[Polymedication in institutionalized elderly and its effect on vitamin B12, folate, and homocysteine levels]

AIM

To determine drug consumption in institutionalized elderly living in the Region of Madrid (Spain) and to assess the relationship between drug intake and biochemical parameters for vitamin B12 (Cobalamin and Holotranscobalamin), serum folate (SF) and homocysteine (Hcy).

METHODS

167 subjects (32% men), mean age 83 ± 7 years, were classified according to biochemical parameter levels (in or out of reference range) and drugs were classified according to ATC system. The relationship between drug intake and biochemical levels was studied by means of the Fisher exact test.

RESULTS

The daily mean drug intake was 5. Psicoleptic and antiacid drugs were the most consumed (both 53%). Cobalamin (median 158.2 pg/mL; 10.7% of individuals), SF (5.3 ng/mL; 52.1%) and holotranscobalamin (11.76 pmoL/L; 7.8%) deficiencies were observed. Hyperhomocysteinaemia (19.4 μmoL/L) was present in 65% of population. Antiaenemic drug intake normalized cobalamin, urologic drug and corticosteroids SF and psicoanaleptics holotranscobalamin levels. Drugs against pulmonar obstruction increased Hcy concentration (all p < 0.05).

CONCLUSION

There is a high prevalence of SF deficiency and hyperhomocysteinaemia in the studied population. The elevated number of drugs taken simultaneously by each subject makes it difficult to analyze which drugs are responsible for those alterations.

Micronutrients in pregnancy: current knowledge and unresolved questions

Micronutrient status is increasingly recognized to play an important role in the health and well-being of pregnant women and in the development and long-term health of the offspring. On 26th - 28th February 2009, The Child Health Foundation invited leading experts in this area to a scientific workshop at Obergurgl, Austria to review and critically discuss current knowledge, to identify issues that may need to be addressed in future recommendations, and to highlight priorities and opportunities for future research. This report summarizes updated key conclusions of the workshop with regards to micronutrients' intake and physiological role related to mother, placenta and fetus, as well as relevance for adverse pregnancy and long-term outcomes.

[6S]-5-methyltetrahydrofolate increases plasma folate more effectively than folic acid in women with the homozygous or wild-type 677C-->T polymorphism of methylenetetrahydrofolate reductase

BACKGROUND AND PURPOSE

5,10-Methylenetetrahydrofolate reductase (MTHFR) is responsible for the synthesis of 5-methyltetrahydrofolate (5-MTHF). The 677C-->T mutation of MTHFR reduces the activity of this enzyme. The aim of this study was, first, to compare pharmacokinetic parameters of [6S]-5-MTHF and folic acid (FA) in women with the homozygous (TT) and wild-type (CC) 677C-->T mutation, and second, to explore genotype differences. The metabolism of [6S]-5-MTHF and FA was evaluated by measuring plasma folate derivatives.

EXPERIMENTAL APPROACH

Healthy females (TT, n= 16; CC, n= 8) received a single oral dose of FA (400 microg) and [6S]-5-MTHF (416 microg) in a randomized crossover design. Plasma folate was measured up to 8 h after supplementation. Concentration-time-profile [area under the curve of the plasma folate concentration vs. time (AUC)], maximum concentration (C(max)) and time-to-reach-maximum (t(max)) were calculated.

KEY RESULTS

AUC and C(max) were significantly higher, and t(max) significantly shorter for [6S]-5-MTHF compared with FA in both genotypes. A significant difference between the genotypes was observed for t(max) after FA only (P < 0.05). Plasma folate consisted essentially of 5-MTHF irrespective of the folate form given. Unmetabolized FA in plasma occurs regularly following FA supplementation, but rarely with [6S]-5-MTHF.

CONCLUSIONS AND IMPLICATIONS

These data suggest that [6S]-5-MTHF increases plasma folate more effectively than FA irrespective of the 677C-->T mutation of the MTHFR. This natural form of folate could be an alternative to FA supplementation or fortification.

Chronic insulin treatment, but not chronic ACTH administration increases plasma dehydroepiandrosterone sulfate levels in adolescent male rats

The chronic effect of daily i. m. administration of ACTH (1 U/kg bodyweight (BW), group A) and of insulin (15/kg BW, group B) on circulating dehydroepiandrosterone sulfate (DHEA-S) and testosterone was investigated in postpubertal male Wistar rats. NaCl-injected animals served as controls (group C). After at least 8 days under the respective hormone or NaCl treatment "basally" circulating testosterone levels were slightly suppressed in insulin- (1.56 +/- 0.86 ng/ml) and markedly reduced (0.54 +/- 0.21 ng/ml) in ACTH-treated rats vs. controls (2.33 +/- 0.69 ng/ml). DHEA-S levels, however, nearly doubled under chronic insulin administration (0.4 +/- 0.18 ng/ml) in comparison to the groups A (0.22 +/- 0.11 ng/ml) and C (0.23 +/- 0.09 ng/ml). Food intake and weight gain were also elevated (vs. groups A and C) as were the basal plasma corticosterone levels (vs. group C) in insulin treated rats. Following an acute ACTH stimulation test (12 U/kg BW i.m.) performed in all three treatment groups, plasma DHEA-S showed a further increase in the animals receiving insulin (0.75 +/- 0.32 ng/ml), whereas no response was detectable in rats from group A (0.27 +/- 0.13 ng/ml) or C (0.24 +/- 0.11 ng/ml). Further measurements of corticosterone or testosterone responses following endocrinological stimulation tests with supraphysiological doses of either ACTH or human chorionic gonadotropin (hCG) indicated that a lowering in the catabolism (metabolic clearance) of corticosteroids or androgens could not be the cause for the elevated DHEA-S levels seen after daily insulin injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin B6 status, deficiency and its consequences--an overview

BACKGROUND

Vitamin B6 is thought to be a most versatile coenzyme that participates in more than 100 biochemical reactions. It is involved in amino acid and homocysteine metabolism, glucose and lipid metabolism, neurotransmitter production and DNA/RNA synthesis. Vitamin B6 can also be a modulator of gene expression. Nowadays, clinically evident vitamin B6 deficiency is not a common disorder, at least in the general population. Nevertheless, a subclinical, undiagnosed deficiency may be present in some subjects, particularly in the elderly.

OBJECTIVE

This review gives a complete overview over the metabolism and interactions of vitamin B6. Further, we show which complications and deficiency symptoms can occur due to a lack of vitamin B6 and possibilities for public health and supplemental interventions.

METHODS

The database Medline (www.ncvi.nlm.nih.gov) was searched for terms like "vitamin B6", "pyridoxal", "cancer", "homocysteine", etc. For a complete understanding, we included studies with early findings from the forties as well as recent results from 2006. These studies were summarised and compared in different chapters.

RESULTS AND CONCLUSION

In fact, it has been proposed that suboptimal vitamin B6 status is associated with certain diseases that particularly afflict the elderly population: impaired cognitive function, Alzheimer's disease, cardiovascular disease, and different types of cancer. Some of these problems may be related to the elevated homocysteine concentrations associated to vitamin B6 deficiency, but there is also evidence for other mechanisms independent of homocysteine by which a suboptimal vitamin B6 status could increase the risk for these chronic diseases.

Homocystein als kardiovaskulärer Marker und Risikofaktor

In context of cardiovascular secondary prevention the D.A.C.H.-Liga (union of scientists from Germany, Austria, and Switzerland doing research on the topic homocysteine) demands that the homocysteine level should be measured and recommends a substitution of folic acid above a value of 10 micromol/l. Numerous studies have proven the therapy's positive effect. Although a threshold could not be acquired in any study there seems to be an association between the homocysteine level and an increased cardiovascular risk. Homocysteine is not only a marker, but also a reason of cardiovascular mortality and morbidity. Further detailed statements concerning homocysteine therapy can be made after completing of current research.

B-vitamin status and intake in European adolescents. A review of the literature

BACKGROUND

National and international recommendations for the intake of B vitamins in adolescents consist of estimates and extrapolations from adult values. Due to increasing growth and therefore relatively high energy and nutrient requirements adolescents are a vulnerable group from the nutritional point of view. In addition, a deficient intake of several B vitamins is strongly connected with the development of cancer, neural tube defects and cardiovascular diseases.

OBJECTIVE

The aim of this work is to assess dietary intake and status of B vitamins and homocysteine of European adolescents on the basis of published data.

METHODS

The database Medline (www.ncvi.nlm.nih.gov) was searched for terms like "Vitamin B", "homocysteine", "Europe", etc. Studies published between June 1980 and December 2004 were analysed for this review. Results of the intake of B vitamins were compared with the EAR or AI, respectively, as recommended by the U.S. Institute of Medicine. Due to lacking reference values for adolescents results of blood status as well as homocysteine were compared to different thresholds for adults.

RESULTS

Considering the limitations of the comparability between the reviewed studies e.g. by different methodologies, sample size, age groups, the average intake of B vitamins surpassed the EAR and AI. Boys were better supplied with B vitamins than girls. The intake decreased with increasing age in both genders. A possible deficiency of folate was noticed and girls in particular seemed to be more at risk. Clear regional tendencies for the vitamin intake could not be observed. Results of vitamin B6, B12, folate in blood, and homocysteine were levelled in-between the thresholds. Though the great standard deviation of folate increased the probability of a deficient supply in parts of the population.

CONCLUSIONS

European girls seem to be at risk of folate deficiency. Supplements and fortified food were not taken into consideration by most of the published studies which additionally distorts the real intake. Standardized methods of dietary surveys and reference values for B vitamins as well as homocysteine still must be established. Hence, further investigations are of great relevance. folate increased the probability of a deficient supply in parts of the population.

CONCLUSIONS

European girls seem to be at risk of folate deficiency. Supplements and fortified food were not taken into consideration by most of the published studies which additionally distorts the real intake. Standardized methods of dietary surveys and reference values for B vitamins as well as homocysteine still must be established. Hence, further investigations are of great relevance.

Research goals for folate and related B vitamin in Europe

In the past decade, the understanding of folate bioavailability, metabolism and related health issues has increased, but several problems remain, including the difficulty of delivering the available knowledge to the populations at risk. Owing to the low compliance of taking folic acid supplements, for example, among women of child-bearing age who could lower the risk of having a baby with a neural tube defect, food-based strategies aimed at increasing the intake of folate and other B-group vitamins should be a priority for future research. These should include the development of a combined strategy of supplemental folate (possibly with vitamin B(12)), biofortification using engineered plant-derived foods and micro-organisms and food fortification for increasing folate intakes in the general population. Currently, the most effective population-based strategy to reduce NTDs remains folic acid fortification. However, the possible adverse effect of high intakes of folic acid on neurologic functioning among elderly persons with vitamin B(12) deficiency needs urgent investigation. The results of ongoing randomized controlled studies aimed at reducing the prevalence of hyperhomocysteinemia and related morbidity must be available before food-based total population approaches for treatment of hyperhomocysteinemia can be recommended. Further research is required on quantitative assessment of folate intake and bioavailability, along with a more thorough understanding of physiological, biochemical and genetic processes involved in folate absorption and metabolism.

Clinical use and rational management of homocysteine, folic acid, and B vitamins in cardiovascular and thrombotic diseases

About half of all deaths are due to cardiovascular disease and its complications. The economic burden on society and the healthcare system from cardiovascular disability, complications, and treatments is huge and becoming larger in the rapidly aging populations of developed countries. As conventional risk factors fail to account for part of the cases, homocysteine, a "new" risk factor, is being viewed with mounting interest. Homocysteine is a sulfur-containing intermediate product in the normal metabolism of methionine, an essential amino acid. Folic acid, vitamin B(12), and vitamin B(6) deficiency and reduced enzyme activities inhibit the breakdown of homocysteine, thus increasing the intracellular homocysteine concentration. Numerous retrospective and prospective studies have consistently found an independent relationship between mild hyperhomocysteinemia and cardiovascular disease or all-cause mortality. Starting at a plasma homocysteine concentration of approximately 10 micromol/l, the risk increase follows a linear dose-response relationship with no specific threshold level. Hyperhomocysteinemia as an independent risk factor for cardiovascular disease is thought to be responsible for about 10 percent of total risk. Elevated plasma homocysteine levels (> 12 micromol/l; moderate hyperhomocysteinemia) are considered cytotoxic and are found in 5 to 10 percent of the general population and in up to 40 percent of patients with vascular disease. Additional risk factors (smoking, arterial hypertension, diabetes, and hyperlipidemia) may additively or, by interacting with homocysteine, synergistically (and hence overproportionally) increase overall risk. Hyperhomocysteinemia is associated with alterations in vascular morphology, loss of endothelial antithrombotic function, and induction of a procoagulant environment. Most known forms of damage or injury are due to homocysteine-mediated oxidative stresses. Especially when acting as direct or indirect antagonists of cofactors and enzyme activities, numerous agents, drugs, diseases, and life style factors have an impact on homocysteine metabolism. Folic acid deficiency is considered the most common cause of hyperhomocysteinemia. An adequate intake of at least 400 microg of folate per day is difficult to maintain even with a balanced diet, and high-risk groups often find it impossible to meet these folate requirements. Based on the available evidence, there is an increasing call for the diagnosis and treatment of elevated homocysteine levels in high-risk individuals in general and patients with manifest vascular disease in particular. Subjects of both populations should first have a baseline homocysteine assay. Except where manifestations are already present, intervention, if any, should be guided by the severity of hyperhomocysteinemia. Consistent with other working parties and consensus groups, we recommend a target plasma homocysteine level of < 10 micromol/l. Based on various calculation models, reduction of elevated plasma homocysteine concentrations may theoretically prevent up to 25 percent of cardiovascular events. Supplementation is inexpensive, potentially effective, and devoid of adverse effects and, therefore, has an exceptionally favorable benefit/risk ratio. The results of ongoing randomized controlled intervention trials must be available before screening for and treatment of hyperhomocysteinemia can be recommended for the apparently healthy general population.

Alcohol consumption and its relation to cardiovascular risk factors in Germany

OBJECTIVE

To analyse the association of alcohol consumption and blood lipids, haemostatic factors, and homocysteine in German adults by gender and age groups.

DESIGN

Cross-sectional population-based survey.

SETTING

Data from the German National Health Interview and Examination Survey 1998, representative for age, gender, community size, and federal state.

SUBJECTS

From a sample of 7124 Germans between 18 and 79 y old, 2420 women and 2365 men were selected. Only individuals who were not currently receiving medical treatment or did not have disorders related to cardiovascular disease were selected for this study.

RESULTS

Using analyses of variance, mean blood levels of total cholesterol, HDL cholesterol, HDL/total cholesterol ratio, total glycerides, fibrinogen, antithrombin III, and homocysteine adjusted for age, socioeconomic status, East/West Germany residence, body mass index, tobacco use, sports activity, and coffee consumption, if appropriate are presented by alcohol consumption groups (0, >0-10, >10-20, >20-30 and >30 g/day). The HDL/total cholesterol ratio increased with higher alcohol groups up to 10-20 g/day (+15%) for women and >30 g/day (+18%) for men, showing the strongest rise among men aged 55-79 y. Fibrinogen decreased with higher alcohol groups up to 10-20 g/day for women and 20-30 g/day for men. Among women, homocysteine levels showed a U-shaped curve with a minimum of 8.49 mmol/l at 10-20 g alcohol/day (-8%, reference: nondrinking), whereas an inverse association was observed for men.

CONCLUSIONS

Moderate alcohol consumption is associated with favourable levels of several cardiovascular risk factors. The most favourable cardiovascular risk factor profile among women was observed among those drinking 10-20 g alcohol/day. Beneficial effects seem to be more pronounced among older men.

Effect of folic acid supplements on homocysteine concentration in plasma of gestating sows

An experiment comprising 19 German Landrace sows was established to evaluate the effect of folic acid supplements (10 mg/kg concentrate) on homocysteine and folic acid concentration in plasma and serum, respectively, of highly pregnant sows as compared to an unsupplemented control (basal diet contained 0.62 mg folic acid/kg concentrate). Blood samples were taken between day 75 and 110 of gestation for homocysteine analysis and on day 100 of gestation for folic acid determination. Due to the folic acid supplements serum folic acid concentration increased significantly (104 nmol/l in controls and 140 nmol/l in supplemented sows). In contrast, homocysteine concentration in the plasma was not significantly influenced by folic acid supplements (16.6 mumol/l in controls and 15.2 mumol/l in supplemented sows). Further investigations seem to be necessary to clarify the physiology of homocysteine metabolism in swine.

Nutrition and cognitive impairment in the elderly

As the number of older people is growing rapidly worldwide and the fact that elderly people are also apparently living longer, dementia, the most common cause of cognitive impairment is getting to be a greater public health problem. Nutrition plays a role in the ageing process, but there is still a lack of knowledge about nutrition-related risk factors in cognitive impairment. Research in this area has been intensive during the last decade, and results indicate that subclinical deficiency in essential nutrients (antioxidants such as vitamins C, E and beta-carotene, vitamin B(12), vitamin B(6), folate) and nutrition-related disorders, as hypercholesterolaemia, hypertriacylglycerolaemia, hypertension, and diabetes could be some of the nutrition-related risk factors, which can be present for a long time before cognitive impairment becomes evident. Large-scale clinical trials in high-risk populations are needed to determine whether lowering blood homocysteine levels reduces the risk of cognitive impairment and may delay the clinical onset of dementia and perhaps of Alzheimer's disease. A curative treatment of cognitive impairment, especially Alzheimer's disease, is currently impossible. Actual drug therapy, if started early enough, may slow down the progression of the disease. Longitudinal studies are required in order to establish the possible link of nutrient intake--nutritional status with cognitive impairment, and if it is possible, in fact, to inhibit or delay the onset of dementia.

Total plasma homocysteine and related amino acids in end-stage renal disease (ESRD) patients measured by gas chromatography-mass spectrometry--comparison with the Abbott IMx homocysteine assay and the HPLC method

Increased concentrations of homocysteine probably contribute to the high cardiovascular morbidity and mortality in hemodialysed end-stage renal disease (ESRD) patients and are determined by a variety of factors such as age, residual renal function, and vitamin status. Fasting plasma concentrations of total homocysteine, methionine, cysteine, and cystathionine were determined by gas chromatography-mass spectrometry (GC-MS) in 131 ESRD patients receiving daily oral folate (160-320 microg) and vitamin B6 (10-20 mg) supplements. Concentrations of homocysteine determined by GC-MS were compared with those measured by high-performance liquid chromatography (HPLC) and an immunofluorescence method (IMx analyzer) using Passing-Bablok regression analysis. Mean plasma concentration of total homocysteine determined by GC-MS (28.7+/-11.9 micromol/l [mean+/-SD]) was significantly lower than that determined by HPLC (34.0+/-14.5 micromol/l; p<0.001) or IMx (32.4+/-13.9 micromol/l; p<0.001). A close correlation existed between GC-MS and HPLC (r=0.931; y=1.203 x+0.279) and GC-MS and IMx (r=0.896; y=1.105 x+0.766). Linear regression analysis showed positive correlations between plasma concentrations of homocysteine and cysteine (r=0.434; p<0.001) and homocysteine and cystathionine (r=0.187; p=0.032). Plasma concentrations of homocysteine correlated negatively with folate (r=-0.281; p=0.001) and vitamin B12 (r=-0.229; p=0.009). GC-MS proved to be a sensitive and reliable method for the determination of total plasma homocysteine and related amino acids. Despite vitamin supplementation, ESRD patients requiring chronic maintenance hemodialysis, have high plasma concentrations of homocyst(e)ine which seems to be metabolized mainly within the transsulfuration pathway, while remethylation to methionine seems to be disturbed.

Beneficial role for folate in the prevention of colorectal and breast cancer

Folate is involved in the synthesis of nucleotides and amino acid metabolism such as methylation of homocysteine to methionine. Methionine is activated by adenosine triphosphate (ATP) to produce S-adenosylmethionine (SAM), the primary intracellular methyl donor. Thus, folate is essential for the synthesis, methylation, and repair of DNA. With regard to its biochemical function it has been hypothesized that a diminished folate status may contribute to carcinogenesis by alteration of gene expression and increased DNA damage. Animal and human studies support this hypothesis, particularly with respect to colorectal cancer. Epidemiological evidence for the association between folate status and cancer was first observed among ulcerative colitis patients. Several case-control studies demonstrated reduction in colorectal cancer risk with better folate status. Two large, prospective cohort studies support the concept that high folate intake is protective against colon cancer. In contrast to colorectal cancer, the potential association of folate status and risk has been less investigated in breast cancer. Recently, convincing epidemiological data establishing a positive effect of folate status on breast cancer risk were published. This review summarizes the epidemiological evidence for the association between folate status and colorectal and breast cancer risk. In addition, a short overview is given on the discussed mechanism(s) by which folate might be involved in carcinogenesis.

Influence of feeding different vegetables on plasma levels of carotenoids, folate and vitamin C. Effect of disruption of the vegetable matrix

Carotenoids, folate and vitamin C may contribute to the observed beneficial effects of increased vegetable intake. Currently, knowledge on the bioavailability of these compounds from vegetables is limited. We compared the efficacy of different vegetables, at the same level of intake (i.e. 300 g/d), in increasing plasma levels of carotenoids, folate and vitamin C and we investigated if disruption of the vegetable matrix would enhance the bioavailability of these micronutrients. In an incomplete block design, sixty-nine volunteers consumed a control meal without vegetables and three out of four vegetable meals (i.e. broccoli, green peas, whole leaf spinach, chopped spinach; containing between 1.7 and 24.6 mg beta-carotene, 3.8 and 26 mg lutein, 0.22 and 0.60 mg folate and 26 and 93 mg vitamin C) or a meal supplemented with synthetic beta-carotene (33.3 mg). Meals were consumed for 4 d and fasting blood samples were taken at the end of each period. Consumption of the spinach-supplemented meal did not affect plasma levels of beta-carotene, although the beta-carotene content was 10-fold those of broccoli and green peas, which induced significant increases in plasma beta-carotene levels (28 (95% CI 6.4, 55)% and 26 (95% CI 2.6, 54)% respectively). The beta-carotene-supplemented meal increased plasma concentrations of beta-carotene effectively (517 (95% CI 409, 648)%). All vegetable meals increased the plasma concentrations of lutein and vitamin C significantly. Broccoli and green peas were, when expressed per mg carotenoid consumed, also more effective sources of lutein than spinach. A significant increase in plasma folate concentration was found only after consumption of the spinach-supplemented meal, which provided the highest level of folate. Disruption of the spinach matrix increased the plasma responses to both lutein (14 (95% CI 3.7, 25)%) and folate (10 (95% CI 2.2, 18)%), whereas it did not affect the response to beta-carotene. We conclude that the bioavailabilities of beta-carotene and lutein vary substantially among different vegetables and that the bioavailabilities of lutein and folate from spinach can be improved by disruption of the vegetable matrix.

Lowering of homocysteine concentrations in elderly men and women

B-vitamin supplementation has previously been shown to lower the concentration of plasma total homocysteine, a risk factor for cardiovascular disease. Little is known about the homocysteine-lowering effects of low-dose B-vitamins in elderly individuals, who are prone to higher homocysteine levels due to advanced age and a greater frequency of impaired vitamin status. We aimed to identify if and to what extent B-vitamins lower total homocysteine and its subfractions in elderly individuals. Men and women (> or = 60 years) received either B-vitamins (400 micrograms folic acid + 1.65 mg pyridoxine + 3 micrograms cyanocobalamin) or a placebo daily for 4 weeks. Subjects in the vitamin group showed a significant decrease in plasma total homocysteine during the first 2 weeks; thereafter, total homocysteine only slightly decreased further resulting in a geometric mean reduction of -16.3% (95% CI: -11.3% to -21.0%) over the entire treatment period. Free homocysteine decreased as well. However, the observed higher ratio of free/total homocysteine after 4 weeks of supplementation suggest a more pronounced reduction in protein-bound homocysteine. Low-dose B-vitamin supplementation is effective in lowering homocysteine in elderly individuals. Further studies are needed to be able to depict the effect of B-vitamin supplementation on different homocysteine sub-fractions in plasma.

Availability of food folate in humans

The aim of our study was to determine whether the area-under-the-plasma-response-curve method with the positive area (AUC+) as primary analysis variable is suitable to evaluate the availability of food folate in humans. Healthy volunteers (n = 20) received four test meals in a randomized, four-period cross-over design as follows: meal A, 600 g spinach; meal B, 300 g spinach; meal C, 0.4 mg folic acid in water; meal D, folate-free control meal. Blood samples were drawn before administration of the test meals and up to 10 h postprandially. Plasma folate was significantly increased for up to 6 h after uptake of spinach and folic acid (P < 0.007), whereas the response curve after the control meal decreased slightly but significantly (P < 0.007). To calculate the net increase of plasma folate, the values were corrected by the individual predose concentrations. The AUC+ was calculated with these corrected values. The mean AUC+ was highest after consumption of meal A (71.2 +/- 24.0 h x nmol/L) followed by meal C (61.8 +/- 23. 8 h x nmol/L) and meal B (41.4 +/- 19.4 h x nmol/L). The AUC+ after meal B was significantly lower than after the other two meals (P < 0. 05). The results suggest that the AUC method with multiple blood sampling is useful for assessing the availability of food folate in humans.

Effects of folic acid and combinations of folic acid and vitamin B-12 on plasma homocysteine concentrations in healthy, young women

BACKGROUND

Elevated plasma homocysteine concentrations are considered to be a risk factor for vascular disease and fetal malformations such as neural tube defects. Recent studies have shown that plasma homocysteine can be lowered by folic acid in amounts corresponding to 1-2 times the recommended dietary allowance. Preliminary evidence indicates that vitamin B-12 may be beneficial when included in supplements or in a food-fortification regimen together with folic acid.

OBJECTIVE

We aimed to compare the homocysteine-lowering potential of a folic acid supplement with that of 2 supplements containing different doses of vitamin B-12 in addition to folic acid.

DESIGN

Female volunteers of childbearing age (n = 150) received a placebo for 4 wk followed by a 4-wk treatment with either 400 microg folic acid, 400 microg folic acid + 6 microg vitamin B-12, or 400 microg folic acid + 400 microg vitamin B-12.

RESULTS

Significant reductions (P < 0.001) in plasma homocysteine were observed in all groups receiving vitamin treatment. The effect observed with the combination of folic acid + 400 microg vitamin B-12 (total homocysteine, -18%) was significantly larger than that with a supplement containing folic acid alone (total homocysteine, -11%) (P < 0.05). Folic acid in combination with a low vitamin B-12 dose (6 microg) affected homocysteine as well (-15%).

CONCLUSIONS

These results suggest that the addition of vitamin B-12 to folic acid supplements or enriched foods maximizes the reduction of homocysteine and may thus increase the benefits of the proposed measures in the prevention of vascular disease and neural tube defects.

Short-term impact of a lactovegetarian diet on adrenocortical activity and adrenal androgens

The aim of this study was to determine whether definite diet changes affect adrenocortical activity and/or adrenal androgen metabolism. A controlled experimental diet study with four consecutive diet periods (repeated measure design) was carried out in six healthy adult volunteers. Four nearly isoenergetic diets, two normal (N) moderately protein-rich, one protein-rich (P), and one low protein lactovegetarian (L), were fed. At the end of each 5-day diet period a blood sample and two 24-h urine specimens were obtained from each subject. Plasma levels of dehydroepiandrosterone sulfate (DHEAS) were elevated with diet L (6.5 +/- 1.4 vs. 5.3 +/- 1.1 mumol/L; P < 0.05) compared to diet N, whereas other plasma hormones, including cortisol and insulin-like growth factor I did not vary markedly. A marked increase of 60% was seen in the urinary 24-h output of 3 alpha-androstanediol glucuronide with diet P. Urinary 24-h excretion rates for C peptide, free cortisol, DHEAS, and total 17-ketosteroid sulfates were clearly reduced with diet L compared to those with diet N or P. Our results show that a lactovegetarian diet can reduce adrenocortical activity (at least after a short term diet change). In addition, this vegetarian nutrition leads to a particular metabolic situation (elevated plasma DHEAS and reduced urinary DHEAS output) that usually is characteristic of fasting. Peripheral androgen metabolism as reflected by urinary 3 alpha-androstanediol glucuronide appears to be influenced only by high protein intake (diet P). Further research (controlled dietary long term investigation) is required 1) to validate whether the effects of diet on adrenocortical activity represent sustained endocrine changes and 2) to elucidate the underlying mechanism.

Folic acid and Vitamin B6 supplementation and plasma homocysteine concentrations in healthy young women

Elevated plasma homocysteine levels are a risk factor for atherosclerotic disease. Elevated fasting plasma homocysteine concentrations can be reduced by vitamin supplementation with folic acid, vitamin B6 and vitamin B12, but the effect of nutritive amounts of single vitamins on homocysteine plasma levels within the normal range is not known. This study was performed to investigate the effect of folic acid supplementation (400 micrograms/d) on fasting plasma homocysteine levels in healthy young women, in comparison to vitamin B6 (2 mg/d) or a combination of both vitamins. Healthy young women with normal homocysteine levels were supplemented for four weeks either with folic acid, vitamin B6 or the combination. The combination of folic acid and vitamin B6 reduced plasma homocysteine by 17%. Supplementation with folic acid reduced plasma homocysteine levels by 11.5%. The effect of folic acid and vitamin B6 was not significantly different from the effect of folic acid alone. Vitamin B6 had no effect on plasma homocysteine concentrations. Results show that homocysteine levels within the normal range are lowered by low-dose vitamin supplementation including folic acid.

Vitamins B12, B6 and folate as determinants of homocysteine concentration in the healthy population

The metabolism of a substrate is closely linked to that of its cofactor(s). In the case of homocysteine, the vitamins B12, B6 and folic acid are involved in its metabolism, acting as coenzymes. To evaluate the role of these vitamins as determinants of homocysteine concentration in the healthy population, only data from this group should be considered. Studies dealing with vitamin deficiency and the occurrence of elevated homocysteine levels as well as with the treatment of elevated homocysteine levels by supplementing one or more of the vitamins have to be omitted. In the healthy population with "normal" homocysteine levels and a vitamin status currently regarded as adequate, folate seems to play the most important role in determining the blood homocysteine level. This has been derived from supplementation studies as well as from statistical correlation analysis regarding the relationship of the three vitamins to homocysteine. Until now, recommended dietary allowances for folate have been defined on the basis of the absence of clinical signs of deficiency as well as morphological alterations of blood cells indicating an early stage of folate deficiency. However, these recommended dietary allowance values do not seem to be sufficient when looking at homocysteine as a functional parameter of folate status. Due to the important role of folate status as a determinant of homocysteine concentration, it may be necessary to redefine an adequate blood folate level and probably reformulate dietary allowances for this B-vitamin.

[Micronutrients in pregnancy]

During pregnancy the demands for energy and far more for micronutrients are increased. Discrepancies between the intake of certain micronutrients such as iodine, iron and folic acid and the recommended quantities during pregnancy are to be expected. Consequences of an unsufficient supply of these micronutrients might be goitre, anemia and with special reference to folic acid the occurrence of neural tube defects. Deficiency can be prevented by careful choice of food. Supplementation with special micronutrients is necessary before respective during pregnancy however for example to prevent neural tube defects by periconceptional supplementation with folic acid.

Causes and consequences of hyperhomocyst(e)inemia

Increased plasma concentrations of the sulfur-containing amino acid homocyst(e)ine are designated as hyperhomocyst(e)inemia. Various definitions have been used to derive cut-off levels for hyperhomocyst(e)inemia. The classification by Kang is now generally used distinguishing moderate, intermediate and severe hyperhomocyst(e)inemia. A variety of causes are discussed for the etiology of the disease which can be grouped into genetic and nongenetic factors. Severe hyperhomocyst(e)inemia is accompanied by homocystinuria and several other symptoms occurring early in life. Treatment is mandatory for normal development and prevention of premature atherosclerosis. Even less severe forms of hyperhomocyst(e)inemia imply a substantially elevated risk for vascular diseases. Etiology and severity of defect(s) leading to hyperhomocyst(e)inemia are the basis for treatment. In genetic defects, supplementation with the cofactor(s) of the affected enzyme is used to enhance enzyme activity. Alternative routes in the pathway may also be enhanced. Nongenetic hyperhomocyst(e)inemia often requires correction of suboptimal vitamin concentrations. Nutritive doses of the vitamins may be sufficient for treatment of less severe forms as well as for prevention of hyperhomocyst(e)inemia.

The role of homocysteine, folate and other B-vitamins in the development of atherosclerosis

Recently, elevated homocysteine blood concentrations have been identified as an independent risk factor for the development of atherosclerotic lesions. The amino acid homocysteine is metabolized in the human body involving the vitamins folic acid, B12 and B6 as essential cofactors and coenzymes, respectively. There is an inverse relationship between the status of the relevant B-vitamins and the homocysteine blood concentration. Supplementation of these vitamins results in a significant reduction of the homocysteine level. Nutritive amounts seem to be sufficient to obtain this reduction, even in the case of elevated homocysteine levels.

Bioavailability of oral vitamins, minerals, and trace elements in perspective

Bioavailability of orally administered vitamins, minerals, and trace elements is subject to a complex set of influences. Still, administrative regulation is necessary on how to quantify it. The most common approach to this problem is to determine the fraction of an oral dose that reaches the systemic circulation. For micronutrients, however, this approach has to consider the physiological plasma concentration as well as the mechanisms that regulate intestinal absorption and distribution of micronutrients between functional and storage compartments in response to the demand. The rate of exchange between these compartments has an impact on the delivery of such compounds into the plasma compartment as well as on the plasma clearance. Monitoring the area under the plasma concentration time curve after oral administration is an inadequate tool for bioavailability determination if there are substantial impacts of homeostatic mechanisms on the plasma concentration of a micronutrient. In nutritional science the term "bioavailability" encompasses the sum of impacts that may reduce or foster the metabolic utilisation of a nutrient. Bioavailability in this sense can be quantified by the rate by which deficiency symptoms are cured or by the weight gain during growth. both of these endpoints, again, are influenced by homeostatic mechanisms. To exemplify the scope of impacts on parameters that are commonly used to quantify the bioavailability of oral micronutrient preparations the basic traits of homeostatic regulation are summarised and compared for iron, magnesium, vitamin A, folic acid, and vitamin B12. The mechanisms that adapt absorption, distribution, and excretion of these five micronutrients to the demand differ to such an extent that no common approach can be derived to consider these impacts in bioavailability determination. In consequence, therefore, we recommend to define and regulate individual strategies for bioavailability testing for each micronutrient with regulated kinetics.

Parasitological and nutritional situation of school children in the Sukaraja district, West Java, Indonesia

A parasitological survey of children aged 8 to 10 years from ten schools located in the rural district Sukaraja, West Java, Indonesia was conducted in December 1995. A total of 348 fecal samples were examined by using modified Kato-Katz thick smear techniques, 365 blood samples for the measurement of hemoglobin concentration, and anthropometric data were obtained from 404 participants. Four nematode (hookworm taken as one species), two cestode and nine protozoan species were detected, but no trematode infection was observed. Among helminths, soil-transmitted nematode infections were predominant, Trichuris trichiura with a prevalence of 76% being the most common infection, followed by Ascaris lumbricoides (44%). Hookworm and Enterobius vermicularis were found in 9% and 3% of the children examined, respectively. Among protozoa, Blastocystis hominis was by far the most common species, detected in 60% of volunteers cases. For the helminths A. lumbricoides, T. trichiura and hookworm, school to school differences in parasite prevalence and infection intensity were observed; these were probably due to different socioeconomic and sanitary-environmental conditions. Intensity of Ascaris and hookworm infection tended to be highly over-dispersed; 85% of the worms identified were harbored by 15% and 7% of the children, respectively. Nutritional status was characterized by an average anemia rate of 13% and a prevalence of 51% stunting. All nutritional indicators differed significantly from school to school. Intensity of geohelminths infection could not be associated to the observed nutritional indicators. Thus, there must be additional factors contributing to the studied nutritional indicators of the school children which overlay a possible influence of moderate to heavy worm burden.

A moderate increase in daily protein intake causing an enhanced endogenous insulin secretion does not alter circulating levels or urinary excretion of dehydroepiandrosterone sulfate

To study the effect of a moderate increase in insulin secretion produced by an increased daily protein intake on dehydroepiandrosterone sulfate (DHEAS), a balanced randomized crossover trial consisting of three strictly controlled dietary regimens was performed in six healthy male volunteers. The basic diet (B) contained 50 g protein/d; diets P and M (also basic diets) were enriched with either 32 g protein/d (P) or 10 mmol L-methionine/d (M). Methionine was given (as a specific nonprotein source of endogenously derived sulfate) to control for possible confounding effects on DHEAS due to an increased sulfate supply. At the end of each 4-day diet period, blood and 24-hour urine samples were collected. Fasting plasma levels of testosterone, cortisol, insulin-like growth factor-I (IGF-I), and insulin, as well as urinary output of total (hot acid-cleaved) testosterone conjugates and 3alpha-androstanediol glucuronide, did not show significant changes in response to dietary manipulations. Endogenous sulfate availability (as reflected by renal sulfate output per 24 hours) approximately doubled with diets P and M. However, plasma levels (6.3 +/- 1.5, 6.8 +/- 1.8, and 6.9 +/- 2.1 micromol/L for B, P, and M, respectively) and urinary excretion (8.8 +/- 9.8, 9.4 +/- 11.2, 8.0 +/- 8.3 micromol/d) of DHEAS remained unaffected. Considering the clear increments (P < .01) in urinary C-peptide excretion with diet P (20.4 +/- 10.3 nmol/d) versus diets B and M (12.6 +/- 5.1 and 13.2 +/- 3.6 nmol/d), respectively, our results suggest that a moderately strong diet-induced increase in daily insulin secretion does not alter urinary and plasma levels of DHEAS.

Maternal and fetal serum and red blood cell folate and vitamin B12 concentrations in pregnancies affected by neural tube defects

In the present study maternal and fetal serum and red cell folate and vitamin B12 concentrations were determined in NTD affected and in control pregnancies. Fetal serum folate (p < 0.001) and red cell folate (p < 0.001) concentrations were significantly higher than maternal levels in the cases as well as in the controls. Maternal and fetal vitamin B12 concentrations did not differ significantly in both groups. There were also no significant differences in maternal and fetal vitamin concentrations in the peripheral blood between cases and controls. However, when a subgroup analysis was performed according to the type of NTD we found significant differences in fetal vitamin B12 status between anencephaly and spina bifida cases as well as between anencephaly cases and the controls.

The effects of weekly iron supplementation with folic acid, vitamin A, vitamin C on iron status of Indonesian adolescents

The goal of the study was to determine whether the addition of vitamins A and C and extra folate to the commonly distributed iron-folate supplement administered on a weekly basis would result in improved iron status in anaemic and non-anaemic female adolescents. Subjects (n=84) were selected if their haemoglobin concentration in venous blood was <= 140g/L. Subjects were randomly allocated into 2 groups. One group received 60mg iron, 500m g folic acid, 20 000 IU vitamin A and 60mg vitamin C weekly, while the other group received 60 mg iron and 250m g folic acid weekly for a period of 5 weeks. Before and after treatment, haemoglobin, serum ferritin and body height and weight were determined. All subjects received anthelmintic drugs before supplementation. A complete data set was obtained from 42 young women in the group supplemented with iron, folic acid, vitamin A and vitamin C and from 40 young women in the group supplemented with iron and folic acid. Haemoglobin, mean cell volume and serum ferritin increased significantly in both groups (p<0.05). Among anaemic adolescents, the rise in haemoglobin concentration in the multisupplement group was higher than that in the iron folate group. The result confirms that weekly supplementation is effective in improving iron status in a short time (5 weeks) and that supplementation with vitamins as well as iron results in an additional improvement in haemoglobin concentration.

Micronutrients during pregnancy: the nutritive situation in Germany

During pregnancy the demands for energy and nutrients are increased. Despite increasing awareness about nutrition in the population of a western country like Germany, there is a discrepancy between actual food intake and recommended quantities of certain nutrients, particularly during pregnancy. There are correlations between deficiencies in micro-nutrients such as iodine, iron and folic acid and the course and outcome of pregnancy. The consequences of an insufficient supply of these micronutrients during pregnancy are described and high-risk-groups for an inadequate supply are defined. Recommendations for nutrition counselling during this period of life are given.

Homocysteine and cardiovascular diseases

Elevated homocysteine blood concentrations have been identified as an independent risk factor for the development of atherosclerotic lesions. The metabolism of the amino acid homocysteine in the human body involves the vitamins folic acid, B-12 and B-6 as essential cofactors and coenzymes, respectively. There is an inverse relationship between the status of the relevant B-vitamins and the homocysteine blood concentration. Supplementation of these vitamins results in a significant reduction of the homocysteine level. However, nutritive amounts seems to be sufficient to obtain this reduction, even in the case of elevated homocysteine levels.

The short-term effect of dietary pectin on plasma levels and renal excretion of dehydroepiandrosterone sulfate

Studies specifically investigating the effects of single dietary components on plasma levels of dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS) are rare. Especially no data is available with regard to specific dietary fibers. Therefore, the impact of pectin (a representative fiber that affects the enterohepatic recirculation of bile acids) was studied in a randomized crossover trial consisting of three diet periods characterized by the same food supply and daily doses of 0 g, 15 g or 30 g pectin. Blood and 24-h-urine samples were collected at the end of each 4-day diet period from 6 healthy male volunteers. Plasma levels of DHEA, cortisol and the major binding protein of DHEAS albumin remained unchanged with the varying pectin supplements. Also, no changes were observed for several urinary analytes including urinary DHEAS. However, effects of pectin intake (30, 15 versus 0 g/d) were seen for plasma DHEAS (9.3 +/- 2.8, 9.2 +/- 2.6, 8.0 +/- 3.1 mumol/L, p < 0.01) and total plasma cholesterol (4.4 +/- 0.7, 4.5 +/- 0.7, 4.7 +/- 0.8 mmol/L, p = 0.1). Obviously, the altered intake of fiber in the form of pectin affects plasma concentrations of DHEAS and cholesterol in an opposite direction. The reason for this is not known but a dietetically induced modulation of the binding properties of plasma albumin for DHEAS appears possible. Our findings suggest that the target tissue-available, not protein-bound fraction of circulating DHEAS (as reflected by the renal DHEAS output) is not necessarily altered when total plasma concentrations of DHEAS vary.

Re-examination of the effect of hCG on plasma levels and renal excretion of dehydroepiandrosterone sulfate in healthy males

To reinvestigate the effect of hCG on circulating and urinary dehydroepiandrosterone sulfate (DHEAS), a hCG stimulation test (5000 IU administered i.m. at 8.30 h on 3 consecutive days) was performed in 6 healthy males (aged 24 to 35 years). Blood specimens and 24-h urine samples were collected immediately before the first and directly after the last hCG administration. Contrary to previous findings in normal men, the present study revealed significant DHEAS responses after testicular stimulation with hCG: plasma DHEAS increased from 7.9 +/- 2.3 to 9.6 +/- 2.2 mumol/L (P < 0.05) and urinary DHEAS from 5.7 +/- 3.6 to 9.3 +/- 5.2 mumol/day (P < 0.05). There was also a marked rise (P < 0.05) in the urinary excretion of total 17-ketosteroid sulfates. Clear increases of unconjugated plasma dehydroepiandrosterone as well as of circulating and renally excreted androstenedione and testosterone definitely confirmed an adequate Leydig cell stimulation. Significant post-hCG changes were additionally observed for plasma and urinary 3 alpha-androstanediol glucuronide (149% and 79% increases, respectively) and for urinary cortisol (21% decrease). Significant correlations were found for the post-hCG percent increases of plasma androstenedione versus plasma DHEAS (r = 0.86) and for the percent increases of plasma testosterone versus urinary DHEAS (r = 0.98), indicating that the extent of gonadal androgen elevations in the circulation of normal men is a determinant of DHEAS increases in blood or urine. These findings provide an explanation for the frequently observed sex differences for DHEAS in adults.(ABSTRACT TRUNCATED AT 250 WORDS)