What are the trans fatty acids issues in foods after discontinuation of industrially produced trans fats? Ruminant products, vegetable oils, and synthetic supplements

Abstract

Adverse health effect of trans fatty acids (TFAs) are well recognized , which has precipitated efforts to reduce their content in food products. With the decline of dietary TFAs derived from partial oil hydrogenation, interest is focused on the remaining sources of dietary TFAs derived from ruminants (rTFA), deo-dorized vegetable oils, trans isomerization during frying, and synthetic conjugated FA (CFA) supplements. Partial hydro-genation and heat-treated oils result in a random distribution of TFA isomers, whereas rTFAs contain specifi c isomers resulting from enzymatic processes. Reviews of human observational and metabolic intervention studies have suggested that consumption of rTFAs at current levels should not raise health concerns. However, these studies were not based on rTFA levels currently sold in retail markets. Current feeding practices of ruminants result in higher total TFAs with trans-18:1 isomers other than vaccenic acid, and many CFAs other than rumenic acid. The defi nition of TFA adopted by several countries does not distinguish among isolated TFAs of concern and ignores CFAs that should be included in total TFA due to their negative health effects. Accurate TFA defi nition establishment and nutritional assessment of individual TFA isomers is needed for labeling purposes. Also required are adoptions of analytical methods to resolve all TFA isomers. This information can then be used to construct a database and as a basis for meaningful recommendations. Practical applications: Areas that require further investigations have been identifi ed: 1) Establish a uniform TFA nomenclature based on chemical structure 2) Standardize, assess and normalize appropriate method-ologies for the analysis of TFAs 3) Synthesize pure reference standards for TFA identifi cation 4) Report individual TFA levels with different biological activities rather than total TFA content 5) Assess the nutritional characteristics of individual TFAs independent of their origin 6) Develop strategies to increase the content of desirable TFA isomers in ruminants 7) Identify potential bioactive trans metabolites produced from PUFAs in ruminants 8) Develop labeling regulations based on specifi c chemical structures and physiological effects regardless of their origin 9) Construct an accurate database complemented with spe-cifi c surveys of ruminant product FA composition that can be accessed by regulatory agencies to make appropriate TFA recommendations. The fi nal version of this Highlight Article was not available in time for inclusion in this special issue. For this reason only the abstract and graphical abstract are presented here. The full-text can be accessed online via the permanent link http://dx.

Differences in intramuscular fatty acid profiles amongBos indicusand crossbredBos taurus × Bos indicusbulls finished on pasture or with concentrate feed in Brazil

“…It has been shown that 18:1 trans-10 is produced in an alternate biohydrogenation route when high-concentrate diets are used (Bessa et al 2005) and our data are fully consistent with this. The occurrence of elevated 18:1 trans-10 concentrations in meat is characteristic of intensive finishing systems for beef cattle and the putative negative health effects of 18:1 trans-10-enriched meats are currently under discussion (Aldai et al 2013). …”

Effect of feeding lambs with a tanniferous shrub (rockrose) and a vegetable oil blend on fatty acid composition of meat lipids

“…The reason for that were the changes in biohydrogenation pathways, resulting in the replacement of t11-18:1 by t10-18:1 as the major biohydrogenation intermediate (hereafter t10-shift), observed when the Cistus and oil increased in the diet. The occurrence of the t10-shift has been frequently reported in ruminants fed low-forage, high-oil diets (Aldai et al, 2013) and in growing ruminants raised on pasture and supplemented with ground corn (Rosa et al, 2014). Polyunsaturated FA intake has a profound and well established effect on the accumulation of biohydrogenation intermediates in rumen and tissues (Shingfield et al, 2013;Shingfield and Wallace, 2014).…”

“…In the present experiment, despite a middle dietary forage inclusion (50%), the Cistus tannins increased mostly the t10-18:1 in NL, with no effect on t11-18:1. The synergy between PUFA and tannins intake promoting the t10-shift is undesirable, assuming that t10-18:1 has deleterious health effects to consumers, as reviewed by Aldai et al (2013) and is not a substrate for endogenous CLA synthesis. Despite the exuberant t10-18:1 increase in NL, oil supplementation also increased t11-18:1, but not c9,t11-18:2.…”

Caracterización comercial y nutricional de la grasa subcutánea de terneros y vacas de desvieje sacrificados en la Comunidad Autónoma del País Vasco

“…Sin embargo, la carne y los productos cárnicos son alimentos que en la actualidad están en entredicho debido a que no todas las grasas tipo trans de origen animal, y en particular las de los rumiantes, presentan efectos adversos sobre la salud humana Roy et al, 2007;Burnyeat, 2015). Como se ha constatado en varios trabajos de revisión (Aldai et al, 2013;Bessa et al, 2015) su perfil lipídico está marcadamente influenciado por la alimentación del animal.…”