Christine Williams

Reading University

12 December 2007

Overview• Trans fatty acids, dietary sources, current

levels, recent changes in intakes

Overview• Trans fatty acids, dietary sources, current

levels, recent changes in intakes

• Impacts on human health- CHD, cancers, type 2 diabetes, weight gain, fetal development

Overview• Trans fatty acids, dietary sources, current

levels, recent changes in intakes

• Impacts on human health- CHD, cancers, type 2 diabetes, weight gain, fetal development

• Epidemiology (disease end points), human dietary intervention studies (biomarker end points)

Overview• Trans fatty acids, dietary sources, current

levels, recent changes in intakes• Impacts on human health- CHD, cancers,

type 2 diabetes, weight gain, fetal development

• Epidemiology (disease end points), human dietary intervention studies (biomarker end points)

• Predicted disease risk reduction for further reduction in trans fatty acid intakes

Trans fatty acids (FA) and health• CHD risk is moderately increased at levels

of intake over the range or slightly higher than UK intakes. Plausible mechanism via increased LDL and decreased HDL

Trans fatty acids (FA) and health• CHD risk is moderately increased at levels

of intake over the range or slightly higher than UK intakes. Plausible mechanism via increased LDL and decreased HDL

• Cancers – epidemiological evidence weak; no plausible mechanism

Trans fatty acids (FA) and health• CHD risk is moderately increased at levels

of intake over the range or slightly higher than UK intakes. Plausible mechanism via increased LDL and decreased HDL

• Cancers – epidemiological evidence weak; no plausible mechanism

• Diabetes- epidemiology limited and inconsistent data. Intervention studies either negative or used un physiological levels

Trans fatty acids (FA) and health• CHD risk is moderately increased at levels of

intake over the range or slightly higher than UK intakes. Plausible mechanism via increased LDL and decreased HDL

• Cancers – epidemiological evidence weak; no plausible mechanism

• Diabetes- epidemiology limited and inconsistent data. Intervention studies either negative or used un physiological levels

• Weight gain- small number of studies. Estimated impact of 1% energy as trans was 0.5-1kg/ 8 years

Trans fatty acids (FA) and health• CHD risk is moderately increased at levels of

intake over the range or slightly higher than UK intakes. Plausible mechanism via increased LDL and decreased HDL

• Cancers – epidemiological evidence weak; no plausible mechanism

• Diabetes- epidemiology limited and inconsistent data. Intervention studies either negative or used un physiological levels

• Weight gain- small number of studies. Estimated impact of 1% energy as trans was 0.5-1kg/ 8 years

• Fetal development- studies poorly designed, failed to control for confounding factors

Evidence CHD• Seven of 10 prospective epidemiological

studies show positive association with CHD risk (1% energy trans increase risk by 12.5%)

Evidence CHD• Seven of 10 prospective epidemiological

studies show positive association with CHD risk (1% energy trans increase risk by 12.5%)

• Controlled interventions consistently show trans FA increase LDL and decrease HDL. Trans FA the only fat shown to reduce HDL

Epidemiology: trans and CHD

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Trans FA intake (g/day)

Risk

of C

HD

Ascherio (1994) Clifton (2004) Lopes (2007) Willett (1993) Ascherio (1996) Pietinen (1997) Hu (1997) Oh (2005)

Health effects – conclusions• Sufficient evidence to estimate risk of CHD

arising from trans FA intakes.

Health effects – conclusions• Sufficient evidence to estimate risk of CHD

arising from trans FA intakes.

• If all individuals consumed < 1% energy as trans FA the reduction in risk CHD = 5-7.5%

Health effects – conclusions• Sufficient evidence to estimate risk of CHD

arising from trans FA intakes.

• If all individuals consumed < 1% energy as trans FA the reduction in risk CHD = 5-7.5%

• Likely to be over estimated due to extrapolation from much higher levels than UK intakes and recent reductions in intakes

Health effects – conclusions• Sufficient evidence to estimate risk of CHD

arising from trans FA intakes.

• If all individuals consumed < 1% energy as trans FA the reduction in risk CHD = 5-7.5%

• Likely to be over estimated due to extrapolation from much higher levels than UK intakes and recent reductions in intakes

• Insufficient evidence for other diseases. Need to monitor effects on insulin/ diabetes and genotype dependent prostate cancer

Natural versus synthetic trans

• Trans FA formed in rumen by action of gut bacteria

• Found in milk, milk products cheese, beef, lamb

• Main trans FA is vaccenic acid 18;2, n-7

NATURAL

Natural versus synthetic trans

• Trans FA formed in rumen by action of gut bacteria

• Found in milk, milk products cheese, beef, lamb

• Main trans FA is vaccenic acid 18;2, n-7

• Trans FA formed during chemical hydrogenation of vegetable oils to form solid and semi solid fats

• Found in margarines, cakes, biscuits, fries

• Main trans FA is elaidic acid 18,2-n-9

NATURAL SYNTHETIC

Are synthetic trans FA more harmful than natural form?

• Early epidemiological studies suggested effects on CHD were due to trans from margarines, biscuits etc but not milk, cheese, ruminant meats

• Later studies have not reported on different effects of the two types of trans FA

• No evidence form metabolic studies to suggest the two forms differ in their effects on lipoproteins