|Harnly, James - Jim|
Submitted to: Food and Nutrition Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/2012
Publication Date: 7/20/2012
Citation: Cross, A.J., Harnly, J.M., Ferrucci, L.M., Risch, A., Mayne, S.T., Sinha, R. 2012. Developing a heme iron database for meats according to meat type, cooking method and doneness level. Food and Nutrition Sciences. 10:4236. Interpretive Summary: Heme iron is the compound that is released when hemoglobin or myoglobin is digested in the stomach. It consists of a single iron atom in the middle of a prophyrin ring. Heme iron is absorbed in the small intestine by an engulfing process; a process different than that for the absorption of inorganic, or non-heme, iron. Many food constituents will interfere with the absorption of non-heme iron while the heme iron is unaffected. Consequently, the concentration of heme and non-heme iron is an important dietary concern. In this study, a method was developed for the analysis of total iron and heme iron and applied to a variety of meats cooked in a variety of ways to different levels of doneness. In agreement with many previous studies, the levels of heme iron varied with the animal and cut of meat. However, there was no significant difference in the levels of heme iron as a function of cooking method or doneness.
Technical Abstract: Background: Animal studies have demonstrated that iron may be related to carcinogenesis, and human studies found that heme iron can increase the formation of N-nitroso compounds, which are known carcinogens. Objectives: One of the postulated mechanisms linking red meat intake to cancer risk involves iron. Epidemiologic studies attempt to investigate the association between heme iron intake and cancer by applying a standard factor to total iron from meat. However, laboratory studies suggest that heme iron levels in meat vary according to cooking method and doneness level. We measured heme iron in meats cooked by different cooking methods to a range of doneness levels to use in conjunction with a food frequency questionnaire to estimate heme iron intake. Methods: Composite meat samples were made to represent each meat type, cooking method and doneness level. Heme iron was measured using atomic absorption spectrometry and inductively coupled plasma-atomic emission spectrometry. Results: Steak and hamburgers contained the highest levels of heme iron, pork and chicken thigh meat had slightly lower levels, and chicken breast meat had the lowest. Conclusions: Although heme iron levels varied, there was no clear effect of cooking method or doneness level. We outline the methods used to create a heme iron database to be used in conjunction with food frequency questionnaires to estimate heme iron intake in relation to disease outcome.