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This is interesting. The link they claim is that it's the iron in the meat, specifically in the form of Fe3+, which activates telomerase in colorectal cancer, a

This is interesting. The link they claim is that it's the iron in the meat, specifically in the form of Fe3+, which activates telomerase in colorectal cancer, advancing the cancer (or causing individual cancer cells to proliferate when they may have been naturally killed off). The huge question this leaves for me, which isn't addressed at all, is why we do not see similar associations with colorectal cancer with other foods high in iron? On a per-serving basis, foods like spinach contain far, far more iron than beef [0]. Furthermore, beef contains mostly heme-based iron, which is chelated Fe2+, not Fe3+. More broadly, most non-heme iron is in Fe3+ form, and must be reduced to Fe2+ in your digestive system [1]. Why don't we see this cancer associated with other iron-rich foods? Also in [1] is mentioned that consuming Vitamin C assists the reduction of Fe3+ to Fe2+, I wonder if we will find that high levels of vitamin C consumption reduce the risk of colorectal cancer. [0] https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-sources-iron https://www.dietaryguidelines.gov/resources/2020-2025-dietar... [1] https://www.crnusa.org/sites/default/files/files/resources/28-CRNVMS3-IRON.pdf https://www.crnusa.org/sites/default/files/files/resources/2...

jjmarr 2y ago
Have studies been run on spinach consumption and cancer?
ethbr1 2y ago
It'll be curious if there are compensating components that are co-ingested with spinach et al. that are not with red meat. I.e. perhaps all high-iron foods promote colorectal cancer, but some foods also contain anti-cancer factors that zero out the net effect
nkrisc 2y ago
> On a per-serving basis, foods like spinach contain far, far more iron than beef [0] And how many servings of each dies the average person eat? Based only on my personal observations, I could believe that people eat enough red meat to far overcompensate for the differences per-serving.
adrian_b 2y ago
The heme-bound iron can be either reduced as Fe(II) or oxidized as Fe(III). When exposed to air, like when the blood passes through the lungs, or in cut meat, it will be oxidized to Fe(III), in which case its color will be a pleasant vivid red. When the iron is reduced, the heme has a much duller color. The iron that can be absorbed or interact in any way with the intestine is either Fe(II), which is soluble in water or Fe(III) that is bound to proteins like hemoglobin or to other organic molecules. Otherwise, the Fe(III) ions form insoluble precipitates that pass through the intestine without effect.

jjmarr 2y ago

Have studies been run on spinach consumption and cancer?

ethbr1 2y ago

It'll be curious if there are compensating components that are co-ingested with spinach et al. that are not with red meat. I.e. perhaps all high-iron foods promote colorectal cancer, but some foods also contain anti-cancer factors that zero out the net effect

nkrisc 2y ago

> On a per-serving basis, foods like spinach contain far, far more iron than beef [0] And how many servings of each dies the average person eat? Based only on my personal observations, I could believe that people eat enough red meat to far overcompensate for the differences per-serving.

adrian_b 2y ago

The heme-bound iron can be either reduced as Fe(II) or oxidized as Fe(III). When exposed to air, like when the blood passes through the lungs, or in cut meat, it will be oxidized to Fe(III), in which case its color will be a pleasant vivid red. When the iron is reduced, the heme has a much duller color. The iron that can be absorbed or interact in any way with the intestine is either Fe(II), which is soluble in water or Fe(III) that is bound to proteins like hemoglobin or to other organic molecules. Otherwise, the Fe(III) ions form insoluble precipitates that pass through the intestine without effect.