Trans fats in food
Why they should be eliminated
Alan Maryon-Davis FRCP FFPH
What exactly are trans fats?
• Short for trans fatty acids (TFAs) – ‘trans’ refers
to their molecular structure
• Non-essential. No known benefits to human
health
• Small amounts occur naturally in milk and milk
products
• Vast majority are man-made by partially
hydrogenating plant oils – industrially produced
TFAs
• Commercial advantages: increased bulk,
improved texture; longer shelf-life, semi-solid
consistency, rancid-resistant, cheaper
Industrially produced
trans fats

Clear
vegetable oils

Solid or
semi-solid fats
by hydrogenation
Trans fats made in cooking

Clear
cooking oil
Low TFAs
Repeated
re-heating

Cloudy
cooking oil
High TFAs
Trans fats are mainly consumed in
fried fast-food, biscuits, pastries,
cakes, pies and cooking fats
Impact of trans fats on the body
• Push up the level of LDL (‘bad’)
cholesterol
• Decrease the level of HDL (’good’)
cholesterol
• Increase the level of triglycerides
• Increase vascular endothelial dysfunction
• May increase insulin resistance
Risks to health
of higher trans fat intakes
• Clear evidence of an increased risk of
coronary heart disease (CHD) – angina,
heart attack, etc
• Some evidence suggesting an increased
risk of type 2 diabetes
• Possible increased risk of prostate cancer
• Possible increased risk of breast cancer
Impact on population health
• Meta-analysis of five large-scale
prospective population studies* found a
24% increase in CHD risk associated
with higher TFA intakes
• Gram for gram, TFAs carry five times the
risk associated with saturated fats
*Mozaffarian D, Katan MB, Ascherio A, Stampfer MJ,
Willett WC. Trans 2 fatty acids and cardiovascular
disease. N Engl J Med 2006;354: 1601-13.
Impact on population health
• Every gram increase in the average intake
increases CHD deaths by 5%
• According to a recent review by NICE* the
current UK consumption of TFAs causes
5000-15000 deaths every year.
• These deaths are totally avoidable
* NICE 2009
COMA 1994
• Recommended that TFAs should
contribute no more than 2% of food energy
(ie. calorie) intake across the whole
population*
*Expressed as the maximum
recommended contribution these nutrients
should make to the population average
diet.
Policy history
• 1994 – COMA (later SACN) recommends population
maximum for TFAs of 2% of food energy intake
• 2003 – WHO recommends a population intake of less
than 1% of total energy
• 2007 – FSA endorses the COMA/SACN population
maximum and recommends no change
• 2009 – a WHO review emphasised the need ‘to
significantly reduce or virtually eliminate industrially
produced TFAs from the food supply’
SACN review of trans fats
2007 recommendations
• Improved monitoring of specific groups,
particularly young adults, at risk of low
nutritional status is required.
• These population groups …and people
(especially adults with children) in lower
socio-economic groups could benefit from
focused health initiatives.
Progress
SACN recommendation
(adults)
< 2% of food energy
1986/87
2.2%
2000/01
1.2%
2010
0.8%
Limitations of the NDNS
• Small sample (<1000 households in the
first year)
• 43% non-response or inadequate
response
• A common reason for non-response was
‘language difficulties’
• Around 20% of food intake is not reported
FSA review 2007
• Reviewed the latest evidence
• Only considered population average intakes
• Concerned that further reductions in TFAs would
lead to compensatory increases in sat fats
• Sat fat reduction programme considered to be a
higher priority
• Recommended no change in COMA/SACN
population-wide limit of 2%
• Recommended continuing the existing voluntary
approach rather than mandatory regulation
TFA consumption
and health inequalities
• There is concern that children and young
people, and those on low incomes, are
consuming worryingly high levels of TFAs in
deep-fried takeaway foods
• A recent study in Tower Hamlets suggests that
some individuals are consuming 6-12% of food
energy as TFAs
• The high intakes among young people and
deprived populations was a key consideration in
the Denmark legislation
CHD mortality in Scotland, 35-64
TFAs in fast foods
• One in six meals is eaten outside the home
• The number of takeaway outlet is rising by about 8% a
year
• Main customers are children and young people, and
those on lower incomes
• Cooking practices vary greatly
• Very high TFA levels can result from re-heating cooking
oil, even when initial levels are low
• Deep-fat fryer in small takeaways of particular concern
• Relatively little UK data on this (ad hoc studies, eg.
Tower Hamlets trading standards study)
Scope for action in UK
• Reduce recommended maximum TFA intake (DRV) to
<0.5% of food energy across the population (Denmark
has achieved this)
• Shift from voluntary to mandatory regulation
• Ban IPTFAs in all manufactured foods
• Mandatory TFA labelling for specific groups of foods
• Improved guidance and tougher regulation for providers
of foods eaten outside the home
• Improved monitoring of TFA intake in specific subgroups,
eg. children, low income groups, ethnic minorities
• Regular mini-surveys of TFA content of fast-foods