Evidence from previous reviews suggests that dietary trans-fatty acid (TFA) intake is positively associated with risk of coronary heart disease and cardiovascular disease. TFA intake has also been linked to increased risk of other health conditions, however these relationships appear to be less consistent. This narrative review aimed to build on the risk assessment included in the 2009 FSANZ report of Trans Fatty Acids in the New Zealand and Australian Food Supply, by evaluating the recent evidence around TFA intake and associations with a variety of chronic disease outcomes, including CVD and CHD, cancer, and type 2 diabetes. We also briefly reviewed studies examining other health conditions including macular degeneration, asthma, and dementia.
We searched databases and reference lists to identify 46 studies suitable for inclusion in the review. Most associations reported by the studies were not significant (55%), but there were more positive associations reported (35%) than inverse associations (10%), indicating the balance leans towards a detrimental effect of TFA. Direction of association did not appear to differ by gender, TFA assessment type (dietary or serum) or study design (prospective vs case-control or cross-sectional). Total mortality, CVD/CHD and colorectal, pancreatic and prostate cancer demonstrated more positive or neutral associations with TFA, while results for type 2 diabetes and breast cancer were more evenly distributed. A category of other health conditions, including macular degeneration, dementia, asthma and eczema, also showed mixed results.
The differences observed between outcomes may be due to differences in study populations, whether different factors such as blood lipids or membrane fluidity are involved in disease progression, and potential differences in effects of specific TFAs. Future research is required to better separate out the effects of TFA from other dietary components within the context of different health conditions.
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Appendix 1 for narrative review (word 180 kb) | (pdf 690 kb)
Appendix 2 for narrative review (word 85 kb) | (pdf 390 kb)