Study adds colon cancer to list for trans fats' harm

10-Sep-2008 -

Increased intakes of trans fatty acids may increase the risk of colorectal
tumours by about 86 per cent, suggests new research from the US.

The study followed almost 622 North Carolinians who underwent complete colon
exams between 2001 and 2002 and found significant colorectal cancer risk
increases for higher intakes of trans fatty acids.

The study, published in the American Journal of Epidemiology, looks set to
heap more pressure on the food industry to remove and reformulate products
without trans fats, one of the industry's bêtes noires.

"These results suggest that consumption of high amounts of trans-fatty acid
may increase the risk of colorectal neoplasia [abnormal cell growth in the
colon and rectum], and they provide additional support to recommendations to
limit trans-fatty acid consumption," wrote lead author Lisa Vinikoor from
the University of North Carolina, Chapel Hill.

Though trace amounts of trans fats are found naturally in dairy and meats,
the vast majority are formed during the partial hydrogenation of vegetable
oil that converts the oil into semi-solids for a variety of food
applications.

Trans fatty acids have been useful in foods due to their extended shelf life
and flavour stability, and displaced natural solid fats and liquid oils in
many areas of food processing.

But scientific reports that trans fatty acids raise serum levels of
LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation,
can cause endothelial dysfunction, and influence other risk factors for
cardiovascular diseases (CVD), has led to a well-publicised bans in New York
City and Philadelphia restaurants, and other cities, like Boston and
Chicago, considering similar measures.

The new study adds to a small number of previous studies reporting that
increased levels of markers of trans-fat intake are associated with an
increase risk of cancer of the colon and rectum.

Colorectal cancer is the third most diagnosed cancer in the US, according to
the American Cancer Society. About 150,000 new cases will be diagnosed in
the US this year, says the society, with an almost 50-50 split between men
and women.

Study details

Vinikoor and co-workers recruited over 600 people from the University of
North Carolina Hospitals. Dietary, lifestyle and other demographic details
about them were achieved via interview, while colorectal health was verified
using results of complete colonoscopies.

The highest trans fatty acid consumption was associated with an 86 per cent
increase in colorectal cancer risk, compared to the lowest consumption.

Further analysis of the colorectal area suggested that trans fatty acid
consumption did not influence the location, size or number of benign tumours
(adenoma).

While further studies are required to verify the results, it is clear that
the study may heap more pressure on the food industry to reformulate and
remove trans fatty's from products.

Alternatives to trans fats

The food industry as a whole has expressed its commitment to removing trans
fatty acids from its products, but such reformulation is not straightforward
and presents challenges.

Paul Wassell and Niall Young from Danisco's Multiple Food Application Group
reviewed the options available to formulators and stated that designing
foods with trans-fat alternatives must be a "multidisciplinary' approach"
(International Journal of Food Science and Technology, Vol. 42, pp 503-517).

"Successful replacements of trans fatty acids is not easily achieved by
simply removing the trans isomer, because of a host of beneficial functional
characteristics that are readily attributable to trans fatty acids," wrote
Wassell and Young, pointing out that the presence of the trans isomer
influences melting behaviour, oxidative stability and textural properties.

At last year's IFT in Chicago, Walter Willett from Harvard School of Public
Health said that limiting and labelling trans fatty acids in food is not
enough, and they should be banned.

Professor Willett told food manufacturers and food professionals in Chicago
that Denmark had taken the right approach to the trans fatty acid issue -
the Scandinavian country introduced legislation in 2004 that required
locally and imported foods to contain less than two per cent industrially
made trans fatty acids, a move that effectively abolished the use of
partially hydrogenated vegetable oils in the country.

Source: American Journal of Epidemiology
Volume 168, Issue 3, Pages 289-297; doi:10.1093/aje/kwn134
"Consumption of trans-Fatty Acid and Its Association with Colorectal
Adenomas"
Authors: L.C. Vinikoor, J.C. Schroeder, R.C. Millikan, J.A. Satia, C.F.
Martin, J. Ibrahim, J.A. Galanko, R.S. Sandler