Deep-fried oil consumption in rats impairs glycerolipid metabolism, gut histology and microbiota structure

Abstract

BackgroundDeep frying in oil is a popular cooking method around the world. However, the safety of deep-fried edible oil, which is ingested with fried food, is a concern, because the oil is exposed continuously to be re-used at a high temperature, leading to a number of well-known chemical reactions. Thus, this study investigates the changes in energy metabolism, colon histology and gut microbiota in rats following deep-fried oil consumption and explores the mechanisms involved in above alterations.MethodsDeep-fried oil was prepared following a published method. Adult male Wistar rats were randomly divided into three groups (n = 8/group). Group 1: basal diet without extra oil consumption (control group); Group 2: basal diet supplemented with non-heated canola oil (NEO group); Group 3: basal diet supplemented with deep-fried canola oil (DFEO group). One point five milliliters (1.5 mL) of non-heated or heated oil were fed by oral gavage using a feeding needle once daily for 6 consecutive weeks. Effect of DFEO on rats body weight, KEGG pathway regarding lipids metabolism, gut histology and gut microbiota were analyzed using techniques of RNA sequencing, HiSeq Illumina sequencing platform, etc.ResultsAmong the three groups, DFEO diet resulted in a lowest rat body weight. Metabolic pathway analysis showed 13 significantly enriched KEGG pathways in Control versus NEO group, and the majority of these were linked to carbohydrate, lipid and amino acid metabolisms. Comparison of NEO group versus DFEO group, highlighted significantly enriched functional pathways were mainly associated with chronic diseases. Among them, only one metabolism pathway (i.e. glycerolipid metabolism pathway) was found to be significantly enriched, indicating that inhibition of this metabolism pathway (glycerolipid metabolism) may be a response to the reduction in energy metabolism in the rats of DFEO group. Related gene analysis indicated that the down-regulation of Lpin1 seems to be highly associated with the inhibition of glycerolipid metabolism pathway. Histological analysis of gastrointestinal tract demonstrated several changes induced by DFEO on intestinal mucosa with associated destruction of endocrine tissue and the evidence of inflammation. Microbiota data showed that rats in DFEO group had the lowest proportion of Prevotella and the highest proportion of Bacteroides among the three groups. In particular, rats in DFEO group were characterized with higher presence of Allobaculum (Firmicutes), but not in control and NEO groups.ConclusionThis study investigated the negative effect of DFEO on health, in which DFEO could impair glycerolipid metabolism, destroy gut histological structure and unbalance microbiota profile. More importantly, this is the first attempt to reveal the mechanism involved in these changes, which may provide the guideline for designing health diet.Electronic supplementary materialThe online version of this article (doi:10.1186/s12944-016-0252-1) contains supplementary material, which is available to authorized users.

Oxidation delay of sunflower oil under frying by moringa oil addition: more than just a blend

“…Nonanal was the most abundant in OO and MOO, from oleic acid, while hexanal was the most abundant in SFO, explained by the higher linoleic acid content . The lower alkadienal amounts could have a serious impact on the toxicity of the oils and the frying fumes during frying …”

“…Human diets and lifestyles have changed dramatically in recent decades, but deep‐frying, probably owing to its sensorial attributes and short processing times, remains as one of the most popular cooking methods worldwide, with a large spread in domestic and industrial environments . However, during this high‐temperature cooking process, severe quality changes occur in the frying oil, with the formation of a multitude of volatile and non‐volatile compounds, some of which are recognized as potentially deleterious to human health . Therefore vegetable oil thermal stability is of major importance, being highly influenced by the fatty acid composition and by some minor lipid components such as phenolic compounds and sterols, both affecting oil stability and performance at elevated temperatures while providing health benefits to consumers …”

In vivo monitoring of hepatic glycolipid distribution of <i>n</i>-6 ∕ <i>n</i>-3 in jugular-vein-cannulated rats as a nutritional research model for monogastric animal

“…Since post-meal intake of lipoprotein particles and their residues can lead to abundant triglycerides in blood plasma due to secretion of chylomicron in the alimentary canal that is competitive against lipoprotein lipase activity, rats can keep secreting very-low-density lipoprotein triacylglycerol (VLDL-TG), which may aggravate their health (Shi and Cheng, 2009;Wilfling et al, 2013). However, studies on the direct relationship between the ratio of dietary n-6 / n-3 in diet intake and metabolic distribution of hepatic glycerolipids in the monogastric animal are insufficient (Irma et al, 2000;Zhou et al, 2016).…”

The Effects of Heated Oils Used in Fast Food Restaurants on Metabolic, Inflammatory and Oxidative Stress Markers, Blood Pressure, and Liver Histology in Sprague-Dawley Rats

“…Even though food intake was higher in the TPC 35 group, no significant difference was observed in weight gain between the groups. Toxic products derived from oil during heating may cause negative effects on energy metabolism, thus energy loss is intensified and prevents weight gain (19). It is also possible for polar toxic compounds that are produced under extreme temperatures to decrease food energy efficacy and impair fat calorigenic ability (20).…”