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 oilLow TFAs

Cloudy cooking oilHigh TFAs

Repeated re-heating

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