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Biomedical subjects

P F Jacques

Publications and source records attributed to P F Jacques.

At least 19 recordsLinked to original sources
PubMed2000

Controlled comparison of L-5-methyltetrahydrofolate versus folic acid for the treatment of hyperhomocysteinemia in hemodialysis patients.

BACKGROUND: The hyperhomocysteinemia regularly found in hemodialysis patients is largely refractory to combined oral B-vitamin supplementation featuring supraphysiological doses of folic acid. We evaluated whether a high-dose L-5-methyltetrahydrofolate-based regimen provided improved total homocysteine (tHcy)-lowering efficacy in chronic hemodialysis patients. METHODS AND RESULTS: We block-randomized 50 chronic, stable hemodialysis patients on the basis of their screening predialysis tHcy levels, sex, and dialysis center into 2 groups of 25 subjects treated for 12 weeks with oral folic acid at 15 mg/d (FA group) or an equimolar amount (17 mg/d) of oral L-5-methyltetrahydrofolate (MTHF group). All 50 subjects also received 50 mg/d of oral vitamin B(6) and 1.0 mg/d of oral vitamin B(12). The mean percent reductions (+/-95% CIs) in predialysis tHcy were not significantly different: MTHF, 17.0% (12.0% to 22.0%); FA, 14.8% (9.6% to 20.1%); P=0.444 by matched ANCOVA adjusted for pretreatment tHcy. Final on-treatment values (mean with 95% CI) were MTHF, 20.0 micromol/L (18.8 to 21.2 micromol/L); FA, 19.5 micromol/L (18.3 to 20.7 micromol/L). Moreover, neither treatment resulted in "normalization" of tHcy levels (ie, final on-treatment values <12 micromol/L) among a significantly different or clinically meaningful number of patients: MTHF, 2 of 25 (8%); FA, 0 of 25 (0%); Fisher's exact test of between-groups difference, P=0.490. CONCLUSIONS: Relative to high-dose folic acid, high-dose oral L-5-methyltetrahydrofolate-based supplementation does not afford improved tHcy-lowering efficacy in hemodialysis patients. The preponderance of hemodialysis patients (ie, >90%) exhibit mild hyperhomocysteinemia refractory to treatment with either regimen. This treatment refractoriness is not related to defects in folate absorption or circulating plasma and tissue distribution.

Administration, Oral↗
PubMed2000

Treatment of mild hyperhomocysteinemia in renal transplant recipients versus hemodialysis patients.

BACKGROUND: Mild hyperhomocysteinemia is common among maintenance hemodialysis (HD) patients and renal transplant recipients (RTR) and may contribute to the excess incidence of arteriosclerotic outcomes experienced by both patient groups. Relative to their RTR counterparts, the hyperhomocysteinemia of HD patients seems to be considerably more refractory to treatment with high-dose folic acid (FA)-based B-vitamin supplementation regimens, although controlled comparison data are lacking. METHODS: We compared the relative responsiveness of (n=10) RTR and (n=39) HD patients with equivalent baseline total homocysteine (tHcy) levels (i.e., RTR range=14.2-23.6 micromol/L; HD range=14.4-24.9 micromol/L) to 12 weeks of tHcy-lowering treatment. The RTR received 2.4 mg/day of FA, 50.0 mg/day of vitamin B6, and 0.4 mg/day of vitamin B12, while the HD patients received 15 mg/day of FA or an equimolar amount (17 mg/day) of the reduced folate, L-5-methyltetrahydrofolate, in addition to 50.0 mg/day of vitamin B6, and 1.0 mg/day of vitamin B12. RESULTS: The mean percent (%) reductions (+/-95% confidence interval) in tHcy were: RTR=28.1% (16.2-40.0%); HD=12.1% (6.6-17.7%), P=0.027 for comparison of between-groups differences by analysis of covariance adjusted for baseline tHcy levels. Moreover, (50.0%) of 10 of the RTR versus only (5.1%) of 39 of the HD patients had final on-treatment tHcy levels <12 micromol/L; P=0.002 for comparison of between-groups differences by Fisher's exact test. CONCLUSION: Relative to RTR with comparable baseline tHcy levels, the mild hyperhomocysteinemia of maintenance HD patients is much more refractory to tHcy-lowering B-vitamin treatment regimens featuring supraphysiological amounts of FA or the reduced folate, L-5-methyltetrahydrofolate. Accordingly, RTR are a preferable target population for controlled clinical trials testing the hypothesis that tHcy-lowering B-vitamin intervention may reduce arteriosclerotic cardiovascular disease event rates in patients with chronic renal disease.

Adult↗
PubMed1999

Serum total homocysteine concentrations in the third National Health and Nutrition Examination Survey (1991-1994): population reference ranges and contribution of vitamin status to high serum concentrations.

BACKGROUND: The concentration of circulating total homocysteine is a sensitive marker of inadequate folate and vitamin B12 status. Elevated homocysteine concentrations are associated with an increased risk for vascular disease. OBJECTIVE: To identify reference ranges for serum total homocysteine concentration in U.S. residents and quantify the contribution of circulating vitamin concentrations to high homocysteine concentrations. DESIGN: Cross-sectional prevalence study. SETTING: United States. PATIENTS: A nationally representative sample of 3563 male participants and 4523 female participants 12 years of age or older who participated in the third National Health and Nutrition Examination Survey. MEASUREMENTS: Reference ranges (5th and 95th percentiles) for the total homocysteine concentration were defined among participants who were folate- and vitamin B12-replete and had normal creatinine concentrations. A high total homocysteine concentration was defined as one that exceeded the sex-specific 95th percentile for the reference sample (participants 20 to 39 years of age). The population attributable risk percentage was calculated to determine the contribution of low folate (<11 nmol/L) and vitamin B12 (<185 pmol/L) concentrations to a high homocysteine concentration. RESULTS: Reference ranges for serum total homocysteine concentration increased with age; these ranges were 4.3 to 9.9 micromol/L for male participants and 3.3 to 7.2 micromol/L for female participants 12 to 19 years of age and from 5.9 to 15.3 micromol/L for men and 4.9 to 11.6 micromol/L for women 60 years of age or older. A high homocysteine concentration was defined as at least 11.4 micromol/L for male participants and at least 10.4 micromol/L for female participants. Approximately two thirds of the cases of high homocysteine concentrations were associated with low vitamin concentrations. CONCLUSIONS: Upper reference limits for the serum total homocysteine concentration increased with age and were higher for male participants than for female participants at all ages. In most cases, high homocysteine concentrations were associated with low serum vitamin concentrations.

Adolescent↗
PubMed1999

Nonfasting plasma total homocysteine levels and stroke incidence in elderly persons: the Framingham Study.

BACKGROUND: Total homocysteine levels are associated with arteriosclerotic outcomes. OBJECTIVE: To determine whether total homocysteine levels predict incident stroke in elderly persons. DESIGN: Prospective population-based cohort study with 9.9 years of follow-up. SETTING: Framingham, Massachusetts. PATIENTS: 1947 Framingham Study participants (1158 women and 789 men; mean age +/- SD, 70 +/- 7 years). MEASUREMENTS: Baseline total homocysteine levels and 9.9-year stroke incidence. RESULTS: The quartiles of nonfasting total homocysteine levels were as follows: quartile 1, 4.13 to 9.25 micromol/L; quartile 2, 9.26 to 11.43 micromol/L; quartile 3, 11.44 to 14.23 micromol/L; quartile 4, 14.24 to 219.84 micromol/L. During follow-up, 165 incident strokes occurred. In proportional hazards models adjusted for age, sex, systolic blood pressure, diabetes, smoking, and history of atrial fibrillation and coronary heart disease, relative risk (RR) estimates comparing quartile 1 with the other three quartiles were as follows: quartile 2 compared with quartile 1--RR, 1.32 (95% CI, 0.81 to 2.14); quartile 3 compared with quartile 1--RR, 1.44 (CI, 0.89 to 2.34); quartile 4 compared with quartile 1--RR, 1.82 (CI, 1.14 to 2.91). The linear trend across the quartiles was significant (P < 0.001). CONCLUSION: Nonfasting total homocysteine levels are an independent risk factor for incident stroke in elderly persons.

Aged↗
PubMed1999

Determinants of fasting plasma total homocysteine levels among chronic stable renal transplant recipients.

BACKGROUND: Although several studies have demonstrated an unadjusted association between folate status and fasting plasma total homocysteine (tHcy) levels among renal transplant recipients, no data confirming the strength or independence of this association have been reported. METHODS: We determined fasting plasma folate, B12, and pyridoxal 5'-phosphate (active vitamin B6) levels, along with other potential determinants of plasma tHcy levels (i.e., age, sex, creatinine levels, and Cockcroft-Gault estimated creatinine clearance, current immunosuppressive regimen, and history of clinical cardiovascular disease), among 86 renal transplant recipients. The recipients were > or =6 months after transplantation, lived in the Providence, Rhode Island metropolitan area, and were examined between February and June 1998. RESULTS: Stepwise general linear modeling with analysis of covariance revealed that only creatinine level, age, and vitamin status were independent regressors (i.e., P<0.100) of tHcy levels. Moreover, creatinine level alone determined most of the variability in tHcy levels (i.e., R2) accounted for by these independent variables (R2=0.416 for creatinine level alone; total R2=0.575). In contrast, the R2 for folate alone was only 0.046, and even for all three B vitamins combined, the R2 was just 0.088. CONCLUSIONS: We conclude that renal function is the overriding independent determinant of fasting tHcy levels among stable renal transplant recipients. In comparison to renal function, vitamin status has a relatively marginal influence on tHcy levels and cyclosporine use has essentially none at all.

Adult↗
PubMed1999

Nonfasting plasma total homocysteine levels and all-cause and cardiovascular disease mortality in elderly Framingham men and women.

BACKGROUND: Elevated fasting total homocysteine (tHcy) levels were recently shown to confer an independent risk for all-cause and cardiovascular disease (CVD) mortality among selected Norwegian patients with confirmed coronary heart disease. We examined whether elevated fasting plasma tHcy levels were predictive of all-cause and CVD mortality in a large, population-based sample of elderly US women and men. METHODS: Nonfasting plasma tHcy levels were determined in 1933 elderly participants (mean age, 70 +/- 7 years; 58.9% women) from the original Framingham Study cohort, examined between 1979 and 1982, with follow-up through 1992. Unadjusted and adjusted (ie, for age, sex, diabetes, smoking, systolic blood pressure, total and high-density lipoprotein cholesterol, and creatinine) relative risk estimates (with 95% confidence intervals [CIs]) for total and CVD mortality were generated by proportional hazards modeling, with tHcy levels (quartiles) as the independent variable. RESULTS: There were 653 total deaths and 244 CVD deaths during a median follow-up of 10.0 years. Proportional hazards modeling revealed that tHcy levels of 14.26 micromol/L or greater (the upper quartile), vs less than 14.26 micromol/L (the lower three quartiles), were associated with relative risk estimates of 2.18 (95% CI, 1.86-2.56) and 2.17 (95% CI, 1.68-2.82) for all-cause and CVD mortality, respectively. The relative risk estimates after adjustment for age, sex, systolic blood pressure, diabetes, smoking, and total and high-density lipoprotein cholesterol levels attenuated these associations, but they remained significant: 1.54 (95% CI, 1.31-1.82) for all-cause mortality; 1.52 (95% CI, 1.16-1.98) for CVD mortality. CONCLUSION: Elevated nonfasting plasma tHcy levels are independently associated with increased rates of all-cause and CVD mortality in the elderly.

Aged↗
PubMed1999

The effect of folic acid fortification on plasma folate and total homocysteine concentrations.

BACKGROUND: In 1996, the Food and Drug Administration issued a regulation requiring all enriched grain products to be fortified with folic acid to reduce the risk of neural-tube defects in newborns. Fortification (140 microg per 100 g) began in 1996, and the process was essentially complete by mid-1997. METHODS: To assess the effect of folic acid fortification on folate status, we measured plasma folate and total homocysteine concentrations (a sensitive marker of folate status) using blood samples from the fifth examination (January 1991 to December 1994) of the Framingham Offspring Study cohort for baseline values and the sixth examination (January 1995 to August 1998) for follow-up values. We divided the cohort into two groups on the basis of the date of their follow-up examination: the study group consisted of 350 subjects who were seen after fortification (September 1997 to March 1998), and the control group consisted of 756 subjects who were seen before fortification (January 1995 to September 1996). RESULTS: Among the subjects in the study group who did not use vitamin supplements, the mean folate concentrations increased from 4.6 to 10.0 ng per milliliter (11 to 23 nmol per liter) (P<0.001) from the baseline visit to the follow-up visit, and the prevalence of low folate concentrations (<3 ng per milliliter [7 nmol per liter]) decreased from 22.0 to 1.7 percent (P< 0.001). The mean total homocysteine concentration decreased from 10.1 to 9.4 micromol per liter during this period (P<0.001), and the prevalence of high homocysteine concentrations (>13 micromol per liter) decreased from 18.7 to 9.8 percent (P<0.001). In the control group, there were no statistically significant changes in concentrations of folate or homocysteine. CONCLUSIONS: The fortification of enriched grain products with folic acid was associated with a substantial improvement in folate status in a population of middle-aged and older adults.

Adult↗
PubMed1999

Prevalence of mild fasting hyperhomocysteinemia in renal transplant versus coronary artery disease patients after fortification of cereal grain flour with folic acid.

Cereal grain flour products fortified with 140 microg folic acid per 100 g flour became widely available in southeast New England by July 1997. We hypothesized that improved folate status secondary to this fortification policy would have a much more limited impact on the prevalence of mild fasting hyperhomocysteinemia in renal transplant versus coronary artery disease patients. Between October 1997 and October 1998, fasting plasma total homocysteine (tHcy), folate and vitamin B12 levels were determined in a total of 86 renal transplant patients with stable allograft function, and 175 coronary artery disease patients whose serum creatinine was (1.4 mg/dl). All subjects lived in the Providence, RI, metropolitan area, and were either non-users of any supplements containing folic acid, vitamins B6 or B12, or had refrained from using such supplements for > or = 6 weeks. Geometric mean fasting tHcy levels were 88.0% higher (15.6 vs. 8.3 micromol/l; P < 0.001), and the prevalence of fasting tHcy levels > or = 12 microM (69.8% vs. 10.9%, P < 0.001) was markedly increased in the renal transplant patients, despite a much younger mean age and a relative preponderance of women. In the era of folic acid fortified flour, hyperhomocysteinemia is much more common in stable renal transplant versus coronary artery disease patients. As a result, renal transplant patients are a preferable high risk target population for controlled trials evaluating the tenable hypothesis that lowering total homocysteine levels will reduce cardiovascular disease outcomes.

Coronary Disease↗
PubMed1999

The potential preventive effects of vitamins for cataract and age-related macular degeneration.

Age-related cataract and age-related macular degeneration (AMD) are important public health problems. Approximately 50% of the 30 to 50 million cases of blindness worldwide result from unoperated cataract. In the US and other developed countries AMD is the leading cause of blindness, but age-related cataract remains the leading cause of visual disability. Age-related cataract and AMD represent an enormous economic burden. In the United States more than 1.3 million cataract extractions are performed annually at a cost of approximately $3.5 billion. Much of the experimental research on the etiology of cataract and AMD has focused on the role of nutritional antioxidants (vitamin C, vitamin E, and carotenoids). Evidence from epidemiologic studies support a role for nutritional antioxidants in delaying the onset of these age-related vision disorders. Although it is not yet possible to conclude that antioxidant nutrients have a role in prevention of cataract or AMD, a summary of the epidemiologic evidence suggests that it is prudent to consume diets high in vitamins C and E and carotenoids, particularly the xanthophylls, as insurance against the development of cataract and AMD.

Antioxidants↗
PubMed1999

Serum total homocysteine concentrations in adolescent and adult Americans: results from the third National Health and Nutrition Examination Survey.

BACKGROUND: The elevation of circulating total homocysteine concentrations in a fasting state is associated with an increased risk of occlusive vascular disease. OBJECTIVE: The primary goals of this study were to describe the distribution of serum total homocysteine concentrations in the United States and to test for differences in homocysteine concentrations among sex, age, and race-ethnicity categories. DESIGN: Using surplus sera from phase 2 of the third National Health and Nutrition Examination Survey, we measured serum total homocysteine concentrations for a nationally representative sample of 3766 males and 4819 females aged > or = 12 y. RESULTS: Age-adjusted geometric mean total homocysteine concentrations were 9.6 and 7.9 mmol/L in non-Hispanic white males and females, 9.8 and 8.2 mmol/L in non-Hispanic black males and females, and 9.4 and 7.4 mmol/L in Mexican American males and females, respectively. Age-adjusted geometric mean total homocysteine concentrations were significantly lower in females than in males in each race-ethnicity group (P < 0.01) and were significantly lower in Mexican American females than in non-Hispanic white and non-Hispanic black females (P < 0.01). There was a significant age-sex interaction (P < 0.01), reflecting the fact that homocysteine concentrations in females tended to diverge from those in males at younger ages and converge with those in males at older ages. CONCLUSIONS: The first data on homocysteine concentrations in a nationally representative sample of Americans confirm the age and sex differences reported previously in nonrepresentative samples. These data also indicate that differences between Mexican American and non-Hispanic females may influence circulating homocysteine concentrations.

Adolescent↗
PubMed1999

Enhanced reduction of fasting total homocysteine levels with supraphysiological versus standard multivitamin dose folic acid supplementation in renal transplant recipients.

The mild fasting hyperhomocysteinemia commonly observed in chronic (ie, >/=6 months posttransplantation) renal transplant recipients (RTRs) can be effectively treated with combined B-vitamin supplementation featuring supraphysiological doses of folic acid. There are no controlled data evaluating the comparative efficacy of supraphysiological versus standard multivitamin dose folic acid supplementation in reducing fasting total homocysteine (tHcy) levels among RTRs. We block-randomized 60 chronic, stable RTRs on the basis of their screening fasting tHcy level to 3 groups of 20 subjects treated for 12 weeks with folic acid at either 2.4 (group 1), 0.4 (ie, standard multivitamin dose) (group 2), or 0.0 (group 3) mg/d. All 60 study participants also received 50 mg/d vitamin B(6) and 0.4 mg/d vitamin B(12). The mean percent reductions (+/-SEM) in fasting tHcy were as follows: group 1, 32.3+/-2.4%; group 2, 23.4+/-2.3%; and group 3, 19.1+/-2.3%. ANCOVA accounting for the pretreatment matching and adjusted for pretreatment levels of fasting tHcy, folate, and albumin; change in creatinine during the study; and cyclosporine A use revealed significant overall group differences (P=0.005) and significant differences between groups 1 and 2 (P=0. 038) and groups 1 and 3 (P=0.001), but not between groups 2 and 3 (P=0.153). Moreover, a chi(2) analysis of participants with pretreatment tHcy levels >/=15 micromol/L (n=29) indicated that a significantly greater proportion of those in group 1 achieved posttreatment levels <12 micromol/L: group 1, 5 of 10 (50%); group 2, 1 of 11 (9%); and group 3, 0 of 8 (0%) (P=0.016; test of trend P=0. 007). We conclude that a supraphysiological dose of folic acid is superior to standard multivitamin dosing for the reduction of fasting tHcy levels in chronic RTRs.

Adult↗
PubMed1999

Cystatin C as a determinant of fasting plasma total homocysteine levels in coronary artery disease patients with normal serum creatinine.

Serum creatinine, a surrogate for both renal function and homocysteine generation, is a determinant of fasting plasma total homocysteine levels in coronary artery disease (CAD) patients. We hypothesized that among stable-CAD patients with normal creatinine levels (ie, </=1.4 mg/dL), serum cystatin C, a more sensitive indicator of glomerular filtration rate, would better predict fasting total homocysteine levels in comparison with serum creatinine. Fasting plasma total homocysteine, folate, vitamin B(12), and pyridoxal 5'-phosphate levels, along with serum cystatin C, creatinine, and albumin levels, were determined in 164 consecutive stable-CAD patients (mean+/-SD age, 61+/-9 years; 78.7% men) whose serum creatinine level was </=1.4 mg/dL. All subjects were examined at least 3 to 4 months after the widespread availability of cereal grain flour products fortified with folic acid. General linear modeling with ANCOVA revealed that serum cystatin C (P<0.001), B(12) (P<0.001), age (P=0.002), albumin (P=0.008), and sex (P=0.024) were independent determinants of fasting total homocysteine levels. Cystatin C alone determined over half of the variability (ie, R(2)) in total homocysteine levels accounted for by these 5 independent regressors. In contrast, creatinine, folate, and pyridoxal 5'-phosphate were not independently predictive of fasting total homocysteine levels (P>0.2). Consistent with the impact of folic acid fortification of cereal grain flour in the general population, only 1 of the CAD subjects (0.6%) had a plasma folate level <3 ng/mL. We conclude that serum cystatin C levels may reflect subtle decreases in renal function that independently predict fasting total homocysteine levels among stable-CAD patients with normal serum creatinine.

Adult↗
PubMed1999

Serum cystatin C as a determinant of fasting total homocysteine levels in renal transplant recipients with a normal serum creatinine.

Serum creatinine, a surrogate for both renal function and homocysteine generation, is an important determinant of fasting plasma total homocysteine levels in stable renal transplant recipients. In this study, it is hypothesized that among stable renal transplant recipients with normal creatinine levels (i.e., < or = 1.5 mg/dl), serum cystatin C, a more sensitive indicator of GFR, would better predict fasting total homocysteine levels compared with serum creatinine. Fasting plasma total homocysteine, folate, vitamin B12, and pyridoxal 5'-phosphate levels, along with serum cystatin C, creatinine, and albumin levels, were determined in 28 consecutive renal transplant recipients (mean age 47 +/- 14 yr; 60.7% men) with stable allograft function, whose serum creatinine was < or = 1.5 mg/dl. General linear modeling with analysis of covariance revealed that serum cystatin C was independently predictive (partial R = 0.494; P = 0.023) of fasting total homocysteine levels after adjustment for age, gender, vitamin status, albumin, and creatinine levels. In contrast, creatinine levels were not predictive of fasting total homocysteine levels in this model (P = 0.110) or an identical model that excluded cystatin C (P = 0.131). Serum cystatin C levels may reflect subtle decreases in renal function that independently predict fasting total homocysteine levels among stable renal transplant recipients with a normal serum creatinine.

Adult↗
PubMed1998

Dietary determinants of iron stores in a free-living elderly population: The Framingham Heart Study.

Epidemiologic studies have found a relation between body iron stores and risk of chronic disease. Iron-absorption studies from single meals have shown that many dietary factors can influence nonheme-iron bioavailability. However, little is known about the association of these dietary factors with iron stores in free-living elderly populations. To address this question, we investigated the consumption of various dietary components and iron stores in an elderly sample of The Framingham Heart Study participants. Serum ferritin was used as a measure of body iron stores in 634 free-living elderly (67-93 y of age), and dietary intake during the previous year was assessed by a food-frequency questionnaire. The relation between serum ferritin and various dietary factors was assessed by multiple regression analysis. Subjects whose ferritin concentrations might be pathologically elevated because of infection, inflammation, liver disease, or genetic hemochromatosis were excluded from the analysis. After we controlled for sex, age, body mass index, total energy intake, smoking, and use of aspirin and other medications known to affect blood loss, we found five significant dietary factors associated with iron stores. Heme iron, supplemental iron, dietary vitamin C, and alcohol were positively associated with serum ferritin, whereas coffee intake had a negative association. As expected, sex was a strong predictor of serum ferritin-women having significantly lower mean concentrations than men. However, age was not related to serum ferritin in our elderly population. Our results suggest that in typical Western-style diets, a small number of dietary factors probably modulate the bioavailability of dietary iron and influence the accumulation of iron stores.

Adult↗
PubMed1997

Treatment of hyperhomocysteinemia in renal transplant recipients. A randomized, placebo-controlled trial.

BACKGROUND: Stable renal transplant recipients have an excess prevalence of hyperhomocysteinemia, which is a risk factor for arteriosclerosis. OBJECTIVE: To determine the effect of treatment with 1) vitamin B6 or 2) folic acid plus vitamin B12 on fasting and post-methionine-loading plasma total homocysteine levels in renal transplant recipients. DESIGN: Block-randomized, placebo-controlled, 2 x 2 factorial study. SETTING: University-affiliated transplantation program. PATIENTS: 29 clinically stable renal transplant recipients. INTERVENTION: Patients were randomly assigned to one of four regimens: placebo (n = 8); vitamin B6, 50 mg/d (n = 7); folic acid, 5 mg/d, and vitamin B12, 0.4 mg/d (n = 7); or vitamin B6, 50 mg/d, folic acid, 5 mg/d, and vitamin B12, 0.4 mg/d (n = 7). MEASUREMENTS: Fasting and 2-hour post-methionine-loading plasma total homocysteine levels. RESULTS: Vitamin B6 treatment resulted in a 22.1% reduction in geometric-mean post-methionine-loading increases in plasma total homocysteine levels (P = 0.042), and folic acid plus vitamin B12 treatment caused a 26.2% reduction in geometric-mean fasting plasma total homocysteine levels (P = 0.027). These results occurred after adjustment for age; sex; and pretreatment levels of total homocysteine, B vitamins, and creatinine. CONCLUSIONS: Vitamin B6 should be added to the combination of folic acid and vitamin B12 for effective reduction of both post-methionine-loading and fasting plasma total homocysteine levels in renal transplant recipients.

Drug Therapy, Combination↗
PubMed1997

Nutrition Screening Initiative Checklist may be a better awareness/educational tool than a screening one.

OBJECTIVE: To evaluate the Nutrition Screening Initiative (NSI) checklist as a screening and an awareness/educational tool in an elderly population. DESIGN: Epidemiologic follow-up study. Information similar to the questions of the NSI checklist was collected by the Nutrition Status Survey of Boston elders between 1981 and 1984. Vital status of volunteers was obtained during 8 to 12 years of follow-up. SUBJECTS/SETTING: Community-dwelling men (n = 200) and women (n = 381) aged 60 years and older who participated in the survey. STATISTICAL ANALYSES PERFORMED: Multivariate analysis was used to assess the association between mortality and each of the NSI-similar questions and the cumulative score, which is the sum of the values assigned to each question. Attributable risk percent, a measure of association, was calculated to measure the percentage of deaths that could potentially be prevented if the risk factors or their consequences were eliminated. RESULTS: Eating meals alone, problems biting or chewing, difficulties with shopping or cooking, and taking more than three medications per day were positively associated with mortality (P < .05). The cumulative score, although significant, was a weaker predictor of mortality. Attributable risk percent of mortality was 19.9% and 51.2% for men and women, respectively. APPLICATIONS/CONCLUSIONS: Some but not all of the individual questions of the NSI checklist equivalent were significantly associated with mortality and identify specific problems that may have a long-term negative effect yet may be missed if the cumulative score were the sole criterion for screening people. The attributable risk percent suggests that the checklist may be best used as an awareness/educational tool as intended originally and could have an important public health effect on early death of community-dwelling elderly people.

Aged↗
PubMed1997

Vitamin C in human and guinea pig aqueous, lens and plasma in relation to intake.

PURPOSE: Given the recent correlation between nutrition and risk for eye disease, there is keen interest in a possible correlation between nutrient intake and eye-tissue nutrient levels. In this work, the objective was (1) to determine, for the first time, the relation between dietary intake of vitamin C and eye tissue levels of the vitamin in free-living humans, (2) to determine the relation between levels of the vitamin in plasma, lens and aqueous, and (3) to compare this information to data gathered for a carefully reared group of guinea pigs that were fed different levels of vitamin C. METHODS: Two hundred sixty-five cataract patients (mean age = 72 years) from a clinical practice were recruited for this study. One hundred thirty-two patients provided the dietary intake data via a food frequency questionnaire, which we used for this work. Plasma, aqueous humor, and lens samples were obtained at the time of lentectomy and preserved for vitamin C analysis. Comparable samples were obtained from male Hartley white guinea pigs that were fed known amounts of vitamin C. Linear and log10-linear statistical models were also used to characterize the relation between vitamin C intake and human ocular tissue levels of the vitamin and to examine potential confounding and the effect of modification by age and sex. RESULTS: In humans, plasma and aqueous vitamin C concentrations were related to intake in a log-linear fashion, with slopes of 0.03 mM plasma vitamin C/log10-mg daily vitamin C intake and 0.41 mM aqueous vitamin C/log10-mg daily vitamin C intake. The best fit of vitamin C levels in lens and diet predicts a linear relationship with a sex-adjusted slope of 0.00094 mM lens vitamin C/mg daily vitamin C intake, although a log-linear relation can also be modeled. In guinea pigs, diet was related to eye tissue and plasma levels of the vitamin by a log10 linear relationship in all cases. Vitamin C in human lens was linearly related to plasma and aqueous vitamin C with slopes of 8.8 and 0.23, respectively. Vitamin C in aqueous was related to plasma in a log10-linear fashion with a slope of 1.6 mM aqueous vitamin C/log10 mM plasma vitamin C. In guinea pigs, vitamin C in plasma was related to aqueous and lens vitamin C by log10-linear relationships, whereas lens and aqueous vitamin C were clearly linearly related. CONCLUSIONS: Plasma and aqueous appear to be saturated in humans with intakes of < 250 mg vitamin C/day. However, a saturating relationship between lens vitamin C and dietary intake in humans was not indicated in this study, although such a relationship is seen in guinea pigs. Intertissue relations between vitamin C levels in humans and guinea pigs are similar for some but not all relations.

Adult↗