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Comment on trans-fatty acids in heated hemp oil
H. Mölleken
Bergische Universität, Physiologische Chemie der Pflanzen, Gauss-Str. 20, 42110 Wuppertal, Germany
Trans-fatty
acids (t-FAs) continue to be the subject of medical and scientific
discussion.
"A controversy has arisen about
the potential health hazards of trans unsaturated fatty acids in the American
diet. Extreme positions range from calling for the elimination of t-FAs
from the diet by avoiding specific foods, to removing them from processed foods
and/or including their amounts on food labels, to denial of any adverse effects
or the need to modify food processing and production, food labels, health
claims, or intakes" (American Society for Clinical Nutrition (ASCN) and
American Institute of Nutrition (AIN) 1998).
Many analyses of possible health
hazards of dietary t-FAs have been made, but to date, it has not been
possible to firmly conclude that the intake of t-FAs is a health risk
factor for the diseases discussed in Callaway (1998) and Mölleken (1998). Major
contributors of t-FAs in the diet are fried and baked foods and margarine
made from hydrogenated vegetable oils (ASCN/AIN 1998, American Heart Association
1998, Kindt 1997). Nevertheless, I support Dr. Callaway in his opinion that t-FAs
must be discussed as possible contributors to many diseases and that the use of
dietary products with high content of t-FAs should be reduced. Mölleken
(1998) purports to show that it is possible to use hemp oil for processes such
as low-temperature frying and steaming. Only a small amount of t-FAs in
sum were shown to be formed. We also analyzed for single t-FAs isomers
and these detailed quantitative analyses, together with analyses for other
possible reaction products (e.g., ketones, hydroxy fatty acids,
hydro-peroxides, etc.) and the function of antioxidants in this context
will be published soon.
With regard to the use of hemp oil,
Mölleken (1998) makes few re-commendations. It did state that in order to
reduce possible risks of disease, many scientists (e.g., Ärzte Zeitung
1994, Wolfram 1994, Ahrndt 1995, etc.) recommend using high-quality
vegetable oils for cooking and frying processes. Deep-frying is surely excluded
from this recommendation, as the oil degrades at elevated temperatures. However,
steaming and brief low-temperature frying at a temperature of up to
approximately 150-170°C (in any case, less than 180 °C) is acceptable.
References
Ahrndt S., 1995/1998. Krank durch trans-Fettsäuren? Schwäbischer Bauer 45:32-33, www.journal-pool.de/home/susanne.ahrndt/trans.html.
American Society for Clinical Nutrition (ASCN) and American Institute of Nutrition (AIN), 1998. Task Force on Trans-Fatty Acids. reprinted from Am. J. Clin. Nutr. 1996. 63: 66-70, www.faseb.org/ascn/ajcn7799.htm.
American Heart Association 1998. www.viahealth.org/disease/cardiac/.
Ärzte Zeitung, 1994. Wenig trans-Fettsäuren in deutscher Margarine. Stellungnahme zu Berichten über schädliche Trans-fettsäuren. June.
Callaway, J. C. 1998. Formation of trans-fatty acids in heated hempseed oil: A rebuttal. Journal of the International Hemp Association 5(2): 106-108.
Kindt M. 1997. Die Bedeutung von trans-Fettsäuren in der menschlichen Ernährung. www.stud.uni-giessen.de/s1781/transistor.html.
Mölleken H. 1998. Trans-fatty acids in heated hemp seed oil. Journal of the International Hemp Association 5(1):21-23.