The NIH/AARP study results suggest animal fat may play a role in the development of pancreatic cancer while plant protein food sources play a protective role. This may be from the saturated fat, which may also cut cancer survival. Trans fats are also found in animal products. The National Academy of Sciences Institute of Medicine notes that there appears to be no safe upper limit of trans-fat intake intake, and one-fifth of the American intake of trans fatty acids comes from animal fat.
The human consumption of industrial carcinogens in animal fat may further increase the risk of disease. Farm animals are fed to other farm animals and toxins accumulate up the food chain. Mercury, thus, isn’t just in fish because fishmeal is fed to other farm animals. No surprise, then, that industrial pollutants impact vegans significantly less than omnivores. While plant based antioxidants such as Vitamin C block the formation of certain carcinogens, adding Vitamin C to meats such as bacon may actually make the meat more carcinogenic.
A high-fat meal from animal sources may also adversely affect our arteries, but a high-fat meal from plant sources evidently does not. This may be because of the saturated animal fat facilitating the absorption of bacterial endotoxins present in meat and other animal products (see here, here, and here). There is also a considerable difference between low carbohydrate diets that base their fat and protein sources on animal rather than plant sources (higher versus lower cardiovascular and cancer rate mortality risk). In countries in which health (rather than agriculture) agencies are in charge of dietary guidance, the daily dietary recommendation is largely vegetarian due to concerns about animal fat intake.
For these reasons, choosing plant-based protein sources may be preferable. Comparing the nutritional aspects of chicken and meat-free chicken, for example, both share similar sodium and protein but chicken has arsenic, toxins, twice the calories, four times the amount of fat, one-third the amount of iron and no fiber. This is why fortified foods and supplements are the safest sources of Vitamin B12.