BackgroundThe incidence of the insulin resistance syndrome has increased at an alarming rate worldwide, creating a serious challenge to public health care in the 21st century. Recently, epidemiological studies have associated the prevalence of type 2 diabetes with elevated body burdens of persistent organic pollutants (POPs). However, experimental evidence demonstrating a causal link between POPs and the development of insulin resistance is lacking.ObjectiveWe investigated whether exposure to POPs contributes to insulin resistance and metabolic disorders.MethodsSprague-Dawley rats were exposed for 28 days to lipophilic POPs through the consumption of a high-fat diet containing either refined or crude fish oil obtained from farmed Atlantic salmon. In addition, differentiated adipocytes were exposed to several POP mixtures that mimicked the relative abundance of organic pollutants present in crude salmon oil. We measured body weight, whole-body insulin sensitivity, POP accumulation, lipid and glucose homeostasis, and gene expression and we performed microarray analysis.ResultsAdult male rats exposed to crude, but not refined, salmon oil developed insulin resistance, abdominal obesity, and hepatosteatosis. The contribution of POPs to insulin resistance was confirmed in cultured adipocytes where POPs, especially organochlorine pesticides, led to robust inhibition of insulin action. Moreover, POPs induced down-regulation of insulin-induced gene-1 (Insig-1) and Lpin1, two master regulators of lipid homeostasis.ConclusionOur findings provide evidence that exposure to POPs commonly present in food chains leads to insulin resistance and associated metabolic disorders.

Black soldier fly (Hermetia illucens) larvae are a promising source of protein and lipid for animal feeds. The nutritional composition of the BSF larvae depend partly on the composition of the feeding medium. The BSF lipid profile in part mimics the feeding media lipid profile, and micronutrients, like minerals and vitamins, can readily accumulate in black soldier fly larvae. However, investigative studies on bioconversion and accumulation of nutrients from media to black soldier fly larvae are scarce. Here we show that inclusion of the brown algae Ascophyllum nodosum in the substrate for black soldier fly larvae can introduce valuable nutrients, commonly associated with the marine environment, into the larvae. The omega-3 fatty acid eicosapentaenoic acid (20:5n-3), iodine and vitamin E concentrations increased in the larvae when more seaweed was included in the diet. When the feeding media consisted of more than 50% seaweed, the larvae experienced poorer growth, lower nutrient retention and lower lipid levels, compared to a pure plant based feeding medium. Our results confirm the plasticity of the nutritional make-up of black soldier fly larvae, allowing it to accumulate both lipid- and water-soluble compounds. A broader understanding of the effect of the composition of the feeding media on the larvae composition can help to tailor black soldier fly larvae into a nutrient profile more suited for specific feed or food purposes.

No abstract

Two insect meal (IM) products were tested as ingredient in diets for Atlantic salmon weighing~250 g. The modern control diet contained 200 g kg À1 fish meal (FM100), which was stepwise replaced by insect meal A (IM A) as a 25% (A25), 50% (A50) or 100% (A100) FM replacement or insect meal B (IM B) as a 25% (B25) or 100% (B100) FM replacement. Selected nutrient parameters and contaminants were measured in the diets. After 15 weeks, fish length and weight were recorded and visceral and hepatic indices calculated. Fatty acid and amino acid digestibility was calculated. Morphology of the liver, kidney, mid-and hind intestine was evaluated. Finally, a sensory testing of the fillets was conducted. A25, A50 and A100 performed equally well as the FM100 diet. The feed intake decreased moderately with increasing IM A inclusion; however, food conversion ratio decreased, resulting in an equal net growth of the fish. Histology did not show any differences between any of the dietary groups, and sensory testing of fillets from FM100, A100 and B25 did not reveal any significant differences in odour, flavour/taste or texture between groups. IM A was suitable to replace up to 100% of dietary FM, whilst IM B did not perform equally well.

No abstract