Epigenetic effects of folate and related B vitamins on brain health throughout life: Scientific substantiation and translation of the evidence for health improvement strategies

Suboptimal status of folate and/or interrelated B vitamins (B12 , B6 and riboflavin) can perturb one-carbon metabolism and adversely affect brain development in early life and brain function in later life. Human studies show that maternal folate status during pregnancy is associated with cognitive development in the child, whilst optimal B vitamin status may help to prevent cognitive dysfunction in later life. The biological mechanisms explaining these relationships are not clear but may involve folate-related DNA methylation of epigenetically controlled genes related to brain development and function. A better understanding of the mechanisms linking these B vitamins and the epigenome with brain health at critical stages of the lifecycle is necessary to support evidence-based health improvement strategies. The EpiBrain project, a transnational collaboration involving partners in the United Kingdom, Canada and Spain, is investigating the nutrition-epigenome-brain relationship, particularly focussing on folate-related epigenetic effects in relation to brain health outcomes. We are conducting new epigenetics analysis on bio-banked samples from existing well-characterised cohorts and randomised trials conducted in pregnancy and later life. Dietary, nutrient biomarker and epigenetic data will be linked with brain outcomes in children and older adults. In addition, we will investigate the nutrition-epigenome-brain relationship in B vitamin intervention trial participants using magnetoencephalography, a state-of-the-art neuroimaging modality to assess neuronal functioning. The project outcomes will provide an improved understanding of the role of folate and related B vitamins in brain health, and the epigenetic mechanisms involved. The results are expected to provide scientific substantiation to support nutritional strategies for better brain health across the lifecycle.

72 SEASONAL VARIATION IN HYPERPARATHYROIDISM IN OLDER IRISH ADULTS

Background

Vitamin D deficiency is common in Ireland, varies by season and can result in secondary hyperparathyroidism. High Parathyroid Hormone (PTH) levels due to low vitamin D status are associated with increased bone turnover and lower bone mineral density, especially at cortical sites such as the hip. Given the variation in vitamin D status by time of year, our study aimed to examine for seasonal differences in hyperparthyroidism in older adults.

Methods

Study participants were from a large cross-sectional study of older Irish adults recruited from hospital outpatient services and GP practices. Exclusion criteria were: eGFR< 30ml/min and elevated serum calcium (>2.5 mmol/l) in order to avoid primary hyperparathyroidism or elevated serum PTH due to advanced renal impairment. Hyperparathyroidism was defined as a PTH level > 65 ng/ml. The relationship between hyperparathyroidism and season was examined in regression models adjusting for potential factors affecting PTH.

Results

There were 4324 participants, mean age 73.8 +/- 7.9 years, 65.4% were female. Hyperparathyroidism was more prevalent in Spring versus Autumn (17.4 vs 11.4 %, P = 0.0002). The increased prevalence remained after adjusting for age, gender, body mass index, timed up and go, dairy intake, eGFR, and smoking (OR 1.6, 1.2- 2.0, P=0.0003). This also corresponded to the seasonal variation in vitamin D status with deficiency (25(OH)D < 30 nmol/l) highest in Spring (23.3%) and lowest in Autumn (16.8%).

Conclusion

We found that hyperparathyroidism fluctuates with season in an inverse relationship with vitamin D. Overall, high PTH levels were 60% more likely in Spring versus Autumn. This emphasises the importance of maintaining adequate vitamin D status all year round. While we adjusted for dairy intake, we did not have accurate measures of total dietary calcium intake which could also vary seasonally and be a contributory factor.

51 VITAMIN D DEFICIENCY IS ASSOCIATED WITH INCREASED RISK OF ATRIAL FIBRILLATION: A CROSS-SECTIONAL ANALYSIS

Background

Atrial Fibrillation (AF) is prevalent (up to 10.9%) in Irish adults aged over 65 and significantly increases stroke risk, as well as being associated with greater stroke severity. Identifying potential contributing factors to development of AF offers opportunity for AF prevention and reduction in associated morbidity. Low vitamin D status has been associated with AF but studies are inconsistent. We aimed to assess the potential relationship between vitamin D deficiency and self-reported AF in older Irish adults.

Methods

Participants were from a large cross-sectional study of Irish adults aged >60 years, recruited from hospital outpatient services and GP practises. The diagnosis of AF was based on self-report so those with a Mini Mental State Examination (MMSE) <25 were excluded. Vitamin D deficiency was defined as a 25(OH)D <30 nmol/l. The relationship between deficiency and AF was explored in regression models.

Results

4264 participants, mean age 73.1± 8.0 years, female (67.4%) and 11.9% had AF. There was a higher prevalence of AF in those who were deficient vs non-deficient (17.2% vs 10.9%, P<0.0001). In a subsample (n = 4043), increased risk remained after adjusting for age, gender, season, vitamin D supplement use, body mass index, timed up and go, alcohol intake, smoking status, hypertension, diabetes, and heart disease (coronary artery disease and/or heart failure) (OR: 1.3, 1.1- 1.7 , P =0.023).

Conclusion

We identified that vitamin D deficiency was independently associated with a 30% increased likelihood of self-reported AF in older adults. Vitamin D is known to inhibit the renin angiotensin, aldosterone system which may play a role in both structural and electrical remodelling of the atrium. It may also have anti-inflammatory properties which could protect against AF. We were not able to distinguish between valvular and non-valvular AF though findings offer an interesting insight for potential further investigation.

73 PREVALENCE OF SECONDARY HYPERPARATHYROIDISM BY VITAMIN D STATUS IN OLDER IRISH ADULTS

Background

Secondary hyperparathyroidism commonly results from vitamin D deficiency and can lead to accelerated bone turnover and bone loss, especially at cortical sites like the hip. It can also attenuate the response to antiresorptive treatments used for osteoporosis. However, several factors may influence PTH response. We aimed to identify the prevalence of secondary hyperparathyroidism by categories of vitamin D status in older Irish adults attending a bone health clinic.

Methods

The study population consisted of older adults (aged over 60 years) attending a bone health clinic at a large hospital. Participants with a serum calcium >2.5 mmol/l and eGFR <30 ml/min were excluded to avoid cases of primary hyperparathyroidism or elevated serum PTH due to advanced renal disease. Hyperparathyroidism was defined as a serum PTH > 65 pg/ml. 25 hydroxyvitamin D (25(OH)D) was measured with liquid chromatography mass spectroscopy.

Results

There were 800 cases identified, mean age 72.9 +/- 7.9 years, and 85.3% were female. The prevalence of secondary hyperparathyroidism by 25(OH)D categories were 28.1% (<30nmol/l), 17.4% (30-49.9 nmol/l) and 8.0% (50-74 nmol/l). Older age (P < 0.03) and lower eGFR (P = 0.01) were associated with hyperparathyroidism independent of vitamin D status.

Conclusion

Nearly one-third of patients who were vitamin D deficient (<30 nmol/L) and one-sixth who were insufficient (30-49.9 nmol/l) had hyperparathyroidism, similar to the results of other studies. However, hyperparathyroidism was also observed in 8% of those with 25(OH)D levels between 50 -74 nmol/l, suggesting that higher levels i.e. ≥ 75 nmol/l may be preferable in older adults. Lower eGFR and older age were also independently associated with higher PTH, consistent with previous research. Higher dietary and supplemental calcium intake is also known to suppress PTH response, though we were not able to account for this in our study.

17 CROSS-SECTIONAL AND LONGITUDINAL RELATIONSHIPS BETWEEN MOBILITY, NEUROPSYCHOLOGICAL PERFORMANCE AND FALLS IN COMMUNITY-DWELLING OLDER ADULTS: DATA FROM TUDA

Background

Impaired mobility is associated with incident cognitive impairment and dementia. However, the complex bi-directional temporal relationships between subtle impairments in neuropsychological performance, mobility trajectories and falls is poorly understood.

Methods

Using data from the Trinity, Ulster Department of Agriculture (TUDA/TUDA5+) study, we evaluated cross-sectional and longitudinal relationships between impaired mobility, neuropsychological performance and falls using regression models adjusted for important clinical confounders. Older adults with potential cognitive impairment (Mini-Mental State Examination score <25) were excluded. Detailed neuropsychological assessment was performed using the RBANS (Repeatable Battery for Neuropsychological Assessment) and FAB (Frontal Assessment Battery). Impaired mobility was assessed using Irish population-specific age/sex/height-specific Timed-Up-and-Go (TUG) cut-offs.

Results

Of 4,103 participants (72.9 ± 7.9 years; 67.4% female), just under one-fifth (17.5%) met criteria for impaired mobility. Older adults with impaired mobility had significantly greater likelihood of impaired neuropsychological performance, in particular for language (OR 1.77; 1.35-2.31; p<0.001) and attention (OR 1.69; 1.37-2.08; p<0.001) domains. In 953 participants followed for a median 5.2 (IQR: 4.83-7.26) years, impaired mobility at baseline significantly predicted incident impairment in immediate memory (OR 2.56; 1.33-4.95; p<0.001). Stronger relationships were seen for impaired neuropsychological performance predicting mobility decline rather than impaired mobility predicting cognitive decline (all p<0.001). Both impaired mobility and neuropsychological performance were associated with incident falls, particularly for impairments in executive function and attention (all p<0.001). Impaired mobility in isolation had poor performance as a sole test to predict incident cognitive impairment (AUC: 0.55-0.65).

Conclusion

In both cross-sectional and longitudinal analyses, impaired mobility is associated with subtle impairments in neuropsychological performance. Whilst impaired neuropsychological performance was a greater predictor of impaired mobility rather than vice versa, our findings highlight the complex relationship between mobility and cognitive trajectories in older adults, emphasising the need for comprehensive cognitive and falls assessment in those presenting with new-onset subtle impairments in mobility and cognition.

261 HIGH FRACTURE RISK IN OLDER IRISH ADULT FALLERS

Background

Fracture risk due to falls depends on several factors including bone density, quality and size, hip geometry (axis length), direction of fall (forward, backwards or sideways), body mass index (BMI), type of surface impacted, body site of impact and mechanism of fall (eg syncope). We aimed to identify the fracture risk per fall in frail older Irish adults.

Methods

Participants were from the hypertensive and cognitive cohort of the Trinity, Ulster, Dept Agriculture (TUDA) study of Irish adults (aged >60) recruited from hospital outpatient services and GP practises. Falls and falls resulting in fracture in the previous year were self-reported so those with an MMSE < 25 were excluded to avoid recall bias. We identified fallers, recurrent fallers and fractures due to falls in the previous year.

Results

892 fallers, mean age 76.3 ± 8.4 yrs, 65.2% female. 23.8% had 2 falls and 24.2% ≥3 falls. Mean timed up and go was 17.3 ± 9.5 seconds. Commonest fracture due to falls were hip (20.1%), upper limb (18.5%) and lower limb (17.9%) with one fracture of neck and skull. Fracture rate per fall was 7.1%: 1.7% for hip, 1.3% for lower and 1.2% for upper limb. Annual fracture rate per faller was 16.5%. The only predictors of fall with fracture versus no fracture were female sex (OR 2.4, 1.6-3.6, P<0.001) and lower body mass index (P=0.001).

Conclusion

We identified similar hip fracture rates (1.7%) due to falls as in other studies. However, one in six fallers had sustained a fracture in the previous year reflecting the high proportion of recurrent fallers. Lower BMI and female sex predicted fall with fracture as both are strongly correlated with risk of osteoporosis. Recent guidelines now factor in recurrent falls when estimating the probability of future osteoporotic fractures.

126 CENTRAL ADIPOSITY IS ASSOCIATED WITH INCREASED PREVALENCE OF VERTEBRAL FRACTURES

Background

Increased body weight and obesity are associated with greater bone mineral density (BMD) though effects on fracture risk appear to be site specific. In particular, the relationship between Body Mass Index (BMI), abdominal weight and Vertebral Fractures (VF) is complex. Some studies have found greater incidence of VF's with obesity though results are inconsistent. Recent evidence supports a stronger association between measures of abdominal fat and VF's. We aimed to examine the association between central adiposity and VF's in older Irish adults.

Methods

Participants were from a large cross-sectional study of older Irish adults (aged >60) attending GP or hospital outpatient services. VF diagnosis was based on self-report (ie. clinical vertebral fracture) so we excluded those with a Mini Mental State Examination (MMSE) < 25. BMD was measured with DXA and patients taking antiresorptive or anabolic therapies were excluded. The relationship of waist hip ratio (a surrogate marker of central adiposity) with VF's was explored in regression models.

Results

2055 identified, mean age 69.8 ± 6.3 years (range 60-99), 58.6% female. Vertebral fracture prevalence was 6.3% (n=130). Waist hip ratio was positively associated with presence of a vertebral fracture after adjusting for age, sex, BMI, timed up and go, smoking, serum vitamin D, lumbar spine BMD and steroid use > 3 months (beta: 0.04, P<0.001).

Conclusion

We identified that central adiposity (as measured by waist/hip ratio) was associated with VF presence independent of several factors including BMI and spine BMD. This suggests that body fat distribution and/or altered bone quality may play a role. Visceral body fat (which is correlated with waist hip ratio) is associated with increased production of adipocytokines, altered vertebral geometry and micro-architecture, increased vertebral bone marrow fat and greater loading forces on the spine, all of which may mediate increased VF risk.

43 REDUCED KIDNEY FUNCTION IS ASSOCIATED WITH POORER GLOBAL AND DOMAIN-SPECIFIC COGNITIVE PERFORMANCE IN COMMUNITY-DWELLING OLDER ADULTS

Background

Chronic Kidney Disease (CKD) is an important risk factor in the development of cognitive impairment. However, the association between reduced estimated Glomerular Filtration Rate (eGFR) and performance on domain-specific cognitive and neuropsychological assessments is less clear and may represent an important target in the promotion of optimal brain health in older adults.

Methods

Participants from the Trinity, Ulster and Department of Agriculture cohort study underwent detailed assessment of cognitive and neuropsychological function using the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB) and Repeatable Battery for Assessment of Neuropsychological Status (RBANS). Mixed-effects Poisson and linear regression was used to assess the relationship between eGFR strata and cognitive/neuropsychological test performance.

Results

4,887 participants were included (73.94 ± 8.25 years; 67.7% female). Reduced eGFR was associated with poorer performance on all three cognitive assessments, most pronounced in those with eGFR <45 mL/mL/1.73m2 (IRR: 1.19; 95% CI: 1.09, 1.29; p < 0.001 for MMSE/IRR: 1.14; 95% CI 1.04, 1.24; p < 0.001 for the FAB/β: -3.23; 95% CI -5.18, −1.30; p = 0.001 for RBANS, fully adjusted). Reduced eGFR was associated with poorer performance on immediate memory, visual–spatial and attention RBANS domains. Associations were strongest in the youngest old (<70 years) with no association observed in those aged >80 years.

Conclusion

Reduced kidney function was associated with poorer global and domain-specific function in community-dwelling older adults. Associations were strongest for those with eGFR <45 mL/min/1.73m2 and the youngest-old, suggesting that this group may be most at risk and may benefit from potential preventative interventions.

135 VITAMIN D FORTIFIED MILK—EFFECT ON VITAMIN D STATUS IN OLDER ADULTS

Background

Vitamin D fortified milk is used by some older adults to boost vitamin D status. Combined vitamin D/calcium supplements often cause gastrointestinal upset which reduces adherence. Consumption of fortified milk may be a more consistent and reliable way of increasing serum 25 hydroxyvitamin D [25(OH)D], though studies of it’s efficacy in older adults are limited.

Methods

We examined the vitamin D status of users of vitamin D fortified milk in participants of a longitudinal study of community dwelling Irish adults aged >60 yrs. Patients taking vitamin D supplements were excluded and independent effects were explored in multinomial regression models. Vitamin D deficiency was defined as a 25(OH)D level < 30 nmol/l.

Results

2496 participants were identified: mean age was 70.5 ± 7.0 years (range 60–96 yrs) and 145 (5.8%) reported using vitamin D fortified milk. In those who consumed fortified milk, there was a lower prevalence of vitamin D deficiency (17.9 vs 34.5%, P < 0.001). Vitamin D fortified milk also predicted less deficiency after adjusting for age, gender, season, BMI and physical frailty (OR 0.30. CI 0.19–0.48, P < 0.001).

Conclusion

Vitamin D fortified milk was associated with a 70% reduction in the risk of vitamin D deficiency in older adults not taking vitamin D supplements. Findings support the use of vitamin D fortified milk as an effective means of improving vitamin D status. Fortified milk also contains additional calcium and so can be used to augment daily calcium intake.

101 FACTORS ASSOCIATED WITH FEAR OF FALLING IN OLDER IRISH ADULTS

Background

Fear of falling is common in older adults and is associated with social isolation, reduced quality of life, depression and increased mortality. We aimed to investigate the factors associated with fear of falling in a cohort of older Irish adults.

Methods

Our study included adults aged ≥60 years attending outpatient services and recruited as part of the TUDA (Trinity, Ulster and Department of Agriculture) study. Physical frailty was measured with the Timed Up and Go (TUG), cognition with the Mini Mental State Examination (MMSE) and depression with the Center for Epidemiological Studies Depression scale (CES-D). Factors associated with fear of falling were explored in multinomial regression models.

Results

5185 adults were included, 67.3% female and mean age 74.0 ± 8.3 yrs. Fear of falling varied by age: 39.4% (60-70 yrs), 51.2% (70-80 yrs), 70.4% (80 + yrs). Independent positive predictors of fear of falling were age (beta 0.01, P = 0.030), female gender (OR 2.6, CI 2.2–3.2, P < 0.001), fall in the previous year (OR 1.9, CI 1.6–2.3, P < 0.001), depression (CES-D ≥ 16) (OR 1.7, CI 1.3–2.2, P < 0.001), use of osteoporosis medications (OR 1.3, CI 1.1–1.6, P = 0.002), self reported dizziness on standing (OR 1.5, CI 1.3–1.8, P < 0.001), physical frailty (TUG >12 seconds, OR 1.30, CI 1.1–1.6, P = 0.004) and limiting outside activities (OR 16.3, CI 13.8–19.3, P < 0.001).

Conclusion

We identified a high prevalence of fear of falling, though our study sample included frail older adults attending geriatric outpatient services. Those who fell in the last year and who were female were about twice as likely to fear falling. It was also more likely in those who were physically frailer, taking osteoporosis medications and reporting orthostatic symptoms. Notably those with a fear of falling were 70% more likely to be depressed and 16 times more likely to limit outside activities highlighting its negative impact.

130 PREDICTORS OF DRIVING STATUS IN OLDER IRISH ADULTS ATTENDING A GERIATRIC OUTPATIENT SERVICE

Background

The main mode of transportation in Ireland remains travel by car. Transport mobility is important for older adults in accessing shops, healthcare, services, community and in maintaining relationships. Cessation of driving is associated with negative effects on mental health, loneliness and physical health. We aimed to explore factors associated with driving status in older adults living in an urban environment.

Methods

Study included adults aged greater than 65 years attending a geriatric outpatient service in an urban environment and recruited as part of the TUDA (Trinity Ulster, Department of Agriculture) study. We excluded those with a MMSE (Mini-Mental State Exam) less than 24 as we aimed to include only non-dementia patients. Physical frailty was measured with the Timed Up and Go (TUG) and depression with the Center for Epidemiological Studies Depression scale (CES-D). Factors associated with driving status were explored in multinomial regression models.

Results

1978 adults, mean age 77.7 ± 7.1 years, 76.0% were female. 35.5% were current drivers but this differed by age category 45.9% (65–75 years), 25% (75–85 years) and 12.5% (85+ years). 28.1% were past drivers. Positive independent predictors of current driving were younger age (P < 0.001), male gender (P < 0.001), married status (P = 0.01), higher socioeconomic status (P < 0.0001) while negative predictors included physical frailty (TUG, P < 0.001), visual impairment (P = 0.01), stroke (P < 0.001), depression (P < 0.001) and self reported loneliness (P = 0.01).

Conclusion

One third of patients attending a geriatric outpatients in an urban environment were currently driving which is much lower than in the general older Irish population. However, our study included frail adults living in more deprived socioeconomic areas and had a high proportion of females who had never learned to drive. Furthermore, access to urban public transport may be a factor. Non-drivers were more likely to have depression and report loneliness independent of other factors highlighting its negative impact.

A holistic approach to healthy ageing: how can people live longer, healthier lives?

BACKGROUND

Although lifespan is increasing, there is no evidence to suggest that older people are experiencing better health in their later years than previous generations. Nutrition, at all stages of life, plays an important role in determining health and wellbeing.

METHODS

A roundtable meeting of UK experts on nutrition and ageing considered key aspects of the diet-ageing relationship and developed a consensus position on the main priorities for research and public health actions that are required to help people live healthier lives as they age.

RESULTS

The group consensus highlighted the requirement for a life course approach, recognising the multifactorial nature of the impact of ageing. Environmental and lifestyle influences at any life stage are modified by genetic factors and early development. The response to the environment at each stage of life can determine the impact of lifestyle later on. There are no key factors that act in isolation to determine patterns of ageing and it is a combination of environmental and social factors that drives healthy or unhealthy ageing. Too little is known about how contemporary dietary patterns and sedentary lifestyles will impact upon healthy ageing in future generations and this is a priority for future research.

CONCLUSIONS

There is good evidence to support change to lifestyle (i.e. diet, nutrition and physical) activity in relation to maintaining or improving body composition, cognitive health and emotional intelligence, immune function and vascular health. Lifestyle change at any stage of life may extend healthy lifespan, although the impact of early changes appears to be greatest.

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.

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.

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.

B-vitamins, homocysteine metabolism and CVD

The present review focuses on the B-vitamins, i.e. folate, vitamin B12, vitamin B6and riboflavin, that are involved in homocysteine metabolism. Homocysteine is a S-containing amino acid and its plasma concentrations can be raised by various constitutive, genetic and lifestyle factors, by inadequate nutrient status and as a result of systemic disease and various drugs. Hyperhomocysteinaemia is a modest independent predictor of CVD and stroke, but causality and the precise pathophysiological mechanism(s) of homocysteine action remain unproven. The predominant nutritional cause of raised plasma homocysteine in most healthy populations is folate insufficiency. Vitamin B12and, to a lesser extent, vitamin B6are also effective at lowering plasma homocysteine, especially after homocysteine lowering by folic acid in those individuals presenting with raised plasma homocysteine. However, riboflavin supplementation appears to be effective at lowering plasma homocysteine only in those individuals homozygous for the T allele of the C677 T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene. This gene codes for the MTHFR enzyme that produces methyltetrahydrofolate, which, in turn, is a substrate for the remethylation of homocysteine by the vitamin B12-dependent enzyme methionine synthase. Individuals with the MTHFR 677 TT genotype are genetically predisposed to elevated plasma homocysteine, and in most populations have a markedly higher risk of CVD.

Investigation of systemic folate status, impact of alcohol intake and levels of DNA damage in mononuclear cells of breast cancer patients

Folate is required for DNA synthesis, repair and methylation. Low folate status has been implicated in carcinogenesis, possibly as a result of higher rate of genetic damage. The aim of this study is to compare folate status and levels of DNA damage between breast cancer and benign breast disease control patients. Fasting blood samples from 64 histologically confirmed untreated breast cancer patients (mean age 57 years) and 30 benign breast disease control patients (mean age 51 years) were obtained. Red cell folate (RCF) and plasma homocysteine were measured. Mononuclear cells (MNC) were isolated for genetic damage analysis using the basic alkaline comet assay. Results are expressed as tail moment. Data were log transformed as appropriate before analysis for normalisation purposes. The geometric mean (95% confidence interval) of RCF (ng ml⁻¹) in breast cancer patients was 339.07 (333.3–404.6) vs 379.5 (335.8–505.2) in control patients (P=0.24). Corresponding plasma homocysteine concentrations (μmol l⁻¹) were 11.9 (10.6–16.4) vs 10.1 (9.3–11.9) (P=0.073), respectively. The mean tail moment (s.d.) of DNA damage in MNC of breast cancer patients detected by the basic comet assay was 1.4 (0.66) vs –0.17 (0.79) in controls (P<0.0001, t-test), the modified comet assay ‘endonuclease III (Endo III)’ was 1.7 (0.70) vs 0.86 (0.81) (P<0.0001, t-test), and the modified comet assay ‘formamidopyrimidine glycosylase (FPG)’ was 1.6 (0.62) vs 0.99 (0.94) (P<0.0001, t-test). There was a significant negative correlation between RCF levels and DNA damage detected by modified comet assay ‘FPG’ (Pearson Correlation Coefficient r²=−0.26, P=0.02) and DNA damage was found to be significantly higher in MNC of breast cancer patients compared to benign breast disease control patients. Breast cancer patients tended to have lower RCF levels and higher levels of plasma homocysteine, but these differences were not significant. The study provides preliminary evidence that reduced folate status may be implicated in the aetiology of breast cancer perhaps by increasing the in vivo level of genetic instability.

Total homocysteine is not a determinant of arterial pulse wave velocity in young healthy adults

AIMS

Hyperhomocysteinaemia has been associated with reduced pulse wave velocity (PWV) in patients with end-stage renal disease and in those with hypertension. The aim of this study was to examine the association between total homocysteine (tHcy) concentrations, the biochemical and genetic determinants of tHcy and PWV in healthy young adults.

METHODS AND RESULTS

A total of 489 subjects aged 20-25 years participated. A fasting blood sample was taken and PWV measured using a non-invasive optical method. tHcy did not correlate with PWV, whether assessed at the aorto-iliac segment (P = 0.18), the aorto-radial segment (P = 0.39) or the aorto-dorsalis-pedis segment (P = 0.22). When tHcy was classified into normal (<15) and high (> or =15micromol/l), PWV did not differ between the two groups at any segment. PWV did not differ by MTHFR C677T or NOS3 G894T genotype, even when smoking and folate sub-groups were considered. Considering aortic PWV as a dependent variable, stepwise regression analysis showed that the only parameter entering the model for all segments was systolic blood pressure (aorto-iliac, P < 0.001; aorto-radial, P = 0.01; aorto-dorsalis-pedis, P = 0.001). Age, sex, COL1A1 genotype and triglycerides entered the model significantly for two of three segments.

CONCLUSION

This study shows that arterial PWV is not associated with tHcy in a healthy young population.

Acute absorption of folic acid from a fortified low-fat spread

OBJECTIVE

To explore the feasibility of low-fat spreads as vehicles for folic acid (FA) fortification by determining the acute absorption of FA from a fortified spread.

DESIGN

Double blind, crossover study to test each of the following treatments administered at 1-weekly intervals: (A) 20 g low-fat (40%) spread fortified with 200 microg FA and a placebo tablet; (B) 20 g low-fat placebo spread and a 200 microg FA tablet; (C) 20 g low-fat placebo spread and a placebo tablet.

SUBJECTS

A total of 13 male volunteers, aged 31.8+/-13.2 y.

MAIN OUTCOME MEASURES

Plasma total folate concentrations, measured before and up to 10 h after each treatment (n=10 samples per treatment).

RESULTS

Plasma folate concentrations were significantly increased compared with baseline values 1 h after administration of the FA tablet, and 1.5 h after the FA spread, and remained significantly higher than the baseline values for up to 7 h after both treatments. The maximum plasma folate response (R(max)), corrected for baseline values and 'placebo response', was established between 1 and 3 h postprandially in response to both FA spread and FA tablet, and no significant difference in R(max) was found between the two treatments (13.4 vs 14.4 nmol/l, P=0.9). The acute absorption of FA from fortified spread relative to that from the tablet, calculated on the basis of area under the plasma folate response curve, was 67% (P=0.04).

CONCLUSION

The absorption of FA from fortified low-fat spread, although lower than from a tablet, is effective. These results suggest that low-fat spreads, typically associated with fat-soluble vitamin fortification, may also be considered feasible as vehicles for FA fortification.

Detection of replicative integrity in small colonic biopsies using the BrdUrd comet assay

The alkaline single-cell gel electrophoresis or comet assay is a relatively simple method of measuring DNA single-strand breaks and alkali-labile sites in individual cells. Previously, we have used a combination of this with bromodeoxyuridine labelling of DNA and immunolocalisation of the BrdUrd to show that DNA replicative integrity can be assessed in single cultured cells. This study demonstrates the application of the technique to single cells derived from small human colonic biopsies isolated at routine endoscopy. A high level of reproducibility within replicate comet slides and between comet slides prepared from various colonic sites within a single patient is shown. Preliminary results demonstrate that defects in replication can be detected in tumour and premalignant colonic tissue adjacent to the tumour, suggesting that alterations in replicative integrity are an early event in neoplasia, appearing in premalignant mucosal cells. This development deems the BrdUrd comet assay suitable as an ex vivo molecular end point that can be measured easily in tissue collected by biopsy at routine colonic endoscopy. Thus, the BrdUrd comet assay has the potential to facilitate trial investigations of diet- or environment-related factors that may affect replicative integrity in the colon and provides a novel biomarker for colon carcinogenesis.

Effect of riboflavin supplementation on plasma homocysteine in elderly people with low riboflavin status

OBJECTIVE

To investigate the effect of riboflavin supplementation on plasma homocysteine (tHcy) concentrations in healthy elderly people with sub-optimal riboflavin status.

DESIGN

A double-blind, randomized, placebo-controlled riboflavin supplementation trial.

SETTING

Community based study in Northern Ireland.

SUBJECTS

From a screening sample of 101 healthy elderly people, 52 had sub-optimal riboflavin status (erythrocyte glutathione reductase activation coefficient, EGRAC>or=1.20) and were invited to participate in the study.

INTERVENTION

The intervention had two parts. Part 1 was a 12 week randomized double blind, placebo-controlled intervention with riboflavin (1.6 mg/day). Following completion of part 1, the placebo group went on to part 2 of the study which involved supplementation with folic acid (400 micro g/day) for 6 weeks followed by folic acid and riboflavin (1.6 mg/day) for a further 12 weeks, with a 16 week washout period post-supplementation. The purpose of part 2 was: (a) to address the possibility that homocysteine-lowering in response to riboflavin may be obscured by a much greater effect of folate, and that, once folate status was optimized, a dependence of homocysteine on riboflavin might emerge; and (b) to demonstrate that these subjects had homocysteine concentrations which could be lowered by nutritional intervention.

RESULTS

Although riboflavin supplementation significantly improved riboflavin status in both parts 1 and 2 of the study (P<0.001 for each), tHcy concentrations were unaffected (P=0.719). In contrast, folic acid supplementation (study part 2) resulted in a homocysteine lowering of 19.6% (P=0.001).

CONCLUSION

Despite the metabolic dependency of tHcy on riboflavin, it did not prove to be an effective homocysteine-lowering agent, even in the face of sub-optimal riboflavin status.

Importance of both folic acid and vitamin B12 in reduction of risk of vascular disease

Fortification of food with folic acid to prevent neural-tube defects in babies also lowers plasma total homocysteine, which is a risk factor for vascular disease. We investigated the effect of folate and vitamin B12 on homocysteine concentrations. 30 men and 23 women received sequential supplementation with increasing doses of folic acid. After supplementation, the usual dependency of homocysteine on folate diminished, and vitamin B12 became the main determinant of plasma homocysteine concentration. This finding suggests that a fortification policy based on folic acid and vitamin B12, rather than folic acid alone, is likely to be much more effective at lowering of homocysteine concentrations, with potential benefits for reduction of risk of vascular disease.

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.

Low-dose vitamin B-6 effectively lowers fasting plasma homocysteine in healthy elderly persons who are folate and riboflavin replete

BACKGROUND

Current data suggest that physiologic doses of vitamin B-6 have no significant homocysteine-lowering effect. It is possible that an effect of vitamin B-6 was missed in previous trials because of a much greater effect of folic acid, vitamin B-12, or both.

OBJECTIVE

The aim of this study was to investigate the effect of low-dose vitamin B-6 supplementation on fasting total homocysteine (tHcy) concentrations in healthy elderly persons who were made replete with folate and riboflavin.

DESIGN

Twenty-two healthy elderly persons aged 63-80 y were supplemented with a low dose of vitamin B-6 (1.6 mg/d) for 12 wk in a randomized, double-blind, placebo-controlled trial after repletion with folic acid (400 microg/d for 6 wk) and riboflavin (1.6 mg/d for 18 wk); none of the subjects had a vitamin B-12 deficiency.

RESULTS

Folic acid supplementation lowered fasting tHcy by 19.6% (P < 0.001). After folic acid supplementation, baseline tHcy concentrations ranged from 6.22 to 23.52 micromol/L and 10 subjects had suboptimal vitamin B-6 status (plasma pyridoxal-P < 20 nmol/L). Two-way analysis of variance showed that the significant improvement in vitamin B-6 status in response to vitamin B-6 supplementation (on the basis of both pyridoxal-P: and the erythrocyte aspartate aminotransferase activation coefficient) was reflected in a significant reduction in plasma tHcy of 7.5%.

CONCLUSIONS

Low-dose vitamin B-6 effectively lowers fasting plasma tHcy in healthy subjects who are both folate and riboflavin replete. This suggests that any program aimed at the treatment or prevention of hyperhomocysteinemia should include vitamin B-6 supplementation.

Effect of supplemental methionine on plasma homocysteine concentrations in healthy men: a preliminary study

Hyperhomocysteinaemia is an established risk factor for vascular disease. The only source of homocysteine in humans is the amino acid methionine found in dietary protein. In an 8-week study, fasting plasma homocysteine concentrations were examined in a group of healthy male subjects (n = 6) under usual dietary conditions (weeks 1-4) and in response to weekly graded (25, 50 and 75 mg/kg/d) supplementary methionine (weeks 5, 6, 7). Nutrient intakes, including methionine, were calculated from 4 x 3 day food records. Under usual dietary conditions (mean methionine intake; 0.95 +/- 0.51 mg/d) weekly mean plasma homocysteine concentrations for the group were not significantly different (ANOVA) from each other ranging from 6.82 +/- 1.77 to 9.42 +/- 2.73 mumol/l. Doubling (supplementing with 25 mg/kg/d; + 2.04 g/d) or quadrupling (50 mg/kg/d; + 4.08 g/d) methionine intakes did not result in a significant increase in plasma homocysteine (8.56 +/- 3.68 mumol/l and 13.37 +/- 5.09 mumol/l respectively). A significant increase, however, was achieved when diets were supplemented with methionine at the highest level of 75 mg/kg/d (+6.14 g/d) resulting in a mean plasma homocysteine concentration of 18.05 +/- 11.8 mumol/l. Mean plasma homocysteine concentration returned to baseline (8.76 +/- 3.42 mumol/l), 10 days post-supplementation. The results of this study indicate that an increased dietary methionine will only cause elevated fasting homocysteine concentrations if ingested at intakes equivalent to five times usual intake. Because it is very unlikely that such levels could be achieved through dietary means alone we conclude that plasma homocysteine is unlikely to be affected by longer-term changes in food methionine intake.

Fluctuations in dietary methionine intake do not alter plasma homocysteine concentration in healthy men

A moderate elevation in plasma total homocysteine (tHcy) has been established as an independent risk factor for vascular disease. An important exogenous source of homocysteine is methionine found in foods rich in animal protein. We investigated the response of tHcy to fluctuations in methionine intake in a cross-over intervention trial (two arms). Healthy men (n = 52; 19-29 y) were screened for habitual methionine intake using a food-frequency questionnaire. Subjects in the top quartile for methionine intake (n = 13), with a baseline fasting tHcy of 7.01 +/- 1.84 micromol/L (mean +/- SD), were randomly assigned to receive either a low-methionine intervention diet for 1 wk followed by a control diet for 1 wk or vice-versa. Simultaneously, those in the bottom quartile for methionine intake (n = 11), with a fasting plasma tHcy of 9.79 +/- 7. 20 micromol/L (mean +/- SD), received either a high methionine intervention diet for 1 wk followed by a control diet or vice-versa. All subjects had serum folate, red-cell folate, serum vitamin B-12 and plasma pyridoxal phosphate (PLP) concentrations within normal ranges. During the intervention, subjects in the top quartile for methionine intake reduced their daily methionine intake 79%, from 1969 +/- 639 to 407 +/- 83 mg/d (P: </= 0.001), and those in the bottom quartile almost doubled their methionine intake, from 1155 +/- 401 to 2112 +/- 379 mg/d (P: </= 0.001). Despite these changes in methionine intake, no corresponding changes in plasma tHcy were observed. These results suggest that in the absence of an obvious deficiency of relevant B-vitamins, fasting plasma tHcy is unaffected by intermediate-term fluctuations (up to 100% of usual intake) in dietary methionine.

Structure, antihyperglycemic activity and cellular actions of a novel diglycated human insulin

Human insulin was glycated under hyperglycemic reducing conditions and a novel diglycated form (M(r) 6135.1 Da) was purified by RP-HPLC. Endoproteinase Glu-C digestion combined with mass spectrometry and automated Edman degradation localized glycation to Gly(1) and Phe(1) of the insulin A- and B-chains, respectively. Intraperitoneal (i.p.) administration of diglycated insulin to mice alone or in combination with glucose (7 nmol/kg) resulted in a 43-61% and 11-34% reduction in glucose lowering activity, respectively, compared with native insulin. Consistent with these findings, diglycated insulin (10(-9) to 10(-7) mol/liter) was 22-38% less effective (P < 0.001) than native insulin in stimulating glucose uptake, glucose oxidation and glycogen production in isolated mouse abdominal muscle.

Impaired ability of glycated insulin to regulate plasma glucose and stimulate glucose transport and metabolism in mouse abdominal muscle

Previous studies have shown that glycated insulin is secreted from pancreatic beta-cells under conditions of hyperglycaemia. This study has investigated the effects of monoglycated insulin on plasma glucose homeostasis and in vitro cellular glucose transport and metabolism by isolated abdominal muscle of mice. Monoglycated insulin was prepared under hyperglycaemic reducing conditions, purified by RP-HPLC and identified by electrospray ionisation mass spectrometry (5971.1 Da). When administered to mice at an intraperitoneal dose of 7 nmoles/kg body weight, insulin (non-glycated) decreased plasma glucose concentrations and substantially reduced the glycaemic excursion induced by conjoint intraperitoneal injection of 2 g glucose/kg body weight. In comparison, the same dose of monoglycated insulin decreased plasma glucose concentrations to a lesser extent (P < 0.05), corresponding to an approx. 20% reduction of glucose lowering potency. Using isolated abdominal muscle, insulin (10(-9)-10(-7) M) stimulated dose-dependent increases in cellular 2-deoxy-D-[1-3H]glucose uptake, D-[U-14C]glucose oxidation and glycogen production. Monoglycated insulin was approx. 20% less effective than native insulin in stimulating glucose uptake and both indices of metabolism, generally requiring 10-fold greater concentrations to achieve significant stimulatory effects. These data indicate that the impaired biological activity of glycated insulin may contribute to glucose intolerance of diabetes.

Response of red blood cell folate to intervention: implications for folate recommendations for the prevention of neural tube defects

Committees worldwide have set almost identical folate recommendations for the prevention of the first occurrence of neural tube defects (NTDs). We evaluate these recommendations by reviewing the results of intervention studies that examined the response of red blood cell folate to altered folate intake. Three options are suggested to achieve the extra 400 microg folic acid/d being recommended by the official committees: increased intake of folate-rich foods, dietary folic acid supplementation, and folic acid fortification of food. A significant increase in foods naturally rich in folates was shown to be a relatively ineffective means of increasing red blood cell folate status in women compared with equivalent intakes of folic acid-fortified food, presumably because the synthetic form of the vitamin is more stable and more bioavailable. Although folic acid supplements are highly effective in optimizing folate status, supplementation is not an effective strategy for the primary prevention of NTDs because of poor compliance. Thus, food fortification is seen by many as the only option likely to succeed. Mandatory folic acid fortification of grain products was introduced recently in the United States at a level projected to provide an additional mean intake of 100 microg folic acid/d, but some feel that this policy does not go far enough. A recent clinical trial predicted that the additional intake of folic acid in the United States will reduce NTDs by >20%, whereas 200 microg/d would be highly protective and is the dose also shown to be optimal in lowering plasma homocysteine, with possible benefits in preventing cardiovascular disease. Thus, an amount lower than the current target of an extra 400 microg/d may be sufficient to increase red blood cell folate to concentrations associated with the lowest risk of NTDs, but further investigation is warranted to establish the optimal amount.

Community-living nonagenarians in northern ireland have lower plasma homocysteine but similar methylenetetrahydrofolate reductase thermolabile genotype prevalence compared to 70-89-year-old subjects

This cross-sectional study assessed relationships between plasma homocysteine, 'thermolabile' methylenetetrahydrofolatereductase (MTHFR) genotype, B vitamin status and measures of renal function in elderly (70-89 years) and nonagenarian (90+ years) subjects, with the hypothesis that octo/nonagenarian subjects who remain healthy into old age as defined by 'Senieur' status might show reduced genetic or environmental risk factors usually associated with hyperhomocysteinaemia. Plasma homocysteine was 9.1 micromol/l (geometric mean [GM]) for all elderly subjects. Intriguingly, homocysteine was significantly lower in 90+ (GM; 8.2 micromol/l) compared to 70-89-year-old subjects (GM; 9.8 micromol/l) despite significantly lower glomerular filtration rate (GFR) and serum B12 in nonagenarian subjects and comparable MTHFR thermolabile (TT) genotype frequency, folate and B6 status to 70-89-year-olds. For all elderly subjects, the odds ratio and 95% confidence intervals for plasma homocysteine being in the highest versus lowest quartile was 4.27 (2.04-8.92) for age <90 compared >90 years, 3.4 (1.5-7.8) for serum folate <10.7 compared >10.7nmol/l, 3.0 (0.9-10.2) for creatinine >140 compared <140 umol/l and 2.1 (1.0-4.4) for male sex. This study shows that plasma homocysteine does not invariably increase with age. Compared to similarly enlisted 70-89-year-olds, apparently well, mentally alert, community-living 90+ year olds approximating 'Senieur' status, show lower homocysteine, which is unexplained by renal function, TT genotype and B vitamin status, suggesting that lower homocysteine may be associated with survival.

Fortification with low amounts of folic acid makes a significant difference in folate status in young women: implications for the prevention of neural tube defects

BACKGROUND

Mandatory fortification of grain products with folic acid was introduced recently in the United States, a policy expected to result in a mean additional intake of 100 microgram/d. One way of predicting the effectiveness of this measure is to determine the effect of removing a similar amount of folic acid as fortified food from the diets of young women who had been electively exposed to chronic fortification.

OBJECTIVE

The objective was to examine the effect on folate status of foods fortified with low amounts of folic acid.

DESIGN

We investigated the changes in dietary intakes and in red blood cell and serum concentrations of folate in response to removing folic acid-fortified foods for 12 wk from the diets of women who reportedly consumed such foods at least once weekly (consumers).

RESULTS

Consumers (n = 21) had higher total folate intakes (P = 0.002) and red blood cell folate concentrations (P = 0.023) than nonconsumers (women who consumed folic acid-fortified foods less than once weekly; n = 30). Of greater interest, a 12-wk intervention involving the exclusion of these foods resulted in a decrease in folate intake of 78 +/- 56 microgram/d (P < 0.001), which was reflected in a significant reduction in red blood cell folate concentrations (P < 0.05).

CONCLUSIONS

Cessation of eating folic acid-fortified foods resulted in removing 78 microgram folic acid/d from the diet. Over 12 wk this resulted in a lowering of red blood cell folate concentrations by 111 nmol/L (49 microgram/L). This magnitude of change in folate status in women can be anticipated as a result of the new US fortification legislation and is predicted to have a significant, although not optimal, effect in preventing neural tube defects.

Riboflavin and vitamin B-6 intakes and status and biochemical response to riboflavin supplementation in free-living elderly people

Free-living elderly people aged > or = 65 y were recruited to assess riboflavin and vitamin B-6 intakes and status and the effect of riboflavin supplementation on biochemical indicators of these 2 vitamins. The status of riboflavin (erythrocyte glutathione reductase activation coefficient; EGRAC) and vitamin B-6 (plasma pyridoxal-5'-phosphate; PLP) were determined in a total sample of 92 subjects, from whom dietary intake data were obtained by using the diet history method (n = 83). Although dietary intakes of both vitamins were considered to be adequate according to current reference values, abnormal EGRAC and plasma PLP values were identified in 49% and 38% of subjects, respectively, with 21% having suboptimal status for both nutrients. A subgroup of subjects from the initial sample (n = 45) was assigned in a double-blind manner to receive either 1.6 or 25 mg riboflavin or placebo daily for 12 wk. In those subjects with a baseline EGRAC or plasma PLP value falling outside the currently accepted threshold value for adequacy, low-dose riboflavin supplementation improved status of the limiting nutrient significantly (P<0.0001 and P = 0.020 for EGRAC and plasma PLP responses, respectively). We conclude that a high proportion of healthy elderly people may have suboptimal status for these nutrients despite apparently adequate dietary intakes. Furthermore, we showed that riboflavin supplementation at physiologic doses corrects biochemical abnormalities of not only EGRAC, but also plasma PLP, confirming the biochemical interdependency of these vitamins and suggesting that riboflavin is the limiting nutrient.

Plasma homocysteine, a risk factor for cardiovascular disease, is lowered by physiological doses of folic acid

Elevated plasma homocysteine, an independent risk factor for cardiovascular disease (CVD) can be lowered by administration of pharmacological doses of folic acid. The effect of lower doses in apparently normal subjects is currently unknown but is highly relevant to the question of food fortification. Healthy male volunteers (n = 30) participated in a chronic intervention study (26 weeks). Folic acid supplements were administered daily at doses increasing from 100 micrograms (6 weeks), to 200 micrograms (6 weeks), to 400 micrograms (14 weeks). Fasting blood samples collected before, during and 10 weeks post intervention were analysed for plasma homocysteine, serum and red-cell folate levels. Results, expressed as tertiles of baseline plasma homocysteine concentration, showed significant (p < or = 0.001) homocysteine lowering in the top (10.90 +/- 0.83 mumol/l) and middle (9.11 +/- 0.49 mumol/l) tertiles only. In the low tertile, where the mean baseline homocysteine level was 7.07 +/- 0.84 mumol/l, no significant response was observed. Of the three folic acid doses, 200 micrograms appeared to be as effective as 400 micrograms, while 100 micrograms was clearly not optimal. There is thus a minimal level of plasma homocysteine below which folic acid has no further lowering effect, probably because an optimal folate status has been reached. A dose as low as 200 micrograms/day of folic acid is effective in lowering plasma homocysteine concentrations in apparently normal subjects. Any public health programme for lowering homocysteine levels, with the goal of diminishing CVD risk, should not be based on unnecessarily high doses of folic acid.