Scientific American, July 14, 2023
by Sarah C. Hull, assistant professor of medicine, and associate director of the Program for Biomedical Ethics, Yale School of Medicine.
The idea that we need to eat meat to get enough protein and iron, a false assumption of some Paleo diet acolytes, is a common misconception. It ignores the abundance of protein and iron in many plant-based foods such as nuts, seeds and legumes. Similarly, consuming dairy is not necessary to obtain adequate dietary calcium, as this mineral is abundant in soy, lentils, beans, nuts, seeds, grains, leafy greens and cruciferous vegetables.
Likewise, while we typically associate omega-3 fatty acids with fish, fish themselves incorporate these into their tissue by eating algae and seaweed, which we can consume directly without the concerns of exposure to accumulated mercury and microplastics in fish flesh. Indeed, a whole-food, plant-based diet can provide all essential nutrients except for vitamin B12, which is made by bacteria in soil and ingested by animals, thereby incorporated into their tissue, milk, and eggs. While modern sanitation allows humans to consume clean produce uncontaminated by dirt or feces, we can easily and cheaply obtain oral B12 supplements.
Furthermore, significantly reducing our consumption of meat would carry vast benefits. As cardiovascular disease remains the leading cause of death around the world, poor diet has now surpassed tobacco smoking as the top risk factor for death in the U.S, where life expectancy has now stagnated, in large part because of a plateau in mortality from cardiovascular disease. Eating highly processed foods and red meat has been repeatedly demonstrated to promote underlying mechanisms of cancer and cardiovascular disease, such as inflammation and damage to the lining of blood vessels.
Mounting evidence points to the benefits of a whole-food, plant-based diet. A meta-analysis of scientific studies from 2017 found that a vegetarian diet is associated with a 25 percent relative risk reduction for coronary heart disease and an 8 percent relative risk reduction for cancer, with a vegan diet conferring a 15 percent relative risk reduction for cancer. The World Health Organization (WHO) has classified processed meat as carcinogenic, and (unprocessed) red meat as probably carcinogenic to humans. Finally, randomized controlled trials have also demonstrated the benefits of a Mediterranean diet (essentially a whole-food, plant-predominant diet) in both the primary and secondary prevention of cardiovascular disease, with enhanced benefits from greater adherence to a provegetarian (more plant-based) dietary pattern.
In addition to harming ourselves, eating meat harms others. Factory farming practices often entail unspeakable cruelty to animals, and working conditions for human laborers are often unsafe and inhumane as well. Overcrowding of livestock and workers promotes the spread of disease among both people and animals, putting us all at risk for future pandemics. The overuse of “routine” antibiotics to accelerate animal growth and preemptively treat the infections anticipated as a result of living in unclean and overcrowded conditions can promote antibiotic resistance. Finally, meat consumption contributes to climate change though deforestation and methane emissions. Food systems make up a third of global greenhouse gas emissions caused by human activity, and animal-based foods contribute twice the emissionsof plant-based foods. Switching from the typical Western diet to a vegetarian diet can reduce one’s personal dietary carbon emissions by 30 percent; a strict vegan diet can reduce them by as much as 85 percent….
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