Hydrogenated fat high in trans monoenes with an adequate level of linoleic acid has no effect on prostaglandin synthesis in rats

Trans-fatty acids and nonlipid risk factors

Consumption of industrially produced trans-fatty acids (TFA) is associated with substantial risk of coronary heart disease (CHD). The magnitude of this relationship, as well as emerging associations with end points such as diabetes and sudden cardiac death, cannot be fully explained by the well-established adverse effects of TFA on serum lipids. We review the evidence for effects of TFA intake on nonlipid risk factors. Based on evidence from randomized controlled trials, observational studies, animal experiments, and in vitro studies, these include effects on systemic inflammation, endothelial dysfunction, visceral adiposity, insulin resistance, and arrhythmic risk. The types and strength of evidence for each of these nonlipid effects varies, but the overall constellation of findings is qualitatively and quantitatively unique among dietary fats. The multiple adverse effects and implicated pathways are consistent with the observed strong associations of TFA consumption with CHD risk. These nonlipid effects also explain why TFA consumption may adversely impact other non-CHD diseases and end points.

Dietary supplementation withtrans-11- andtrans-12-18 : 1 increasescis-9,trans-11-conjugated linoleic acid in human immune cells, but without effects on biomarkers of immune function and inflammation

Trans-fatty acid intake is associated with an increased risk of CHD and diabetes. The effects of singletrans-fatty acid isomers are largely unexplored. The present study examined the effects of a 6-week supplementation with twotrans-18 : 1 isomers (trans-11 andtrans-12) in human subjects on immune cells, several inflammatory and immunological biomarkers (for example, IL, TNFα, C-reactive protein, adiponectin, intercellular adhesion molecule-1, prostacyclin, phagocytic process). Following a 2-week adaptation period without supplements, the test group (n12) received vaccenic acid (trans-11-18:1) andtrans-12-18 : 1 in equal amounts (6·0 g/d) for 6 weeks. The control group (n12) consumed an oil withouttrans-fatty acids and conjugated linoleic acids (CLA). Samples were collected at the end of both periods.Trans-11- andtrans-12-18 : 1 were significantly increased in cellular lipids. The endogenous synthesis ofcis-9,trans-11-CLA fromtrans-11-18 : 1 was demonstratedviaincreased CLA in cellular lipids of the test group. Generally,trans-isomer supplementation did not affect either inflammatory biomarkers (for example, IL-6, IL-8, TNFα) or immune function (for example, phagocytosis) during the present study. The dietary supplementation oftrans-11- andtrans-12-18 : 1 (6 g/d) and their accumulation in leucocytes had no effects on biomarkers of inflammation and immune function. However, because of the limited data on the safety oftrans-fatty acid intake and effects of individualtransisomers on human health (for example,trans-9-18 : 1,trans-10-18 : 1) at present, it is prudent to reducetrans-fat intake in general.

Efeito da gordura vegetal parcialmente hidrogenada sobre a incorporação de ácidos graxos trans em tecidos de ratos

A composição lipídica da dieta pode influenciar o perfil de ácidos graxos dos tecidos. O objetivo do presente estudo foi avaliar a incorporação de ácidos graxos trans no fígado e coração de ratos. Dois grupos com doze ratos Wistar recém-desmamados foram alimentados com duas dietas diferentes por oito semanas. Uma das dietas (experimental) foi rica em isômeros trans (33,0% da fração lipídica) e apresentou quantidades mínimas de ácidos linoléico e alfa-linolênico (8,0% e 0,7%, respectivamente, da fração lipídica da dieta), enquanto a outra (controle) foi nutricionalmente adequada. O perfil de ácidos graxos das dietas e dos tecidos foi avaliado por cromatografia gasosa. Houve incorporação de 14,0% dos ácidos graxos trans no fígado e 8,6% no coração dos animais. Não foi observado efeito inibitório dos ácidos graxos trans no fígado sobre a formação dos ácidos araquidônico e docosahexaenóico. No entanto, no coração houve uma diminuição significante da concentração do ácido docosahexaenóico, provavelmente como reflexo da deficiência de ácido a-linolênico e da incorporação dos trans.

Metabolic effects of trans fatty acids on an experimental dietary model

The aim of the present study was to investigate the potential nutritional and metabolic impact of trans (t) fatty acids (FA) on an appropriate experimental dietary model. Since previously reported experimental designs have been matter of concern, we developed a dietary model to compare the effect of t isomers and/or the saturation of FA independently of other variables. Wistar rats were fed diets containing identical amounts of nutrients and high levels of dietary fats (200 g/kg) for 30 d. Dietary fat rich in t-FA was compared with fat rich in saturated (s) FA or rich in cis (c) FA, maintaining the same length of C chain of the FA. The fats were obtained through isomerization or hydrogenation of the c-FA present in the control fat. Apparent fat absorption, energy efficiency and triacylglycerol levels in serum and liver were different in rats fed t-FA or s-FA than c-FA. The apparent fat absorption was (%): s-FA 85.7 (sd 3.4)<t-FA 93.1 (sd 0.4)<c-FA 96.7 (sd 1.1) (P<0.05). The efficiency of energy utilization was lower in t-FA (11.7 %) and s-FA (18.5 %) diets, reaching statistical significance only between s-FA and c-FA. A striking finding was the change in the lipid profile in serum and liver. Serum and hepatic triacylglycerol levels were greater for t-FA and s-FA diets than in c-FA; however, the increases on serum triacylglycerol concentrations were greater with the s-FA diet and the increases on hepatic triacylglycerol content were greater with t-FA. Knowledge of the t-FA effects on this kind of experimental dietary model could contribute to determine the potential risk of t-FA intake for man.

Trans-fatty acids and colon cancer

Trans-fatty acids have been hypothesized to be carcinogenic, although there are limited data in humans testing this hypothesis. In this study, we examine the association between trans-fatty acids and colon cancer using data from a case (n = 1,993)-control (n = 2,410) study conducted in Utah, Northern California, and Minnesota. Dietary data were collected using a detailed diet history questionnaire, and nutrient values were generated from the Nutrition Coordinating Center nutrient database. After adjustment for other variables, including age at diagnosis, body size, physical activity, aspirin and/or nonsteroidal anti-inflammatory drug (referred to collectively as NSAIDs) use, energy intake, and dietary fiber and calcium, we found a weak association in women [odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.1-2.0] but not in men (OR = 1.2, 95% CI = 0.9-1.7); no increased risk was observed for the cis form of the fatty acids. For men and women, slightly stronger associations were observed in those > or = 67 years of age (OR = 1.4, 95% CI = 0.9-2.1 for men; OR = 1.6, 95% CI = 1.0-2.4 for women). Those who did not use NSAIDs were at a 50% greater risk of developing colon cancer when they consumed high levels of trans-fatty acids. Women who were estrogen negative, i.e., postmenopausal not taking hormone replace therapy, had a twofold increase in risk from high levels of trans-fatty acids in the diet, while women who were estrogen positive did not experience an increased risk of colon cancer, regardless of level of trans-fatty acids consumed. We believe that these data have important public health implications. It seems prudent to avoid consuming partially hydrogenated fats, since no increased risk was observed for the cis form of fatty acids, while suggestions of increased risk from trans-fatty acids exist for subsets of the population.