Vitamin C status and nutrient interactions in a healthy elderly population.

Vitamin C status and interactions with other nutrients were studied in 677 healthy, noninstitutionalized elderly people aged 60-98 y. Although 6% of the males and 3% of the females showed marginal vitamin C status (plasma ascorbic acid 11 to less than 23 mumol/L), only one person had a plasma ascorbic acid (AA) level less than 11 mumol/L. At all levels of total vitamin C intake, mean plasma AA levels were higher in females than males. Vitamin C supplement use was associated with generally higher blood levels of vitamins B-6, B-12, and E and folate in both sexes and with higher levels of retinol in females. However, after both age and the total dietary intake of the specific nutrient being examined were controlled for, plasma AA levels were significantly correlated only with plasma levels of vitamin E and folate in females.

Studies on the application of the relative-dose-response test for assessing vitamin A status in older adults.

We investigated the time course and the reproducibility of the relative-dose-response (RDR) test for assessing vitamin A status in older adults. The maximum plasma retinol response to 480 retinol equivalents (RE) of retinyl palmitate in abnormal responses was at 6 or 7 h after dosing compared with the 5-h sampling interval recommended by others for younger adults and children. With respect to reproducibility, the diagnostic concordance of two RDR tests at 7-d intervals in 14 elders was 71%. In 29% of tests, one test was abnormal and the other normal. Linear regression of the two RDR values in these 14 subjects gave a correlation coefficient of -0.08. We conclude that the procedure for the RDR should be modified when applied to persons greater than 60 y of age, and that multiple repetitions of the test are needed to provide a stable indication of vitamin A stores in an elderly individual.

Use of p-aminobenzoic acid to monitor compliance with prescribed dietary regimens during metabolic balance studies in man.

A new method is described for simultaneously monitoring compliance with prescribed-diet and urine-collection regimens during metabolic balance studies. It involves incorporation of the potassium salt of p-aminobenzoic acid (PABA) into provided foods and measurement of its extent of recovery in urine. A validation study was conducted in 10 healthy adults. During three consecutive 24-h periods, subjects consumed four foods per day that had each been supplemented with 72.0 mg PABA and also made complete urine collections. An additional 24-h urine collection was made by each subject for determination of baseline PABA excretion. The PABA was easily incorporated into the test foods and was not detected by taste. The recovery of the PABA in urine, determined by colorimetric assay, was 98.7 +/- 3.7% (means +/- SD) of intake. Thus, in metabolic studies for greater than or equal to 3 d, PABA can be used to provide a sensitive index of dietary compliance.

Vitamin E supplementation enhances cell-mediated immunity in healthy elderly subjects.

The effect of vitamin E supplementation on the immune response of healthy older adults was studied in a double-blind, placebo-controlled trial. Subjects (n = 32) resided in a metabolic research unit and received placebo or vitamin E (800 mg dl-alpha-tocopheryl acetate) for 30 d. Alpha-tocopherol content of plasma and peripheral blood mononuclear cells (PBMCs), delayed-type hypersensitivity skin test (DTH), mitogen-stimulated lymphocyte proliferation, as well as interleukin (IL)-1, IL-2, prostaglandin (PG) E2, and serum lipid peroxides were evaluated before and after treatment. In the vitamin E-supplemented group 1) alpha-tocopherol content was significantly higher (p less than 0.0001) in plasma and PBMCs, 2) cumulative diameter and number of positive antigen responses in DTH response were elevated (p less than 0.05), 3) IL-2 production and mitogenic response to optimal doses of concanavalin A were increased (p less than 0.05), and 4) PGE2 synthesis by PBMCs (p less than 0.005) and plasma lipid peroxides (p less than 0.001) were reduced. Short-term vitamin E supplementation improves immune responsiveness in healthy elderly individuals; this effect appears to be mediated by a decrease in PGE2 and/or other lipid-peroxidation products.

Vitamin B-6 deficiency impairs interleukin 2 production and lymphocyte proliferation in elderly adults.

The effect of vitamin B-6 deficiency on immune response was studied in eight healthy elderly adults. The protocol consisted of a 5-d baseline (BL) period; a vitamin B-6-depletion period of less than or equal to 20 d; three stages of vitamin B-6-repletion, each lasting 21 d; and a 4-d final phase. The amounts of vitamin B-6 ingested during the different phases of the study were 3.00, 15.00, 22.50, and 33.75 micrograms.kg body wt-1.d-1, respectively. During the final phase the subjects ingested 50 mg vitamin B-6/d. Fasting blood was collected at the end of each period. Vitamin B-6 depletion significantly decreased percentage and total number of lymphocytes, mitogenic responses of peripheral blood lymphocytes to T- and B-cell mitogens, and interleukin 2 production. These indices returned to BL values after the third vitamin B-6-repletion period, when the total vitamin B-6 intakes were 1.90 +/- 0.18 mg/d for women and 2.88 +/- 0.17 mg/d for men. Vitamin B-6 deficiency impairs in vitro indices of cell-mediated immunity in healthy elderly adults. This impairment is reversible by vitamin B-6 repletion.

Effect of vitamin B-6 deficiency on fasting plasma homocysteine concentrations.

The catabolism of homocysteine through cystathionine synthesis requires pyridoxal-5'-phosphate, thus the effect of vitamin B-6 deficiency on plasma homocysteine concentrations was evaluated. Total fasting plasma homocysteine concentrations were measured in 11 elderly subjects aged 64.4 +/- 1.7 y (mean +/- SE) who consumed a vitamin B-6-deficient diet for less than or equal to 20 d. Only 1 of the 11 subjects was found to have elevated homocysteine concentrations even though all subjects exhibited high urinary xanthurenic acid concentrations after a tryptophan load, a measure indicative of vitamin B-6 deficiency. In a supporting study, fasting plasma homocysteine concentrations were measured in 3- and 23-mo-old rats fed vitamin B-6-deficient diets and were compared with those of vitamin B-6-replete, pair-fed controls. There was no difference in homocysteine concentrations between deficient and pair-fed animals after 6 wk of the dietary regimen for either age group; after 9 wk a modest elevation was observed in the 3-mo-old deficient rats whereas no difference was observed for the 23-mo-old rats. It is concluded that fasting plasma homocysteine concentrations are not initially elevated in vitamin B-6 deficiency and therefore fasting plasma homocysteine concentrations are not a good indicator of vitamin B-6 status.

B complex vitamin patterns in geriatric and young adult inpatients with major depression.

This study compared the B complex vitamin status at time of admission of 20 geriatric and 16 young adult non-alcoholic inpatients with major depression. Twenty-eight percent of all subjects were deficient in B2 (riboflavin), B6 (pyridoxine), and/or B12 (cobalamin), but none in B1 (thiamine) or folate. The geriatric sample had significantly higher serum folate levels. Psychotic depressives had lower B12 than did non-psychotic depressives. Poorer blood vitamin status was not associated with higher scores on the Hamilton Depression Rating Scale or lower scores on the Mini-Mental State Examination in either age group. The data support the hypothesis that poorer status in certain B vitamins is present in major depression, but blood measures may not reflect central nervous system vitamin function or severity of affective syndromes as measured by the assays and scales in the present study.

Effect of gamma irradiation on the B vitamins of pork chops and chicken breasts.

A study was made of the effect of low-dose gamma irradiation on the content of thiamine (B1), riboflavin (B2), niacin, pyridoxine (B6) and cobalamin (B12) in pork chops, and thiamine, riboflavin and niacin in chicken breasts. Gamma irradiation from a caesium-137 source was used to irradiate the samples in a range of 0.49 to 6.65 kGy from -20 to +20 degrees C. Over the range of dose and temperature studied it was possible to derive a mathematical expression for predicting the losses. A calculation was made of the effect of the loss of thiamine, riboflavin and niacin due to irradiation on the overall loss of these vitamins in the American diet. The losses of riboflavin and niacin were of the order of a fraction of a per cent. Pork is an important source of thiamine, but the calculated loss at 1.0 kGy of this vitamin in cooked pork was only 1.5 per cent. There were initial increases with radiation doses up to 2-4 kGy in the measured concentrations of riboflavin and niacin in both pork and chicken. The increases were highly significant, and are of concern both to the study of radiation effects and the chemical method of the determination of these two vitamins.

Vascular disease risk factors, urinary free cortisol, and health histories in older adults: shyness and gender interactions.

We studied relationships between shyness and health during a health screening survey of older adults (ages 50-88) living in an active retirement community in the southwestern United States (n = 232). As in previous studies of infants, older individuals with hay fever, insomnia and constipation were more shy than those without these problems. Shy persons overall showed higher sitting systolic blood pressure and a larger fall in orthostatic systolic blood pressure on standing; shy men had a greater prevalence of hypertension histories than did low-shy men. Shy subjects of both sexes had lower HDL cholesterol and higher triglycerides than did low-shy subjects; shy women tended to have higher LDL cholesterol than did low-shy women. In contrast with findings of elevated salivary cortisol in extremely inhibited children of both sexes, only shy women had higher 24 h urinary free cortisol excretion than did low-shy women; men showed the opposite pattern, possibly related to suppression of aggression. Shy men also tended to report a higher prevalence of thyroid disease history than did low-shy men (20% versus 6%). Notably, autoimmune thyroiditis has previously been linked with panic and depression, disorders which in turn have been associated with shyness. Taken together with previous work in shy children and their families, the data raise the possibility of (a) increased risk for arteriosclerotic vascular disease; and (b) increased risk of adrenal- and/or thyroid-related diseases in certain shy older adults.

Quantitation of hepatic fatty acid-binding proteins by post-chromatographic ligand binding assay.

A new procedure for the detection and quantitation of small molecular weight cytosolic fatty acid-binding proteins (FABP) in chromatographic fractions is described. Aliquots of the fractionated cytosol are incubated with radiolabeled palmitate and the unbound fatty acid ligand is quickly removed by addition of a dextran-gelatin-coated charcoal suspension. Quantitation of the FABP is accomplished by counting the protein-bound radioactivity in the supernatant fraction after a brief centrifugation step. Validation studies have shown the assay to be linear over a range of 10-40 micrograms or 20-80 micrograms of FABP depending on specific activity of [14C]palmitate used. Bovine serum albumin can be included as an external binding protein to correct for the nominal day-to-day variation in the assay system. The assay has been found to give consistent results with a wide variety of buffer salts, ionic strength, and pH, and therefore is compatible with the usual conditions of gel filtration, ion exchange, and affinity chromatography. Compared to detection methods involving prechromatographic addition of bromosulfophthalein or radiolabeled fatty acids to cytosolic proteins, the post-chromatographic binding assay offers the advantage of leaving the bulk of the FABP preparation free of these marker ligands.

Copper- and zinc-binding proteins in sheep liver and intestine: effects of dietary levels of the metals.

Liver cytosol from sheep fed diets containing 2.2, 11.3 or 47 microgram Cu/g diet with or without supplemental zinc (543 or 46 microgram Zn/g diet), fractionated on Sephadex G-100, yielded three main copper- and zinc-containing proteins with approximate molecular weights of greater than 150,000, 27,000 and 10,000. Amino acid analysis of the 10,000-molecular-weight proteins were of the metallothionein type. Copper-chelatin was not present in sheep liver cytosol. Copper concentration of the metallothionein fraction increased (P less than 0.01) as dietary copper increased from 2.2 to 11.3 microgram Cu/g, but did not increase further when dietary copper increased to 47 microgram Cu/g in unsupplemented sheep. A low-molecular-weight (approximately 3,500) copper-, but not zinc-containing fraction appeared at this highest level of copper. Zinc supplementation of the diet increased not only the zinc content of the metallothionein fraction but also its copper content, most dramatically in sheep fed the highest copper level. In intestinal mucosal cytosol, no copper and little zinc was associated with the metallothionetin fraction which was not affected by dietary treatment. Evidence from this study suggests that sheep have limited capacity to synthesize metallothionein in response to increased dietary copper.

Intact parathyrin in postmenopausal women.

To establish a reference range, we measured intact parathyrin (parathyroid hormone, PTH) in 245 healthy postmenopausal women, ages 42-75 years, with use of the Allegro Intact PTH Kit from Nichols Institute Diagnostics. We also assayed serum from a subset of 120 of the women with kits specific for mid-molecule PTH. The mean intact PTH concentration for the 245 women was 32 ng/L (95% confidence interval 14-60 ng/L). Intact PTH values in these subjects were not normally distributed, although calcium concentrations in the same samples were. There was positive, but not significant (r = 0.12, P = 0.06), correlation between intact PTH and age, and a significant negative correlation between serum calcium and intact PTH that was not observed between calcium and mid-molecule PTH. The improved sensitivity of the intact PTH assay makes it useful in studies of calcium homeostasis in the normal population.

Low thyroxine levels in female psychiatric inpatients with riboflavin deficiency: implications for folate-dependent methylation.

Intermediates in the folate-dependent methylation pathways may play a role in the etiology and treatment of such mental disorders as major depression. These pathways include a step dependent on a riboflavin (B2)-derived coenzyme, flavin adenine dinucleotide (FAD), which is reportedly sensitive to thyroid status and to phenothiazine and tricyclic drug exposure. In a sample of 52 male and female acute psychiatric inpatients, 17% (n = 9) showed B2 deficiency (i.e., insufficient FAD activity) on a functional red blood cell enzyme assay, but only one B2-deficient individual showed deficiency in another B-complex vitamin (folate). All patients with B2 deficiency were women, who were also significantly younger than the rest of the sample. The B2-deficient women had significantly lower thyroxine levels, even when controlling for sex and covarying for age. B2-deficient patients exhibited a nonsignificant trend toward more unipolar depression (44% vs 14%), but not toward bipolar or schizophrenic disorders. As in a previous study, drug exposure did not show a relationship to riboflavin deficiency in this sample. The findings suggest that B2 (FAD) activity may serve as a sensitive marker of thyroxine status in certain female psychiatric inpatients and that B2 deficiency may play an etiological role in defects of the methylation pathways in a subset of mentally ill individuals.

Test-retest reproducibility of the relative dose response for vitamin A status in Guatemalan adults: issues of diagnostic specificity.

The relative dose response (RDR) test was examined with regard to specificity and reproducibility in subjects with adequate dietary intake and normal liver reserves of vitamin A. Twelve subjects were administered an RDR test four times over 22 d, including one placebo test in which the oral dose of vitamin A was omitted. Additionally, static measures of retinol, tocopherol, retinol binding protein (RBP) and prealbumin (PAL) were taken to determine the intra- and inter-individual coefficient of variation for these blood constituents. Intra-individual coefficients of variation were as follows: retinol, 8.8%; RBP, 11.5%; PAL, 7.6%; and alpha-tocopherol, 8.8%. The mean RDR in vitamin A-replete subjects was 1.2% and ranged from approximately -25% to 11%. No differences were observed between placebo and true RDR (i.e., with vitamin A) test responses, and there was no difference among the three true RDRs over a period of 22 d. Consistent with the hypothesis upon which the RDR test is based, nascently absorbed vitamin A evidently entered a storage pool in the liver of vitamin A-replete subjects without immediate release to peripheral sites of utilization. Because the RDR test results were normal in all subjects, the procedure appears to offer high test specificity and does not falsely diagnose hypovitaminosis A. Nevertheless, the magnitude and direction of the RDR within an individual over 22 d were highly variable, and this variability may preclude the use of a single measure of the RDR to grade the relative vitamin A nutriture of an individual subject.

Establishment of creatinine clearance reference values for older women.

Age-adjusted reference ranges for creatinine clearance were determined in 279 women, ages 40-95 years, who were housed in a metabolic research unit and consumed a meat-free diet. Creatinine clearance, but not serum creatinine, declined with age by 0.63 mL/min per 1.73 m2 per year. Serum and urine creatinine concentrations, used to calculate clearances, were analyzed by a kinetic Jaffé procedure. In a subset of 100 subjects, fasting serum creatinine values averaged 8.3 +/- 5.2 (SD) mumol/L higher when measured by the kinetic Jaffé procedure than by an enzymatic method (creatinine PAP). The Cockcroft-Gault formula for estimating creatinine clearance from serum creatinine in women was validated, and the modification factor for the male equation was determined to be 0.84 (95% confidence interval 0.83-0.86) confirming the suggested 15% correction. A prediction formula derived from this population was similar in accuracy to the Cockcroft-Gault formula.

Nutritional correlates of atrophic glossitis: possible role of vitamin E in papillary atrophy.

Atrophy of the filiform papillae of the tongue is a sign of malnutrition. However, papillary atrophy has not been correlated with laboratory indices of nutritional status. We studied photographs of tongues from 30 elderly subjects and determined the percentage of normal papillary development (%NPD) relative to a reference photograph. We also determined 16 nutritional blood levels and used stepwise multiple linear regression to examine their relationship to %NPD. We found that %NPD correlated significantly (p < 0.0031) with levels of vitamin E and prealbumin, but not with 14 other laboratory indices. Subjects with overt atrophic glossitis (%NPD < 50%) tended to have multiple nutritional deficiencies. The high correlation of plasma vitamin E levels with %NPD may be related to its role as an antioxidant and in the maintenance of cellular membrane integrity.

A comparison of the in vitro lipogenic rates and other physiologic parameters in two strains of lean and obese chickens.

Selection for abdominal fat pad size in mature hens has yielded two divergent strains of lean and obese chickens. The females in the obese line have been shown to have a greater amount of total body lipid by six weeks of age. Liver slices from 6- and 17-week old obese chickens incorporated significantly more 3H2O into extracted fractions of total lipid and saponified fatty acids. Palmitate esterification by abdominal fat pad slices from 12-week old pullets was the same for both strains when activity was expressed per unit weight of tissue. The twofold difference in size between the lean and obese fat pads at this age, however, indicates a significantly greater degree of total esterification in the obese birds. At 6-, 12-, and 17-weeks of age, the two lines exhibited similar concentrations of plasma glucose, total protein, and triglycerides.

Test-retest reproducibility of the relative dose response for vitamin A status in Guatemalan adults: issues of diagnostic sensitivity.

The relative dose response (RDR) test has been used as a functional measure of whole-body stores of vitamin A in humans. We have examined the reproducibility of the RDR procedure in a population of Guatemalan adult subjects who would be expected to show a moderate prevalence of hypovitaminosis A. Fifty-one subjects were administered a standard RDR test, and the plasma samples were analyzed for retinol, tocopherol, retinol binding protein (RBP) and prealbumin (PAL). Thirty-four of the subjects underwent repeat RDR tests 7 d later. Plasma levels in fasted subjects were as follows: retinol, 1.35 +/- 0.30 mumol/L; RBP, 37.8 +/- 7.7 mg/L; PAL, 187.0 +/- 39.0 mg/L; and tocopherol, 16.6 +/- 6.2 mumol/L. RDRs ranged from -35.2% to +63.1%, with a mean of 2.6 +/- 10.4%. Overall, we observed poor within-subject reproducibility of the RDR procedure whether expressed numerically or by diagnostic classification. Moreover, in contrast to previous studies in children, we observed fewer positive RDR tests than would be expected for the population studied. Nevertheless, the mean RDR was inversely proportional to fasting retinol levels, thus confirming the validity of the biological basis of the RDR procedure in humans. Because of high intra-individual variability with this test, investigators should be cautious when using the RDR procedure in serial studies to monitor the efficacy of therapeutic interventions or subject compliance to dietary regimens.

Reversal of protein-bound vitamin B12 malabsorption with antibiotics in atrophic gastritis.

The role of bacteria in the bioavailability of protein-bound vitamin B12 was examined in eight elderly subjects who had atrophic gastritis and in eight normal controls. On separate days and in random order, vitamin B12 absorption tests were performed using either radiolabeled crystalline or protein-bound vitamin B12. At the same time, bacterial samples were collected from the upper gastrointestinal tract. The tests and gastrointestinal aspirates were performed before and during tetracycline therapy. Crystalline vitamin B12 was absorbed to the same extent in the two study groups. Atrophic gastritis subjects absorbed significantly less protein-bound vitamin B12 than normal controls (mean +/- SEM, 0.7% +/- 0.2% vs. 1.9% +/- 0.5%, respectively). However, protein-bound vitamin B12 absorption in these subjects normalized after antibiotic therapy. These results suggest that the small amounts of vitamin B12 released from the protein binders is readily absorbed (as shown in vitro) and/or metabolized by bacteria.

Vitamin B-6 requirements of elderly men and women.

The vitamin B-6 requirements of 12 men and women over 60 y old were studied. The protocol consisted of a 5-d baseline period and four experimental periods during which the subjects successively received 0.003, 0.015, 0.0225 and 0.03375 mg of vitamin B-6/(kg body wt.d). Dietary protein was 1.2 or 0.8 g/(kg body wt.d). At 5- or 6-d intervals, xanthurenic acid (XA) after a 5-g L-tryptophan load and 4-pyridoxic acid (4-PA) in 24-h urine, erythrocyte aspartate aminotransferase activity coefficient (EAST-AC) and plasma pyridoxal-5'-phosphate (PLP) were measured. These measurements were abnormal during vitamin B-6 depletion but returned to normal during repletion. Men who ingested approximately 120 g protein/d required 1.96 +/- 0.11 mg of vitamin B-6 to normalize XA; women who ingested 78 g protein/d required 1.90 +/- 0.18 mg of vitamin B-6 to normalize XA. To attain normal levels of EAST-AC and 4-PA in men, 2.88 +/- 0.17 mg of vitamin B-6 were needed; to normalize PLP, 1.96 +/- 0.11 mg of vitamin B-6 were required. Women required 1.90 +/- 0.18 mg or more of vitamin B-6 to normalize these measurements. Vitamin B-6 requirements were not decreased in two of three subjects who ingested 54 g of protein daily. Thus, vitamin B-6 requirements of elderly men and women are about 1.96 and 1.90 mg/d, respectively.