Diets varying in SFA and MUFA content can impact glycaemic control; however, whether underlying differences in genetic make-up can influence blood glucose responses to these dietary fatty acids is unknown. We examined the impact of dietary oils varying in SFA/MUFA content on changes in blood glucose levels (primary outcome) and whether these changes were modified by variants in the stearoyl-CoA desaturase (SCD) gene (secondary outcome). Obese men and women participating in the randomised, crossover, isoenergetic, controlled-feeding Canola Oil Multicenter Intervention Trial II consumed three dietary oils for 6 weeks, with washout periods of ˜6 weeks between each treatment. Diets studied included a high SFA/low MUFA Control oil (36·6 % SFA/28·2 % MUFA), a conventional canola oil (6·2 % SFA/63·1 % MUFA) and a high-oleic acid canola oil (5·8 % SFA/74·7 % MUFA). No differences in fasting blood glucose were observed following the consumption of the dietary oils. However, when stratified by SCD genotypes, significant SNP-by-treatment interactions on blood glucose response were found with additive models for rs1502593 (P = 0·01), rs3071 (P = 0·02) and rs522951 (P = 0·03). The interaction for rs3071 remained significant (P = 0·005) when analysed with a recessive model, where individuals carrying the CC genotype showed an increase (0·14 (sem 0·09) mmol/l) in blood glucose levels with the Control oil diet, but reductions in blood glucose with both MUFA oil diets. Individuals carrying the AA and AC genotypes experienced reductions in blood glucose in response to all three oils. These findings identify a potential new target for personalised nutrition approaches aimed at improving glycaemic control.

Limited availability of fish oils (FO), rich in n-3 long-chain (≥C20) PUFA, is a major constraint for further growth of the aquaculture industry. Long-chain n-3 rich oils from crops GM with algal genes are promising new sources for the industry. This project studied the use of a newly developed n-3 canola oil (DHA-CA) in diets of Atlantic salmon fingerlings in freshwater. The DHA-CA oil has high proportions of the n-3 fatty acids (FA) 18 : 3n-3 and DHA and lower proportions of n-6 FA than conventional plant oils. Levels of phytosterols, vitamin E and minerals in the DHA-CA were within the natural variation of commercial canola oils. Pesticides, mycotoxins, polyaromatic hydrocarbons and heavy metals were below lowest qualifiable concentration. Two feeding trials were conducted to evaluate effects of two dietary levels of DHA-CA compared with two dietary levels of FO at two water temperatures. Fish increased their weight approximately 20-fold at 16°C and 12-fold at 12°C during the experimental periods, with equal growth in salmon fed the FO diets compared with DHA-CA diets. Salmon fed DHA-CA diets had approximately the same EPA+DHA content in whole body as salmon fed FO diets. Gene expression, lipid composition and oxidative stress-related enzyme activities showed only minor differences between the dietary groups, and the effects were mostly a result of dietary oil level, rather than the oil source. The results demonstrated that DHA-CA is a safe and effective replacement for FO in diets of Atlantic salmon during the sensitive fingerling life-stage.

In this study we found that Japanese consumers value the conventional health claim “low in saturated fat” more than the relatively newer claims, such as “high in oleic acid.” In addition, consumers do not prefer oil with genetically modified ingredients or oil that is not domestically produced, but they are willing to pay extra for “organic” or “functional food” features. We also found that the scope and source of information on these credence attributes may also affect consumers' choices and willingness to pay and that the effects may not be completely consistent with what one would expect.

The present narrative review compares evidence from experimental, epidemiological and clinical studies of the health benefits of rapeseed oil (RO) (known as canola oil) and olive oil (OO) in order to assess whether rapeseed oil is suitable as a sustainable alternative to OO as part of a Mediterranean-style diet in countries where olive trees do not grow. From epidemiological studies, the evidence for cardiovascular protection afforded by extra-virgin OO is ‘convincing’, and for cancers ‘limited-suggestive’, especially oestrogen receptor-negative breast cancer, but more studies are required in relation to cognitive impairment. Evidence for RO is limited to short-term studies on the biomarkers of risk factors for CVD. Any benefits of RO are likely to be due to α-linolenic acid; however, it is prone to oxidation during frying. We conclude that due to a lack of evidence from observational or intervention studies indicating that RO has comparable health benefits to extra-virgin OO, RO cannot currently be recommended as a suitable substitute for extra-virgin OO as part of a Mediterranean-style diet.

We determined the relative importance of cholecystokinin (CCK), leptin, and fatty acid concentrations in plasma in mediating the satiety effects of supplemental fat in lactating cows. Five ruminally and duodenally cannulated Holstein cows in late lactation were used in a 3×5 incomplete Latin square design with three treatments: 1) Control: basal diet (CON), 2) Control+supplementation of canola oil at 1 kg/d in the feed (FED) and 3) Control+abomasal infusion of canola oil at 1 kg/d (INF). Relative to CON, feed intake was reduced by INF but not by FED. We provide evidence that both FED and INF treatments stimulated CCK gene expression in the duodenum and elevated plasma CCK concentrations. However, our results did not support a role for CCK in mediating satiety through an endocrine mechanism of action. We speculate that CCK might be acting either through paracrine and/or neurocrine routes to influence feed intake in cattle. Both FED and INF had no effect on the mRNA abundance of leptin, lipoprotein lipase, or acetyl-CoA carboxylase in adipose tissue. Plasma concentrations of leptin, insulin and IGF-I were not altered by FED or INF, indicating that these signals may not be involved in mediating short-term hypophagic effects of dietary fat. Plasma concentrations of 18[ratio ]1n-9 and 18[ratio ]2n-6 were significantly greater for INF than for FED or CON. We conclude that the hypophagic effects of supplemental fat in cattle depend on the amount of unsaturated fatty acids reaching the intestine and that this satiety effect is mediated through CCK, oleic acid and (or) linoleic acid, but leptin is not involved.

We determined the effects of feeding canola oil or infusing it into the abomasum on rumen fermentation, nutrient digestibility, duodenal flows of fatty acids, and milk composition in Holstein cows. Five ruminally and duodenally cannulated Holstein cows in late lactation were used in a 3×5 incomplete Latin square design. Treatments were 1) Control: basal diet (CON), 2) Control+supplementation of canola oil at 1 kg/d in the feed (FED), and 3) Control+abomasal infusion of canola oil at 1 kg/d (INF). Compared with CON, feed intake, ruminal fermentation characteristics, ruminal and total tract digestibilities of nutrients were not significantly affected by FED treatment but duodenal flows and milk concentrations of fatty acids (FA) such as trans-11 18[ratio ]1 and cis-9 trans-11 18[ratio ]2 (conjugated linoleic acid, CLA) were increased. In contrast to the effects of FED, INF reduced feed intake, total VFA production, intestinal flows of nutrients, FA digestibility and yields of milk and milk fat. Both FED and INF significantly reduced the proportions of saturated and medium-chain FA, and increased cis 18[ratio ]1 in milk. Concentrations of 18[ratio ]2n-6 and 18[ratio ]3n-3 in milk were increased nearly 2-fold with INF relative to CON. Dietary or postruminal supplementation of canola oil to late-lactation cows reduced saturated FA and increased unsaturated C18 in milk but nutrient digestion was adversely affected with abomasal infusion of canola oil.