Ruminant and industrially produced trans fatty acids: health aspects

Abstract

Fatty acids of trans configuration in our food come from two different sources - industrially produced partially hydrogenated fat (IP-TFA) used in frying oils, margarines, spreads, and in bakery products, and ruminant fat in dairy and meat products (RP-TFA). The first source may contain up to 60% of the fatty acids in trans form compared to the content in ruminant fat which generally does not exceed 6%. In Western Europe, including Scandinavia, the average daily intake of IP-TFA has decreased during the recent decade due to societal pressure and a legislative ban, whereas the intake of RP-TFA has remained stable.In spite of this decrease we have found that in many countries consumption >20 g of IP-TFA in a one-meal menu consisting of some popular foods is possible, even though the average intake of IP-TFA in these countries is low. Subgroups of the populations may therefore, on average, consume >5 g IP-TFA per day. This level of consumption is generally not possible for RP-TFA. A daily intake of 5 g TFA (primarily IP-TFA) is associated with a 29% increased risk of coronary heart disease. Such an association is not found for RP-TFA up to a daily intake of 4 g.The high amount of IP-TFA in popular foods, the evidence of a more harmful effect on health by IP-TFA than by RP-TFA, and the feasibility of eliminating IP-TFA from foods without side effects for the population, suggest that a selective elimination of IP-TFA from our food is a 'low hanging fruit' in the quest for a more healthy diet for subgroups of the population.

Keywords: cardio-vascular disorders; health aspects; hydrogenated fats; industrial; obesity; ruminant; trans fatty acids.

Fig 1.

Isomeric distribution of trans-octadecenoic acids in industrially produced and ruminant trans fat (mean wt% of trans-18:1 fatty acids) adapted from Wolff et al. .

Fig 2.

(A) The average intake of industrially produced and ruminant trans fatty acids in Denmark from 1978 to 2005. The intake of ruminant fat was measured in 1996 . Some studies suggest that this intake has been constant from 1972 to 2005. (B) Mortality curves for coronary heart disease in Denmark during the period with decreasing intake of industrially produced trans fatty acids, but constant intake of ruminant trans fatty acids.

Fig 3.

Grams of industrially produced trans fatty acids in a ‘high trans fat menu’. A large serving of fast food consists of 160 g of nuggets and 171 g of French fries. In each country, the products with the highest amount of trans fatty acids per 100 g product in each category are shown. Values in brackets are percent trans fatty acids of total fat in French fries, biscuits/cakes/wafers and microwave oven popcorn, respectively. The foods were bought between 2005 and 2008.

Fig 4.

Trans fatty acids in 160 g meat from two different sources. Values in brackets are percent trans fatty acids of total fat.

Fig 5.

Spline regression analysis of the log hazard ratios of coronary heart disease according to intake of ruminant trans fatty acid (RP-TFA) in an 18-year prospective study ending in 2000 of 3,686 Danish women and men aged 30–71 years. Adapted from Jakobsen et al. .

Fig 6.

Prevalence of obesity among young Danish males attending mandatory draft boards (% with BMI >20 kg/m²). Data up to 2000 were modified from Sorensen and Price and Sørensen et al. , data after 2000 were kindly provided by the Danish Ministry of Interior and Health.