Following a vegan diet has become increasingly widespread in affluent countries — Britain saw its popularity rise quickly in 2017, for example. From a nutritional standpoint, a vegan diet can supply all essential nutrients except vitamin B12, which must be obtained from appropriate supplementation. From a social perspective, some vegans pat themselves on the back because they feel they're not complicit in cruel aspects of animal husbandry or possible environmental effect of large-scale food animal production. Okay, we're not in favor of cruelty or environmental degradation either. We wonder, though, if a broader view might be informative.
For example, let's look at the economics of the situation. Yasmin Alibhai-Brown recently wrote about the effect of upscale foodies raising the profile of quinoa, a high protein grain grown in the Andes. The demand for this grain has increased astronomically — so that should be good for the folks who grow it, right? The problem is, she says that as demand has risen, so has the price — and the less wealthy can no longer afford to purchase the crops they had depended on. And last year, Joann Blythman documented the increased demand for Mexican avocados — a demand that profits producers, but is unlikely to benefit workers, and that increases deforestation as farmers chase increased profits.
Further, vegans often declare that eliminating the production of animals for meat would free up land for other, more sustainable crops, as well as eliminating the problem of dealing with animal wastes. While the latter is certainly true, the benefits of changes in land use are more questionable. For example, Peters et al. noted:
Modeling studies suggest that the largest fraction of land needs for ruminant animals are from forages and grazing lands, which are often grown on non-arable land. Thus, reducing the most land-intensive products in the diet does not necessarily equate to freeing up land for cultivation.
These investigators modeled the carrying capacity of land used (i.e., number of people fed per unit land area) under varying types of diet. That of the vegan diet was lower than that of two types of less restrictive vegetarian diets — the ovo-lacto-vegetarian diet and the lacto-vegetarian diet.
Vegans should be more careful about the benefits they claim for their chosen lifestyle — while there are some positive aspects of a vegan lifestyle, not all can be substantiated.