My wife asked me last night why too much red meat is bad for you. The man who first saw this was not a physician but a very gifted food scientist, Al Tappel.
It was this remarkable scientist who in 2007 realised that “heme iron of red meat is likely a catalyst for oxidative damage promoting many chronic diseases. Red meat contains oxymyoglobin, deoxymyoglobin, oxyhemoglobin, deoxyhemoglobin, cytochromes of mitochondria, and other heme pigments. After ingestion, heme proteins are hydrolyzed to amino acids and peptides and the heme group. The iron of the heme group can coordinate with potent ligands, such as sulfur, nitrogen, or oxygen of amino acids and other constituents.” (Omaye, et al, 2019)
“Iron is an indispensable element for almost all organisms; however, in excess, iron can be toxic, promoting redox reactivity and oxidative stress. Balanced iron metabolism is the key to health and preventing associated iron diseases.” (Omaye, et al, 2019)
In his groundbreaking 2007 publication, he noted that “dietary epidemiological studies indicate correlations between the consumption of red meat and/or processed meat and cancer of the colon, rectum, stomach, pancreas, bladder, endometrium and ovaries, prostate, breast and lung, heart disease, rheumatoid arthritis, type 2 diabetes and Alzheimer’s disease. The correlation of all these major diseases with dietary red meat indicates the presence of factors in red meat that damage biological components. This hypothesis will focus on the biochemistry of heme compounds and their oxidative processes. Raw red meat contains high levels of oxymyoglobin and deoxymyoglobin and oxyhemoglobin and deoxyhemoglobin and cytochromes in muscle and other tissues. Cooked and processed meat contain hemichromes and hemochromes. After being eaten heme proteins are hydrolyzed to amino acids and peptides and the heme group which is coordinated with strong ligands. The iron of heme coordinates to the sulfur, nitrogen or oxygen of amino acids and peptides and other biological components. The coordinated heme groups are absorbed and transported by the blood to every organ and tissue. Free and coordinated heme preferentially catalyze oxidative reactions. Heme catalyzed oxidations can damage lipids, proteins, DNA and other nucleic acids and various components of biological systems. Heme catalysis with hydroperoxide intermediates can initiate further oxidations some of which would result in oxidative chain reactions. Biochemical and tissue free radical damage caused by heme catalyzed oxidations is similar to that resulting from ionizing radiation. Oxidative biochemical damage is widespread in diseases. It is apparent that decreasing the amount of dietary red meat will limit the level of oxidative catalysts in the tissues of the body. Increasing consumption of vegetables and fruits elevates the levels of antioxidative components, for example, selenium, vitamin E, vitamin C, lycopene, cysteine-glutathione and various phytochemicals. These detrimental processes of heme catalysis of oxidative damage hypothesized here are not well recognized. More investigative studies in this field need to be done.”
I was intrigued to find out more about this formidable man. Davidsen Enterprise did the best obituary in my view on his life and I quote it here in full. It touches many of the highlights of a remarkable mans career and personal life.
The Remarkable Life of Al Tappel
Nov. 21, 1926 — Nov. 25, 2017
Aloys L. Tappel, 91, of Davis passed away on Nov. 25, 2017, at his home with loving family members and a caregiver at his bedside, from pneumonia, after living with Parkinson’s Disease for many years.
Al was born on Nov. 21, 1926, in a house in St. Louis, to Aloys and Julian Tappel. Al developed an early interest in science while he was educated at parochial schools and he graduated from St. Louis University High School. He received his bachelor’s degree in Chemical Engineering at Iowa State University. Al received his Ph.D. In Biochemistry under Paul Boyer, later a Nobel laureate, and Walt Lundberg of the Hormel Institute and the University of Minnesota.
Al met his future wife, Ardelle Amber Fish, in lipids class on the St. Paul campus of the University of Minnesota. They became acquainted on long walks after lunch. Al and Ardelle married on May 26, 1951, in the Chapel of the Cathedral in St. Paul, Minnesota.
When the Department of Food Science and Technology moved from UC Berkeley to UC Davis, Al was interviewed and hired by Emil Mrak, then the chairman of the Department of Food Science and Technology. Al and Ardelle moved to Davis in 1951, where Al joined the Department of Food Science and Technology as an instructor until 1953 when he was appointed assistant professor in 1953. Appointments to follow, all in the department of food science and technology: associate professor, 1957-1961; professor, 1961-1994; and professor emeritus from 1994 onward.
During Al’s 50 years on the faculty, he taught food biochemistry for graduate students and food analysis for undergraduates. Al’s main activity was research on food biochemistry, nutrition and related subjects in collaboration with graduate students, postdoctoral scientists and visiting scientists. Al’s research resulted in more than 450 peer-reviewed scientific publications in a broad range of scientific journals. Al collaborated with 13 Ph.D. students, 34 post-Ph.D.s and 58 visiting scientists and faculty members.
Al coined the scientific term “peroxidation” in order to distinguish the oxidative reactions involving peroxide (which are deleterious to tissue) from the oxidative reactions involved in the benign metabolic utilization of lipids for energy. Al conducted pioneering research on the peroxidation of lipids in vivo and its effects on cellular damage.
He was the first to demonstrate that combinations of antioxidants are more effective in preventing peroxidation than each acting alone. A wide spectrum of blended compounds offers twice as much protection as single antioxidants. The synergistic effect provides anti-cancer protection. Al also worked on other topics including lysosomal enzymes, biological effects of selenium, and new analytical methods in biochemisty.
Some of the 13 awards Al received included the 1965 Guggenheim Fellowship, 1973 Borden Award from American Institute of Nutrition, 1991 Award of the Agricultural and Food Chemistry Division of the American Chemical Society, 1992 Supelco American Oil Chemists Society Research Award, 1995 Alton E. Bailey Medal of the American Chemists Society, 1995 Chang Award of the American Oil Chemists Society, 1997 The Oxygen Club of California Award, and also 1997 the Nicholas Appert Award.
Al enjoyed spending time with his family, reading, camping, hiking, backpacking, cross-country skiing, and traveling in his RV with his wife. Al and (Ardelle) Amber were very close and loving in their relationship.
Al is survived by his loving wife of 66 years, (Ardelle) Amber; daughters Susan Tappel (Norman) of Davis, Mary Tappel (John) of Sacramento, Cathy Steele Tappel (Marc) of Vancouver, Wash., and Liz Brownfield of San Jose; sons Steve Tappel of Davis and Paul Tappel (Kerry) of Brier, Wash.; 13 grandchildren; and one great-grandchild. Al is also survived by his brother Ed Tappel of Cincinnati, and his brother-in-law Ron Fish (Belva) of Shafer, Minnesota.
The family wishes to thank Al’s caregivers in his final years: Latileta Soqonatabua, Sala Rokomatu and Vinnie Vasuikoro.”
Excellent Video where Tappel is interviewed: https://video.ucdavis.edu/media/ALoys+Tappel/0_0x0iieb3
Omaye, A. T., & Omaye, S. T. (2019). Caveats for the Good and Bad of Dietary Red Meat. Antioxidants (Basel, Switzerland), 8(11), 544. https://doi.org/10.3390/antiox8110544
Tappel A. Heme of consumed red meat can act as a catalyst of oxidative damage and could initiate colon, breast and prostate cancers, heart disease and other diseases. Med Hypotheses. 2007;68(3):562-564. doi:10.1016/j.mehy.2006.08.025