A 24-month dietary carcinogenicity study of DAG in mice

Glyceryl Diesters

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 2002, along with updated information regarding product types and concentrations of use, and confirmed that these 17 glyceryl diesters are safe as cosmetic ingredients in the practices of use and concentration as described in this report.

Re-evaluation of mono- and di-glycerides of fatty acids (E 471) as food additives

The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of mono- and di-glycerides of fatty acids (E 471) when used as a food additive. The Panel considered that it is very likely that hydrolysis of mono- and di-glycerides of fatty acids by lipases in the gastrointestinal tract would occur, resulting in the release of glycerol and fatty acids. Glycerol (E 422) and fatty acids (E 570) have been re-evaluated and the Panel concluded that there was no safety concern regarding their use as food additives. Toxicological studies with mono- and di-glycerides rich in unsaturated fatty acids were considered for the re-evaluation of E 471. No evidence for adverse effects was reported in short-term, subchronic studies, chronic, reproductive and developmental toxicity studies. Neither carcinogenic potential nor a promotion effect in initiation/promotion was reported. The available studies did not raise any concern with regard to genotoxicity. The refined estimates were based on 31 out of 84 food categories in which E 471 is authorised. The Panel noted that the contribution of E 471 represented at the mean only 0.8-3.5% of the recommended daily fat intake. Based on the approach described in the conceptual framework for the risk assessment of certain food additives re-evaluated under Commission Regulation (EU) No 257/2010 and taking into account the considerations mentioned above, the Panel concluded that there was no need for a numerical acceptable daily intake (ADI) and that the food additive mono- and di-glycerides of fatty acids (E 471) was of no safety concern at the reported uses and use levels. The Panel recommended some modifications of the EU specifications for E 471.

Alpha-linolenic acid-enriched diacylglycerol oil does not promote tumor development in tongue and gastrointestinal tract tissues in a medium-term multi-organ carcinogenesis bioassay using male F344 rat

Alpha-linolenic acid (ALA)-enriched diacylglycerol (DAG) oil is an edible oil enriched with DAG (>80%) and ALA (>50%). The present study investigated whether ALA-DAG oil promotes tumorigenesis in the tongue and gastrointestinal tract, using a rat medium-term multi-organ carcinogenesis bioassay model. Rats were treated with five genotoxic carcinogens to induce multi-organ tumorigenesis until week 4, and from 1 week after withdrawal, fed a semi-synthetic diet (AIN-93G) containing ALA-DAG oil at concentrations of 0, 13,750, 27,500, and 55,000 ppm. Rats fed AIN-93G containing 55,000 ppm ALA-triacylglycerol or a standard basal diet served as reference and negative control groups, respectively. Animals were euthanized at week 30. ALA-DAG oil was shown to have no effects on survival, general condition, body weight, food consumption, or organ weight. More discolored spots were observed in the stomachs of the 13,750- and 55,000-ppm ALA-DAG groups than in those of the control groups; however, there were no differences in the frequency of histopathological findings across groups. There were no meaningful increases in the incidence of pre-neoplastic and neoplastic lesions in the tongue and gastrointestinal tract among the groups. We therefore conclude that ALA-DAG oil does not promote tumor development in the digestive system.

No enhancing effects of diacylglycerol oil on tumor development in a medium-term multi-organ carcinogenesis bioassay using male F344 rats

The modifying potential of diacylglycerol (DAG) oil on tumor development was investigated in a medium-term multi-organ carcinogenesis bioassay. DAG oil is a cooking oil that contains >80% diglycerides, <20% triglycerides and <5% monoglycerides. Male 6-week-old F344 rats (20 in each group) were sequentially treated with five carcinogens for initiation in different organ target sites for 4 weeks (DMBDD treatment), and then administered DAG oil at dietary levels of 0% (control), 1.375%, 2.75% or 5.5% [triacylglycerol (TGs), with the same fatty acid composition as DAG oil were also added at dietary levels of 5.5%, 4.125%, 2.75% and 0%, respectively, to maintain the same lipid level], or 5.5% high linoleic acid TG (HLTG), 5.5% high oleic acid TG (HOTG), or 5.5% medium-chain TG (MCTG) (as reference substances, mostly consisting of triacylglycerols) admixed into AIN-93G semi-synthetic diet, for an additional 24 weeks. Controls received standard diet without any supplementation as non-treated control. All animals were killed at the end of week 28, and the major organs were carefully examined for preneoplastic and neoplastic lesions. No DAG oil treatment-related changes were noted in survival, general conditions, body weights, food consumption and organ weights. Upon quantitative analysis of glutathione S-transferase placental form (GST-P) positive foci of the liver, DAG oil was not found to exert any effects. The incidence of colon adenomas was significantly increased in rats given 1.375% DAG oil, but not 2.75% and 5.5% DAG oil, when compared to the control (5.5% TG group) value. Furthermore, incidences and multiplicity of hyperplasias and adenomas and/or adenocarcinomas were comparable across all DAG oil-treated groups. In contrast, incidences of colon adenomas and/or adenocarcinomas were significantly increased in rats given 5.5% HOTG, and adenomas with MCTG, but not 5.5% HLTG, as compared to the 5.5% TG value. Preneoplastic and neoplastic lesions induced by DMBDD treatment in various organs other than the large intestine were comparable in all cases. Thus, the current results indicate that DAG oil may not exert modifying potential on tumor development, even in the colon because of the lack of dose-dependence. DAG oil was equivalent to HOTG (standard cocking oil composed of naturally occurring fatty acids), with regard to colon tumor development. Further dose-response study concerning HOTG may be needed to confirm whether the enhancing effect of large intestine carcinogenesis exert or not.

Diacylglycerol oil for the metabolic syndrome

Excess adiposity has been shown to play a crucial role in the development of the metabolic syndrome. The elevated fasting and postprandial triglyceride-rich lipoprotein levels is the central lipid abnormality observed in the metabolic syndrome. Recent studies have indicated that diacylglycerol (DAG) is effective for fasting and postprandial hyperlipidemia and preventing excess adiposity by increasing postprandial energy expenditure. We will here discuss the mechanisms of DAG-mediated improvements in hyperlipidemia and in postprandial energy expenditure, and effects of DAG oil on lipid/glucose metabolism and on body fat. Further, the therapeutic application of DAG for the metabolic syndrome will be considered.

Possible enhancing activity of diacylglycerol on 4-nitroquinoline 1-oxide induced carcinogenesis of the tongue in human c-Ha-ras proto-oncogene transgenic rats

1,2-diacylglycerol (1,2-DAG) is involved in cell proliferation as an activator of protein kinase C (PKC) and has been shown to stimulate growth of cancer cells, raising the possibility of a role in tumor promotion. Ingested DAG oil, containing 70% 1,3-DAG and 30% 1,2-DAG, is digested and considered to be safe as edible oil. However, DAG may directly contact with oral cavity mucosa in undigested form. The present study was conducted to examine the effects of DAG oil on carcinogenesis in c-Ha-ras proto-oncogene transgenic (Tg) rats administered 4-nitroquinoline 1-oxide (4NQO, 10 ppm) in their drinking water for 10 weeks for initiation of mainly upper digestive organs. DAG oil added in basal diet at 5.5%, 2.75%, 1.38% and 0% with total fat made up to 5.5% with triacylglycerol (TAG) was administered during the initiation and post-initiation period. The study was terminated at week 12 (Tg females) and 20 (Tg males, wild females and males). The fatty acid composition of DAG oil was similar to TAG (linoleic acid 46.6% and oleic acid 38.9%). In Tg male rats, DAG oil administration was associated with significant increase (P<0.05) in the incidence of squamous cell carcinomas (SCC) of the tongue (5.5% DAG, 43.8%; 2.75% DAG, 20%; 1.38% DAG, 14.3%; 0%, 12.3%) with the Cochran-Armitage trend test and also number of tumors in coefficients for linear contrast trend tests. Tongue SCC induction of wild males and all females was not significant. The present results suggest that DAG oil may have enhancing and/or promotion potential for tongue carcinogenesis in male Tg featuring elevated ras expression.