also by depletion/ repletion studies using a variety of indices of status (Section 9.6.2). These studies have generally been conducted on young adults, and there is inadequate information to determine the requirements of elderly people, because apparent status assessed by a variety of indices declines with increasing age, despite intake as great as in younger people (Bates et al., 1999a). As discussed in Section 9.6.3, there is also inadequate information to estimate the requirements of infants. 

Kodentsova VM, Vrzhesinskaya OA, and SpirichevVB (1995) Eluorometric riboflavin titration in plasma by riboflavin-binding apoprotein as a method for vitamin B2 status assessment. Amnals of Nutrition and Metabolism 39,355-60. 

Kretsch MJ, Sanberlich HE, Skala JH, and Johnson HL (1995) Vitamin B-6 requirement and status assessment young women fed a depletion diet followed by a plant- or animal-protein diet with graded amounts ofvitamin B-6. American Journal of Clinical Nutrition61,1091-1101. 

Vitamin status can be assessed by a direct test for the levels of 25-(OHin the serum, This competitive binding test involves three components (1) a serum sample, (2) radioactive 25-hydroxy[ Hjvitamin Dj, and (3) vitamin D-binding protein. The source of vitamin D-binding protein may be sheep serum. The functional tests for deternrination of vitamin D irvdude the diagnostic tests for rickets and osteomalacia. A test for osteomalacia, for example, may include measurement of the width of the osteoid in a bone biopsy. The osteoid is described later. 

Flavins are lost from the body as intael riboflavin, rather than as a breakdown product of riboflavin. Hence, vitamin status may be assessed by measuring the level of urinary riboflavin. Generally, the loss of 30 ig of riboflavin/g creatinine or less per day indicates a deficiency. This metht>d of assessment is not preferred because it is influenced by a number of factors unrelated to vitamin status. Another problem with this method is its great sensitivity to a short-term deficiency thus, it does not necessarily reflect the true concentrations of FAD and FMN in tissues. The most reliable way to assess riboflavin status is by a functional test. The test involves the assay of glutathione reductase, using red blood cells as the source of... 

FIGURE 9.75 Results of the FAD sHmuJation test used to assess vitamin status in high school Students. (Redrawn with permission from Sauberlich el a ., 1972.)... 

Shane, B, and Contractor, S-1 (1975), Assessment of vitamin status. Studies on pregnant women and oral contraceptive users. Ant. J. din. Wm/t. 28, 739-747. 

The existence of apoenzyme and holoenzyme forms of various enzymes is of use to the clinician. The proportion of a specific enzyme occurring in apoenzyme and holoenzyme forms is used to assess vitamin status in the cases of vitamin Bg, thiamin, and riboflavin. Vitamin status is determined by measuring the percentage stimulation of enzyme activity that occurs after adding the appropriate cofactor to a biological sample (blood) containing the enz3me of interest. 

Shearer MJ. Measurement of phyUoquione (vitamin Kl) in serum and plasma by HPLC, In Fidanza F, ed. Nutritional status assessment—A manual for population studies. London Chapman and HaH, 1991 214-20. 

Talwar D, Davidson H, Cooney J, St JO Reilly D. Vitamin B(l) status assessed by direct measurement of thiamin pyrophosphate in erythrocytes or whole blood by HPLC comparison with erythrocyte transketolase activation assay. Clin Chem 2000 46 704-10. 

Before transplant, BMD should be measured and vitamin D and gonadal status assessed. Bone-healthy lifestyle changes and therapy should be instituted as needed (see Fig. 88-4) and hypogonadism corrected before and after transplant. Intermittent pamidronate has decreased bone loss in most transplant recipients." Use of bisphosphonates in children and when creatinine clearance is less than 30 mL/min is being explored. Glucocorticoid doses should be... 

Considerable uncertainty and controversy exists concerning the folate requirement for humans. Hie review of data concerning the human folate requirement by the Food and Nutrition Board (1989) suggests that the daily maintenance requirement is 100-200 fig of avaUable folic acid equivalents. The 1989 RDAs were reduced to 200 and 180 fig for adult men and women, respectively, from the previous RDA of 400 on the basis of such evidence (Food and Nutrition Board, 1989). Similarly, the Canadian RDA for folate was set at 3 /ig/kg body wt or 210 fig for a 70-kg individual. These lower RDAs may be inadequate for certain population groups, however (Sauberlich, 1990 Bailey, 1992 McPartlin etai, 1 3). It is currently difficult or impossible to predict the quantitative effect on folate nutritional status of factors such as (a) changes in folate intake, (b) differences in folate bioavailability, (c) effects of pregnancy and lactation on folate requirements, and (d) pharmaceuticals with antifolate properties. In addition, the development of mathematical models would improve our ability to evaluate methods of nutritional status assessment for this vitamin. 

Status assessment in humans includes assessment of vitamin intake, measurement of vitamin concentration in blood or urine, and/or measurement of metabolites/enzyme activity. 

Snell, E.E., 1980. Vitamin Bg analysis some historical aspects. In Leklem, J.E., and Reynolds, R.D. (ed.) Methods in Vitamin B-6 Nutrition Analysis and Status Assessment. Plenum Press, New York, USA, pp. 1-20. 

The assessment of serum holoTC concentrations is clinically and diagnostically useful. In fact, the biologically active form of vitamin B12 represents the best predictor of cobalamin status from infancy to old age maternal holoTC concentrations can predict newborns vitamin status, serum holoTC levels correlate with infants dietary cobalamin intake, holoTC measurement is useful to diagnose cognitively impaired patients (Refsum et al. 2006). 

Ascorbic acid is an important essential nutrient for the health maintenance of the population. Nevertheless, its importance must not be overestimated. The status assessment of the vitamin in well-nourished populations showed only a small percentage of subjects with an insufficient plasma ascorbic acid concentration. It has been documented that risk factors for the development of an ascorbic acid deficiency exist (e.g., smoking, alcohol use, pregnancy, certain pathophysiological conditions). These deficiencies can, however, be overcome without any problems when the current recommendations on vitamin C intake are fulfilled by the intake of either... 

A water soluble vitamin which cannot be synthesized by man and therefore has to be obtained from the diet. It is found extensively in vegetables and fruit, especially the citrus varieties. Since the vitamin is carried mainly in the leukocytes, its measurement in these cells gives some indication of the vitamin C status of the body. The ascorbic acid saturation test can also be used to assess the vitamin status. The biochemical role of the vitamin is obscure although it does seem to be required for collagen formation. Deficiency of the vitamin causes scurvy, the symptoms of which can be related to poor collagen formation. These include poor wound-healing, osteoporosis (due to bone matrix deficiency), a tendency to bleed (due to deficiences in the vascular walls) and anaemia. 

In summary, while hair analysis has been used to detect certain types of heavy metal poisoning (e.g., lead, arsenic, mercury) in populations, its value on an individual basis remains to be established. There are a number of limitations to hair analysis both in terms of analytical procedures and in interpretation of results. For example, the relationship between hair concentration of a trace element or of a vitamin and the concentration of other body tissues is unknown. Basically, hair analysis is of limited value for assessing mineral status and questionable for assessing vitamin status. 

Further papers have been published showing impairment of carbohydrate tolerance (115, 117 ). Some light on the underlying mechanisms has been shed by Adams et al. (113 ). In an investigation comprising 46 women the carbohydrate and vitamin status were assessed before and after pyridoxine administration. Eighteen women had evidence of tissue depletion of vitamin Be. All the women had abnormal tryptophan metabolism including increased urinary xanthurenic acid excretion. 

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