Research Highlights - February

Nutrition Reviews

• Insufficient folate status disrupts DNA methylation and integrity and increases blood homocysteine levels. Elevated levels of follicular fluid homocysteine correlate with oocyte immaturity and poor early embryo quality, while methylenetetrahydrofolate reductase (MTHFR) gene variants are associated with lower ovarian reserves, diminished response to follicular stimulation, and reduced chance of live birth after in vitro fertilization. Embryos carrying multiple MTHFR variants appear to have a selective disadvantage; however, the heterozygous MTHFR 677CT genotype in the mother and fetus provides the greatest chance for a viable pregnancy and live birth, possibly due to a favorable balance in folate cofactor distribution between methyl donor and nucleotide synthesis. The results of previous studies clearly emphasize that imbalances in folate metabolism and related gene variants may impair female fecundity as well as compromise implantation and the chance of a live birth.

American Journal Clinical Nutrition

• Both DNA methylation and gene expression are responsive to caloric restriction and provide new insights about the molecular pathways involved in body weight loss as well as methylation regulation during adulthood.

• Greater adherence to a Mediterranean diet is associated with a significant reduction in the risk of incident gastric adenocarcinoma (stomach cancer).

• Findings support an association between higher food and total folate intakes and decreased risk of pancreatic cancer in women but not in men.

• Low vitamin B6 concentrations were associated with inflammation, higher oxidative stress and metabolic conditions in older Puerto Rican adults. Researchers measured plasma pyridoxal-5'-phosphate (PLP), C-reactive protein (CRP), and an oxidative DNA damage marker, urinary 8-hydroxydeoxyguanosine (8-OHdG). There was a strong dose-response relation of plasma PLP concentration with plasma CRP. Increasing quartiles of PLP were significantly associated with lower CRP concentrations and with lower urinary 8-OHdG concentrations after multivariate adjustment. These negative associations persisted after plasma homocysteine was controlled for. Plasma PLP concentrations were significantly correlated with plasma fasting glucose, glycated hemoglobin and homeostasis model assessment of beta-cell function. Metabolic syndrome, obesity and diabetes were also significantly associated with low plasma PLP concentrations.

American Journal Preventive Medicine

• A 50% lower risk of colorectal cancer was associated with a serum 25(OH)D level ≥33 ng/mL, compared to ≤12 ng/mL. Conclusion: the evidence to date suggests that daily intake of 1000-2000 IU/day of vitamin D3 could reduce the incidence of colorectal with minimal risk.

Archives of Neurology

• High C-Reactive Protein may be a marker of memory and visuospatial impairment in the elderly.

Food and Chemical Toxicology

• A safety evaluation of ingested Acrylamide by humans was conducted using a newly developed, state-of-the-art physiologically-based toxicokinetic (PBPK or PBTK) model to compare internal doses and its metabolite glycidamide (GA) in humans and rats. Based on modes of action (MoA), a nonlinear dose–response approach was applied for neurotoxicity (non-genotoxicity) and carcinogenicity. Tolerable daily intake (TDI) for neurotoxicity was estimated to be 40 μg/kg-day; TDIs for cancer were estimated to be 2.6 and 16 μg/kg-day based on AA or GA, respectively.