Low-dose folic acid supplementation decreases plasma homocysteine concentrations: a randomized trial

A comparison of the effect of advice to eat either '5-a-day' fruit and vegetables or folic acid-fortified foods on plasma folate and homocysteine

OBJECTIVE

To assess and compare the effects of natural folate (100 micro g) with those of folic acid from fortified sources (100 micro g/day) on plasma folate and homocysteine.

DESIGN

Randomized controlled trial (parallel groups).

SETTING

Men and women living in South Wales, UK.

SUBJECTS

A total of 135 healthy individuals recruited from the local workforce and blood donor sessions. All subjects possessed the 'wild-type' CC genotype for C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR).

INTERVENTIONS

Subjects underwent one of the following dietary interventions for 4 months: (1) fortified diet-usual diet plus 100 microg/day folic acid from fortified foods; (2) natural folate diet-usual diet plus 100 microg/day folate from natural sources; (3) control-usual diet.

RESULTS

The fortified group increased reported intake of folic acid from fortified foods compared to other groups (P<0.001) achieving an extra 98 microg/day (95% CI 88-108). The natural folate group increased reported intake of natural source folates compared with the other two groups (P<0.001), but achieved a mean increase of only 50 microg/day (95% CI 34-66). Plasma folate increased (P<0.01) by a similar amount in both intervention groups compared to controls (fortified group 2.97, 95% CI 0.8-5.1; natural group 2.76, 95% CI 0.6-4.9. Plasma homocysteine, vitamins B(6) and B(12) were not significantly changed.

CONCLUSIONS

Subjects achieved increases in folate intake using fortified foods more easily than by folate-rich foods, however both sources increased plasma folate by a similar amount. These levels of intake were insufficient to reduce homocysteine concentrations in MTHFR CC homozygotes, but may be more effective in other genotypes.

Folate: a key to optimizing health and reducing disease risk in the elderly

Inadequate folate status is associated with an increased risk for chronic diseases that may have a negative impact on the health of the aging population. Folate, a water-soluble vitamin, includes naturally occurring food folate and synthetic folic acid in supplements and fortified foods. Inadequate folate status may result in hyperhomocysteinemia, a significant risk factor for atherosclerotic vascular disease, changes in DNA that may result in pro-carcinogenic effects and increased risk for cognitive dysfunction. Folate status may be negatively influenced by inadequate intake, genetic polymorphisms and interactions with various drugs. In the US, folic acid is now added to enriched grain products and continues to be included in the majority of ready-to-eat breakfast cereals. Recent data indicate that the folate status in the US population has improved significantly, presumably due to the effects of fortification. Folic acid (not food folate) intake in excess of the Tolerable Upper Intake Level may mask the diagnosis of a vitamin B(12) deficiency, which is more prevalent in the elderly than younger individuals. When folic acid supplements are recommended, a multivitamin that includes vitamin B(12) should also be advised. To safely and effectively increase folate intake in the elderly, naturally occurring folate-rich food sources should be promoted. Folate-rich foods include orange juice, dark green leafy vegetables, asparagus, strawberries and legumes. These foods are also excellent sources of other health-promoting nutrients associated with chronic disease risk reduction.

Folate intake, plasma folate and homocysteine status in a random Finnish population

OBJECTIVE

To assess the folate status of Finnish adults using plasma folate and homocysteine as biomarkers and to evaluate dietary and supplementary folate intakes.

MATERIALS AND METHODS

Plasma folate, vitamin B(12) and total homocysteine (tHcy) were determined in a random sample of 643 subjects aged 25-74 y living in the Helsinki area. The methylenetetrahydrofolate reductase (MTHFR)-genotypes were analyzed from a subsample (n=394). Dietary intake data by 24 h recall and use of vitamin supplements were collected.

RESULTS

Plasma folate was normal (>/=5 nmol/l) in 99% of subjects and optimal (>/=8 nmol/l) in terms of a minimum tHcy in 90%. Mean plasma folate of non-supplement users was 13.7 and 12.9 nmol/l and tHcy 11.3 and 9.2 micro mol/l for men and women, respectively. Elevated tHcy (>14 micro mol/l) was found in 11% of subjects. Homozygote frequency for MTHFR genotype TT was 5.0% and their plasma tHcy was 14.8 micro mol/l compared to the mean of the other subjects, 10.5 micro mol/l, P<0.05. The mean dietary folate intake was 241 micro g/day (29 micro g/MJ of energy) for men and 205 micro g/day (33 micro g/MJ) for women, respectively. The main dietary sources of folate were vegetables 12%, wholemeal ryebread 11%, fruits 10%, and potato 10%. Regular supplement users (n=97) received on average 207 micro g folic acid per day from supplements.

CONCLUSIONS

The folate status of Finnish adults seems to be adequate according to energy adjusted folate intake, plasma folate and homocysteine. The MTHFR homozygote frequency was low compared to other countries. Regular use of supplementary folic acid less than 300 micro g increased plasma folate, but supplemental folic acid over 300 micro g was required to lower tHcy values significantly.

Connective tissue: Vascular and hematological (blood) support

Connective Tissue (CT) is a ubiquitous component of all major tissues and structures of the body (50% of all body protein is CT), including that of the blood, vascular, muscle, tendon, ligament, fascia, bone, joint, IVD's (intervertebral discs) and skin. Because of its ubiquitous nature, CT is an often overlooked component of any essential nutritional program that may address the structure, and/or function of these tissues. The central role of CT in the health of a virtually all cells, tissues, organs, and organ systems, is discussed. General nutritional CT support strategies, as well as specific CT support strategies that focus on blood, vascular, structural system (eg, muscles, tendons, ligaments, fascia, bone, and joints), integument (skin) and inflammatory and immune mediation will be discussed here and will deal with connective tissue dynamics and dysfunction. An overview of the current scientific understanding and possible options for naturally enhancing the structure and function of CT through the application of these concepts will be discussed in this article, with specific attention on the vascular and hematological systems.

The H475Y polymorphism in the glutamate carboxypeptidase II gene increases plasma folate without affecting the risk for neural tube defects in humans

In the diet, folate exists predominantly in the form of polyglutamates. Before absorption, these polyglutamates must be deconjugated to monoglutamates by the enzyme folylpoly-gamma-glutamate carboxypeptidase (FGCP), which is located in the jejunum. Recently, a H475Y polymorphism in the glutamate carboxypeptidase II (GCPII) gene, encoding the FGCP enzyme, was reported to be associated with decreased plasma folate and increased plasma homocysteine (tHcy) levels. Low folate and elevated tHcy levels are risk factors for neural tube defects (NTD). Therefore, we examined whether this polymorphism is associated with NTD risk and plasma folate, erythrocyte folate and plasma tHcy levels in 96 NTD patients, 113 mothers, 97 fathers and 101 controls. This variation was associated with increased plasma folate (P < 0.04) and tended to be associated with decreased plasma tHcy (P < 0.09). It was not associated with erythrocyte folate or the risk for NTD. The H475Y polymorphism in the GCPII gene may increase the deconjugation activity of the FGCP enzyme, resulting in an increased absorption of folate in the body, as reflected by the increased plasma folate and decreased plasma homocysteine concentrations.

Folate content in strawberries (Fragaria x ananassa): effects of cultivar, ripeness, year of harvest, storage, and commercial processing

Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH(3)-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 microg/100 g of dry matter (DM) for cv. Senga Sengana to 644 microg/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degrees C (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries ( approximately 125 microg of folate) supplies approximately 50% of the recommended daily folate intake in various European countries (200-300 microg/day) or 30% of the U.S. recommendation (400 microg/day).

Differential relations between cognition and 15N isotopic content of hair in elderly people with dementia and controls

BACKGROUND

Previous researchers have suggested that a vegetarian diet or one rich in fish may protect against Alzheimer's disease (AD). However, assessing diet is difficult in AD patients. (15)N:(14)N isotopic ratios (delta(15)N) of body proteins can estimate long-term dietary habits in a way that does not depend on memory. delta(15)N is high in people who eat a lot of fish and low in vegetarians.

METHODS

To choose between the vegetarian and fish hypotheses of AD, we compared dietary questionnaire reports and delta(15)N of hair samples from AD patients and controls.

RESULTS

Patients' cognitive scores related directly to reported frequency of eating fish and to hair delta(15)N(AIR), but inversely to reported frequency of eating beans. Homocysteine levels related inversely to hair delta(15)N(AIR) in controls, but not in patients. Dietary questionnaire reports accounted for slightly more variance in delta(15)N(AIR) in patients than controls. Therefore, our questionnaire assessed dietary habits as reliably for individuals with AD as for cognitively unimpaired controls.

CONCLUSIONS

A diet rich in fish may ameliorate AD, possibly by lowering homocysteine, but more vegetarian diets do not. In fact, eating beans correlated with worse cognition in AD patients. Further studies should test if restricting the intake of beans slows the progression of AD.

Betaine supplementation decreases plasma homocysteine concentrations but does not affect body weight, body composition, or resting energy expenditure in human subjects

BACKGROUND

Betaine (trimethylglycine) is found in several tissues in humans. It is involved in homocysteine metabolism as an alternative methyl donor and is used in the treatment of homocystinuria in humans. In pigs, betaine decreases the amount of adipose tissue.

OBJECTIVE

The aim of the study was to examine the effect of betaine supplementation on body weight, body composition, plasma homocysteine concentrations, blood pressure, and serum total and lipoprotein lipids.

DESIGN

Forty-two obese, white subjects (14 men, 28 women) treated with a hypoenergetic diet were randomly assigned to a betaine-supplemented group (6 g/d) or a control group given placebo for 12 wk. The intervention period was preceded by a 4-wk run-in period with a euenergetic diet.

RESULTS

Body weight, resting energy expenditure, and fat mass decreased significantly in both groups with no significant difference between the groups. Plasma homocysteine concentrations decreased in the betaine group ( +/- SD: 8.76 +/- 1.63 micro mol/L at 4 wk, 7.93 +/- 1.52 micro mol/L at 16 wk; P = 0.030 for the interaction of time and treatment). Diastolic blood pressure decreased without a significant difference between the groups. Serum total and LDL-cholesterol concentrations were higher in the betaine group than in the control group (P < 0.05).

CONCLUSION

A hypoenergetic diet with betaine supplementation (6 g daily for 12 wk) decreased the plasma homocysteine concentration but did not affect body composition more than a hypoenergetic diet without betaine supplementation did.

Short-term folic acid supplementation induces variable and paradoxical changes in plasma homocyst(e)ine concentrations

Folic acid is presently the mainstay of treatment for most subjects with elevated plasma homocyst(e)ine concentrations [Plasma or serum homocyst(e)ine, or total homocysteine, refers to the sum of the sulfhydryl amino acid homocysteine and the homocysteinyl moieties of the disulfides homocystine and homocystein-cysteine, whether free or bound to plasma proteins.] Changes in homocyst(e)ine in response to folic acid supplementation are characterized by considerable interindividual variation. The purpose of this study was to identify factors that contribute to heterogeneity in short-term responses to folic acid supplementation. The effects of folic acid supplementation (1 or 2 mg per day) for 3 wk on plasma homocyst(e)ine concentrations were assessed in 304 men and women. Overall, folic acid supplementation increased mean plasma folate 31.5 +/- 98.0 nmol/L and decreased mean plasma homocyst(e)ine concentrations 1.2 +/- 2.4 micromol/L. There was evidence of substantial interindividual variation in the homocyst(e)ine response from -18.5 to +7.1 micromol/L, including an increase in homocyst(e)ine in 20% of subjects (mean increase 1.5 +/- 1.4 micromol/L). Basal homocyst(e)ine, age, male gender, cigarette smoking, use of multivitamins, methylene tetrahydrofolate reductase, and cystathionine beta-synthase polymorphisms accounted for 47.6% of the interindividual variability in the change in homocyst(e)ine after folic acid supplementation, but about 50% of variability in response to folic acid was not explained by the variables we studied.

Hyperhomocysteinemia and thrombosis

Homocysteine (Hcy) is a sulfhydryl amino acid derived from the metabolic conversion of methionine, which is dependent on vitamins (folic acid, B12, and B6) as cofactors or cosubstrates. In 1969, McCully first reported the presence of severe atherosclerotic lesions in patients with severe hyperhomocysteinemia and hypothesized the existence of a pathogenic link between hyperhomocysteinemia and atherogenesis. Several case-control and cross-sectional studies were consistent with the initial hypothesis of McCully, showing that moderate hyperhomocysteinemia is also associated with heightened risk of occlusive arterial disease. Less consistent results have been reported by prospective cohort studies of subjects who were healthy at the time of their enrollment, whereas prospective cohort studies of patients with overt coronary artery disease or other conditions at risk consistently confirmed the association between moderate hyperhomocysteinemia and cardiovascular morbidity and mortality. More recently, an association between moderate hyperhomocysteinemia and heightened risk of venous thromboembolism has been documented, suggesting that hyperhomocysteinemia might be involved not only in atherogenesis, but also in thrombogenesis. The mechanisms by which hyperhomocysteinemia might contribute to atherogenesis and thrombogenesis are incompletely understood. The mainstay of treatment of hyperhomocysteinemia is folic acid, alone or in combination with vitamin B12 and vitamin B6. Although it is quite clear that vitamins effectively reduce the plasma levels of total homocysteine (tHcy), we do not yet know whether they will decrease the risk of vascular disease. The results of ongoing randomized, placebo-controlled, double-blind trials of the effects of vitamins on the thrombotic risk will help in defining whether the relationship between hyperhomocysteinemia and thrombosis is causal, and will potentially have a dramatic effect in the prevention of thromboembolic events.

Homocysteine and occlusive arterial disease

BACKGROUND

An increased plasma level of homocysteine has been proposed as an independent risk factor for atherosclerosis; this review examines the evidence.

METHODS

A Medline search was undertaken for English language articles on homocysteine and vascular disease. Further papers were identified by cross-referencing from the reference lists of relevant major articles.

RESULTS

Although much interest has been generated about homocysteine and atherosclerotic disease, contradictory data exist regarding its role in disease progression. There is insufficient current evidence to regard increased homocysteine level as a causative factor in atherosclerotic disease.

CONCLUSION

It is not known whether lowering plasma homocysteine concentration will reduce cardiovascular risk in the long term. Until such data become available, there is no evidence for the widespread use of folic acid therapy to reduce cardiovascular disease risk.

Treatment of hyperhomocysteinemia with folic acid: effects on homocysteine levels, coagulation status, and oxidative stress markers

The aim of the study was to determine whether folic acid treatment in subjects with homocysteinemia would change their coagulation and oxidative status. Thirty-three patients with peripheral vascular disease and 26 elderly subjects with no symptoms of atherosclerosis, all of whom had total homocysteine >20 microM, were treated with folic acid (5 or 10 mg) for 3 months. In the 33 patients with peripheral vascular disease, homocysteine levels decreased from a median of 26.7 microM at baseline to 20.0 microM (p < 0.0001), whereas in the 26 asymptomatic elderly subjects, homocysteine level decreased from 24.4 microM to 18.6 microM (p < 0.0001). Plasma fibrinogen decreased whereas plasminogen and anti-thrombin increased; the differences between pre- and posttreatment values were significant in both patients and healthy subjects. Oxidative status markers showed a shift toward lower oxidative stress. This effect was observed in both study groups. An association of the therapeutic effect with the genetic polymorphism of 5,10-methylenetetrahydrofolate reductase was not detected. Folic acid supplementation to hyperhomocysteinemic subjects resulted in a decrease in total blood homocysteine concentrations; moreover, there was a tendency to reverse the coagulation status and oxidative stress.

Neural tube defects

The purpose of this article is to describe the etiology of neural tube defects (NTDs) and the role of folic acid in their prevention. NTDs are all too common and devastating outcomes of many pregnancies. The brain and spinal cord malformations that develop during gestation in the NTD-affected pregnancies are expressed through various anomalies. Estimates by the Centers for Disease Control and Prevention (CDC) for 1995 reported over 4,000 occurrences of NTDs in the United States alone. Research has demonstrated that the preconception and prenatal addition of folic acid can greatly reduce the incidence of NTDs. Recent advances in genetic studies have increased awareness of the important role of folic acid in preventing NTDs. Identification of a genetic marker will allow for specific treatment of those women at high risk for NTDs. Despite recommendations from the CDC for folic acid supplementation, there is insufficient awareness of these guidelines by both the public and by healthcare providers. A National campaign to promote awareness of the role of folic acid in the prevention of NTDs has been initiated, and has been successful at reducing NTDs's by 19%. Nurses can be instrumental in the dissemination of information not only to women of childbearing age, but also to other nurses and physicians.

Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial

OBJECTIVE

To study the effects of folic acid and zinc sulfate treatment on semen variables in fertile and subfertile men.

DESIGN

Double-blind, placebo-controlled interventional study.

SETTING

Two outpatient fertility clinics and nine midwifery practices in The Netherlands.

PARTICIPANT(S)

One hundred eight fertile and 103 subfertile men.

INTERVENTION(S)

Both groups were randomly assigned to receive one of four treatments for 26 weeks: folic acid and placebo, zinc sulfate and placebo, zinc sulfate and folic acid, and two placebos. Folic acid was given at a daily dose of 5 mg, and zinc sulfate was given at a daily dose of 66 mg.

MAIN OUTCOME MEASURE(S)

Before and after treatment, standardized semen and blood samples were obtained for determinations of sperm concentration, motility, and morphology according to World Health Organization guidelines; semen morphology according to strict criteria; and blood folate and zinc concentrations. Effects of the four interventions were evaluated separately in subfertile and fertile men.

RESULT(S)

Subfertile men demonstrated a significant 74% increase in total normal sperm count and a minor increase of 4% abnormal spermatozoa. A similar trend was observed in fertile men. Pre-intervention concentrations of folate and zinc in blood and seminal plasma did not significantly differ between fertile and subfertile men.

CONCLUSION(S)

Total normal sperm count increases after combined zinc sulfate and folic acid treatment in both subfertile and fertile men. Although the beneficial effect on fertility remains to be established, this finding opens avenues of future fertility research and treatment and may affect public health.

Nutritional advice to increase soluble fibre intake does not change plasma folate or homocysteine in men with angina: a randomised controlled trial

OBJECTIVE

To study the effect of advice to increase dietary soluble fibre, including fruit and vegetables, on plasma folate and homocysteine in men with angina.

DESIGN

Data were collected on a subset of subjects from the Diet and Angina Randomised Trial (DART II). In a randomised (2 x 2) factorial design, subjects received advice on either, neither or both interventions to: (1) increase soluble fibre intake to 8.0 g day(-1) (fruit, vegetables and oats); (2) increase oily fish intake to 2 portions week(-1). Those who received soluble fibre advice were compared with those who did not. Subjects were genotyped for C677T variant 5,10-methylenetetrahydrofolate reductase (MTHFR).

SETTING/SUBJECTS

Seven hundred and fifty-three male angina patients were recruited from general practice.

RESULTS

Plasma homocysteine concentrations were at the upper end of the normal range (median 11.5, 25% 9.4, 75% 14.0 micromol l(-1)). Baseline intake of fruit and vegetables was positively correlated with plasma folate (r(s) = 0.29, P < 0.01). Smokers had lower intakes of fruit and vegetables, lower plasma folate and higher homocysteine (all P < 0.01). Homozygotes for variant MTHFR had higher homocysteine concentrations at low plasma folate (P < 0.01). Reported intakes of fruit and vegetables and estimated dietary folate increased in the intervention group (ca. +75 g day(-1), P < 0.01 and ca. +20 g day(-1), P < 0.05, respectively). However, neither plasma folate (baseline/follow-up 4.5 vs. 4.4 microg l(-1), P = 0.40) nor homocysteine (baseline/follow-up 11.7 vs. 11.7 micromol l(-1), P = 0.31) changed.

CONCLUSIONS

Plasma homocysteine, a cardiovascular risk factor, is influenced by MTHFR genotype, plasma folate and smoking status. Dietary advice successfully led to changes in fruit and vegetable intake, but not to changes in plasma folate or homocysteine, possibly because the fruits and vegetables that were chosen were not those richest in folate.

The Chilean flour folic acid fortification program reduces serum homocysteine levels and masks vitamin B-12 deficiency in elderly people

Hyperhomocysteinemia is considered a risk factor for cardiovascular disease and is prevalent in the elderly. Supplementation with folic acid, vitamin B-6 and B-12 lowers homocysteine levels. In January 2000, the Chilean government initiated a flour folic acid fortification program to decrease the occurrence of neural tube defects. The aim of this study was to evaluate the effect of this program on serum homocysteine and folate levels in elderly subjects after 6 mo. A total of 108 elderly people were studied. We measured serum folate, homocysteine and vitamin B-12 levels before the fortification started and 6 mo later. At baseline, folate deficiency (<6.8 nmol/L) was present in 1.8%, vitamin B-12 deficiency (<165 pmol/L) in 27.6% and hyperhomocysteinemia (>14 micromol/L) in 31% of the sample. Six months later, serum folate levels increased from 16.2 +/- 6.2 to 32.7 +/- 7.1 nmol/L (P < 0.001), homocysteine levels decreased from 12.95 +/- 3.7 to 11.43 +/- 3.6 micromol/L (P < 0.001) and vitamin B-12 levels were unchanged. Flour fortification with folic acid had a moderate lowering effect on homocysteine levels. Given that vitamin B-12 deficiency was more common than folate deficiency, it may be more appropriate to add vitamin B-12 to food, at least in foods for this age group.

5,10-Methylenetetrahydrofolate reductase genotype determines the plasma homocysteine-lowering effect of supplementation with 5-methyltetrahydrofolate or folic acid in healthy young women

BACKGROUND

Elevated plasma total homocysteine (tHcy) is a risk factor for vascular disease and neural tube defects. The polymorphism in the gene encoding 5,10-methylenetetrahydrofolate reductase (FADH(2)) (MTHFR) influences the tHcy concentration and the response to tHcy-lowering therapy. Supplementation with folic acid (FA) decreases plasma tHcy, but limited data are available on the effect of 5-methyltetrahydrofolate (MTHF).

OBJECTIVE

We evaluated the tHcy-lowering potential of low-dose FA and of MTHF with respect to the MTHFR genotype.

DESIGN

In this randomized, placebo-controlled, double-blind study, 160 women received 400 microg FA, the equimolar amount of MTHF (480 microg, racemic mixture), or a placebo daily during an 8-wk treatment period. Blood samples were collected at baseline and at 4 and 8 wk.

RESULTS

Changes in plasma tHcy concentration depended on the supplemented folate derivative and the MTHFR genotype. Supplementation with FA significantly decreased tHcy concentrations by > or = 13% in women of all 3 genotypes after both 4 and 8 wk. The greatest decrease was 20% (P < 0.05) in the women with the TT genotype after 4 wk. MTHF supplementation also decreased tHcy, but only the women with the CT genotype had a significant decrease after 4 wk (7%; P < 0.05). The largest nonsignificant reduction (15%) occurred in the women with the TT genotype after 4 wk of MTHF supplementation.

CONCLUSIONS

The response to tHcy-lowering therapy is influenced by MTHFR genotype. Women with the TT genotype seem to benefit the most from supplementation with either FA or MTHF. In women with the CT or CC genotype, FA is more effective than MTHF in lowering plasma tHcy.

Quantifying the effect of folic acid

BACKGROUND

Folic acid is known to prevent neural-tube defects (NTDs) but the size of the effect for a given dose is unclear. We aimed to quantify such an effect.

METHODS

We used published data from 13 studies of folic acid supplementation on serum folate concentrations and results from a large cohort study of the risk of NTDs according to serum folate, to measure the preventive effect of specified increases in intake of folic acid.

FINDINGS

Serum folate concentrations increase by 0.94 ng/mL (95% CI 0.77-1.10) for every 0.1 mg/day increase in folic acid intake in women aged 20-35 years, and about double that in people aged 40-65. Every doubling of serum folate concentration roughly halves the risk of an NTD. These two effects can be combined to predict the reduction in risk according to intake of extra folic acid and background serum folate concentration. Such results predict that the preventive effect is greater in women with low serum folate than in those with higher concentrations. The results have also been used to predict direct observations from large randomised trials and the effect of food fortification. From a typical western background serum folate of 5 ng/mL, about 0.2 mg/day (the US level of folic acid fortification) would be expected to reduce NTDs by about 20%; a similar effect can be expected from the current British recommendation (0.24 mg/day). An increase of 0.4 mg/day would reduce risk by about 36%, of 1 mg/day by 57%, and taking a 5-mg tablet daily would reduce risk by about 85%.

INTERPRETATION

Folic acid fortification levels should be increased. Additionally women planning a pregnancy should take 5 mg folic acid tablets daily, instead of the 0.4 mg dose presently recommended.

Dietary sugars and micronutrient dilution in normal adults aged 65 years and over

OBJECTIVE

To examine the relationship between non-milk extrinsic sugars (NMES) concentration and micronutrient intakes and status in free-living older people.

DESIGN

The National Diet and Nutrition Survey of people aged 65 years and over; a cross-sectional study in Britain in 1994/5.

SUBJECTS AND METHODS

Eight hundred and six men and women living in private households who were not on medication for nutritional disorders. Subjects were classified into four groups (Q1 to Q4), using cut-off points corresponding to quartiles of energy from NMES. Relationships were examined between dietary NMES concentration and intakes of calcium, iron, riboflavin, folate, vitamin C and vitamin D. Status indices were also assessed in each group.

RESULTS

Overall, a small proportion of men and women had intakes below the Lower Reference Nutrient Intake (LRNI) for calcium, iron, folate, riboflavin or vitamin C, while vitamin D intakes were universally low. Intakes of micronutrients tended to be highest at moderate levels of NMES in the diet (Q2 and Q3, equivalent to 8-15% of energy from NMES). Micronutrient status was low for riboflavin in 38% of the sample, while 15% had low vitamin C status and more than 10% were anaemic. There was little evidence that poorer nutrient status was associated with higher levels of dietary NMES. Although some indices of folate status were lower in Q4, this is most likely to reflect confounding by smoking. Energy intake accounted for 20-40% of the variance in micronutrient intakes, compared with less than 5% for NMES concentration.

CONCLUSIONS

A diet moderately high in NMES (up to around 15% of energy) is unlikely to have a detrimental impact on micronutrient intake or status in this age group. Energy intake is the major determinant of micronutrient adequacy.

Polymorphisms of key enzymes in homocysteine metabolism affect diet responsiveness of plasma homocysteine in healthy women

High plasma total homocysteine (tHcy), low dietary intake of folate and other B vitamins, and genetic polymorphisms related to metabolism of homocysteine may interactively contribute to the risk of cardiovascular disease. We investigated whether known mutations in genes regulating homocysteine metabolism affect the responsiveness of serum folate and plasma tHcy to high intake of natural folate from food. Healthy females (n = 37) aged 22-57 y volunteered to participate in a crossover dietary intervention with two 5-wk diet periods (low and high folate diets). Concentrations of serum and RBC folate, serum vitamin B-12 and plasma tHcy were measured at baseline and at the end of each diet period. The prevalences of C677T transition of methylenetetrahydrofolate reductase (MTHFR) gene, 844ins68 of cystathionine beta-synthase (CBS) gene and A2756G mutation of methionine synthase (MS) gene were determined. Compared with the low folate diet, the high folate diet increased the serum folate concentration by 85% (P < 0.001), 77% (P < 0.001) and 55% (P < 0.05) in the subjects with the genotypes C/C (n = 19), C/T (n = 13) and T/T (n = 5), respectively, of the MTHFR gene. Also, the plasma tHcy of the subjects with the genotypes C/C, C/T and T/T was decreased by 11% (P < 0.001), 15% (P < 0.01) and 18% (P < 0.05), respectively, during the high folate diet period. The subjects carrying the G2756 allele of the MS gene (n = 15) had a more extensive reduction (P < 0.05) of plasma tHcy during the high folate diet period than the subjects with the genotype A/A (n = 22). The 844ins68 of CBS gene did not affect plasma tHcy concentrations or diet responsiveness. In conclusion, diet responsiveness of plasma homocysteine may be genetically regulated.

Effects of preparation and cooking of folic acid-fortified foods on the availability of folic acid in a folate depletion/repletion rat model

The practice of food fortification with folic acid offers the potential to increase the folate intake of the general population. To fully exploit the potential of fortification for raising folate nutriture, appropriate food vehicles need to be selected. Selection should involve determination of the availability of folic acid as affected by characteristics of the carrier food, food matrix, food preparation, and cooking. The present study investigated the effects of preparation and cooking of a range of folic acid-fortified foods on the folate status of folate-deficient rats. Fifty-six weanling male rats (Wistar strain) were fed a folate-deficient diet containing 1% succinyl sulfathiazole for 28 days. Following depletion, six rats were randomly assigned to each of eight repletion diets containing cooked or uncooked meringue mix, quick bread mix, brownie mix, or pizza base mix. The test foods were fortified with 1400 microg of folic acid/kg of food and incorporated as 19% of the repletion diets. Each of the first four groups was pair-fed a diet containing a cooked fortified food with another group fed the corresponding uncooked fortified food. After a further 28 days, plasma, liver, and kidney folate concentrations were determined by microbiological assay. Mean plasma and liver folate concentrations of rats fed diets containing cooked fortified foods were similar to those of rats fed uncooked fortified foods. Preparation and cooking did not affect the availability of folic acid from the selected cereal-based convenience foods in this rat model system, suggesting that these foods are appropriate vehicles for fortification with folic acid.

Pyridoxine improves endothelial function in cardiac transplant recipients

BACKGROUND

Endothelial dysfunction is common in cardiac transplant recipients and predicts the development of transplant coronary artery disease. Hyperhomocysteinemia is associated with endothelial dysfunction in the general population, is common in transplant recipients, and has been associated with transplant coronary artery disease. Thus therapy that decreases homocysteine concentrations might also improve endothelial function and decrease the risk of transplant coronary artery disease. Folate and pyridoxine are important cofactors in distinct aspects of homocysteine metabolism. The purpose of this study was to determine whether folate or pyridoxine supplementation improves endothelial function in cardiac transplant recipients.

METHODS AND RESULTS

This was a double-blind, randomized, placebo-controlled trial. We assigned 31 transplant recipients to either pyridoxine (n = 11:100 mg/day), folate (n = 12:5 mg/day), or placebo (n = 8) for 10 weeks. Fasting and post-methionine-load (methionine 100 mg/kg orally) homocysteine concentrations were determined. Brachial artery flow-mediated dilatation was used as a measure of endothelial function. At follow-up, we noted no significant changes in homocysteine concentrations in any of the groups. However, pyridoxine supplementation was associated with a significant improvement in endothelial function (2.8 +/- 6.7 to 6.9 +/- 6.3, p = 0.05). No significant changes were seen in patients treated with folate or placebo.

CONCLUSIONS

Pyridoxine, but not folate supplementation, significantly improves endothelial function in cardiac transplant recipients.

Assessment of nutritional folate status and selected vitamin status of women of childbearing age

OBJECTIVE

The aim of the study was to investigate folate and other selected vitamin status (ascorbic acid, tocopherol, retinol, vitamin B12), haematological indices and total homocysteine concentration of serum in women of childbearing age.

DESIGN

A cross-sectional study.

SETTING

Warsaw.

SUBJECTS

Healthy women aged 18-30 y (n=78) not pregnant presently or previously, and not taking drugs.

RESULTS

Haemoglobin and haematocrit values according to WHO criteria for 18 to 30-y-old women were normal. The optimal levels of serum tocopherol, >1.29 mg/dl (>29.9 micromol/l) to preventing civilization diseases, were found in 5.5% and serum retinol >71.6 mcg/dl (>2.5 micromol/l) in 6.4% of all studied persons. The analysis of serum folate concentration showed high-risk deficiency,<3 ng/ml (<6.8 nmol/l), in 6.4%, moderate and low risk together (7.0-14.9 nmol/l) in 61.6% and optimal folate levels (>14.9 nmol/l) in 32.0% of the studied group. Folate body stores were insufficient in almost all women. There was no high or moderate deficiency risk of vitamin B12 or ascorbic acid. None of the women under study had serum total homocysteine (tHcy) concentration >15 micromol/l, indicating hyperhomocysteinaemia. Serum total homocysteine concentrations in the range of 5-15 micromol/l were found in 71.8%, and serum tHcy >10 micromol/l in 7.7% of the studied group of women.

SPONSORSHIP

The study was sponsored by the Polish Committee for Scientific Research.

Terminal ileum resection is associated with higher plasma homocysteine levels in Crohn's disease

BACKGROUND

Elevated plasma total homocysteine (tHcy) is associated with a higher risk of thrombosis. Crohn's disease (CD) is associated with hypercoagulability of undefined etiology. We investigated tHcy in patients with CD and its relationship with vitamin status, disease activity, location, duration, and history of terminal ileum (TI) resection.

STUDY

We examined fasting plasma tHcy, folate, serum vitamin B12 levels, and sedimentation rate in consecutive adult patients with CD. Harvey-Bradshaw index of CD activity and history of TI resection and thromboembolism were recorded.

RESULTS

Median plasma tHcy was 10.2 micromol/L in 125 patients with CD. Men (n = 60) had higher plasma tHcy than women (n = 65) (11.2 vs. 9.1 micromol/L; p = 0.004). Patients with a history of TI resection showed lower serum B12 levels (293 vs. 503 pg/mL; p < 0.001) and higher plasma tHcy levels (11.0 vs. 9.35 micromol/L; p = 0.027) than patients without such history. Multivariate analysis showed history of TI resection, serum B12, and creatinine levels to be significant predictors of elevated plasma tHcy. Fourteen patients with CD with a history of thrombosis had an elevated median plasma tHcy of 11.6 micromol/L.

CONCLUSIONS

Terminal ileum resection contributes to elevated plasma tHcy levels in CD cases. We recommend tHcy screening in patients with CD, especially in those with prior history of TI resection, and the initiation of vitamin supplementation when appropriate.

A critical evaluation of the application of biomarkers in epidemiological studies on diet and health

One of the problems which may beset epidemiological studies is the difficulty of accurately measuring the dietary intakes of participants. Biomarkers of diet promise to provide a more accurate measure of dietary intake and a more objective one in that they are not reliant on the subject's memory. This review considers some issues of importance in epidemiology when information is obtained from biomarkers. The approach taken is to use examples both of normal dietary constituents and of contaminants in relation to a range of diet and health questions to illustrate these points. A brief overview of the role of sample collection, processing and storage is given including some generic recommendations for maximising the reliability of subsequent analytical data. Using the examples of phytoestrogens and iodine the question of whether biomarkers can accurately reflect the intake of the dietary constituents of interest at the population level or at the individual level is considered. The relationship of the biomarker to the natural history of the disease is exemplified using the role of folate in neural tube defects. Finally, intakes of vitamin D and heterocyclic amines are used to illustrate the integration of biomarkers into epidemiological studies of prostate and colorectal cancer, respectively. It is concluded that biomarkers may provide a more accurate and objective measure of diet than estimates of current or usual intake but that this approach also has limitations. A combination of methods will probably prove to be most valuable and this approach is being taken in current large prospective studies.

Biomarkers in disease and health

Biomarkers have considerable potential in aiding the understanding of the relationship between diet and disease or health. However, to assess the role, relevance and importance of biomarkers on a case by case basis it is essential to understand and prioritise the principal diet and health issues. In the majority of cases, dietary compounds are only weakly biologically active in the short term, have multiple targets and can be both beneficial and deleterious. This poses particular problems in determining the net effect of types of foods on health. In principle, a biomarker should be able to contribute to this debate by allowing the measurement of exposure and by acting as an indicator either of a deleterious or of an enhanced health effect prior to the final outcome. In this review, the examples chosen - cancer (stomach, colon/rectal, breast); coronary heart disease and osteoporosis - reflect three major diet-related disease issues. In each case the onset of the disease has a genetic determinant which may be exacerbated or delayed by diet. Perhaps the most important factor is that in each case the disease, once manifest, is difficult to influence in a positive way by diet alone. This then suggests that the emphasis for biomarker studies should focus on predictive biomarkers which can be used to help in the development of dietary strategies which will minimise the risk and be of greater benefit.

Plasma Homocysteine Is Not Subject to Seasonal Variation

Background: Studies investigating the relationship between plasma total homocysteine (tHcy) and vascular disease usually rely on a single measurement. Little information is available, however, on the seasonal variability of plasma tHcy. The aim of this study was to investigate the seasonal variation in fasting plasma tHcy and related B-vitamin intake and status in a group of people who did not consume fortified foods or take B-vitamin supplements.

Methods: In this longitudinal study, a group of 22 healthy people were followed for 1 year. A fasting blood sample and dietary information were collected from each individual every 3 months, i.e., at the end of each season.

Results: There was no significant seasonal variation in plasma tHcy or in B-vitamin intake or status with the exception of red cell folate (significantly lower in spring compared with autumn or winter) and serum folate (significantly lower in spring compared with the other seasons). Although the between-person variation in plasma tHcy was high (47%), the within-person variation was low (11%). This low variation, combined with the low methodologic imprecision of 3.8%, yielded a high reliability coefficient for plasma tHcy (0.97).

Conclusions: Although there was a small seasonal variation in folate status, there was no corresponding seasonal variation in plasma tHcy. The high reliability coefficient for plasma tHcy suggests that a single measurement is reflective of an individual’s average plasma tHcy concentration, thus indicating its usefulness as a potential predictor of disease. This, however, needs to be confirmed in different subgroups of the population.

Association between B vitamin intake and plasma homocysteine concentration in the general Dutch population aged 20-65 y

BACKGROUND

An elevated plasma total homocysteine (tHcy) concentration is associated with an increased risk of cardiovascular diseases. Folate, riboflavin, vitamin B-6, and vitamin B-12 are essential in homocysteine metabolism.

OBJECTIVE

The objective was to describe the association between dietary intakes of folate, riboflavin, vitamin B-6, and vitamin B-12 and the nonfasting plasma tHcy concentration.

DESIGN

A random sample of 2435 men and women aged 20-65 y from a population-based Dutch cohort examined in 1993-1996 was analyzed cross-sectionally.

RESULTS

Univariately, intakes of all B vitamins were inversely related to the plasma tHcy concentration. In multivariate models, only folate intake remained inversely associated with the plasma tHcy concentration. Mean plasma tHcy concentrations (adjusted for intakes of riboflavin, vitamin B-6, vitamin B-12, and methionine and for age, smoking, and alcohol consumption) in men with low (first quintile: 161 microg/d) and high (fifth quintile: 254 microg/d) folate intakes were 15.4 and 13.2 micromol/L, respectively; in women, plasma tHcy concentrations were 13.7 and 12.4 micromol/L at folate intakes of 160 and 262 microg/d, respectively. In men, the difference in the mean plasma tHcy concentration between men with low and high folate intakes was greater in smokers than in nonsmokers (2.8 compared with 1.6 micromol/L) and greater in nondrinkers than in drinkers of >2 alcoholic drinks/d (3.5 compared with 1.4 micromol/L). In women, the association between folate intake and plasma tHcy was not modified by smoking or alcohol consumption.

CONCLUSIONS

In this Dutch population, folate was the only B vitamin independently inversely associated with the plasma tHcy concentration. Changing dietary habits may substantially influence the plasma tHcy concentration in the general population.

Randomized control study of the effects of raloxifene on serum lipids and homocysteine in older women

OBJECTIVE(S)

Raloxifene, a selective estrogen receptor modulator, has beneficial estrogen agonist effects on bone and cardiovascular risk factors and estrogen antagonist effects on the breast and uterus. Limited clinical data have shown a sustained decrease in total cholesterol, low-density lipoprotein cholesterol, and homocysteine levels; an elevated homocysteine level is an independent risk factor for atherosclerosis. All of these studies were conducted in relatively young populations of women (mean age, 52-54 years). Raloxifene does not affect hot flushes, a major immediate symptom of menopause. This drug may therefore be useful in older women to prevent osteoporosis and cardiovascular disease. The aim of this clinical study was to evaluate the effects of raloxifene on plasma lipids and homocysteine in older women.

STUDY DESIGN

The subjects were 45 healthy postmenopausal women, aged 60 to 70 years. The women were randomly assigned to therapy with raloxifene or placebo, 60 mg/d for 1 year. Twenty-six women received raloxifene and 19 received placebo. Checkups were performed every 3 months. At baseline and after 3, 6, 9, and 12 months of treatment we measured homocysteine, total serum cholesterol, triglycerides, and both high-density lipoprotein and low-density lipoprotein cholesterol.

RESULTS

An effect on lipids was evident by 3 months with no significant additional modification at 12 months. Mean low-density lipoprotein cholesterol levels were lowered by 15% and total cholesterol was lowered by 8.5%. No reduction in high-density lipoprotein cholesterol or triglycerides was observed. After 3 months of therapy, homocysteine was significantly lower than at baseline (9.9 +/- 1.6 vs 11 +/- 2.1 micromol/L; P < .05). The greatest reduction with respect to baseline was reached after 6 months of therapy (-19.5% +/- 3%; P < .05).

CONCLUSION(S)

The results of our study show that raloxifene at a dose of 60 mg/d reduces serum concentrations of low-density lipoprotein cholesterol and total cholesterol in healthy older women. Our study shows that in older women raloxifene leads to a 19.5% +/- 3% reduction in fasting homocysteine levels. Raloxifene may have a favorable effect on the incidence of cardiovascular disease in older women.

Nutrient-dense foods and exercise in frail elderly: effects on B vitamins, homocysteine, methylmalonic acid, and neuropsychological functioning

BACKGROUND

Frail elders are at risk of suboptimal micronutrient status, functional decline, and neurologic disorders. The influence of oral multimicronutrients in physiologic doses and of moderately intense physical exercise on homocysteine (Hcy), methylmalonic acid (MMA), and neurologic functioning have not yet been investigated.

OBJECTIVE

Our goal was to determine the effects of enriched foods and exercise on blood vitamins, Hcy, MMA, and neuropsychological functioning in the frail.

DESIGN

A 17-wk randomized controlled intervention trial was used to study 1) enriched foods plus a social program, 2) regular foods plus exercise, 3) enriched foods plus exercise, and 4) regular foods plus a social program. Enriched foods contained multiple micronutrients (25-100% of the Dutch recommended dietary allowances); exercises focused on strength, coordination, flexibility, and endurance. Vitamin (cobalamin, red blood cell folate, and pyridoxal 5'-phosphate), Hcy, and MMA concentrations were measured and 2 neuropsychological tests were conducted.

RESULTS

Vitamin concentrations were higher in the supplemented groups than in the unsupplemented groups (P < 0.001; total n = 130). Compared with baseline, cobalamin in the supplemented groups was increased by 22%, plasma folate by 101%, red blood cell folate by 87%, and pyridoxal 5'-phosphate by 68%. Concentrations in the unsupplemented groups changed by -2%, -6%, 1%, and -13%, respectively. Hcy decreased by 25% and MMA by 30% in the supplemented groups, compared with a small increase in Hcy (2%) and decrease in MMA (9%) in the unsupplemented groups. Exercise did not significantly affect vitamin, Hcy, or MMA concentrations. No significant effect of either intervention was observed on the neuropsychological tests.

CONCLUSIONS

The decrease in Hcy and MMA in frail elders confirms a subclinical metabolic deficiency state. Enriched foods containing physiologic amounts of micronutrients have a beneficial effect on these metabolites. No effects of B vitamins on mental health were identified.

Association between dietary patterns and plasma biomarkers of obesity and cardiovascular disease risk

BACKGROUND

Although the effects of individual foods or nutrients on the development of diseases and their risk factors have been investigated in many studies, little attention has been given to the effect of overall dietary patterns.

OBJECTIVE

Our objective was to examine the associations of 2 major dietary patterns, Western and prudent, with biomarkers of obesity and cardiovascular disease (CVD) risk.

DESIGN

We used factor analysis to define major dietary patterns for a subsample of men (n = 466) from the Health Professionals Follow-up Study by using dietary information collected from food-frequency questionnaires (FFQs) in 1994. We calculated partial correlation coefficients between pattern scores and biomarker values adjusted for age, smoking status, energy and alcohol intake, physical activity, hours of television watching, and body mass index.

RESULTS

We derived 2 major dietary patterns that were generally reproducible over time. The first pattern (prudent) was characterized by higher intakes of fruit, vegetables, whole grains, and poultry. The second pattern (Western) was characterized by higher intakes of red meats, high-fat dairy products, and refined grains. Using pattern scores from 1994 and adjusting for potential confounders, we found significant positive correlations between the Western pattern and insulin, C-peptide, leptin, and homocysteine concentrations, and an inverse correlation with plasma folate concentrations. The prudent pattern was positively correlated with plasma folate and inversely correlated with insulin and homocysteine concentrations.

CONCLUSION

Major dietary patterns are predictors of plasma biomarkers of CVD and obesity risk, suggesting that the effect of overall diet on CVD risk may be mediated through these biomarkers.

Multivitamin/mineral supplementation improves plasma B-vitamin status and homocysteine concentration in healthy older adults consuming a folate-fortified diet

Elevated homocysteine has been identified as an independent risk factor for cardiovascular and cerebrovascular disease. Although multivitamin use has been associated with low plasma homocysteine concentrations in several observational studies, no clinical trials have been conducted using multivitamin/mineral supplements to lower homocysteine. We determined whether a multivitamin/mineral supplement formulated at about 100% Daily Value will further lower homocysteine concentration and improve B-vitamin status in healthy older adults already consuming a diet fortified with folic acid. In this randomized, double-blind, placebo-controlled trial, 80 free-living men and women aged 50-87 y with total plasma homocysteine concentrations of > or =8 micromol/L received either a multivitamin/mineral supplement or placebo for 56 d while consuming their usual diet. After the 8-wk treatment, subjects taking the supplement had significantly higher B-vitamin status and lower homocysteine concentration than controls (P: < 0.01). Plasma folate, pyridoxal phosphate (PLP) and vitamin B-12 concentrations were increased 41.6, 36.5 and 13.8%, respectively, in the supplemented group, whereas no changes were observed in the placebo group. The mean homocysteine concentration decreased 9.6% in the supplemented group (P: < 0.001) and was unaffected in the placebo group. There were no significant changes in dietary intake during the intervention. Multivitamin/mineral supplementation can improve B-vitamin status and reduce plasma homocysteine concentration in older adults already consuming a folate-fortified diet.

The role of folic acid in the prevention of cardiovascular disease

Coronary heart disease is the leading cause of death in the developed world. Current surgical and pharmacological interventions are essentially palliative and interest in preventive strategies, particularly through nutrition and avoidance of tobacco has increased in recent years. Basic scientific, clinical and epidemiological evidence indicates a positive association between the plasma level of the amino acid homocysteine and vascular disease. Homocysteine levels are inversely related to both intake and plasma levels of folate. Less strong evidence indicates an inverse relationship between folate intake and coronary heart disease risk. It is likely that current estimates of dietary folate requirements are lower than optimal. Folic acid supplementation reliably reduces homocysteine levels, and may also modify endothelial function independent of this effect on homocysteine. Such treatment is cheap and appears to be essentially free of risk. However, until present randomised control trials are complete, it will not be known definitively whether or not increasing folate intake reduces cardiovascular risk.

HDL-cholesterol-raising effect of orange juice in subjects with hypercholesterolemia

BACKGROUND

Orange juice-a rich source of vitamin C, folate, and flavonoids such as hesperidin-induces hypocholesterolemic responses in animals.

OBJECTIVE

We determined whether orange juice beneficially altered blood lipids in subjects with moderate hypercholesterolemia.

DESIGN

The sample consisted of 16 healthy men and 9 healthy women with elevated plasma total and LDL-cholesterol and normal plasma triacylglycerol concentrations. Participants incorporated 1, 2, or 3 cups (250 mL each) of orange juice sequentially into their diets, each dose over a period of 4 wk. This was followed by a 5-wk washout period. Plasma lipid, folate, homocyst(e)ine, and vitamin C (a compliance marker) concentrations were measured at baseline, after each treatment, and after the washout period.

RESULTS

Consumption of 750 mL but not of 250 or 500 mL orange juice daily increased HDL-cholesterol concentrations by 21% (P: < 0.001), triacylglycerol concentrations by 30% (from 1.56 +/- 0.72 to 2.03 +/- 0.91 mmol/L; P: < 0.02), and folate concentrations by 18% (P: < 0.01); decreased the LDL-HDL cholesterol ratio by 16% (P: < 0.005); and did not affect homocyst(e)ine concentrations. Plasma vitamin C concentrations increased significantly during each dietary period (2.1, 3.1, and 3.8 times, respectively).

CONCLUSIONS

Orange juice (750 mL/d) improved blood lipid profiles in hypercholesterolemic subjects, confirming recommendations to consume >/=5-10 servings of fruit and vegetables daily.

Folate intake, lifestyle factors, and homocysteine concentrations in younger and older women

BACKGROUND

An elevated total homocysteine (tHcy) concentration is considered to be an independent risk factor for cardiovascular diseases and has also been associated with an increased risk of neural tube defects.

OBJECTIVE

The objective of this study was to investigate folate intake, folate status, and the association between folate intake, other dietary and lifestyle factors, and tHcy concentrations in young and older women.

DESIGN

tHcy concentrations were measured in 290 young women aged 25-30 y and in 288 older women aged 60-65 y. All participants completed questionnaires about factors including lifestyle, health, and use of vitamin supplements. Red blood cell folate was measured in 204 of the participants. A subgroup of 258 participants completed dietary records.

RESULTS

Median tHcy was 7.6 micromol/L (range: 6.5-8.9) in the younger women and 9.4 micromol/L (7.7-11.1) in the older women. Folate intake from diet was 283 (224-348) and 268 (210-326) microg/d, respectively, in the 2 age groups. Folic acid intake from supplements (P: < 0.001 for the younger women and P: = 0.026 for the older women) and total folate intake (P: = 0.024 and P: = 0.079) were inversely associated with log tHcy in multiple linear regression analyses. Smoking status, coffee consumption, systolic blood pressure, and body mass index were positively associated and estrogen replacement therapy and tea consumption were inversely associated with log tHcy in some of the models.

CONCLUSIONS

According to the criteria used, between 1% and 36% of the women had suboptimal folate intake. Folic acid is a strong predictor of tHcy concentration; however, several dietary and other lifestyle factors seem to be important as well.

The effects of a multivitamin/mineral supplement on micronutrient status, antioxidant capacity and cytokine production in healthy older adults consuming a fortified diet

BACKGROUND

Inadequate micronutrient intake among older adults is common despite the increased prevalence of fortified/enriched foods in the American diet. Although many older adults take multivitamin supplements in an effort to compensate, studies examining the benefits of this behavior are absent.

OBJECTIVE

To determine whether a daily multivitamin/mineral supplement can improve micronutrient status, plasma antioxidant capacity and cytokine production in healthy, free-living older adults already consuming a fortified diet.

METHODS

An eight-week double-blind, placebo-controlled clinical trial among 80 adults aged 50 to 87 years (mean = 66.5 +/- 8.6 years).

RESULTS

Multivitamin treatment significantly increased (p<0.01, compared to placebo) plasma concentrations of vitamins D (77 to 100 nmol/L), E (27 to 32 micromol/L), pyridoxal phosphate (55.1 to 75.2 nmol/L), folate (23 to 33 nmol/L), B12 (286 to 326 pmol/L)), C (55 to 71 micromol/L), and improved the riboflavin activity coefficient (1.23 to 1.15), but not vitamins A and thiamin. The multivitamin reduced the prevalence of suboptimal plasma levels of vitamins E (p=0.003), B12 (p=0.004), and C (p=0.08). Neither glutathione peroxidase activity nor antioxidant capacity (ORAC) were affected. No changes were observed in interleukin-2, -6 or -10 and prostaglandin E2, proxy measures of immune responses.

CONCLUSIONS

Supplementation with a multivitamin formulated at about 100% Daily Value can decrease the prevalence of suboptimal vitamin status in older adults and improve their micronutrient status to levels associated with reduced risk for several chronic diseases.

Fruits and vegetables increase plasma carotenoids and vitamins and decrease homocysteine in humans

Observational epidemiologic studies have shown that a high consumption of fruits and vegetables is associated with a decreased risk of chronic diseases. Little is known about the bioavailability of constituents from vegetables and fruits and the effect of these constituents on markers for disease risk. Currently, the recommendation is to increase intake of a mix of fruits and vegetables ("five a day"). We investigated the effect of this recommendation on plasma carotenoids, vitamins and homocysteine concentrations in a 4-wk dietary controlled, parallel intervention study. Male and female volunteers (n = 47) were allocated randomly to either a daily 500-g fruit and vegetable ("high") diet or a 100-g fruit and vegetable ("low") diet. Analyzed total carotenoid, vitamin C and folate concentrations of the daily high diet were 13.3 mg, 173 mg and 228.1 microg, respectively. The daily low diet contained 2.9 mg carotenoids, 65 mg vitamin C and 131.1 microg folate. Differences in final plasma levels between the high and low group were as follows: lutein, 46% [95% confidence interval (CI) 28-64]; beta-cryptoxanthin, 128% (98-159); lycopene, 22% (8-37); alpha-carotene, 121% (94-149); beta-carotene, 45% (28-62); and vitamin C, 64% (51-77) (P < 0.05). The high group had an 11% (-18 to -4) lower final plasma homocysteine and a 15% (0.8-30) higher plasma folate concentration compared with the low group (P < 0.05). This is the first trial to show that a mix of fruits and vegetables, with a moderate folate content, decreases plasma homocysteine concentrations in humans.

[Lowering high levels of fasting total homocysteine with folic acid and vitamins B in patients with venous thromboembolism: relationship between response and the C677T methylenetetrahydrofolate reductase (MTHRF) genotype]

BACKGROUND

High levels of plasma total homocysteine (tHcy) are involved in arterial or venous occlusive diseases. It essentially depends on the nutritional status of folic acid (FA) and vitamins B12 or B6, but also on the methylenetetrahydrofolate reductase (MTHFR) enzymatic activity. We aim to evaluate the response of the hyperhomocysteinemia (HHcy) to a standard schedule of vitamin supplementation, according with the MTHFR genotype.

PATIENTS AND METHODS

227 patients, diagnosed with venous thromboembolism (VTE) were analysed for tHcy (in fasting conditions), and for the MTHFR-C677T gene polymorphism. When the tHcy exceeded the cut-off point (men = 16, women = 15 mumol/l), the patients were supplemented with a dose equivalent to 1 mg FA, 0.2 mg B12 and 100 mg of B6, daily by 6 weeks. Afterwards they were reanalysed and the reduction was stratified by MTHFR genotype, looking for any difference in the response.

RESULTS

The mean fasting tHcy was 12.3 mumol/l (SD = 8). The 51 hyperhomocysteinemic patients (22%) were older (65.1 y) than the normal ones (55.0 y) (p = 0.0001). The treatment was carried out properly in 46 patients (90%). The pre-treatment mean Hcy was 23.2 (SD = 10.5) mumol/l, and it was reduced to 13.0 (SD = 5.9) (p = 0.0001) (mean reduction = 42.1%). By genotype, the C/C reduced from 21.0 to 13.2 mumol/l (37%) (n = 18), the C/T from 25.0 to 12.6 mumol/l (46%) (n = 24), and the abnormal homozygotes T/T from 22.7 to 14.5 mumol/l (39%) (n = 4), although no statistical significant differences were found. In 80% of cases (37/46), tHcy values normalised. A negative correlation (r = -0.471) (p = 0.005) was observed between age and response.

CONCLUSIONS

The FA/B6/B12 based therapy reduces in a simple, quick and effective way (> 40% in 6 weeks) the pathologic tHcy levels on a VTE population and this is not influenced by the MTHFR genotype. As HHcy seems related with recurrences of venous thrombosis, we could speculate if it would be useful to analyse routinely the tHcy, attempting reduction in selected cases.

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.

Low-dose folic acid supplementation does not influence plasma methionine concentrations in young non-pregnant women

An elevated plasma total homocysteine (tHcy) concentration is a risk factor for cardiovascular disease and for having offspring with a neural-tube defect. Folate is a methyl donor in the remethylation of homocysteine into methionine. Although folic acid supplementation decreases tHcy concentrations, effects of folic acid supplementation on plasma methionine concentrations are unclear. There is also concern that folic acid supplementation negatively affects vitamin B12 status. We studied effects of low-dose folic acid supplementation on methionine and vitamin B12 concentrations in plasma. We also investigated whether baseline plasma methionine and tHcy concentrations correlated with the baseline folate and vitamin B12 status. For a period of 4 weeks, 144 young women received either 500 micrograms folic acid each day, or 500 micrograms folic acid and placebo tablets on alternate days, or a placebo tablet each day. Plasma methionine, tHcy and plasma vitamin B12 concentrations were measured at start and end of the intervention period. Folic acid supplementation had no effect on plasma methionine or plasma vitamin B12 concentrations although it significantly decreased tHcy concentrations. Plasma methionine concentrations showed no correlation with either tHcy concentrations (Spearman rs-0.01, P = 0.89), or any of the blood vitamin variables at baseline. Baseline tHcy concentrations showed a slight inverse correlation with baseline concentrations of plasma vitamin B12 (rs-0.25, P < 0.001), plasma folate (rs-0.24, P < 0.01) and erythrocyte folate (rs-0.19, P < 0.05). In conclusion, low-dose folic acid supplementation did not influence plasma methionine or plasma vitamin B12 concentrations. Furthermore, no correlation between plasma methionine concentrations and the blood folate and vitamin B12 status was shown.

Dietary folate from vegetables and citrus fruit decreases plasma homocysteine concentrations in humans in a dietary controlled trial

Elevated total plasma homocysteine (tHcy) concentrations are considered a risk factor for neural tube defects (NTD) and cardiovascular disease. Supplementation with folic acid decreases the risk of women having children with NTD. In both sexes, it decreases tHcy levels. We investigated the efficacy of natural dietary folate in improving folate and homocysteine status. We performed a 4-wk dietary controlled, parallel design intervention trial with 66 healthy subjects (18-45 y) divided into 3 treatment groups: the dietary folate group, the folic acid group and the placebo group. Each day each group was fed a different diet. The dietary folate group received a diet high in vegetables and citrus fruit (total folate content approximately 560 microgram) plus a placebo tablet. The folic acid group received a diet naturally low in folate (approximately 210 microgram) plus 500 microgram folic acid and placebo tablet on alternate days, i.e., 250 microgram folic acid/d. And the placebo group received the same low-folate diet as the folic acid group plus a placebo tablet. After 4 wk of intervention, folate status improved, and tHcy concentrations decreased in both the dietary folate and the folic acid groups. From the amount of additional folate (350 microgram/d) and folic acid (250 microgram/d) consumed, the relative bioavailability of dietary folate compared to folic acid was calculated to be 60-98%, depending on the endpoint used. In conclusion, increasing the consumption of vegetables and citrus fruit, both good sources of folate, will improve folate status and decrease tHcy concentrations. This may contribute to the prevention of cardiovascular disease and NTD in the general population