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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.

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