Dairy Intakes in Older Irish Adults and Effects on Vitamin Micronutrient Status: Data from the TUDA Study.

BACKGROUND: Consumption of dairy products has been associated with positive health outcomes including a lower risk of hypertension, improved bone health and a reduction in the risk of type 2 diabetes. The suggested dairy intake for health in older adults is three servings per day but recent analysis of the NHANES data for older adults reported 98% were not meeting these recommendations. No studies have investigated the consequences of such declines in the dairy intakes of Irish older adults and the subsequent effects on vitamin micronutrient status. OBJECTIVES: To study the daily dairy intakes of older Irish adults and to examine how the frequency of dairy food consumption affects vitamin micronutrient status. METHODS: Participants (n 4,317) were from the Trinity Ulster Department of Agriculture (TUDA) Study, a large study of older Irish adults (aged >60 yrs) designed to investigate gene-nutrient interactions in the development of chronic diseases of aging. The daily intake portion for milk, cheese and yoghurt was calculated from food frequency questionnaire (FFQ) responses. Blood samples were analysed for vitamin biomarkers as follows: vitamin B12 (total serum cobalamin and holotranscobalamin (holoTC)), folate (red cell folate (RCF) and serum folate), vitamin B2 (erythrocyte glutathione reductase activation coefficient (EGRac)), vitamin B6 (serum pyridoxal phosphate) and vitamin D (serum 25(OH)D). RESULTS: The mean total reported dairy intake was 1.16 (SD 0.79) portions per day with males consuming significantly fewer total dairy portions compared to females (1.07 vs 1.21 respectively) (P<0.05). There was no significant difference in total daily dairy serving intakes by age decade (60-69, 70-79, >80 yrs). Overall, only 3.5% of the total population (n 151) achieved the recommended daily dairy intake of three or more servings per day. A significantly higher proportion of females (4%) compared to males (2.4%) met these dairy requirements (P=0.011). Blood concentrations of vitamin B12 biomarkers, RCF, vitamin B2 and vitamin B6 were significantly worse in those with the lowest tertile of dairy intake (0-0.71 servings) compared to those in the highest tertile (1.50-4.50 servings) (P<0.05). CONCLUSION: This study found that more than 96% of the older adults sampled did not meet current daily dairy intake recommendations. The study is the largest to-date examining dairy intakes in older Irish adults, and provides evidence that daily dairy intakes (in particular yogurt) contribute significantly to the B-vitamin and vitamin D biomarker status of older adults. These results suggest that older adults who are already vulnerable to micronutrient inadequacies, are forgoing the nutritional advantages of vitamin-rich dairy products.

Greater yogurt consumption is associated with increased bone mineral density and physical function in older adults.

In this cohort of community dwelling older adults (>60 years), we observed significant positive associations between the frequencies of yogurt intake with measures of bone density, bone biomarkers, and indicators of physical function. Improving yogurt intakes could be a valuable health strategy for maintaining bone health in older adults. INTRODUCTION: The associations of yogurt intakes with bone health and frailty in older adults are not well documented. The aim was to investigate the association of yogurt intakes with bone mineral density (BMD), bone biomarkers, and physical function in 4310 Irish adults from the Trinity, Ulster, Department of Agriculture aging cohort study (TUDA). METHODS: Bone measures included total hip, femoral neck, and vertebral BMD with bone biochemical markers. Physical function measures included Timed Up and Go (TUG), Instrumental Activities of Daily Living Scale, and Physical Self-Maintenance Scale. RESULTS: Total hip and femoral neck BMD in females were 3.1-3.9% higher among those with the highest yogurt intakes (n = 970) compared to the lowest (n = 1109; P < 0.05) as were the TUG scores (-6.7%; P = 0.013). In males, tartrate-resistant acid phosphatase (TRAP 5b) concentrations were significantly lower in those with the highest yogurt intakes (-9.5%; P < 0.0001). In females, yogurt intake was a significant positive predictor of BMD at all regions. Each unit increase in yogurt intake in females was associated with a 31% lower risk of osteopenia (OR 0.69; 95% CI 0.49-0.96; P = 0.032) and a 39% lower risk of osteoporosis (OR 0.61; 95% CI 0.42-0.89; P = 0.012) and in males, a 52% lower risk of osteoporosis (OR 0.48; 95% CI 0.24-0.96; P = 0.038). CONCLUSION: In this cohort, higher yogurt intake was associated with increased BMD and physical function scores. These results suggest that improving yogurt intakes could be a valuable public health strategy for maintaining bone health in older adults.

Genome-wide studies of von Willebrand factor propeptide identify loci contributing to variation in propeptide levels and von Willebrand factor clearance.

UNLABELLED: Essentials Variants at ABO, von Willebrand Factor (VWF) and 2q12 contribute to the variation in plasma in VWF. We performed a genome-wide association study of plasma VWF propeptide in 3,238 individuals. ABO, VWF and 2q12 loci had weak or no association or linkage with plasma VWFpp levels. VWF associated variants at ABO, VWF and 2q12 loci primarily affect VWF clearance rates. SUMMARY: Background Previous studies identified common variants at the ABO and VWF loci and unknown variants in a chromosome 2q12 linkage interval that contributed to the variation in plasma von Willebrand factor (VWF) levels. Whereas the association with ABO haplotypes can be explained by differential VWF clearance, little is known about the mechanisms underlying the association with VWF single-nucleotide polymorphisms (SNPs) or with variants in the chromosome 2 linkage interval. VWF propeptide (VWFpp) and mature VWF are encoded by the VWF gene and secreted at the same rate, but have different plasma half-lives. Therefore, comparison of VWFpp and VWF association signals can be used to assess whether the variants are primarily affecting synthesis/secretion or clearance. Methods We measured plasma VWFpp levels and performed genome-wide linkage and association studies in 3238 young and healthy individuals for whom VWF levels had been analyzed previously. Results and conclusions Common variants in an intergenic region on chromosome 7q11 were associated with VWFpp levels. We found that ABO serotype-specific SNPs were associated with VWFpp levels in the same direction as for VWF, but with a much lower effect size. Neither the association at VWF nor the linkage on chromosome 2 previously reported for VWF was observed for VWFpp. Taken together, these results suggest that the major genetic factors affecting plasma VWF levels, i.e. variants at ABO, VWF and a locus on chromosome 2, operate primarily through their effects on VWF clearance.

Vitamin D deficiency is associated with inflammation in older Irish adults.

CONTEXT: Inadequate vitamin D status is common within elderly populations and may be implicated in the etiology of autoimmune disease and inflammation. Few studies have investigated the relationship between vitamin D status and age-related immune dysfunction in humans. OBJECTIVE: The aim of this study was to investigate the association between vitamin D status and immune markers of inflammation in a large sample of older adults. DESIGN, SETTING, AND PARTICIPANTS: An observational investigation of 957 Irish adults (>60 years of age) recruited in Northern Ireland (55°N latitude) as part of the Trinity Ulster Department of Agriculture aging cohort study. MAIN OUTCOME MEASURE: We measured serum 25-hydroxyvitamin D (25(OH)D) by liquid chromatography tandem mass spectrometry and serum cytokines IL-6, TNF-α, IL-10, and C-reactive protein (CRP) by ELISA. RESULTS: Concentrations of IL-6, CRP, and the ratios of IL-6 to IL-10 and CRP to IL-10 were significantly higher in individuals with deficient (<25 nmol/L) serum 25(OH)D compared with those with sufficient (>75 nmol/L) status after adjustment for age, sex, and body mass index (P < .05). Vitamin D status was a significant predictor of the IL-6 to IL-10 cytokine ratio, and those participants defined as deficient were significantly more likely to have an IL-6 to IL-10 ratio >2:1 compared with those defined as sufficient. CONCLUSIONS: This study demonstrated significant associations between low vitamin D status and markers of inflammation (including the ratio of IL-6 to IL-10) within elderly adults. These findings suggest that an adequate vitamin D status may be required for optimal immune function, particularly within the older adult population.

Associations between holotranscobalamin, vitamin B12, homocysteine and depressive symptoms in community-dwelling elders.

BACKGROUND: Vitamin B12 and homocysteine have been shown to be associated with depression or depressive symptoms, but the relationship has not been universal. Both vitamin B12 and homocysteine may exert an effect via vascular mechanisms; it is possible that other mechanisms apply. Holotranscobalamin is a novel, more accurate measure of tissue vitamin B12. OBJECTIVES: To examine associations between vitamin B12, serum folate, holotranscobalamin, homocysteine and depressive symptoms in a sample of healthy elderly. METHODS: Cross-sectional, observational community based study. RESULTS: Lower levels of holotranscobalamin and vitamin B12 were associated with higher levels of depressive symptoms when controlled for Mini-mental state examination scores and psychosocial and cardiovascular risk factors. Homocysteine was not associated with depressive symptoms when biological and psychosocial covariates were included. CONCLUSIONS: It is possible that low levels of vitamin B12 or holotranscobalamin are associated with depressive symptoms via mechanisms other than vascular pathology.

Vitamin B12 status, homocysteine and mortality amongst community-dwelling Irish elders.

BACKGROUND: Vitamin B12 deficiency is associated with hyperhomocysteinaemia, which is associated with atherosclerosis and increased mortality. High levels of vitamin B12 have also been associated with increased mortality in certain patient populations. AIMS: We examined vitamin B12 and homocysteine status and mortality rates in a population of Irish community-dwelling elders over a 3-year period. METHODS: Prospective, community-based observational cohort study. RESULTS: Subjects in the highest quartile of homocysteine had increased mortality rates (14.68 vs. 7.32%, relative risk 2.09). This relationship was attenuated when controlled for the presence or absence of a history of stroke or myocardial infarction. There was no relationship between vitamin B12 status and mortality during the observation period. CONCLUSION: Vitamin B12 levels are not associated with death rates in Irish community-dwelling elders. Homocysteine levels are associated with mortality and may act via the mechanism of atherosclerotic disease.

Transcobalamin II receptor polymorphisms are associated with increased risk for neural tube defects.

OBJECTIVE: Women who have low cobalamin (vitamin B(12)) levels are at increased risk for having children with neural tube defects (NTDs). The transcobalamin II receptor (TCblR) mediates uptake of cobalamin into cells. Inherited variants in the TCblR gene as NTD risk factors were evaluated. METHODS: Case-control and family-based tests of association were used to screen common variation in TCblR as genetic risk factors for NTDs in a large Irish group. A confirmatory group of NTD triads was used to test positive findings. RESULTS: 2 tightly linked variants associated with NTDs in a recessive model were found: TCblR rs2336573 (G220R; p(corr)=0.0080, corrected for multiple hypothesis testing) and TCblR rs9426 (p(corr)=0.0279). These variants were also associated with NTDs in a family-based test before multiple test correction (log-linear analysis of a recessive model: rs2336573 (G220R; RR=6.59, p=0.0037) and rs9426 (RR=6.71, p=0.0035)). A copy number variant distal to TCblR and two previously unreported exonic insertion-deletion polymorphisms were described. CONCLUSIONS: TCblR rs2336573 (G220R) and TCblR rs9426 represent a significant risk factor in NTD cases in the Irish population. The homozygous risk genotype was not detected in nearly 1000 controls, indicating that this NTD risk factor may be of low frequency and high penetrance. 9 other variants are in perfect linkage disequilibrium with the associated single nucleotide polymorphisms. Additional work is required to identify the disease-causing variant. Our data suggest that variation in TCblR plays a role in NTD risk and that these variants may modulate cobalamin metabolism.

Folate and clefts of the lip and palate--a U.K.-based case-control study: Part II: Biochemical and genetic analysis.

OBJECTIVE: To investigate associations between nonsyndromic oral clefts and biochemical measures of folate status and the MTHFR C677T variant in the United Kingdom, where there has been no folic acid fortification program. METHOD: Dietary details were obtained from the mothers of 112 cases of cleft lip with or without cleft palate (CL+/-P), 78 cleft palate only (CP) cases, and 248 unaffected infants. Infant and parental MTHFR C677T genotype was determined. Red blood cell (RBC) and serum folate and homocysteine levels were assessed in 12-month postpartum blood samples from a subset of mothers. The data were analyzed by logistic and log-linear regression methods. RESULTS: There was an inverse association between CL+/-P and maternal MTHFR CT (odds ratio [OR] = 0.5, 95% confidence interval [CI] = 0.31-0.95) and TT (OR = 0.6, 95% CI = 0.21-1.50) genotypes, with similar risk estimates for CP. There was no clear association with infant MTHFR genotype. Higher levels of maternal postpartum RBC and serum folate were associated with a lower risk for CL+/-P and an increased risk for CP. Higher levels of serum homocysteine were associated with a slightly increased risk for both CL+/-P and CP. CONCLUSION: While the inverse relation between the mother's having the MTHFR C677T variant and both CL+/-P and CP suggests perturbation of maternal folate metabolism is of etiological importance, contrasting relations between maternal postpartum levels of RBC and serum folate by type of cleft are difficult to explain.

Low-dose folic acid lowers plasma homocysteine levels in women of child-bearing age.

BACKGROUND: Ongoing clinical trials are investigating whether lowering plasma homocysteine reduces the risk of vascular disease. If so, food fortification with folic acid will be the likely result, and sub-optimal amounts are likely to be preferred, for safety reasons. Dose-finding studies are needed before the outcomes of these trials, to establish the benefits and risks of folic acid consumption over the widest intake range likely to be encountered. AIM: To find the lowest dose of folic acid that effectively reduces plasma homocysteine in premenopausal women. DESIGN: Double-blind, randomized placebo-controlled trial. METHODS: Women of child-bearing age (n=95) were randomly allocated to 0, 100, 200, or 400 microg/day of folic acid. Red-cell folate and plasma homocysteine were measured at baseline and after 10 weeks supplementation. RESULTS: Median red cell folate levels increased significantly in the 200 microg(p=0.0001) and 400 microg(p=0.0001) groups; but not in the placebo (0 microg) (p=0.25) or the 100 microg (p=0.5) groups. Only the 200 microg and the 400 microg groups had significant decreases in plasma homocysteine, (p=0.04 and p=0.0008, respectively). However, when subjects whose initial plasma homocysteine was <8 micromol/l (already optimally low) were removed from the analysis, there were significant plasma homocysteine decreases in all three treatment groups, but not the placebo group. DISCUSSION: In this sub-population, low doses of folic acid significantly lower plasma homocysteine. This could be achieved safely by fortification.

Elevated plasma homocysteine in early pregnancy: a risk factor for the development of severe preeclampsia.

OBJECTIVE: The aim of our study was to determine if an elevated plasma homocysteine level in early pregnancy is associated with the development of severe preeclampsia. STUDY DESIGN: Blood samples were obtained from patients attending their first antenatal visit. Cases were asymptomatic women who subsequently developed severe preeclampsia. Controls were matched for gestational age and date of sample collection. Plasma homocysteine level was measured by using fluorescence polarization immunoassay. RESULTS: There were 56 patients with severe preeclampsia from whom blood samples were obtained at a mean (+/-SD) gestation of 15.3 weeks (+/-4.04 weeks) and 112 controls at 14.9 weeks (+/-3.41 weeks). The preeclampsia cases had a mean (+/-SD) homocysteine level of 9.8 micromol/L (+/-3.3 micromol/L), whereas controls had a mean homocysteine level of 8.4 micromol/L (+/-1.9 micromol/L), P < or = .0001. CONCLUSION: Women who develop severe preeclampsia have higher plasma homocysteine levels in early pregnancy than women who remain normotensive throughout pregnancy. An elevated plasma homocysteine level in early pregnancy can increase the risk of developing severe preeclampsia by almost threefold.

Folates and prevention of disease.

Research in the past decade has established that low or inadequate folate status may contribute to congenital malformations and the development of chronic disease in later life. Using an evidence based approach, there are clear guidelines for recommending folic acid supplementation or fortification in certain disease conditions but further proof of its efficacy is required in other circumstances. There is conclusive evidence that maternal periconceptional supplementation with folic acid prevents the majority of NTDs, probably by overcoming one or more genetically inherited metabolic blocks in folate dependent enzymes. Public health efforts to advise women to increase their folate intake have not been successful. As a result, the U.S. government passed legislation to have all flour fortified with folic acid. This intervention has had a dramatic effect on folate status in the U.S. To date, countries of the EU have not adopted mandatory fortification policies. The amino acid homocysteine is an essential intermediate in folate metabolism. Substantial evidence indicates that elevated plasma homocysteine is an independent risk factor for heart disease and stroke. Plasma homocysteine levels can be reduced by folic acid supplements. A food fortification policy would probably be an effective population strategy to reduce plasma homocysteine. However, many experts believe that this would be premature without first showing that such reduction would cause a decrease in the prevalence of cardiovascular disease. The contribution of folate to cancer risk is not well defined although there is reasonable evidence to implicate low folate status in the specific case of colorectal cancer. In particular, long-term folic acid supplementation may reduce risk of colorectal cancer substantially. Various mental disorders including Alzheimer's Disease have been associated with low folate status or elevated plasma homocysteine. While it is hard to determine if this is cause or effect, there is little doubt that if it were true then low dose folic acid intervention would be highly effective.

The methylenetetrahydrofolate reductase (MTHFR) gene in colorectal cancer: role in tumor development and significance of allelic loss in tumor progression.

BACKGROUND AND AIM: Folate deficiency predisposes to sporadic colorectal cancer (CRC). Methylenetetrahydrofolate reductase (MTHFR) is a critical folate-metabolising enzyme and a polymorphism at position 677 (C677T), is associated with reduced enzyme activity. We investigated whether this functional polymorphism modulates the risk of developing CRC. METHODS: This was a retrospective case-control study. 136 unselected cases of sporadic CRC and 848 normal population controls were genotyped for the MTHFR C677T polymorphism. Tumor tissue was genotyped to assess loss of heterozygosity (LOH). RESULTS: MTHFR CT heterozygotes had a significantly increased risk of developing CRC (53.7% of CRC cases vs 38.4% of controls), odds ratio 1.86 (95% CI 1.3-2.7, p < 0.005). No increased cancer risk was observed in TT homozygotes. The MTHFR 'T' allele frequency was significantly higher in the cancer group (0.3713) as compared to controls (0.2900, p < 0.008). LOH at the MTHFR locus was observed in 18% of informative cancers, with exclusive loss of the variant 'T' allele, in all cases. CONCLUSION: In this study of a homogenous northern European population, MTHFR CT heterozygotes had an almost two-fold increased risk of developing sporadic CRC. The exclusive pattern of MTHFR allele loss in cases of LOH, suggest that functional MTHFR activity within a tumor might play an important role in the survival and progression of a colonic neoplasm.

Association between historically high frequencies of neural tube defects and the human T homologue of mouse T (Brachyury).

The human T developmental gene has been implicated in the etiology of neural tube defects (NTDs) on the basis both of mouse studies of its homologue, T (Brachyury), and of allelic association in a Caucasian population. We have investigated the frequency of the T allelic variant TIVS7-2 in 218 Irish NTD case-parent triads. This population showed the same trend as previously reported, with an excess of the TIVS7-2 allele among cases. Log-linear modeling of case and maternal genotypic effects within families indicated that TIVS7-2 was elevated in cases (relative risk, RR = 1.36) but not in mothers (RR = 0.91). The TIVS7-2 allele is markedly associated with cases born before 1980 (RR = 2.09; CI = 1.23-3.55; corrected p = 0.030), but not with more recent cases (RR = 0.92). Cases carrying a TIVS7-2 allele did not show any increased tendency to be homozygous for the thermolabile variant of the folate-dependent enzyme 5,10-methylene tetrahydrofolate reductase, which is an established genetic risk factor for NTDs. Since the incidence of NTDs has declined markedly in Ireland over the last few decades, we suggest that the T-associated risk is potentiated by nutritional or environmental risk factor(s), the impact of which have been diminishing over time.

Folate status and neural tube defects.

Periconceptional folic acid supplementation prevents approximately 70% of neural tube defects (NTDs). While most women carrying affected fetuses do not have deficient blood folate levels, the risk of having an NTD affected child is inversely correlated with pregnancy red cell folate levels. Current research is focused on the discovery of genetic abnormalities in folate related enzymes which might explain the role of folate in NTD prevention. The first candidate gene to emerge was the C677T variant of 5,10-methylenetetrahydrofolate reductase. Normal subjects who are homozygous for the mutation (TT) have red cell folate status some 20% lower than expected. It is now established that the prevalence of the TT genotype is significantly higher among spina bifida cases and their parents. Nevertheless, our studies show that the variant does not account for the reduced blood folate levels in many NTD affected mothers. We conclude that low maternal folate status may in itself be the most important risk factor for NTDs and that food fortification may be the only population strategy of benefit in the effort to eliminate NTDs.

The influence of 5,10 methylenetetrahydrofolate reductase genotypes on enzyme activity in placental tissue.

OBJECTIVE: To study the effects of heterozygosity and homozygosity for the C677T mutation of the 5,10 methylenetetrahydrofolate reductase (MTHFR) gene on the activity of this enzyme in placental tissue from pregnancies not affected by neural tube defect. DESIGN: Placental tissue was genotyped for the C677T variants of MTHFR. Total enzyme activity and residual activity after heating to 46 degrees C for 5 minutes was then measured. SETTING: A teaching hospital. SAMPLE: Placental samples (n = 200), one from each of 200 uncomplicated term deliveries. MAIN OUTCOME MEASURES: Total and residual enzyme activity for MTHFR. RESULTS: Placentae heterozygous for the C677T mutation of the MTHFR gene had significantly lower total enzyme activity than those without the mutation; the lowest activity occurred in homozygotes for the mutation. The same pattern was seen in relation to enzyme activity after heating. CONCLUSION: This study demonstrates that reduced enzyme activity is associated with the C677T variant of MTHFR in placental tissue. This is an important metabolic step in folic acid metabolism and pro-

Methylenetetrahydrofolate reductase thermolabile variant and oral clefts.

Folic acid can prevent neural tube defects; in some cases the mechanism is probably a correction of a metabolic defect caused by thermolabile methylenetetrahydrofolate reductase (MTHFR) found in increased frequency in cases. It is less clear whether folic acid can prevent oral clefts, in part because it is not known whether thermolabile MTHFR is more common in those with oral clefts. This study examined the prevalence of the mutation (677 C-->T) that causes thermolabile MTHFR in subjects with oral clefts from a national Irish support group, and an anonymous control group randomly selected from a neonatal screening program covering all births in Ireland. Eighty-three of 848 control subjects were homozygous (TT) thermolabile MTHFR (9.8%). This defect was almost three times as common in the 27 subjects (25.9%) with isolated cleft palate (odds ratio 3.23, 95% confidence interval 1.32 -7.86, P = 0. 02) and somewhat more common in the 66 subjects with cleft lip with or without cleft palate (15.2%, odds ratio 1.65, 95% confidence interval 0.81-3.35, P = 0.20). When the two groups with different etiologies were combined, the overall odds ratio was 2.06 (95% confidence interval 1.16-3.66, P = 0.02). In the Irish population homozygosity for the common folate-related polymorphism associated with thermolabile MTHFR is significantly more frequent in those with isolated cleft palate, and could be etiologically important. Am. J. Med. Genet. 86:71-74, 1999. Published 1999 Wiley-Liss, Inc.

Methionine synthase: high-resolution mapping of the human gene and evaluation as a candidate locus for neural tube defects.

Periconceptual folate supplementation has been found to prevent the occurrence of many neural tube defects (NTDs). Consequently, genetic variation in folate metabolism genes is expected to contribute to the risk for neural tube defects. Methionine synthase catalyzes the vitamin B(12)-dependent conversion of homocysteine and 5-methyltetrahydrofolate to methionine and tetrahydrofolate. The observation that homocysteine and vitamin B(12) levels are independent predictors of NTD risk suggested that methionine synthase could be a candidate gene for NTDs. To assess the role of the MS gene in NTDs, we performed high-resolution physical mapping of the MS locus, isolated highly polymorphic markers linked to the MS gene, and tested for an association between specific MS alleles and NTDs. We mapped the MS gene to a position between 909 and 913 cR(10000) on chromosome 1 by radiation hybrid mapping. Polymorphic markers D1S1567 and D1S1568 map to locations no more than 900 and 194 kb from the MS gene, respectively. The segregation of these polymorphic markers was measured in 85 Irish NTD families. No allele of either marker showed a significant association with NTDs using the transmission disequilibrium test. A lack of association was also observed for the D1919G missense mutation within the gene. Our results suggest that inherited variation in the MS gene does not contribute to NTD risk in this population.