Although research has demonstrated the positive nutritional value and environmental benefits associated with edible insect consumption, several factors challenge the growth and development of the edible insect industry for human consumption in the US and Canada. Cultural and psychological factors account for much of the aversion US and Canadian consumers display. The absence of specific regulation also constitutes a structural barrier to more widespread production and sale of edible insects. Compared to the US, the European Union has a more developed edible insect industry and has enacted legislation that removes some of the barriers. As consumer awareness of the putative health benefits of edible insects increases, more comprehensive regulations may emerge to keep pace with the growth of this industry. Overall, a multi-disciplinary approach that addresses both benefits and barriers to consumption is needed to facilitate a robust market for edible insects in the US and Canada.

Multilayered films comprising alternating layers of polycarbonate (PC) and poly(vinylidene fluoride-hexafluoropropylene) (P[VDF-HFP]) show an enhanced dielectric strength (E B> 750 kV/mm) and an increased energy storage density (U d ~ 13.5 J/cm3) compared to monolithic PC and P[VDF-HFP] films. Here the role of electromechanical effects in the breakdown of multilayer films is explored both by imaging the changes in the layer structure caused by electrical fields below the breakdown field and by a direct measurement of the strain in multilayer PC/ P[VDF-HFP] films subjected to similar fields. Focused Ion Beam (FIB)/ Scanning Electron Microscopy (SEM) images of the layer structure in films subjected to repeated cycles at near-breakdown fields showed local changes in the thickness of individual layers, suggesting that mechanical forces arising from field-induced compression may play a role in the steps preceding the breakdown. The directly measured field induced strain showed evidence for both an elastic and a flow component to the strain. The mechanical responses of films with ≤ 50 vol% P[VDF-HFP] were modeled as simply the sum of an elastic and viscous flow. The observed electromechanical properties vary with the layer structure. This suggests that multilayering polymers may provide a means to mitigate deleterious electromechanical effects in low modulus, high dielectric materials.

Older age, dietary folate and chronic alcohol consumption are important risk factors for the development of colon cancer. The present study examined the effects of ageing, folate and alcohol on genomic and p16-specific DNA methylation, and p16 expression in the murine colon. Old (aged 18 months; n 70) and young (aged 4 months; n 70) male C57BL/6 mice were pair-fed either a Lieber-DeCarli liquid diet with alcohol (18 % of energy), a Lieber-DeCarli diet with alcohol (18 %) and reduced folate (0·25 mg folate/l) or an isoenergetic control diet (0·5 mg folate/l) for 5 or 10 weeks. Genomic DNA methylation, p16 promoter methylation and p16 gene expression were analysed by liquid chromatography–MS, methylation-specific PCR and real-time RT-PCR, respectively. Genomic DNA methylation was lower in the colon of old mice compared with young mice (P < 0·02) at 10 weeks. Alcohol consumption did not alter genomic DNA methylation in the old mouse colon, whereas it tended to decrease genomic DNA methylation in young mice (P = 0·08). p16 Promoter methylation and expression were higher in the old mouse colon compared with the corresponding young groups. There was a positive correlation between p16 promoter methylation and p16 expression in the old mouse colon (P < 0·02). In young mice the combination of alcohol and reduced dietary folate led to significantly decreased p16 expression compared with the control group (P < 0·02). In conclusion, ageing and chronic alcohol consumption alter genomic DNA methylation, p16 promoter methylation and p16 gene expression in the mouse colon, and dietary folate availability can further modify the relationship with alcohol in the young mouse.

Some countries have introduced mandatory folic acid fortification, whereas others support periconceptional supplementation of women in childbearing age. Several European countries are considering whether to adopt a fortification policy. Projections of the possible beneficial effects of increased folic acid intake assume that the measure will result in a considerable reduction in neural-tube defects (NTD) in the target population. Therefore, the objective of the present study is to evaluate the beneficial effects of different levels of folic acid administration on the prevalence of NTD. Countries with mandatory fortification achieved a significant increase in folate intake and a significant decline in the prevalence of NTD. This was also true for supplementation trials. However, the prevalence of NTD at birth declined to approximately five cases at birth per 10 000 births and seven to eight cases at birth or abortion per 10 000 births. This decline was independent of the amount of folic acid administered and apparently reveals a ‘floor effect’ for folic acid-preventable NTD. This clearly shows that not all cases of NTD are preventable by increasing the folate intake. The relative decline depends on the initial NTD rate. Countries with NTD prevalence close to the observed floor may have much smaller reductions in NTD rates with folic acid fortification. Additionally, potential adverse effects of fortification on other vulnerable population groups have to be seriously considered. Policy decisions concerning national mandatory fortification programmes must take into account realistically projected benefits as well as the evidence of risks to all vulnerable groups.

The availability of folate is implicated as a determinant of DNA methylation, a functionally important feature of DNA. Nevertheless, when this phenomenon has been examined in the rodent model, the effect has not always been observed. Several reasons have been postulated for the inconsistency between studies: the rodent is less dependent on folate as a methyl source than man; juvenile animals, which most studies use, are more resistant to folate depletion than old animals; methods to measure genomic DNA methylation might not be sensitive enough to detect differences. We therefore examined the relationship between folate and genomic DNA methylation in an elder rat model with a newly developed method that can measure genomic DNA methylation sensitively and precisely. Thirty-nine 1-year-old rats were divided into three groups and fed a diet containing 0, 4·5 or 18 μmol folate/kg (folate-deplete, -replete and -supplemented groups, respectively). Rats were killed at 8 and 20 weeks. At both time points, mean liver folate concentrations increased incrementally between the folate-deplete, -replete and -supplemented rats (P for trend <0·001) and by 20 weeks hepatic DNA methylation also increased incrementally between the folate-deplete, -replete and -supplemented rats (P for trend=0·025). At both time points folate-supplemented rats had significantly increased levels of DNA methylation compared with folate-deplete\ rats (P<0·05). There was a strong correlation between hepatic folate concentration and genomic DNA methylation in the liver (r 0·48, P=0·004). In the liver of this animal model, dietary folate over a wide range of intakes modulates genomic DNA methylation.