Very long-chain n-3 polyunsaturated fatty acids: a head start to win some years between the ears?

Very long-chain n-3 (or omega-3) polyunsaturated fatty acids have attracted considerable public interest during the past few years for their potential beneficial role in cognitive performance. The proposed benefits stretch from advantages in developing brains of infants and children to preventing cognitive decline at old age. In this thesis, we first examined the role of very long-chain n-3 PUFA at the beginning of the lifespan. We investigated the effects of dietary very long-chain n-3 PUFA on the fatty acid composition of the several brain lobes in juvenile pigs, and showed that a diet enriched with fish oil resulted in higher proportions of DHA in the frontal, parietal and occipital brain lobes compared with the temporal brain lobe. These findings suggest a region-specific incorporation of DHA in the developing brain, which may guide future research into the mechanism by which very long-chain n-3 PUFA may in involved in brain development and function. Subsequently, we investigated the role of very long-chain n-3 PUFA near the end of the lifespan. In a population of older adults, we investigated the association between very long-chain n-3 PUFA and cognitive decline over three years in multiple cognitive domains. We demonstrated that higher plasma proportions of very long-chain n-3 PUFA were associated with less decline in the cognitive domains sensorimotor speed and complex speed, but not in memory, information-processing speed and word fluency, compared with lower plasma proportions of very long-chain n-3 PUFA. These results suggest a beneficial role of very long-chain n-3 PUFA in the speed-related cognitive domains, which justifies future research in this area with sensitive cognitive outcome measurements that provide domain-specific information. Finally, we touched upon the role of very long-chain n-3 PUFA in the macrovascular and the microvascular blood supply in the head region. We showed that plasma very long-chain n-3 PUFA were not associated with changes in carotid intima-media thickness and common carotid distension in a healthy older adult population. This may suggest that the role of very long-chain n-3 PUFA in a healthy population extends in particular to the smaller blood vessels. The role of very long-chain n-3 PUFA in the microcirculation of the brain could therefore be an interesting future direction of research. Although we did not directly investigate the role of very long-chain n-3 PUFA in the brain microcirculation, we did investigate whether plasma very long-chain n-3 PUFA were associated with age-related hearing loss over a period of three years in older adults. Since microvascular disease may decrease the blood supply to the highly vascularised cochlea, this may result in age-related hearing loss. We showed that higher plasma proportions of very long-chain n-3 PUFA were indeed associated with less age-related hearing loss compared with lower plasma proportions of very long-chain n-3 PUFA which implies that the hypothesis of improved microcirculation, if proven correct, may have far-reaching consequences. In summary, this thesis showed that very long-chain n-3 PUFA have region-specific effects on the developing brain and that higher plasma proportions of very long-chain n-3 PUFA were associated with less decline in the speed-related cognitive domains and less age-related hearing loss. Further research is required to establish the role of very long-chain n-3 PUFA in the developing as well as the aging brain and to investigate the underlying mechanisms. “Very long-chain n-3 polyunsaturated fatty acids: a head start to win some years between the ears?” PhD-thesis by Carla Dullemeijer, Top Institute Food and Nutrition and Division of Human Nutrition, Wageningen University, Wageningen, the Netherlands, May 15, 2009 <br/

Transformations of summary statistics as input in meta-analysis for linear dose-response models on a logarithmic scale: a methodology developed within EURRECA

Background: To derive micronutrient recommendations in a scientifically sound way, it is important to obtain and analyse all published information on the association between micronutrient intake and biochemical proxies for micronutrient status using a systematic approach. Therefore, it is important to incorporate information from randomized controlled trials as well as observational studies as both of these provide information on the association. However, original research papers present their data in various ways. Methods: This paper presents a methodology to obtain an estimate of the dose-response curve, assuming a bivariate normal linear model on the logarithmic scale, incorporating a range of transformations of the original reported data. Results: The simulation study, conducted to validate the methodology, shows that there is no bias in the transformations. Furthermore, it is shown that when the original studies report the mean and standard deviation or the geometric mean and confidence interval the results are less variable compared to when the median with IQR or range is reported in the original study. Conclusions: The presented methodology with transformations for various reported data provides a valid way to estimate the dose-response curve for micronutrient intake and status using both randomized controlled trials and observational studies

An annotated bibliography of C.J. van der Klaauw with notes on the impact of his work

Van der Klaauw was a professor of Descriptive Zoology in the period 1934–1958. This paper presents a concise annotated overview of his publications. In his work three main topics can be recognized: comparative anatomy of the mammalian auditory region, theoretical studies about ecology and ecological morphology, and vertebrate functional morphology. In particular van der Klaauw developed new concepts on functional morphology, based upon a holistic approach. A series of studies in functional morphology of Vertebrates by his students is added. An overview of recent morphological and theoretical studies show that this new approach had a long lasting impact in studies of functional morphology

Eliciting a predatory response in the eastern corn snake (Pantherophis guttatus) using live and inanimate sensory stimuli: implications for managing invasive populations

North America's Eastern corn snake (Pantherophis guttatus) has been introduced to several islands throughout the Caribbean and Australasia where it poses a significant threat to native wildlife. Invasive snake control programs often involve trapping with live bait, a practice that, as well as being costly and labour intensive, raises welfare and ethical concerns. This study assessed corn snake response to live and inanimate sensory stimuli in an attempt to inform possible future trapping of the species and the development of alternative trap lures. We exposed nine individuals to sensory cues in the form of odour, visual, vibration and combined stimuli and measured the response (rate of tongue-flick [RTF]). RTF was significantly higher in odour and combined cues treatments, and there was no significant difference in RTF between live and inanimate cues during odour treatments. Our findings suggest chemical cues are of primary importance in initiating predation and that an inanimate odour stimulus, absent of simultaneous visual and vibratory cues, is a potential low-cost alternative trap lure for the control of invasive corn snake populations

Folate intake and markers of folate status in women of reproductive age, pregnant and lactating women : a meta-analysis

Background. Pregnant and breastfeeding women are at risk for folate deficiency. Folate supplementation has been shown to be associated with enhanced markers of folate status. However, dose-response analyses for adult women are still lacking. Objective. To assess the dose-response relationship between total folate intake (folic acid plus dietary folate) and markers of folate status (plasma/serum folate, red blood cell folate, and plasma homocysteine); to evaluate potential differences between women in childbearing age, pregnant and lactating women. Methods. Electronic literature searches were carried out on three databases until February 2010. The overall pooled regression coefficient (\u3b2) and SE(\u3b2) were calculated using meta-analysis on a double-log scale. Results. The majority of data was based on nonpregnant, nonlactating women in childbearingage. The pooled estimate of the relationship between folate intake and serum/plasma folate was 0.56 (95% CI = 0.40-0.72, P < 0.00001); that is, the doubling of folate intake increases the folate level in serum/plasma by 47%. For red blood cell folate, the pooled-effect estimate was 0.30 (95% CI = 0.22-0.38, P < 0.00001), that is, +23% for doubling intake. For plasma-homocysteine it was -0.10 (95% = -0.17 to -0.04, P = 0.001), that is, -7% for doubling the intake. Associations tended to be weaker in pregnant and lactating women. Conclusion. Significant relationships between folate intake and serum/plasma folate, red blood cell folate, and plasma homocysteine were quantified. This dose-response methodology may be applied for setting requirements for women in childbearing age, as well as for pregnant and lactating women

EURRECA-Estimating Zinc Requirements for Deriving Dietary Reference Values

Zinc was selected as a priority micronutrient for EURRECA, because there is significant heterogeneity in the Dietary Reference Values (DRVs) across Europe. In addition, the prevalence of inadequate zinc intakes was thought to be high among all population groups worldwide, and the public health concern is considerable. In accordance with the EURRECA consortium principles and protocols, a series of literature reviews were undertaken in order to develop best practice guidelines for assessing dietary zinc intake and zinc status. These were incorporated into subsequent literature search strategies and protocols for studies investigating the relationships between zinc intake, status and health, as well as studies relating to the factorial approach (including bioavailability) for setting dietary recommendations. EMBASE (Ovid), Cochrane Library CENTRAL, and MEDLINE (Ovid) databases were searched for studies published up to February 2010 and collated into a series of Endnote databases that are available for the use of future DRV panels. Meta-analyses of data extracted from these publications were performed where possible in order to address specific questions relating to factors affecting dietary recommendations. This review has highlighted the need for more high quality studies to address gaps in current knowledge, in particular the continued search for a reliable biomarker of zinc status and the influence of genetic polymorphisms on individual dietary requirements. In addition, there is a need to further develop models of the effect of dietary inhibitors of zinc absorption and their impact on population dietary zinc requirements.This is the peer-reviewed version of the article: Lowe Nicola M., Dykes Fiona C., Skinner Anna-Louise, Patel Sujata, Warthon-Medina Marisol, Decsi Tamas, Fekete Katalin, Souverein Olga W., Dullemeijer Carla, Cavelaars Adrienne E., Serra-Majem Lluis, Nissensohn Mariela, Bel Silvia, Moreno Luis A., Hermoso Maria, Vollhardt Christiane, Berti Cristiana, Cetin Irene, Gurinović Mirjana A., Novaković Romana, Harvey Linda, Collings Rachel, Hall-Moran Victoria, "EURRECA-Estimating Zinc Requirements for Deriving Dietary Reference Values" 53, no. 10 (2013):1110-1123, [https://doi.org/10.1080/10408398.2012.742863

THE IMPACT OF DIETARY PROTEIN OR AMINO ACID SUPPLEMENTATION ON MUSCLE MASS AND STRENGTH IN ELDERLY PEOPLE: INDIVIDUAL PARTICIPANT DATA AND META-ANALYSIS OF RCT’S

Objectives Increasing protein or amino acid intake has been promoted as a promising strategy to increase muscle mass and strength in elderly people, however, long-term intervention studies show inconsistent findings. Therefore, we aim to determine the impact of protein or amino acid supplementation compared to placebo on muscle mass and strength in older adults by combining the results from published trials in a metaanalysis and pooled individual participant data analysis. Design We searched Medline and Cochrane databases and performed a meta-analysis on eight available trials on the effect of protein or amino acid supplementation on muscle mass and strength in older adults. Furthermore, we pooled individual data of six of these randomized double-blind placebo-controlled trials. The main outcomes were change in lean body mass and change in muscle strength for both the meta-analysis and the pooled analysis. Results The meta-analysis of eight studies (n=557) showed no significant positive effects of protein or amino acid supplementation on lean body mass (mean difference: 0.014 kg: 95% CI -0.152; 0.18), leg press strength (mean difference: 2.26 kg: 95% CI -0.56; 5.08), leg extension strength (mean difference: 0.75 kg: 95% CI: -1.96, 3.47) or handgrip strength (mean difference: -0.002 kg: 95% CI -0.182; 0.179). Likewise, the pooled analysis showed no significant difference between protein and placebo treatment on lean body mass (n=412: p=0.78), leg press strength (n=121: p=0.50), leg extension strength (n=121: p=0.16) and handgrip strength (n=318: p=0.37). Conclusions There is currently no evidence to suggest that protein or amino acid supplementation without concomitant nutritional or exercise interventions increases muscle mass or strength in predominantly healthy elderly people

Fish, docosahexaenoic acid and Alzheimer’s disease

Cognitive decline in the elderly, particularly Alzheimer’s disease (AD), is a major socio-economic and healthcare concern. We review here the literature on one specific aspect of diet affecting AD, that of the ω3 fatty acids, particularly the brain’s principle ω3 fatty acid – docosahexaenoic acid (DHA). DHA has deservedly received wide attention as a nutrient supporting both optimal brain development and for cardiovascular health. Our aim here is to critically assess the quality of the present literature as well as the potential of ω3 fatty acids to treat or delay the onset of AD. We start with a brief description of cognitive decline in the elderly, followed by an overview of well recognized biological functions of DHA. We then turn to epidemiological studies, which are largely supportive of protective effects of fish and DHA against risk of AD. However, biological studies, including blood and brain DHA analyses need careful interpretation and further investigation, without which the success of clinical trials with DHA may continue to struggle. We draw attention to some of the methodological issues that need resolution as well as an emerging mechanism that may explain how DHA could be linked to protecting brain function in the elderly