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Interesterified fats: What are they and why are they used? A briefing report from the Roundtable on Interesterified Fats in Foods

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)363-380
JournalNutrition Bulletin
Issue number4
Early online date23 Oct 2019
Publication statusPublished - Dec 2019


King's Authors


Interesterification rearranges the position of fatty acids within triacylglycerols, the main
component of dietary fat, altering physical properties such as the melting point and
providing suitable functionality for use in a range of food applications. Interesterified
(IE) fats are one of a number of alternatives which have been adopted to reformulate
products to remove fats containing trans fatty acids generated during partial
hydrogenation, which are known to be detrimental to cardiovascular health. The use of
IE fats can also reduce the saturated fatty acid (SFA) content of the final product (e.g. up
to 20% in spreads), while maintaining suitable physical properties (e.g. melt profile). A
novel analysis was presented during the roundtable which combined data from the UK
National Diet and Nutrition Survey (2012/2013–2013/2014) with expert industry
knowledge of the IE fats typically used in food products, to provide the first known
estimate of population intakes of IE fats among UK children and adults. IE fats were
found to contribute approximately 1% of daily energy across all ages. The major
contributors to overall IE fat intakes were fat spreads (~54%) and bakery products
(~22%), as well as biscuits (~8%), dairy cream alternatives (~6%) and confectionery (~6%).
Increasing use of IE fats could contribute towards reducing total SFA intakes in the
population, but would depend on which food products were reformulated and their
frequency of consumption among sub‐groups of the population. Studies comparing the
effect of IE and non‐IE fats on markers of lipid metabolism have not shown any
consistent differences, either in the fasted or in the postprandial state, suggesting a
neutral effect of IE fats on cardiovascular disease risk. However, these studies did not
use the type of IE fats present in the food supply. This issue has been addressed in two
studies by King's College London, which measured the postprandial response to a
commercially relevant palm stearin/palm kernel (80:20) IE ‘hard stock’, although again
no consistent effects of the IE fat on markers of lipid metabolism were found. Another
study is currently investigating the same IE hard stock, consumed as a fat spread
(blended with vegetable oil), and will measure a broader range of postprandial
cardiometabolic risk factors. However, further long‐term trials using commercially
relevant IE fats are needed. Subsequent to the roundtable, a consumer survey of UK
adults (n = 2062; aged 18+ years) suggested that there is confusion about the health
effects of dietary fats/fatty acids, including trans fats and partially hydrogenated fats.
This may indicate that providing evidence‐based information to the public on dietary
fats and health could be helpful, including the reformulation efforts of food producers
and retailers to improve the fatty acid profile of some commonly consumed foods.

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