Sustainable production of healthy food for a growing global population, in the face of the uncertainties of climate change, represents a major challenge for the coming decade. Livestock provide food with high nutritional value but are frequently fed on human-edible crops and are associated with significant production of greenhouse gases. Recent years have seen increasing interest in the farming of insects as a sustainable source of human food, or as a replacement of ingredients such as soya or fishmeal in the feeds of terrestrial livestock or fish. This review provides an overview of insect physiology and growth regulation, considers the requirements for insect farming and mass production, and summarizes the nutritional value of the 10 most commonly studied insect species, before reviewing the literature on the use of insects as feed and food. We highlight the challenges required to develop a sustainable, safe, and affordable insect farming industry.

The nutritional environment encountered during fetal life is strongly implicated as a determinant of lifelong metabolic capacity and risk of disease. Pregnant rats were fed a control or low-protein (LP) diet, targeted to early (LPE), mid-(LPM), or late (LPL) pregnancy, or throughout gestation (LPA). The offspring were studied at 1, 9, and 18 mo of age. All LP-exposed groups had similar plasma triglyceride, cholesterol, glucose, and insulin concentrations to those of controls at 1 and 9 mo of age, but by 18 mo there was evidence of LP-programmed hypertriglyceridemia and insulin resistance. All LP-exposed groups exhibited histological evidence of hepatic steatosis and were found to have two- to threefold more hepatic triglyceride than control animals. These phenotypic changes were accompanied by age-related changes in mRNA and protein expression of the transcription factors SREBP-1c, ChREBP, PPARγ, and PPARα and their respective downstream target genes ACC1, FAS, L-PK, and MCAD. At 9 mo of age, the LP groups exhibited suppression of the SREBP-1c-related lipogenic pathway but between 9 and 18 mo underwent a switch to increased lipogenic capacity with a lower expression of PPARγ and MCAD, consistent with reduced lipid oxidation. The findings indicate that prenatal protein restriction programs development of a metabolic syndrome-like phenotype that develops only with senescence. The data implicate altered expression of SREBP-1c and ChREBP as key mediators of the programmed phenotype, but the basis of the switch in metabolic status that occurred between 9 and 18 mo of age is, as yet, unidentified.

In 1991, the Committee on Medical Aspects of Food Policy produced a report on the dietary reference values for food energy and nutrients for groups of people in the United Kingdom. The resulting recommendations, which included specific limits for intakes of total, saturated, trans- and cis-polyunsaturated fatty acids (PUFA) have remained a cornerstone of public health policy ever since, and similar recommendations have been adopted by the World Health Organization. These recommendations were made largely on the basis of specific effects of these fatty acids on the risk of developing atherosclerotic cardiovascular disease (CVD). The intervening years have seen a plethora of human epidemiological and intervention trials to further elucidate the specific relationship between dietary fatty acid intake, plasma lipids and lipoproteins and cardiovascular morbidity and mortality. A number of recent meta-analyses and systematic reviews have revisited the role of specific dietary fatty acid classes and CVD risk. In general, these continue to support a link between saturated fatty acids (SFA) and CVD morbidity/mortality. They also highlight the potent adverse effects of trans fatty acids derived from partially hydrogenated vegetable oil. The most recent data suggest that replacing SFA with cis-PUFA (primarily linoleic acid) has the greatest impact on reducing CVD risk. Evidence of specific beneficial effects of n-3 PUFA is generally stronger for secondary, rather than primary, CVD risk, and it is restricted to very long chain fatty acids of marine origin as opposed to alpha-linolenic acid. Taken together, these data suggest that recent focus on dietary n-6-to-n-3 PUFA ratios may have been misguided, and that future strategies should focus on replacing dietary SFA with total PUFA, rather than concentrating on n-6 : n-3 PUFA ratio.

The evidence that omega-3 (n-3) and -6 (n-6) polyunsaturated fatty acids (PUFAs) have differential effects on ovarian function, oocytes and embryo quality is inconsistent. We report on the effects of n-3 versus n-6 PUFA-enriched diets fed to 36 ewes over a 6-week period, prior to ovarian stimulation and follicular aspiration, on ovarian steroidogenic parameters and embryo quality. Follicle number and size were unaltered by diet, but follicular-fluid progesterone concentrations were greater in n-3 PUFA-fed ewes than in n-6 PUFA-fed ewes. The percentage of saturated FAs (mostly stearic acid) was greater in oocytes than in either granulosa cells or plasma, indicating selective uptake and/or de novo synthesis of saturated FAs at the expense of PUFAs by oocytes. High-density lipoproteins (HDLs) fractionated from sera of these ewes increased granulosa cell proliferation and steroidogenesis relative to the FA-free BSA control during culture, but there was no differential effect of n-3 and n-6 PUFAs on either oestradiol or progesterone production. HDL was ineffective in delivering FAs to embryos during culture, although n-6 PUFA HDL reduced embryo development. All blastocysts, irrespective of the treatment, contained high levels of unsaturated FAs, in particular linoleic acid. Transcripts for HDL and low-density lipoprotein (LDL) receptors (SCARB1 and LDLR) and stearoyl-CoA desaturase (SCD) are reported in sheep embryos. HDL reduced the expression of transcripts for LDLR and SCD relative to the BSA control. The data support a differential effect of n-3 and n-6 PUFAs on ovarian steroidogenesis and pre-implantation development, the latter in the absence of a net uptake of FAs. Abstract The evidence that omega-3 (n-3) and -6 (n-6) polyunsaturated fatty acids (PUFAs) have differential effects on ovarian function, oocytes and embryo quality is inconsistent. We report on the effects of n-3 versus n-6 PUFA-enriched diets fed to 36 ewes over a 6-week period, prior to ovarian stimulation and follicular aspiration, on ovarian steroidogenic parameters and embryo quality. Follicle number and size were unaltered by diet, but follicular-fluid progesterone concentrations were greater in n-3 PUFA-fed ewes than in n-6 PUFA-fed ewes. The percentage of saturated FAs (mostly stearic acid) was greater in oocytes than in either granulosa cells or plasma, indicating selective uptake and/or de novo synthesis of saturated FAs at the expense of PUFAs by oocytes. High-density lipoproteins (HDLs) fractionated from sera of these ewes increased granulosa cell proliferation and steroidogenesis relative to the FA-free BSA control during culture, but there was no differential effect of n-3 and n-6 PUFAs on either oestradiol or progesterone production. HDL was ineffective in delivering FAs to embryos during culture, although n-6 PUFA HDL reduced embryo development. All blastocysts, irrespective of the treatment, contained high levels of unsaturated FAs, in particular linoleic acid. Transcripts for HDL and low-density lipoprotein (LDL) receptors (SCARB1 and LDLR) and stearoyl-CoA desaturase (SCD) are reported in sheep embryos. HDL reduced the expression of transcripts for LDLR and SCD relative to the BSA control. The data support a differential effect of n-3 and n-6 PUFAs on ovarian steroidogenesis and pre-implantation development, the latter in the absence of a net uptake of FAs.

Butter, which is naturally enriched in cis-9, trans-11 conjugated linoleic acid (rumenic acid; RA) and vaccenic acid (VA), has been shown to be an effective anticarcinogen in studies with animal models; however, there has been no examination of the effects of a naturally derived source of VA and RA on atherosclerosis-related biomarkers. The current study was designed to determine the effect of a diet containing VA/RA-enriched butter on plasma lipoproteins and tissue fatty acid profiles in cholesterol-fed hamsters. Male Golden Syrian hamsters were fed diets containing 0.2% cholesterol and 20% added fat as: 1) Control, 20% standard butter (CT); 2) 5% standard butter + 15% VA/RA-enriched butter (EB); 3) 15% standard butter + 5% partially-hydrogenated vegetable oil (VO). After 4 wk, plasma lipoproteins were isolated, cholesterol quantified, and tissue fatty acid profiles determined. Tissue concentrations of VA and RA were increased by consumption of the EB diet compared with both the CT and VO diets, whereas the VO diet increased their concentration compared with the CT diet only. Total and LDL cholesterol concentrations were significantly reduced in hamsters fed EB and VO compared with CT, whereas VLDL cholesterol concentrations were reduced in hamsters fed EB compared with those fed CT and VO. HDL cholesterol concentrations did not differ among treatments. The ratio of potentially atherogenic lipoproteins [VLDL + intermediate density lipoproteins (IDL) + LDL] to antiatherogenic HDL was significantly lower in hamsters fed VA/RA-enriched butter (0.60) than in those fed either control diet (1.70) or the diet containing partially hydrogenated vegetable oil (1.04). Thus, increasing the VA/RA concentration of butter results in a plasma lipoprotein cholesterol profile that is associated with a reduced risk of atherosclerosis.