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Parkinson’s disease (PD) is the second most common neurodegenerative disorder. It is characterised by the progressive degeneration of dopaminergic (DA) neurons. The cause of degeneration is not well understood; however, both genetics and environmental factors, such as nutrition, have been implicated in the disease process. Deficiencies in one-carbon metabolism in particular have been associated with increased risk for PD onset and progression, though the precise relationship is unclear. The aim of the present review is to determine the role of one-carbon metabolism and elevated levels of homocysteine in PD onset and pathology and to identify potential mechanisms involved. A search of PubMed, Google Scholar and Web of Science was undertaken to identify relevant human and animal studies. Case–control, prospective cohort studies, meta-analyses and non-randomised trials were included in the present review. The results from human studies indicate that polymorphisms in one-carbon metabolism may increase risk for PD development. There is an unclear role for dietary B-vitamin intake on PD onset and progression. However, dietary supplementation with B-vitamins may be beneficial for PD-affected individuals, particularly those on l-DOPA (levodopa or l-3,4-dihydroxyphenylalanine) treatment. Additionally, one-carbon metabolism generates methyl groups, and methylation capacity in PD-affected individuals is reduced. This reduced capacity has an impact on expression of disease-specific genes that may be involved in PD progression. During B-vitamin deficiency, animal studies report increased vulnerability of DA cells through increased oxidative stress and altered methylation. Nutrition, especially folates and related B-vitamins, may contribute to the onset and progression of PD by making the brain more vulnerable to damage; however, further investigation is required.
Recent studies have shown that micronutrients are involved in the pathology of type 2 diabetes. Antioxidant effects of vitamins C and B2 and homocysteine-lowering effects of vitamins B6, folate and B12 may have protective roles. However, a few reports have investigated the association between dietary water-soluble vitamin intakes and risk of diabetes. In a prospective study encompassing 19 168 healthy Japanese men and women aged 40–79 years, we examined the associations between dietary intakes of water-soluble vitamins, determined by a validated self-administered FFQ, with the risk of 5-year cumulative incidence of type 2 diabetes by using the logistic regression model. Within the 5-year period, there were 494 self-reported new cases of diabetes. Higher dietary intakes of vitamins C, B2 and folate were associated with lower risk of incident diabetes only in women, whereas no associations of dietary intakes of vitamins B1, B3, B5, B6 and B12 were observed in either sex. The multivariable OR in the highest v. the lowest quartile of intakes among women were 0·61 (95 % CI 0·44, 0·94; P-trend = 0·04) for vitamin C, 0·56 (95 % CI 0·34, 0·93; P-trend = 0·03) for vitamin B2 and 0·70 (95 % CI 0·46, 0·98; P-trend = 0·03) for folate. Other than that for sex (P < 0·05), the P-interactions with age, BMI, smoking status or having a family history of diabetes were >0·10. In conclusion, higher dietary intakes of vitamins C, B2 and folate, but not other water-soluble vitamins, were associated with reduced risk of type 2 diabetes in Japanese women.
Heat stress due to increasing extremes in ambient temperature and humidity results in reduced semen quality in boars. This has caused reduced efficiency of the swine industry, requiring more boars to breed the same number of sows. Vitamins such as vitamin C (VC) and E (VE) have been shown to improve semen quality in boars. Recently, vitamin D has been shown to improve semen quality in boars. The purpose of this experiment was to evaluate the effects of increased supplemental vitamins on boar reproduction during the summer season in a commercial boar stud. One hundred and sixty Pig Improvement Company (PIC) terminal line boars (n = 32 per treatment) and 39 maternal, heat-sensitive boars (n = 7 or 8 per treatment) were randomly allocated to treatment and fed a corn and soybean meal-based diet adjusted based on individual boar body condition score. A control (CNT) diet was used that met PIC recommendations for boars. Increased supplementation of specific vitamins was given in the form of a top-dress and consisted of CNT wheat middlings, CNT plus VC (560 mg/day), CNT plus 25-hydroxy vitamin D3 (VD) (125 µg/day), CNT plus VE (275 mg/day) and CNT plus VC, VD and VE (CDE). The experiment was split into three periods based on maximum daily high temperatures in the barn, where period 1 was weeks 1 to 4, period 2 was weeks 5 to 11 and period 3 was weeks 12 to 14. Semen was collected from boars as needed using the stud’s normal production schedule and was analyzed for sperm quantity and quality characteristics. There were no dietary effects on semen volume, sperm concentration or total sperm production (P ≥ 0.553). Total motility of sperm was not impacted by diet (P = 0.115); although, VC tended (P = 0.064) to have a greater progressive motility than CDE. Percentages of morphologically normal sperm and normal acrosomes were not affected by dietary supplementation (P ≥ 0.157). Period effects were observed for most semen quality parameters, with quality generally becoming reduced over time. The present study demonstrates that increased supplementation of vitamins beyond PIC recommendations was not beneficial for boar reproduction during the summer.
Lipid-based nutrient supplements (LNS) may be beneficial for malnourished HIV-infected patients starting antiretroviral therapy (ART). We assessed the effect of adding vitamins and minerals to LNS on body composition and handgrip strength during ART initiation. ART-eligible HIV-infected patients with BMI <18·5 kg/m2 were randomised to LNS or LNS with added high-dose vitamins and minerals (LNS-VM) from referral for ART to 6 weeks post-ART and followed up until 12 weeks. Body composition by bioelectrical impedance analysis (BIA), deuterium (2H) diluted water (D2O) and air displacement plethysmography (ADP), and handgrip strength were determined at baseline and at 6 and 12 weeks post-ART, and effects of LNS-VM v. LNS at 6 and 12 weeks investigated. BIA data were available for 1461, D2O data for 479, ADP data for 498 and handgrip strength data for 1752 patients. Fat mass tended to be lower, and fat-free mass correspondingly higher, by BIA than by ADP or D2O. At 6 weeks post-ART, LNS-VM led to a higher regain of BIA-assessed fat mass (0·4 (95 % CI 0·05, 0·8) kg), but not fat-free mass, and a borderline significant increase in handgrip strength (0·72 (95 % CI −0·03, 1·5) kg). These effects were not sustained at 12 weeks. Similar effects as for BIA were seen using ADP or D2O but no differences reached statistical significance. In conclusion, LNS-VM led to a higher regain of fat mass at 6 weeks and to a borderline significant beneficial effect on handgrip strength. Further research is needed to determine appropriate timing and supplement composition to optimise nutritional interventions in malnourished HIV patients.
Micronutrient deficiencies are of growing public health concern. An understanding of how micronutrient deficiencies affect health and measures that can be taken to improve micronutrient status are essential to improve population health. The main purpose of the 2018 Irish Section Meeting ‘Targeted approaches to tackling current nutritional issues’ was to provide an overview of current issues in relation to micronutrient status at various stages of the lifecycle. Novel biomarkers of nutrient status, global strategies to improve micronutrient status and implications for policy were also considered. The papers presented demonstrated recent advancements in this field and highlighted areas that warrant priority at the public health level, on both a national and global scale. Novel methods and biomarkers are being developed that will enhance the assessment of micronutrient status in specific population groups. It is evident that mild-to-moderate deficiency, or low status (in the absence of deficiency), of some micronutrients have important ramifications for public health that should be considered alongside the implications of severe deficiency. It is imperative that policy makers, public health workers and scientists work together to ensure that sustainable programmes are implemented to address micronutrient deficiencies at the population level.
Objective: To summarize the findings of randomized controlled trials (RCTs) on the efficacy and safety of vitamins and minerals for migraine prophylaxis. Methods: We systematically searched bibliographic databases and relevant websites for parallel and crossover RCTs reporting efficacy and/or safety of vitamins and/or minerals for migraine prophylaxis. Our primary outcomes were migraine frequency (number of attacks) and duration (hours). Secondary outcomes were severity (intensity), days with migraine, and adverse events. Meta-analysis was conducted when analyzable data were available from at least two trials. Results: Eighteen placebo-controlled trials met our eligibility criteria. Only coenzyme Q10 and magnesium contributed to meta-analyses. In adults, compared with placebo, coenzyme Q10 did not significantly decrease migraine frequency (mean difference (MD) −0.44 (−2.14 to 1.26); I2 53%; 2 trials; 97 participants; moderate strength of the evidence), duration (MD −1.97 (−4.82 to 0.87); I2 0%; 2 trials; 97 participants; moderate strength of the evidence), or severity (ratio of means (RoM) −0.05 (−0.20 to 0.11); I2 0%; 2 trials; 97 participants). In adults, compared with placebo, magnesium did not significantly decrease migraine severity (RoM −0.17 (−0.36 to 0.02); I2 48%; 3 trials; 226 participants; low strength of the evidence). Meta-analysis of other vitamins and minerals, and other outcomes were not feasible due to a lack of sufficiently reported data. Conclusions: Based on insufficient evidence, it is unknown if coenzyme Q10 and magnesium are effective for migraine prophylaxis in adults. High-quality, adequately powered RCTs are needed to fully evaluate the efficacy and safety of vitamins and minerals for migraine prophylaxis.
The role of fat-soluble vitamins in the pathology of type 2 diabetes needs further research. Possible protective effects could be expected for vitamins A and E via their antioxidant properties, vitamin K via its modulating effects on cytokines and insulin resistance and vitamin D via the enhancement of insulin sensitivity. However, the evidence on association between fat-soluble vitamins from diet and risk of diabetes is limited. Therefore, among 19 168 healthy Japanese of both sexes aged 40–79 years, we used the logistic regression analyses to examine the prospective association between FFQ-estimated dietary fat-soluble vitamins (A, K, E and D) and the risk of type 2 diabetes incident over a 5-year period. During this 5-year period, 494 new cases of diabetes were self-reported. Vitamins K and E from diet were associated with lowered risk of incident diabetes, whereas no associations with dietary intake of vitamin A or D were observed. The multivariable OR in the highest v. lowest quartiles of intakes were 0·71 (95 % CI 0·54, 0·93, Ptrend=0·01) for vitamin K and 0·72 (95 % CI 0·55, 0·95, Ptrend=0·02) for vitamin E. Mutual adjustment for dietary intake of these vitamins did not change the association. There were no interactions with sex, age, smoking status, BMI or having a family history of diabetes, P were >0·10. In conclusion, higher dietary intake of fat-soluble vitamins K and E, but not vitamin A or D, were associated with lowered risk of type 2 diabetes among Japanese population.
Optimising micronutrient status globally is a major health priority. Nutritional biomarkers are critical for the identification of nutrient inadequacies in light of the limitations of dietary assessment methods. Early diagnosis and prevention of nutrient inadequacies require sensitive, validated and harmonised methods to determine and monitor micronutrient status in individual healthcare and population-based surveys. Important criteria in the identification, validation and implementation of nutritional biomarkers include the testing of biomarker specificity and sensitivity, and their response to dietary as well as physiologic changes, e.g. age or pregnancy. Nutritional status can be categorised into deficient, suboptimal, adequate and excess status, where appropriate, and provided cut-offs are available. Cut-offs are quantitative measures to reflect health outcomes and are important in validating nutritional surveys, interventions and monitoring of populations. For many biomarkers, available cut-offs have limited interpretability and are most commonly derived in adult populations only. For the comparison of studies from across the globe, the harmonisation of analytical methods is essential and can be realised with the use of internationally available reference material and interlaboratory comparison studies. This narrative review describes current efforts on identifying and validating existing and new biomarkers, the derivation of biomarker cut-offs, and international efforts on harmonisation of laboratory methods for biomarker quantitation and their interpretation, in the example of B-vitamins. Establishing sensitive, reliable and cost-efficient biomarkers and related cut-offs for use in populations across the globe are critical to facilitating the early diagnosis of micronutrient inadequacies on the clinical and community-based level for timely intervention and disease prevention.
In recent decades, clinical trials in Alzheimer’s disease (AD) have failed at an unprecedented rate. The etiology of AD has since come under renewed scrutiny, both to elucidate the underlying pathologies and to identify novel therapeutic strategies. Here, diet has emerged as a potential causative/protective agent. A variety of nutrients, including lipids, minerals, vitamins, antioxidants and sugars as well as broader dietary patterns and microbiotal interactions have demonstrated associations with AD. Although clinical trials have yet to definitively implicate any singular dietary element as therapeutic or causative, it is apparent that dietary preferences, likely in complex synergies, may influence the risk, onset and course of AD. This review catalogs the impact of major dietary elements on AD. It further examines an unexplored reciprocal association where AD may modulate diet, as well as how potential therapeutics may complicate these interactions. In doing so, we observe diet may have profound effects on the outcome of a clinical trial, either as a confounder of a drug/disease interaction or as a generally disruptive covariate. We therefore conclude that future clinical trials in AD should endeavor to control for diet, either in study design or subsequent analyses.
We examined the association between plasma antioxidant levels and markers of inflammation, including C-reactive protein (CRP) and fibrinogen (FG) in US adults. National Health and Nutrition Examination Survey participants examined between 2001 and 2002 were included, if data on CRP or FG levels. Serum vitamins A and E, two retinyl esters, and six carotenoids were measured using HPLC with photodiode array detection. Multivariable-adjusted linear regression analyses accounted for the survey design and sample weights. A total of 784 eligible participants were included; 47·5 % (n 372) were men. In multivariable linear regression models, serum α-carotene, trans-β-carotene, cis-β-carotene, β-cryptoxanthin, combined lutein/zeaxanthin, trans-lycopene, retinyl palmitate, α-tocopherol, retinol and 25-hydroxy vitamin D were negatively associated with serum CRP (P<0·001 for all comparisons). Serum α-carotene, trans-β-carotene, cis-β-carotene, combined lutein/zeaxanthin, trans-lycopene, α-tocopherol, retinol and 25-hydroxy vitamin D were negatively associated with serum FG levels (P<0·001 for all comparisons). In the same model, the risk of CVD, defined as CRP levels >3 mg/l, decreased with increasing levels of antioxidants (α-carotene, trans-β-carotene, cis-β-carotene, vitamins A and E). Furthermore, we found a moderate impact of adiposity on the link between antioxidants and CRP. Our results suggest that the lower the antioxidants levels, the higher the inflammatory burden, based on CRP and FG levels. Adiposity moderately affects this association. Furthermore, an inverse relationship between CVD risk and antioxidant levels was observed. This finding suggests that reduced levels of vitamins with antioxidant properties may predispose to increased CVD risk.
The proportion of adults aged 60 years and over is expected to increase over the coming decades. This ageing of the population represents an important health issue, given that marked reductions to cerebral macro- and microstructural integrity are apparent with increasing age. Reduced cerebral structural integrity in older adults appears to predict poorer cognitive performance, even in the absence of clinical disorders such as dementia. As such, it is becoming increasingly important to identify those factors predicting cerebral structural integrity, especially factors that are modifiable. One such factor is nutritional intake. While the literature is limited, data from available cross-sectional studies indicate that increased intake of nutrients such as B vitamins (for example, B6, B12 and folate), choline, n-3 fatty acids and vitamin D, or increased adherence to prudent whole diets (for example, the Mediterranean diet) predicts greater cerebral structural integrity in older adults. There is even greater scarcity of randomised clinical trials investigating the effects of nutritional supplementation on cerebral structure, though it appears that supplementation with B vitamins (B6, B12 and folic acid) or n-3 fatty acids (DHA or EPA) may be beneficial. The current review presents an overview of available research examining the relationship between key nutrients or adherence to select diets and cerebral structural integrity in dementia-free older adults.
Micronutrients such as trace elements and vitamins are important as enzyme cofactors in the metabolism of all cells in the body and therefore key to determining nutritional status. The present systematic review examined the evidence of the impact of the systemic inflammatory response on plasma micronutrient status in acute (surgical) and chronic tissue injury. A literature review using targeted subject headings was carried out. Plasma C-reactive protein was used to classify minor (<10 mg/l), moderate (11–80 mg/l) and major (>80 mg/l) inflammation. The literature search produced 2344 publications and plasma vitamin D, zinc and carotenoids were most commonly studied and plasma vitamins K, B2 and B6 were least studied. In acute injury thirteen studies (all prospective) and in chronic injury twenty-four studies (largely retrospective) were included in the review. There was consistent evidence that most common measured micronutrients in the plasma (zinc, selenium, vitamins A, D, E, K, B2, B6, B12, C, lutein, lycopene, α- and β-carotene) were significantly lowered from minor to moderate to major inflammation. The results of the present systematic review indicate that most plasma micronutrients fall as part of the systemic inflammatory response irrespective of acute or chronic injury. Therefore, in the presence of a systemic inflammation, plasma micronutrient concentrations should be interpreted with caution. There are a number of methods applied to adjust plasma micronutrient concentrations to avoid misdiagnosis of deficiency. Alternatively, intracellular measurements appear to obviate the need for such plasma adjustment to assess micronutrient status.
Mandatory fortification of staple grains with folic acid and/or vitamin B12 (B12) is under debate in many countries including Ireland, which has a liberal, but voluntary, fortification policy. Older adults can be at risk of both deficiency and high folate status, although little is known on the actual prevalence and the major predictors. Population prevalence estimates from older adults (n 5290 ≥50 years) from the Irish Longitudinal Study on Ageing (TILDA) (Wave 1) are presented here. Measures included plasma total vitamin B12 and folate, whereas predictors included detailed demographic, socio-economic, geographic, seasonal and health/lifestyle data. The prevalence of deficient or low B12 status (<185 pmol/l) was 12 %, whereas the prevalence of deficient/low folate status was 15 %. High folate status (>45 nmol/l) was observed in 8·9 %, whereas high B12 status was observed in 3·1 % (>601 pmol/l). The largest positive predictor of B12 concentration was self-reported B12 injection and/or supplement use (coefficient 51·5 pmol/; 95 % CI 9·4, 93·6; P=0·016) followed by sex and geographic location. The largest negative predictor was metformin use (−33·6; 95 % CI −51·9, −15·4; P<0·0001). The largest positive predictor of folate concentration was folic acid supplement use (6·0; 95 % CI 3·0, 9·0 nmol/l; P<0·001) followed by being female and statin medications. The largest negative predictor was geographic location (−5·7; 95 % CI −6·7, −4·6; P<0·0001) followed by seasonality and smoking. B-vitamin status in older adults is affected by health and lifestyle, medication, sampling period and geographic location. We observed a high prevalence of low B12 and folate status, indicating that the current policy of voluntary fortification is ineffective for older adults.
In a representative sample of US adults, we investigated the associations of nutrient patterns (NP) with bone mineral density (BMD) and fractures.
US community-based National Health and Nutrition Examination Survey (NHANES).
Participants with measured data on dietary intake and BMD from 2005 to 2010 were included. Principal components analysis was used to identify NP. BMD was measured using dual-energy X-ray absorptiometry. ANCOVA, adjusted logistic and linear regression models were employed, accounting for the complex survey design and sample weights.
We included a total of 18 318 participants, with 47·0 % (n 8607) being men. The mean age was 45·8 years with no sex difference. Three NP emerged, explaining 55·9 % of the variance in nutrient consumption. Multivariable-adjusted linear regressions revealed significant inverse associations between the ‘high-energy’ NP (rich in carbohydrates and sugar, total fat and saturated fat) and total femur, femoral neck, trochanter and intertrochanter BMD (β coefficient: −0·029, −0·025, −0·034 and −0·021, respectively, all P<0·001), while there were significant associations between the ‘nutrient-dense’ NP (rich in vitamins, minerals and fibre) and ‘healthy fat’ NP (high dietary PUFA and MUFA) and BMD at total femur, femoral neck, trochanter and intertrochanter (all P<0·001). In adjusted logistic regression models, the odds of hip, wrist or spine fractures did not vary significantly across NP quartiles.
Nutrient-dense and healthy fat NP are associated with higher BMD at various bone sites, while the high-energy NP is inversely associated with BMD measures.
Animals are common hosts of mutualistic, commensal and pathogenic microorganisms. Blood-feeding parasites feed on a diet that is nutritionally unbalanced and thus often rely on symbionts to supplement essential nutrients. However, they are also of medical importance as they can be infected by pathogens such as bacteria, protists or viruses that take advantage of the blood-feeding nutritional strategy for own transmission. Since blood-feeding evolved multiple times independently in diverse animals, it showcases a gradient of host–microbe interactions. While some parasitic lineages are possibly asymbiotic and manage to supplement their diet from other food sources, other lineages are either loosely associated with extracellular gut symbionts or harbour intracellular obligate symbionts that are essential for the host development and reproduction. What is perhaps even more diverse are the pathogenic lineages that infect blood-feeding parasites. This microbial diversity not only puts the host into a complicated situation – distinguishing between microorganisms that can greatly decrease or increase its fitness – but also increases opportunity for horizontal gene transfer to occur in this environment. In this review, I first introduce this diversity of mutualistic and pathogenic microorganisms associated with blood-feeding animals and then focus on patterns in their interactions, particularly nutrition, immune cross-talk and gene exchange.
Evidence on adherence to diet-related cancer prevention guidelines and associations with colorectal cancer (CRC) risk is limited and conflicting. The aim of this cohort analysis is to evaluate associations between adherence to the World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) 2007 recommendations and incident CRC. The UK Women’s Cohort Study comprises over 35 372 women who filled in a FFQ at baseline in 1995. They were followed up for CRC incidence for a median of 17·4 years, an individual score linking adherence to eight of the WCRF/AICR recommendations was constructed. Cox proportional hazards regression provided hazard ratios (HR) and 95 % CI for the estimation of CRC risk, adjusting for confounders. Following exclusions, 444 CRC cases were identified. In the multivariate-adjusted model, women within the second and third (highest) categories of the WRCF/AICR score had HR of 0·79 (95 % CI 0·62, 1·00) and 0·73 (95 % CI 0·48, 1·10), respectively, for CRC compared with those in the lowest, reference category. The overall linear trend across the categories was not significant (P=0·17). No significant associations were observed between the WCRF/AICR score and proximal colon, distal colon and rectal cancers separately. Of the individual score components, a BMI within the normal weight range was borderline significantly protective only for rectal cancer in the fully adjusted model. In view of the likely different causes of CRC subtypes, further research is needed to identify the optimal dietary patterns associated with reducing colon and rectal cancer risk, respectively.
Globally populations are ageing. By 2050, it is estimated that there will be two billion people aged 60 years or over, of which 131 million are projected to be affected by dementia, while depression is predicted to be the second leading cause of disability worldwide by 2020. Preventing or delaying the onset of these disorders should therefore be a public health priority. There is some evidence linking certain dietary patterns, particularly the Mediterranean diet, with a reduced risk of dementia and depression. Specific dietary components have also been investigated in relation to brain health, with emerging evidence supporting protective roles for n-3 PUFA, polyphenols, vitamin D and B-vitamins. At this time, the totality of evidence is strongest in support of a role for folate and the metabolically related B-vitamins (vitamin B12, vitamin B6 and riboflavin) in slowing the progression of cognitive decline and possibly reducing the risk of depression in ageing. Future studies incorporating new technologies, such as MRI and magnetoencephalography, offer much promise in identifying effective nutrition interventions that could reduce the risk of cognitive and mental disorders. This review will explore the ageing brain and the emerging evidence linking diet and specific nutrients with cognitive function and depression in ageing, with the potential to develop strategies that could improve quality of life in our ageing population.
This study focused on the hypothesis that cognitive decline in aged dogs could be attenuated by dietary supplementation with a nutrient blend consisting of antioxidants, B vitamins, fish oil and l-arginine, referred to hereafter as the Brain Protection Blend (BPB). Baseline cognitive assessment before the start of treatment was used to establish cognitively equivalent control (10·464+2·33 kg) and treatment (12·118+3·386 kg) groups of aged dogs between 9·1 and 11·5 years of age and with body condition score of 5. After an initial wash-in period, all dogs were tested over a 6-month period on cognitive test protocols that assessed four phases of a landmark discrimination learning protocol, which assessed a spatial learning skill based on utilisation of external cues, and egocentric discrimination task, which assessed spatial learning based on internal body-centred cues. The BPB-supplemented group showed significantly better performance than the controls on the landmark 1 (P=0·0446) discrimination learning tasks, and on two egocentric discrimination reversal learning tasks (P=0·005 and P=0·01, respectively). The groups did not differ significantly (P>0·10) on the landmark zero discrimination task and the egocentric discrimination learning task. These results suggest beneficial effects are positively linked to task complexity. Many of the nutrients supplemented in the BPB diet were significantly higher in plasma, including arginine, α-tocopherol, DHA and EPA. These results indicate that long-term supplementation with the BPB can have cognition-improving effects and support the use of nutritional strategies in targeting brain ageing-associated risk factors as an intervention to delay cognitive ageing.
Nutraceuticals have generated interest as a way to mitigate the cognitive decline in older adults. The aim of this systematic review was to determine the evidence for these claims from the scientific literature in randomised, double-blinded, controlled trials (duration: ≥1 year; participants: n≥100; age(mean): ≥65 years). Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched four electronic databases (PubMed, Scopus, CINAHL and Web of Science) and identified twenty-five studies published between the 15·June·2006 and 14·June·2016. Interventions included B-vitamins, n-3 fatty acids, antioxidant vitamins and herbs. Of the B-vitamin studies, four found benefits to cognition with supplementation. The first of these B-vitamin studies, in individuals with mild cognitive impairment (n 266; duration=2 years), included benefit to executive function (P=0·015) and improvements in the Mini-Mental State Examination (MMSE) among participants with baseline homocysteine above 11·3 µmol/l (P<0·001). In the same sample, the second study found cognitive benefits of B-vitamins dependent on the higher baseline plasma n-3 fatty acid status. The third B-vitamin study (n 900; duration=2 years) reported improved performance in immediate (P=0·046) and delayed recall (P=0·013), whereas the fourth study (n 856; duration=2 years) reported slower rate of cognitive decline in the MMSE (P=0·05). One study investigating DHA treatment (n 402; duration=1·5 years) revealed the slower rate of cognitive change in apoE e4 non-carriers (P=0·03). As only five included studies revealed notable benefits, presently based on the specific compounds explored here, there is not compelling evidence to support the use nutraceuticals to improve cognition in the elderly. Future long-term trials of nutraceuticals should investigate interactions with lifestyle, blood biomarkers and genetic risk factors.
Ovine reproduction efficiency in herds at high altitude (ha) is lower than that at low altitude (la). In ewes, ha effects are due to hypoxia and oxidative stress. Our aim was to establish the effect of antioxidant vitamin supplementation on semen traits and antioxidant status of rams exposed to short or long time ha. A total of 32 rams native to la (~500 m) were used, 16 were kept at la and the other 16 were brought to ha (~3600 m), where they were placed in the same flock as the ha native rams (n=16). Half of the animals in each group were supplemented daily with vitamins C 600 mg and E 450 IU per os, during the entire experimental period, starting the 4th day after animal’s arrival at ha (day 0). At days 0, 30 and 60 of treatment, blood and semen samples were collected for evaluation of antioxidant status and semen standard characteristics. Data were compared within each experimental time by analysis of variance using a general linear model. Elevated concentrations of oxidative stress biomarkers were present in blood from animals maintained at ha. Ejaculates from ha exposed rams showed decreased sperm concentration, progressive motility and viability, in addition to decreased antioxidant status in seminal fluid. A total of 30 days of oral supplementation with vitamins C and E prevented some ha negative effects on semen characteristics, mainly in recently ha exposed rams. It is concluded that exposure of rams to ha negatively affects semen quality, where oxidative stress plays a predominant role. These effects are mainly prevented by oral supplementation of vitamins C and E, which constitutes a simple and cheap alternative to improve semen quality of rams when they are moved to ha.