Folic acid and cognition in older persons

Fragile X Premutation: Medications, Therapy and Lifestyle Advice

The fragile X premutation is characterized by 55–200 CGG repeats in the 5ʹ untranslated region of FMR1, whereas full fragile X mutation has greater than 200 repeats and full methylation, which manifests as fragile X syndrome (FXS). The premutation spectrum of clinical involvement includes fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND). In addition, premutation carriers also suffer from various other health problems such as endocrine abnormalities and autoimmune problems. In this paper, we have discussed different health issues faced by the carriers and interventions including medications, therapy and lifestyle changes that could improve their health.

Hyperhomocysteinemia-related serum metabolome alterations not normalized by short-term folic acid treatment

INTRODUCTION

Hyperhomocysteinemia (HHCys) is an independent risk factor for various diseases such as cardiovascular diseases, Alzheimer's, and cancers. Folate deficiency is one of the significant reasons for HHCys. However, it is not known whether folate deficiency with HHCys is associated with any serum metabolites.

OBJECTIVES

Our objective was to identify the metabolic alterations in people having folate deficiency with HHCys and check whether a short-term folic acid therapy could reverse those metabolic changes.

METHODS

The study enrolled 34 participants aged between 18 and 40 years having folate deficiency (< 4.6 ng/mL) with HHCys (> 15 μmol/L) and 21 normal healthy individuals. A short-term intervention of oral folic acid (5 mg/day) was done in the HHCys group for 30 days. Untargeted metabolomics analysis of serum was performed in all study subjects before and after the folic acid treatment. Different univariate methods and the multivariable-adjusted linear regression models were employed to determine an association between homocysteine level and metabolite profile.

RESULTS

Metabolomics analysis data showed that many metabolites involved in the biochemical pathways of lipid metabolisms such as polyunsaturated fatty acids, glycerolipids, and phospholipids were downregulated in the HHCys group. Short-term oral folic acid therapy significantly reduced their serum homocysteine level. However, the metabolic pathway alterations observed in folate-deficient HHCys-condition were unaltered even after the folic acid treatment.

CONCLUSIONS

Our study revealed that people who have a folic acid deficiency with HHCys have an altered metabolite profile related to lipid metabolism, which cannot be reversed by short-term folic acid therapy.

Folic acid and diseases - supplement it or not?

INTRODUCTION

folic acid is a water soluble vitamin, which is synthetically-produced and found in fortified foods and supplements. Folate is found naturally in plants, such as the dark green leafy vegetables. Folate is not synthesized de novo by humans, therefore the daily requirements are met from the dietary intake of folic acid supplements or food rich in this vitamin. Folate deficiency could lead to numerous common health problems. Hyperhomocysteinemia and the possibility of malignancy developments are the long term consequences of this deficit albeit contradictory findings on these claims.

METHODS

the articles included in this review focused on recent updated evidence-based reports and meta-analyses on the associations of the serum folate/folic acid and the various diseases found globally.

RESULTS

the benefit of folic acid supplementation in the pre-conception period for the prevention of neural tube defects (NTDs) was well established and it was suggested that counseling sessions should be given to women with previous pregnancies affected by NTDs. However, supplementation of folic acid and its medicinal effects in the treatment of other diseases were contradictory and unclear.

CONCLUSION

more detailed investigations into the health benefits of folic acid are needed before it could be recommended for supplementation, treatment or prevention of some of the diseases discussed in this review.

Folate, vitamin B-6, and vitamin B-12 intake and mild cognitive impairment and probable dementia in the Women's Health Initiative Memory Study

BACKGROUND

Whether higher B vitamin intake (ie, B-6, B-12, and folate) is protective against cognitive decline in later life remains uncertain. Several prospective, observational studies find higher B vitamin intake to be associated with lower risk of dementia; other studies, including most trials of B vitamin supplementation, have observed no effect on cognition. We examined this question in a large population of older women carefully monitored for development of mild cognitive impairment (MCI) and probable dementia.

OBJECTIVE

To determine whether baseline folate, vitamin B-6, and/or vitamin B-12 intake, alone or in combination, are associated with incident MCI/probable dementia among older women.

DESIGN

Prospective, longitudinal cohort study. Participants were enrolled between 1993 and 1998, and B vitamin intake was self-reported using a food frequency questionnaire administered at baseline.

PARTICIPANTS/SETTING

Postmenopausal women (N=7,030) free of MCI/probable dementia at baseline in the Women's Health Initiative Memory Study.

MAIN OUTCOME MEASURES

Over a mean follow-up of 5.0 years, 238 cases of incident MCI and 69 cases of probable dementia were identified through rigorous screening and expert adjudication.

STATISTICAL ANALYSES

Cox proportional hazard models adjusting for sociodemographic and lifestyle factors examined the association of B vitamin intake above and below the Recommended Daily Allowance and incident MCI/probable dementia.

RESULTS

Folate intake below the Recommended Daily Allowance at study baseline was associated with increased risk of incident MCI/probable dementia (hazard ratio 2.0, 95% CI 1.3 to 2.9), after controlling for multiple confounders. There were no significant associations between vitamins B-6 or B-12 and MCI/probable dementia, nor any evidence of an interaction between these vitamins and folate intake.

CONCLUSIONS

Folate intake below the Recommended Daily Allowance may increase risk for MCI/probable dementia in later life. Future research should include long-term trials of folic acid supplementation to examine whether folate may impart a protective effect on cognition in later life.

Folic acid handling by the human gut: implications for food fortification and supplementation

BACKGROUND

Current thinking, which is based mainly on rodent studies, is that physiologic doses of folic acid (pterylmonoglutamic acid), such as dietary vitamin folates, are biotransformed in the intestinal mucosa and transferred to the portal vein as the natural circulating plasma folate, 5-methyltetrahydrofolic acid (5-MTHF) before entering the liver and the wider systemic blood supply.

OBJECTIVE

We tested the assumption that, in humans, folic acid is biotransformed (reduced and methylated) to 5-MTHF in the intestinal mucosa.

DESIGN

We conducted a crossover study in which we sampled portal and peripheral veins for labeled folate concentrations after oral ingestion with physiologic doses of stable-isotope-labeled folic acid or the reduced folate 5-formyltetrahydrofolic acid (5-FormylTHF) in 6 subjects with a transjugular intrahepatic porto systemic shunt (TIPSS) in situ. The TIPSS allowed blood samples to be taken from the portal vein.

RESULTS

Fifteen minutes after a dose of folic acid, 80 ± 12% of labeled folate in the hepatic portal vein was unmodified folic acid. In contrast, after a dose of labeled 5-FormylTHF, only 4 ± 18% of labeled folate in the portal vein was unmodified 5-FormylTHF, and the rest had been converted to 5-MTHF after 15 min (postdose).

CONCLUSIONS

The human gut appears to have a very efficient capacity to convert reduced dietary folates to 5-MTHF but limited ability to reduce folic acid. Therefore, large amounts of unmodified folic acid in the portal vein are probably attributable to an extremely limited mucosal cell dihydrofolate reductase (DHFR) capacity that is necessary to produce tetrahydrofolic acid before sequential methylation to 5-MTHF. This process would suggest that humans are reliant on the liver for folic acid reduction even though it has a low and highly variable DHFR activity. Therefore, chronic liver exposure to folic acid in humans may induce saturation, which would possibly explain reports of systemic circulation of unmetabolized folic acid.

Folic acid metabolism in human subjects revisited: potential implications for proposed mandatory folic acid fortification in the UK

Following an introduction of the importance of folates and the rationale for seeking to estimate fractional folate absorption from foods (especially for countries not having a mandatory folic acid fortification policy), scientific papers covering the mechanisms of folate absorption and initial biotransformation are discussed. There appears (post-1983) to be a consensus that physiological doses of folic acid undergo biotransformation in the absorptive cells of the upper small intestine to 5-methyltetrahydrofolic acid (as happens for all naturally-occurring reduced 1-carbon-substituted folates). This 'validates' short-term experimental protocols assessing 'relative' folate absorption in human subjects that use folic acid as the 'reference' dose. The underlying scientific premise on which this consensus is based is challenged on three grounds: (i) the apparent absence of a 5-methyltetrahydrofolic acid response in the human hepatic portal vein following absorption of folic acid, (ii) the low dihydrofolate reductase activity peculiar to man and (iii) the implications derived from recent stable-isotope studies of folate absorption. It is concluded that the historically accepted case for folic acid being a suitable 'reference folate' for studies of the 'relative absorption' of reduced folates in human subjects is invalid. It is hypothesised that the liver, and not the absorptive cells of the upper small intestine, is the initial site of folic acid metabolism in man and that this may have important implications for its use as a supplement or fortificant since human liver's low capacity for reduction may eventually give rise to saturation, resulting in significant (and potentially deleterious) unmetabolised folic acid entering the systemic circulation.