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REVIEW
WHO Scientific Update on trans fatty acids: summary
and conclusions
R Uauy
1,2
, A Aro
3
, R Clarke
4
, R Ghafoorunissa
5
, M L’Abbe
´
6
, D Mozaffarian
7,8,9
, M Skeaff
10
,
S Stender
11
and M Tavella
12
1
Department of Public Health Nutrition, Instituto de Nutricion y Tecnologia de los Alimentos, University of Chile, Santiago, Chile;
2
Department of Epidemiology and Public Health, London School of Hygiene and Tropical Medicine, London, UK;
3
Department of
Health and Functional Capacity, National Public Health Institute (KTL), Helsinki, Finland;
4
Clinical Trial Service Unit, University of
Oxford, Oxford, UK;
5
Department of Biochemistry, National Institute of Nutrition, Hyderabad, India;
6
Bureau of Nutritional Sciences,
Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada;
7
Division of Cardiovascular Medicine, Brigham and
Women’s Hospital, Harvard Medical School, Boston, MA, USA;
8
Department of Epidemiology, Harvard School of Public Health, Boston,
MA, USA;
9
Department of Nutrition, Harvard School of Public Health, Boston, MA, USA;
10
Department of Human Nutrition,
University of Otago, Dunedin, New Zealand;
11
Department of Clinical Biochemistry, Gentofte University Hospital, Hellerup, Denmark
and
12
Program for the Prevention of Infarcts in Argentina (PROPIA), Department of Medicine, Faculty of Medicine La Plata National
University, La Plata, Argentina
The purpose of the WHO scientific review on trans fatty acids (TFAs) was to examine the evidence generated since the 1993 Joint
FAO/WHO Expert Consultation on Fats and Oils in Human Nutrition, and to inform member countries on the health
consequences of TFAs consumption that have emerged since the last report was released. The new information was deemed
sufficient to recommend the need to significantly reduce or to virtually eliminate industrially produced TFA from the food supply
in agreement with the implementation of the 2004 WHO Global Strategy on Diet, Physical Activity and Health. This goal has
been accomplished in some countries and cities, by the virtual elimination of partially hydrogenated vegetable oils in the human
food supply, replacing them with healthy cis-unsaturated fatty acids. The document provides the evidence base to promote
discussion between the international scientific community related to nutrition and health as well as between agriculturalists,
food producers, relevant health professionals, national and international food regulatory agencies, civil society and the private
sector to achieve the stated goal.
European Journal of Clinical Nutrition (2009) 63, S68–S75; doi:10.1038/ejcn.2009.15
Keywords: trans fatty acids; coronary heart disease; partially hydrogenated vegetable oils; feasibility; Scientific Update
Introduction
The WHO Scientific Update considered new evidence on the
health consequences that have emerged on trans fatty acids
(TFAs) since the last Joint FAO/WHO Expert Consultation
on Fats and Oils in Human Nutrition was held in 1993 (FAO,
1994) and the Joint WHO/FAO Expert Consultation on Diet,
Nutrition and the Prevention of Chronic Diseases (WHO,
2003; Nishida et al., 2004). The new data considered by the
group was deemed sufficient to support recommendations,
leading to a significant reduction or virtual elimination of
industrially produced TFA for the implementation of the
Global Strategy on Diet, Physical Activity and Health (WHO,
2004). The Scientific Update enabled a number of conclu-
sions to be drawn and to establish recommendations for the
elimination of industrially produced TFA from the food
supply. This Scientific Update applied similar criteria to
those used by the 2002 WHO/FAO Expert Consultation on
Diet, Nutrition and the Prevention of Chronic Diseases
(WHO, 2003) and the Joint FAO/WHO Scientific Update on
carbohydrates in human nutrition (Nishida and Martinez
Nocito, 2007) to describe the strength of evidence and to
draw conclusions from the scientific review of the totality of
the evidence, including both randomized controlled studies
in humans and observational studies involving long-
term follow-up of cohorts and experimental animal and
laboratory studies when no other data were available. The
aim of the present report is to provide a summary of the
Correspondence: Professor R Uauy, Instituto de Nutricion y Tecnologia de los
Alimentos, University of Chile, Casilla 138-11, Santiago, Chile.
E-mail: Ricardo.uauy@lsthm.ac.uk or ruauy@inta.cl
European Journal of Clinical Nutrition (2009) 63, S68 – S75
&
2009 Macmillan Publishers Limited All rights reserved 0954-3007/09 $
32.00
www.nature.com/ejcn
scientific reviews of the evidence prepared by the experts and
the conclusions of the discussions of this expert group
prepared in response to the updated evidence presented at
the meeting in Geneva on 29–30 October 2007. This
Scientific Update represents the collective view of the
participating experts, acting in their own personal capacity.
The experts included Antti Aro, Robert Clarke, Rasheed
Ghafoorunissa, Mary L’Abbe
´(Rapporteur), Dariush
Mozaffarian, C Murray Skeaff, Steen Stender, Marcelo Tavella
and Ricardo Uauy (Chairman), who were selected on the
basis of their scientific background and geographic repre-
sentation. The Secretariat members included Denis Aitken,
Timothy Armstrong, Vanessa Candeias, Chizuru Nishida,
Christophe Roy, Jorgen Schlundt and Jonathan Siekmann
and Frank Martinez Nocito who served as a temporary
advisor. FAO, represented by Gina Kennedy, also participated
in the meeting.
Health effects of trans fatty acids
The Joint WHO/FAO Expert Consultation on Diet, Nutrition
and the Prevention of Chronic Disease (WHO, 2003; Nishida
et al., 2004) confirmed that dietary TFAs have adverse effects
on blood lipoprotein profiles and coronary heart disease
(CHD) risk impacting individuals and populations. The
adverse effects on CHD are mediated by increases in plasma
concentrations of low-density lipoprotein cholesterol (LDL-
C) and lipoprotein(a) (Lp(a)), and reductions in high-density
lipoprotein cholesterol (HDL-C), promotion of inflamma-
tion and endothelial dysfunction, and possible effects on
coagulation, insulin resistance and displacement of essential
fatty acids from membranes, affecting prostanoid-related
functions and possibly other key membrane-related func-
tions. The current body of evidence further indicates that
TFA enhances multiple cardiovascular risk factors and
increases CHD-related events.
As part of this WHO Scientific Update on TFA, the
evidence for effects of TFA consumption on CHD was
reviewed (Mozaffarian et al., 2009). Controlled trials and
observational studies provide concordant evidence that
consumption of TFA from partially hydrogenated oils
adversely affects several cardiovascular risk factors and
contributes significantly to an increased risk of CHD events.
Despite the inherent differences in chemical structure,
limited evidence indicates that industrial and ruminant
TFAs may have similar effects on serum lipoproteins when
ruminant TFA are consumed in sufficient quantities (much
higher than seen with usual dietary intakes) in experimental
studies. TFAs increase the ratio of serum levels of total/
HDL-C, the best single lipid predictor of CHD risk, and
therefore intakes of TFA should be avoided. Although
ruminant TFAs cannot be removed entirely from the diet,
their intake is low enough in most populations that they
do not constitute a significant risk factor for CHD. Because
TFAs produced by partial hydrogenation are not normally
present naturally in foods and have no known health
benefits, the group considered them as industrial additives;
as such, food services, restaurants, and food and cooking fat
manufacturers should avoid their use as well (Mozaffarian
et al., 2009).
As reviewed by L’Abbe et al. (2009), the experience from
Denmark indicates that it is possible to largely eliminate
industrial TFAs in foods, whereas experiences from Canada
and New York City indicate that focused efforts can also
bring about reductions. Experiences from Argentina and
India also illustrate successes and serve to demonstrate the
variety of approaches that have been or can be used to
remove TFA. Attention should also be given to possible
health effects of TFAs created during other industrial
processes, such as light deodorization of marine oils and
prolonged deep-frying. The removal of partially hydro-
genated vegetable oil (PHVO), a main source of TFAs in
processed foods, would result in substantial health benefits,
with the greatest advantage obtained when TFAs are replaced
by oils rich in polyunsaturated fatty acids (PUFAs) and/or
monounsaturated fatty acids (MUFAs) (Mozaffarian and
Clarke, 2009). Significant benefits would be expected based
on both effects on cardiovascular risk factors in controlled
trials and observed relationships with clinical CHD events.
Industrial TFA consumption is believed to increase cardio-
vascular risk in multiple ways. The effects consistently
observed in both randomized controlled trials and obser-
vational epidemiological studies include changes in lipo-
proteins, increased LDL-C and Lp(a), reduced HDL-C and
an increased total/HDL-C ratio; proinflammatory effects
and endothelial dysfunction, assessed by both circulating
markers and functional measures. Each of these effects is
most prominent when contrasted with the effect of
cis-unsaturated fats (PUFA or MUFA) replacement; the adverse
effects of TFA on the total/HDL-C ratio and endothelial
dysfunction have also been documented relative to saturated
fatty acid (SFA) replacement. Controlled trials and obser-
vational studies suggest that high intakes of TFAs may worsen
insulin resistance, particularly among susceptible individuals
such as those with visceral adiposity, preexisting insulin
resistance or lower physical activity; further studies are needed
to confirm possible effects on weight gain and on diabetes
incidence in normal individuals (Mozaffarian et al., 2009).
Together these findings suggest that, among dietary fats, TFA
consumption induces characteristic cardiovascular and meta-
bolic effects (Mozaffarian and Willett, 2007), aggravating
multiple related interlinked pathways that appear linked to
the insulin resistance syndrome. Long-term effects of habitual
TFA consumption on clinical outcomes have not been assessed
under fully controlled dietary conditions in humans; ethical
limitations make it unlikely that such trials could ever be
performed.
The differential effects of specific TFAs based on carbon
chain length or trans isomer bond(s) position are less well
established. Too few studies have evaluated partially hydro-
genated fish oils to draw strong conclusions on the
WHO Scientific Update on TFAs
R Uauy et al
S69
European Journal of Clinical Nutrition
difference between 18-carbon as compared to 20- or 22-
carbon isomers on CHD risk. Performing controlled trials
comparing 18:2 against 18:3, TFA isomers are limited by the
relatively lower concentrations of these isomers in partially
hydrogenated oils. In observational studies utilizing biomar-
kers of TFA consumption, both 18:1 and 18:2 isomers appear
to contribute to risk of CHD; conversely, most studies did not
detect any effect of 16:1 TFA. The available data also suggest
that trans-18:2 isomers may be more strongly associated with
CHD risk than trans-18:1 isomers, but the current evidence
on this is limited and precludes definitive conclusions. This
distinction has potential implications as some processes,
such as light hydrogenation or deodorization, may create
proportionally more 18:2 trans isomers and thus could have
greater effects than would be expected based on content of
total TFA alone (Mozaffarian et al., 2009).
Experimental studies of ruminant trans fats are limited by
difficulty in distinguishing effects of changes in TFA from
changes in other fats in ruminant products; the few small
trials reported to date provide inconclusive evidence on
whether the effects of ruminant TFA are different from
industrial TFA. However, evidence from observational studies
in which estimated TFA consumption from industrial and
ruminant sources of TFA has been distinguished and from
studies in which specific TFAs have been measured utilizing
biomarkers generally do not support an adverse effect of
ruminant TFA, in the low amounts usually consumed, on risk
of CHD. Whether very high intakes of ruminant TFA could
affect CHD risk is unresolved, but because consumption levels
are low this does not appear to be critical in practice.
CHD effects of replacing PHVO with other fats/oils
A growing number of food manufacturers, restaurants and
government agencies have implemented or are considering
voluntary, labeling initiatives or regulatory efforts to reduce
the content of industrial TFA in foods. On the basis of
changes in blood lipids, for example, the ratio of total/
HDL-C in short-term randomized controlled trials and on
associations of habitual TFA consumption with disease
outcomes in prospective cohort studies, the estimated effects
on CHD risk of replacing TFA with equivalent calories
from carbohydrate or cis-unsaturated fats were previously
estimated. However, in practice, TFAs in foods cannot be
specifically fully replaced on a 1:1 basis by other nutrients.
Rather, PHVO or other fats/oil sources that contain TFAs
must be removed and replaced with alternative fats or oils. A
variety of alternatives to PHVO include different combina-
tions of SFA, PUFA and MUFA, for example, vegetable oils,
tropical oils, lard or butter (Mozaffarian and Clarke, 2009).
The predicted effects on CHD risk of replacing different
PHVO formulations with alternative fats and oils were
calculated (Mozaffarian and Clarke, 2009). To provide the
more robust and reliable estimates of the importance of TFA
for CHD risk, they performed two quantitative estimates: the
first based on the effects of dietary fats (TFA, SFA, MUFA and
PUFA) on blood lipids, lipoproteins and C-reactive protein
(CRP) obtained from randomized controlled trials, and the
second based on the relationship of habitual consumption of
dietary fats with CHD events based on data from prospective
observational studies.
To establish the quantitative effects of TFA consumption,
as a replacement for other fats, on blood lipids, apolipopro-
teins and Lp(a), Mozaffarian and Clarke (2009) performed a
meta-analysis of 13 randomized controlled dietary trials.
This demonstrated clear effects of TFA, in comparison with
SFA, MUFA or PUFA, on blood lipid concentrations, ApoB,
ApoA-I and Lp(a). Notable effects of TFA included an increase
in the total/HDL-C ratio and ApoB levels, particularly versus
MUFA or PUFA but also versus SFA; lower HDL-C and ApoA-I
and an increase in Lp(a). The effects on ApoB and ApoA-I
were only partly attenuated (B50%) after adjustment for
changes in the total/HDL-C ratio, indicating that TFA
consumption independently affects both blood lipid concen-
trations and apolipoprotein levels. A separate meta-analysis
of prospective cohort studies evaluating habitual TFA
consumption and CHD events demonstrated that a 2%
higher energy intake from TFA, as an isocaloric replacement
for carbohydrate, was associated with 24% higher CHD risk
(Mozaffarian and Clarke, 2009).
Results of calculations predicting changes in CHD risk
indicated that replacement of PHVO (having 20, 35 or 45%
TFA) providing 7.5% total energy with any of the alternative
fats/oils would lower CHD risk, though the magnitude of
the predicted benefits varied. For a 20% TFA PHVO,
replacement with butter would have minimal effects on
CHD risk, whereas replacement with vegetable oils would
lower risk by B10%. For PHVO with 35 or 45% TFA, any of
the alternative fats/oil, including butter, lard, palm oil or
vegetable oils, would lower risk by 12–20%, with larger
benefits coming from vegetable oils compared with
animal fats.
A comparison of these results—the estimates based on
documented effects on cardiovascular risk factors in
controlled trials versus observed associations between diet-
ary intakes and CHD events in cohort studies—serve to
derive important conclusions relevant to quantitating the
risk from TFA consumption (Mozaffarian and Clarke, 2009).
First, for the replacement of PHVO with butter, lard or palm
oil, the predicted effects based on risk factor changes
obtained from short-term randomized trials were qualita-
tively and quantitatively similar to those derived from
observed associations obtained from observational cohort
studies of long-term differences in diet. The effects of TFA on
risk factor levels consistently accounted for most (65–80%)
of the differences in CHD risk reduction predicted by the
observational studies, suggesting that most of the observed
effects may be explained by effects on total/HDL-C ratio,
ApoB, ApoA-I, Lp(a) and CRP.
Conversely, for the replacement of PHVO with different
vegetable oils, the predicted effects on CHD based on risk
WHO Scientific Update on TFAs
R Uauy et al
S70
European Journal of Clinical Nutrition
factor changes from trial data accounted for only B50% of
the estimated effects derived from observed associations in
cohort studies. This could be due to either underestimation
of benefits based on risk factor changes in trials or over-
estimation of benefits based on CHD incidence from cohort
studies. Because the estimates of CHD benefits of vegetable
oils calculated only from changes in selected risk factors
(total/HDL-C ratio, ApoB, ApoA-I, Lp(a) and CRP) may not
account for other benefits (for example, on insulin sensitiv-
ity or endothelial function), the magnitude of benefits
calculated from the cohort studies may be closer to the true
effects (Mozaffarian and Clarke, 2009). The analysis identi-
fied several strengths and potential limitations of the
approach taken in these estimations (for additional details
see Mozaffarian and Clarke, 2009). However, these analyses
of data suggest that when removing PHVO from foods,
manufacturers and restaurants should take advantage of the
expense and effort of food reformulation to maximize the
overall healthiness of the foods by using cis-unsaturated fats
for replacement.
The discussion by the experts on the merits and limita-
tions of the analysis presented by Mozaffarian and Clarke
(2009) centered on its usefulness as a risk assessment and
management tool. The group considered that the suggested
approach was extremely useful provided there was informa-
tion on the energy from industrial TFA being consumed by a
given individual or population and on the proportion of TFA
in the PHVO being consumed. The overall approach is
clearly useful to assess risk management options based on
the prediction of potential effectiveness of the PHVO
replacement by the specific oil/fat sources based on the
health benefit to be derived. The absolute effects on risk will
depend on the contribution of PHVO-derived energy being
replaced. In addition, as the average TFA content of PHVO
changes, so will the relative benefits in terms of the various
replacement fat or oils. This is of relevance in the choice of
alternative fats and oils used to replace PHVO; for example,
the replacement of PHVO with butter might be beneficial for
PHVO with higher content (35–45%) of TFA but neutral for
PHVO with lower content (o20%) of TFA. Unfortunately, for
most countries the quality of data on TFA content of PHVO
and the %E from industrially derived TFA consumed is
insufficient if available at all. Nevertheless, these data
indicate, based on the currently available evidence, the best
estimates of effects of replacing PHVO with different fats or
oils, with direct implications for product reformulation by
manufacturers and restaurants.
Another critical element of the Mozaffarian and Clarke’s
(2009) proposal was selection of indicators to define CHD risk
reduction because the choice of lipoprotein outcome as
affected by the replacement fat is highly relevant to the final
conclusions. Total/HDL-C ratio and the ApoB/ApoA-I, rather
than solely LDL-C, were chosen as two of the criteria by which
the predicted risk can be estimated. On the other hand, if the
analysis were to be based exclusively on the changes in LDL-C
as the only factor to define risk reduction, the effect of
replacement of PHVO with animal fats and tropical oils would
appear considerably less beneficial, particularly if the PHVO
has the lower TFA relative content (tropical oils and animal
fats rich in lauric and palmitic acid raise both LDL-C and HDL-C
in comparison to TFAs that raise LDL but lower HDL). Some of
the experts believed that the latter approach would be supported
bytheevidencefromdrugtrialsofstatinsinwhichtheabsolute
reduction in CHD risk is largely determined by lowering of
LDL-C; however, others believed that such extrapolation of the
results of controlled trials of statin therapy to potential effects of
dietary interventions could not be justified. However, the group
in examining both alternatives agreed with the proposed model
based on both HDL and LDL effects highlighting the need for
close monitoring of both the fatty acid composition of the oils
sources to be used in replacement but also the biological impact
in terms of lipoprotein levels and actual risk reduction within
the specific populations being intervened.
The challenge to agriculturists and food producers by TFA
replacement is to examine the issue in a comprehensive way
starting from the breeding of oil seeds, through to the
production of edible fats and oils, food processing and final
consumption, considering the impact of the changes on human
health, on the environment and on the availability of
replacement fats and oils in a particular region. The ultimate
goal of TFA elimination is to maximize the benefits, minimizing
risk for human health and the environment in a cost-effective
way. The actual choices of fats and oils used in many countries
will be restricted by availability, actual costs of the replacement
alternatives and their capacity to innovate.
Feasibility of recommending replacement fats
The 2002 Joint WHO/FAO Expert Consultation on Diet,
Nutrition, and the Prevention of Chronic Diseases recom-
mended that mean population intake of TFA, for example,
hydrogenated oils and fats, should be less than 1% of daily
energy intake. This figures correspond to at most 2% of total
fat (WHO, 2003). Although this recommendation was based
on an extensive body of epidemiological and experimental
evidence concerning the health effects of TFAs, the evidence
upon which to judge the feasibility of recommending
particular replacement or alternative fats is not as accessible
or of similar quality (Skeaff, 2009). The use of PHVO
containing TFA is widespread in the global food supply as
ingredients in manufactured foods, in foods prepared in the
food service industry and as cooking fats in the home in
lower income countries. Although there is limited informa-
tion about the distribution of TFA intakes in most countries,
it is likely that many subgroups within the population,
particularly those who use PHVO for cooking or consume a
high proportion of industrially processed foods or restaurant
foods, would have mean TFA intakes considerably higher
than the population mean. Thus, evaluation of mean
population intakes is insufficient; the distribution of those
at higher risk should also be evaluated.
WHO Scientific Update on TFAs
R Uauy et al
S71
European Journal of Clinical Nutrition
Present knowledge on TFA intakes in most countries is not
robust because it is often obtained from pragmatic dietary
assessment surveys that do not rely on nutrient composition
databases with complete TFA data. The transition phase in
implementing governmental and/or industry-led initiatives
to reduce TFA in the diet offers an excellent opportunity to
develop or to strengthen existing nutrient and fatty acid
food composition databases. The monitoring of TFA reduc-
tion or elimination policies should consist of systematic
sampling and analysis of foods likely to contain PHVO and
analysis of the saturated fat content of reformulated foods
once TFAs have been removed. Furthermore, biomarkers
should be used to assess TFA exposures in representative
samples of the population. Monitoring is not only for the
purpose of assessing changes in TFA intakes but also to assess
the fatty acids that replace them. The effort to monitor the
impact of regulatory and nonregulatory initiatives on TFA
intakes should be commensurate with the degree of effort
their introduction has required (Skeaff, 2009).
Currently, there is an insufficient world supply of high
cis-unsaturated, zero TFA replacement fats and oils to meet
the demand if all PHVO were to be removed from the global
food supply over a short period of time. Substitute vegetable
oils with zero or low TFA and high cis-unsaturated fatty acid
can replace PHVO and maintain food product quality. There
is a clear need to alert oil seed producers and agriculturists
that there will likely be a need for an increased supply of
substitute oils and that this represents an opportunity to
expand or develop new oil seed varieties. International
efforts to reduce the use of PHVO by the agriculture and food
industry will need to be coordinated with supplies of
appropriate alternative oils to avoid a decrease in TFA intake
accompanied by a larger increase in SFAs, which would
reduce the potential health gain derived from the reformu-
lation of manufactured foods containing TFA.
The introduction of regulations to remove TFA from the
food supply will require coordination with the food industry
to increase the availability of cost-effective zero-TFA fats or oils
that are higher in cis-unsaturated fatty acids and lower in SFAs
(Skeaff, 2009). Considering all upfront costs are in product
reformulation, the food industry should consider all elements
of fat content, not just TFA, to create an overall healthier
product. Regulatory measures to reduce TFA in the food supply
should ideally be accompanied by efforts to monitor intake of
TFA as well as intakes of other fatty acids likely to be used as
substitutes. Removing industrially produced TFA requires the
replacement of PHVO with alternative fats, preferably vege-
table oils high in cis-unsaturated fats rather than with fats and
oils that are high in saturated fat. However, in the case of
PHVO with very high TFA content, even replacement with
saturated fat oils may convey some benefit. It is widely held
that the easiest substitutions are to use tropical oils such as
palm, palm kernel or coconut oils. Supply of these oils is
abundant, the price is low, the food industry has long used
them and their physical and sensory properties produce foods
with favorable characteristics. However, replacing TFAs with
vegetable oils high in PUFA and MUFA is the preferred option
for health benefits. As TFAs are industrially made and not
intrinsic to the food supply, there is no harm in removing
them from the food supply, that is, eliminating use of
TFA-containing PHVO should be considered as hazard
removal, in line with risk management models used to address
many other food safety issues.
Approaches to removing trans fatty acids from
the food supply
In assessing the approaches to reduce or remove TFA from
the food supply in industrialized and developing countries,
the experts considered a number of successful public health
initiatives adopted by government agencies and public
health organizations in some cases with the collaboration
of the food industry. The examples of past and current
initiatives reviewed were from Denmark, Canada, United
States (New York City), Argentina and India. These include
nutrition recommendations about TFAs and the selection of
healthy fats, awareness programs through nutrition and
health claims on the adverse effects of TFAs, voluntary or
mandatory labeling of the trans content of foods, voluntary
or legislated programs to encourage industry to reformulate
food products in an effort to remove TFA, promoting the
reduction of TFAs through health and agricultural policies
that also support the production of healthy alternatives, and
mandatory regulation of food standards to remove or reduce
TFA content (L’Abbe
´et al., 2009).
The public health initiatives implemented in Denmark to
eliminate the consumption of TFA appeared to provide a
model for other countries worldwide, as it involved a
multisectoral approach supported by widespread media and
political involvement. Their efforts involved a solid science
base of population intake patterns, risk assessment of
exposure to TFA and economic considerations, which lead
to risk management policies that received wide-based
political support from both the community and the govern-
ment. The results were closely monitored and disseminated
widely both in the scientific literature and in the lay press.
The driving force in the process to virtually eliminate the
consumption of industrially produced TFA in Danish foods
was the Danish Nutrition Council. In the neighboring
Nordic countries a different approach was chosen. Self-
regulation by industry has resulted in markedly reduced
intakes of TFA from PHVO. Total TFA intakes have been
reduced to 0.5–0.8% of energy intake in Finland and Norway
despite not having taken up legislation similar to that of
Denmark, as ongoing reduction in the TFA content of the
frying oil used by European fast food chains may have been
triggered by the Danish example.
Since the late 1970s, Canadian scientists have raised
concerns about the detrimental effects of rising TFA levels
in the diet, first focusing on margarines and subsequently
these warnings led to national recommendations. This focus
WHO Scientific Update on TFAs
R Uauy et al
S72
European Journal of Clinical Nutrition
on TFA led to the development of a number of fat spreads
with low TFA specifically targeted to health-conscious
consumers. However, the use of PHVOs continued to
increase in other categories of processed foods. The
estimated TFA intakes placed Canadians among those
populations with the highest exposure to TFAs in the world
during the mid-1990s. In recognition of these concerns and
various local and international initiatives, Canada became
the first country to require that TFA levels be included in the
mandatory nutrition label on prepackaged foods. Currently
available evidence from Canada demonstrates that the TFA
reduction strategy is having the desired effect.
Further actions that affect food services and restaurants
have been taken by Canada at the municipal and provincial
level as well as by the United States at the state and city level.
These include a variety of measures to reduce and/or to
eliminate industrially derived TFAs in foods, for example,
bans on foods containing high levels of TFA from school
cafeterias, hospitals, day-care centers and other institutions
under local jurisdiction. The example of New York City is
one of best known because it has been widely disseminated
by mass communication media (including TV and news-
papers). As one of the first cities to limit trans fats on a wide
scale, the New York City Board of Health on 5 December
2006 approved an amendment to their Health Code to phase
out artificial trans fat in all New York City restaurants and
other food service establishments. This was planned as a two-
stage process; in the first stage, by 1 July 2007, all restaurants
had to ensure that all oils, shortening and margarines
containing industrially derived trans fat used for frying or
for spreads had less than 0.5 g of trans fat per serving; by
1 July 2008, all foods sold in restaurants would be required to
have less than 0.5 g of trans fat per serving if they contain
any industrially derived trans fat. The New York City
Department of Health and Mental Hygiene has prepared a
number of information materials to assist restaurants in
reformulating products and to comply with the new
regulations. Although the amendments to phase out trans
fats from restaurants and other food service establishments
in New York City are still underway and an evaluation of the
results and impact of the New York City amendments has yet
to be published, New York City Department of Health staff
plan to publish this in the near future (L’Abbe
´et al., 2009).
In 1990, the Program for the Prevention of Infarcts in
Argentina (PROPIA) was created, supported by La Plata
National University, the Buenos Aires Scientific Investiga-
tions Commission and the Buenos Aires Health Ministry.
Results from baseline evaluations conducted in Balcarce city
showed that almost all foods contained high levels of TFAs
and o-3 fatty acids were practically absent in the local diet.
This investigation was the starting point for the planning of
intervention strategies necessary to modify the situation
observed in Balcarce city. Successful collaboration with the
suppliers of fats and oils and the food industry from 2001
served to secure a stable supply of replacement fats and oils;
product reformulation was actively encouraged by providing
a tax bonus to those companies that met the suggested WHO
limit of less than 1% of energy from TFA in specific food
products. These actions served to facilitate government
efforts in establishing public policies to promote healthier
choices in diet and physical activity in line with the WHO
Global Strategy to prevent nutrition related chronic disease.
The systematic mass media dissemination of the trans fat
reduction program served as a strong incentive because it
created a demand for trans-free products that translated into
a commercial advantage. In addition, the Mercosur (the
South American Common Market integrated by Argentina,
Brazil, Paraguay and Uruguay) agreed in July 2007 on a
regulation that all foods must include information on its
trans content. As a result of this successful experience, in
2005 the regional UNU network of Latin American institu-
tions part of the United Nations University Food and
Nutrition Program asked PROPIA to lead an applied research
program to evaluate the health impact of interventions
addressed at improving the quality of the fat supply carried
out in the Latin America (Uruguay, Chile, Mexico and several
Central American countries).
Today, India faces the double burden of malnutrition due
to chronic energy deficiency (associated with low intakes of
nutrients including n3 PUFAs) and also rising prevalence of
diet-related chronic diseases. A wide range of oilseeds occupy
a prominent place in the national food economy of India,
second only to cereals. Vanaspati, a PHVO that contains TFA,
is widely used in the preparation of commercially fried,
processed, ready-to-eat and street foods, and for the
preparation of Indian snacks, sweets and savory items,
frozen foods, packaged and premixed foods. The high intake
of TFA may be part of several changes in dietary and other
lifestyle patterns contributing to the present day high
prevalence of diet-related chronic diseases in India. Because
a large proportion of the Indian population is predisposed to
insulin resistance and there is a high prevalence of diabetes
and CHD, the reduction of TFA from partially hydrogenated
oils and foods consumed in India needs to be actively
pursued on grounds of the projected health benefits.
The analysis of the case of India suggests some recom-
mendations can be of relevance to other developing
countries facing a similar situation. Considerations to take
into account in policies to address the reduction and/or
elimination of industrially derived TFA, including the food
processing industry, should use blends of natural vegetable
oils that furnish higher stability to products wherever
feasible, especially indigenous oils with potentially addi-
tional health benefits; the government should consider
specifying achievable lower limits for TFA and SFA content
in vegetable oil products, refined oils and processed foods;
labels on processed foods should provide the content of TFA
and SFA separately and state the optimal recommended
ranges based on local conditions and options within the
socioeconomic reality of the country; restaurants should
disclose the use of ‘partially hydrogenated oils’ in served
preparations; consumer awareness should be heighten
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through food-based dietary guidelines regarding the
negative health impact of TFA and the need to reduce TFA
content of foods; and the food industry should replace
hydrogenation technology with newer technologies that
produce zero trans fats with desired functionality for various
food applications.
Overall a multisectoral and proactive approach is required
to successfully reduce or remove industrially produced
TFAs from the food supply. In the example of the edible
oil and food industries support, investment and incentives
to develop, establish and operate new technologies will be
needed.
Conclusions
The current growing body of evidence from controlled trials
and observational studies indicates that TFA consumption
from partially hydrogenated oils adversely affects multiple
cardiovascular risk factors and contributes significantly to
increased risk of CHD events. Although ruminant TFAs
cannot be removed entirely from the diet, their intake is low
in most populations and to date there is no conclusive
evidence supporting an association with CHD risks in the
amounts usually consumed. In contrast, TFA produced by
partial hydrogenation of fats and oils should be considered
industrial food additives having no demonstrable health
benefits and clear risks to human health. The WHO Scientific
Update on TFA concludes that restaurants and food manu-
facturers should avoid using industrially derived TFA in food
products and that governments should take steps to support
alternative fats or oils for TFA replacement The evidence on
the effects of TFA and disease outcomes strongly supports the
need to remove PHVO from the human food supply. The
result would be a substantial health gain for the population
at large, with greatest health benefits obtained when
replacement oils are rich in n3 and n6 PUFA and in
MUFA. Additionally, controlled studies and observational
studies suggest that TFA may worsen insulin resistance,
particularly among predisposed individuals with risk factors,
for example, preexisting insulin resistance, visceral adiposity
or lower physical activity. Further studies are needed to
confirm the apparent effects of TFA on weight gain and
diabetes incidence in humans.
Findings indicate that the replacement of TFAs in PHVO
with alternative fats and oils would lower CHD risk through
mechanisms beyond changes in blood lipid levels, thus
explaining in large part the difference derived from estimates
based on controlled dietary interventions focusing mainly
on serum cholesterol fractions versus prospective cohort
studies having CHD events as the outcome. Health benefits
are projected to be greatest for replacement of PHVO with
vegetable oils, but even replacement with tropical oils or
animal fats would result in benefits, particularly for PHVO
having higher (35–45%) levels of TFA as consumed in some
developing countries. Thus, the choice of replacement fat/oil
for PHVO needs to consider the effect of the replacement oil
as well as the level of risk associated with the specific TFA
containing sources to be replaced. It is also important to
consider environmental sustainability in choosing appro-
priate replacement fats and oils.
Manufacturers, restaurants and food services should take
advantage of making the most of the effort required for food
product/preparation reformulations to not only reduce the
TFA content but also maximize the overall healthiness of
the foods destined for human consumption by increasing
the content of cis-unsaturated fats. Reformulation should
consider in the upfront potential cost–benefit analysis, not
only TFA removal but also the favorable health conse-
quences of using the most healthful fats and oils for TFA
replacement during product reformulation.
The evidence to assess a specific source of fats/oils as a
replacement or alternative to TFAs reflects the complexity
of the corresponding scientific evidence. The use of PHVO-
containing TFA is widespread in the global food supply as a
basic ingredient of manufactured foods and food prepara-
tions used and sold by the food service industry. Although
there is limited information on the distribution of TFA
intakes in most countries, it is likely that many subgroups
within the population, particularly those who use PHVO for
cooking in the home (common in developing countries) or
consume a high proportion of bakery foods or fast-service
restaurant foods, have mean TFA intakes considerably higher
than the population mean. Removing industrially produced
TFA requires the replacement of PHVO with alternative fats,
preferably vegetable oils high in cis-unsaturated fats. How-
ever, in the case of PHVO with very high TFA content,
replacement even with fats and oils high in SFAs may convey
some, albeit smaller, benefit. The introduction of regulations
to remove TFA from the human food supply will require
coordination with the food industry and agricultural and
food production sectors to increase the supply and to reduce
the cost of their substitution by zero TFA, cis-unsaturated fat
and oil sources that are also low in SFAs; thus, increasing cost
effectiveness of the proposed intervention.
The experts acknowledged the need to review the current
recommendation that the mean population intake of TFA,
that is, partially hydrogenated oils and fats, should be less
than 1% of daily energy intake. There is sufficient epide-
miological and experimental evidence to support revising
this recommendation so that it encompasses the great
majority of the population, and not just the population
mean, to protect large subgroups from having high intakes.
This could be accomplished, and has been in some countries
and cities, by the virtual elimination of PHVO in the human
food supply. The outcomes of this Scientific Update provide
the evidence and scientific bases to promote discussions
between the international scientific community related to
nutrition and health as well as to agriculture and food
production, relevant health professionals, national and
international food regulatory agencies, civil society and the
private sector to achieve this goal.
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European Journal of Clinical Nutrition
Conflict of interest
During the preparation and peer review of this paper in
2007, the authors and peer-reviewers declared the following
interests:
Professor Ricardo Uauy: Scientific Advisor to Unilever and
Wyeth (ad-hoc basis); Scientific Advisor to Knowles and
Bolton, Danone, DSM and Kellogs (ad-hoc basis).
Dr Antti Aro: Consultancy with the Scientific Advisory
Board, Valio Ltd (current).
Dr Robert Clarke: None declared.
Dr Ghafoorunissa: Chairperson of the Edible Oils and Fats
Subcommittee PFA, Central Committee of Foods Standards
(Ministry of Health and FW, Government of India) (current);
Member of the Nutrition Advisory Council for the Malaysian
Palm Oil Promotion Council (2004–2005); Consultant in
the area of ‘heart health’ for Hindustan Unilever Limited
(2006–2007); Life Member of the Nutrition Society of India
(current).
Dr Mary L’Abbe
´: None declared.
Dr Dariush Mozaffarian: None declared.
Professor Murray Skeaff: Led a research project that tested the
effects of a plant-sterol enriched fat spread on blood cholesterol
concentrations; costs of research partially funded by Unilever
Research and Development (2003–2004); participated in a
subcontract to conduct a randomized controlled trial of a milk
product enriched with an antioxidant extract from vegetables,
which was partially funded by Fonterra, a milk company in
New Zealand (2005–2007). All industry-supported research
projects were organized and administered through the
University of Otago Research and Enterprise Unit.
Professor Steen Stender: None declared.
Professor Marcelo Tavella: Scientific advice provided to
Dow Agrosciences, Argentina (current).
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