Red and processed meat, and human and planetary healthBMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j2190 (Published 09 May 2017) Cite this as: BMJ 2017;357:j2190
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Chicken thigh contains an equal amount of heme iron to bacon, and about half as much heme iron as a steak - processed white meats have as much nitrites and nitrite as the red, and many types of fish also supply appreciable amounts of heme iron.
These components of meat thus do not explain why the associations of red and white meat tend in opposite directions in this paper (with the notable exception of Alzheimer's mortality).
Nor do they explain why the associations for the more biologically implausible outcomes, liver disease and respiratory mortality, are so strong.
Table one shows a high potential for residual confounding, and the US population as a whole, having been exposed to advice to limit red meat for decades, is at high risk of healthy-user bias, where the most conscientious in a population adopt all the behaviours recommended by public health experts, avoid risk n general, and are more likely to enjoy healthy workplace and living environments..
We can farm animals in a more sustainable manner, though it is hard to beat the way lamb is raised in New Zealand, and we can farm vegetables in a more sustainable manner if we properly synchronise their production with that of animal fertilizer rather than fossil deposits, but I would welcome a professor of epidemiology explaining the methodology of an unusual and unusually confounded paper (vide table 1), and a professor of agriculture writing on that subject.
Is, for example, free range chicken as sustainable as free range lamb in New Zealand? Chicken is fed on grain and other crops, as well as some added supplements, much like beef in the US, whereas lamb is almost exclusively fed on grass raised with rainwater.
There are people who cannot afford meat tonight, but can afford sugar-sweetened beverages or white bread with their dinners for a fraction of the price, and we should not be so quick to tell them that meat is unhealthy just because it appears so in American studies, as opposed to European or Asian ones. In New Zealand, an otherwise privileged country, respondents in the 2008/2009 Adult Nutrition survey reported that they were already consuming more iron and protein from cereals than from red meat, .
Etimadi and colleagues provide no information about a plant-based diet - their comparison is only with chicken and fish, replacement animal foods. The WHO website states that 0.8 million (1.5%) of deaths worldwide are attributable separately to iron, retinol, and zinc deficiencies, deficiency diseases that animal foods would easily prevent.
Competing interests: No competing interests