A General Argument Against Veganism/Vegetarianism

I came across this image in my Instagram feed months ago, and I hesitated to comment for good reason.  First, let's assume that the creator of this image probably meant to say "waiting for a sound argument", rather than "waiting for a valid argument".  Anyone can make a valid argument against veganism, given that the premises need not be true to create a valid argument (e.g. 'Vegan diets have been proven to cause cancer.  Cancer is bad.  Therefore, vegan diets should be avoided' is a valid argument).  Making a sound argument against Veganism is much harder.  It is easy to create a personal argument against veganism, such as "I enjoy eating meat too much to give it up", or "Plant based diets make me sick", but in the context of who is actually sharing this image, it is more likely that the poster is waiting for a sound argument against veganism in general.

This is a nearly impossible task, simply because veganism (and vegetarianism for that matter) is a very broad topic, and the arguments in favor of it stem from multiple, diverse premises.  For some it is simply a dietary decision, but for others, it is an ethical ideology.  To argue against something, you have to know at least a little bit about the arguments in favor of that particular position.  Since most people choose vegetarian and vegan diets for personal reasons, it would only be reasonable to argue against such diets on a case by case basis.

So is there any real general argument against veganism?  I can think of at least one: Veganism/vegetarianism is generally unnecessary, and when adopted without proper education and planning can result in negative health consequences.

Just a few weeks ago I was forwarded an article from Science Daily which indicated that a recent study by the Mayo Clinic found that some vegans risk being deficient in B-12, iron, calcium, vitamin D, protein, and Omega-3 fatty acids.  This article is what got me thinking about this subject lately.  While this information does not suggest that veganism is inherently unhealthy (the article points to poor planning and lack of education in nutrition), it does go against many of the arguments and implications that meatless diets are somehow essentially healthier.

In closing their article Vegetarianism: Healthful but Unnecessary, Susan Dingott and Johanna Dwyer (both Registered Dieticians) write:

Vegetarianism based on sound nutrition principles can be a healthful choice, but neither vegetarians nor omnivores have a monopoly on healthful eating. Vegetarians are just as diverse in their health status as are nonvegetarians. Similar health benefits can be gained from both well-selected omnivorous and vegetarian diets.

I couldn't have said it better myself.