Nutrition, or: Will Veganism Save or Destroy the World?
Periodically, someone objects to veganism on the ground that vegans don’t get adequate nutrition and so are unhealthy. I’ve talked to people about vegetarianism periodically over the last >20 years, and it seems as if this concern has recently become more popular. (It used to come up rarely or never.) One reader got mad at me for not talking about it in my book (https://www.amazon.com/dp/1138328294/).
One argument that I recently heard claims that vegans are increasing existential risks to humanity, and thus possibly causing some astronomical amount of expected harm (or averted benefit). How so? Because vegans are going to be less good at thinking of potential solutions to existential threats, due to their malnutrition.
You might think that sounds like a stretch. (It did to me!) But how else are you going to argue that the benefits of meat are even comparable to the amount of harm that we’re causing? As you might know (if you read my posts), we’re killing ~74 billion animals on factory farms per year, and pretty much all of those animals suffered throughout most or all of their lives. There have only ever been ~110 billion humans. So it’s hard to see how any human good could be thought to justify the amount of harm we’re causing. So that’s why meat-eaters would need to appeal to something like the ‘existential risk’ argument. (I’ve only ever heard one person give that argument, though.)
So let’s think about all that.
1. Some Healthy Vegans
Obviously, it’s possible to be unhealthy on a vegan diet. (Potato chips and Coke are vegan! So is lying on the couch all day.) Is it also possible to be healthy on a vegan diet?
Well, I found a list of some vegans who are also world-class athletes (https://www.pledgesports.org/2018/03/top-10-most-successful-vegan-athletes/). A few names from the list:
Venus and Serena Williams (tennis players; won a total of 12 Wimbledon singles titles and 30 Grand Slam titles between them):
Tony Gonzales (American football player; played 17 seasons in the NFL):
Scott Jurek (runner; won 16 ultramarathon titles, set record for fastest completion of the Applachian trail):
Patrick Baboumian (body builder; twice broke the world record for the yoke walk by carrying >1200 pounds for 10 feet):
Those people seem healthy to me; indeed, about the most healthy that a person can be. This shows that it’s possible to be a healthy vegan.
Of course, as scientists would say, that is anecdotal. Maybe most vegans are less healthy, and those are just unusual cases. We need to look at scientific studies.
2. Studies
Caveat: I’m not a doctor or nutritionist. I’ve just done a little reading on the internet. From that, here’s how it looks to me:
Vegan diets lower your heart disease risk and help you lose weight. Those points are well known and not controversial. (https://www.healthline.com/nutrition/vegan-diet-studies, https://pubmed.ncbi.nlm.nih.gov/26707634/)
There is evidence of a decrease in cardiovascular disease risk. (https://pubmed.ncbi.nlm.nih.gov/30828449/)
And it may also reduce your cancer risk. (https://pubmed.ncbi.nlm.nih.gov/26853923/)
Those are the major health benefits, unless I’ve overlooked something. Btw, I did not cherry pick those sources. I searched for “vegan health”, “vegan cancer”, etc., which should turn up results showing poor health, increased cancer risk, etc., if there were such studies. And I didn’t rely on pro-vegan sources either. Healthline is just a generic health-information site, and PubMed is a general (very large) medical research repository maintained by the National Institutes of Health.
Now the bad side:
Vegans are at risk of micronutrient deficiencies. Vitamin B12 deficiency is common in U.S. vegans. There is also a risk of deficiency in vitamin D, calcium, and omega-3 fatty acids (https://pubmed.ncbi.nlm.nih.gov/19279075/).
Also zinc and iodine (https://link.springer.com/article/10.1007/s00394-015-1079-7/tables/3). By the way, all groups in that study – omnivores, vegetarians, and vegans – showed deficiencies in some nutrients. The omnivores had a different pattern of deficiencies. So don’t think that you can ignore nutrition just because you’re an omnivore.
3. Recommendations for Vegans
(Caveat: Again, not a doctor. Consult an actual doctor for detailed advice.)
If you’re vegan, I recommend taking supplements for the vitamins that you’re most likely to be deficient in, such as B12, calcium, D, zinc, and omega-3's, and use iodized salt (like most salt). Also possibly useful: taurine, carnosine, creatine (these are other nutrients that are found only in animal products). You should not ignore nutrition. I have heard that some people who become vegan later quit because of health problems. I suspect that this is because they’re not taking the needed vitamins.
About vitamin B12 and omega-3’s: Clams and other bivalves are an alternative, ethical source (https://www.nutritionadvance.com/clams-nutrition-benefits/). It’s ethical because they don’t have a brain. However, seafood in general can contain small amounts of heavy metals (mercury, lead, etc.), which are neurotoxic. I’m not sure how big of a problem this is (?), so … I wouldn’t do it more than twice a week (which is what the USDA recommends -- https://ask.usda.gov/s/article/How-often-should-I-eat-seafood).
For more, see this page of advice for new vegans: https://veganhealth.org/tips-for-new-vegans/
4. Recommendations for Non-Vegans
If you’re not a vegan, I first recommend becoming one.
If you’re not going to do that, then I recommend buying only Humane Certified animal products, which have the logo shown here. I see them at Whole Foods. (Btw, “free range” and “cage free” isn’t enough – those labels don’t really mean very much.)
If you refuse to do even that, then we know that your appeals to “muh nutrition” are BS and you’re probably just amoral. Because humanely raised animals have exactly the same nutrients as cruelly raised animals – there’s no special nutrient that’s produced by pain and suffering.
5. Back to Existential Risks
Anyway, let’s get back to the “existential risk” argument that we started with. It cites an imaginable but highly speculative harm resulting from veganism. But this harm could be very large, since perhaps the future of humanity might contain an extremely large number of happy lives, provided that we don’t kill ourselves in the near future. We might even be able to drastically improve the lives of the non-human animals all over the planet. (Obviously, that would be a far-future project.) So that could outweigh all the harm that we’re doing to animals in the near-term.
My thoughts:
It seems that the risk could be addressed, without having to support animal cruelty, by supplementing your vegan diet, as suggested above.
Alternately, you could move to only humanely raised meat.
The argument is reminiscent of Pascal’s Mugging (https://nickbostrom.com/papers/pascal.pdf). Someone comes up to you and claims to be an incredibly powerful being from another dimension. He threatens to create and then torture 10^100 people, unless you give him your wallet now. The probability that he’s telling the truth is extremely low, but … can you really take that chance? If there’s even a 1 in 10^100 chance that he’s telling the truth, then expected utility calculations suggest that you better hand over the wallet.
I’m not sure exactly what Pascal’s Mugging shows, but the reasoning seems wrong – it seems that you shouldn’t hand over the wallet. This seems similar to the above Existential Risk Argument. Both involve extremely low-probability hypotheses, tied to astronomical costs or benefits, designed to support an action that serves some obvious interest of the person giving the argument. This makes me suspicious of the Existential Risk Argument.
Now imagine that, instead of just your wallet, the Pascalian Mugger wants you to make a huge sacrifice, say, killing an innocent person. In that case, it is completely clear that you reject the demand. This would be more analogous to the Existential Risk argument for meat-eating.
Here are some alternative hypotheses about how veganism might save the world:
Maybe some genius will avoid having a heart attack at a young age by adopting a vegan diet; then he goes on to save the world.
Maybe seeing more vegans around will cause people to become more ethically sensitive and empathic. And maybe this will stop us from destroying the world through war, or some other unethical behavior.
Maybe the rise of veganism will lower the price of food in general (meat is more costly to produce), and this will reduce malnutrition in the developing world, and maybe some person in a poor country will save the world who otherwise wouldn't have done so, because he was able to get adequate nutrition and not starve.
Maybe the rise of veganism will reduce our impact on the natural environment, just enough to avert some global environmental catastrophe.
Maybe there is some zoonotic disease that we would have acquired, and that would have wiped out the human species, but we’ll avoid getting it because the people who would have first contracted it become vegans. (Most new infectious diseases come from animals! -- https://fakenous.net/?p=1397)
I’m not asserting that any of those are in fact true. But they’re all possible, and I don’t see that any of them is less plausible than the story about how veganism might destroy the world.
Perhaps this is what’s wrong with Pascal’s Mugging-type arguments. There are always multiple speculative hypotheses suggesting enormous possible costs and benefits to any action. Maybe we disregard them because we have no good way of assessing the probabilities, or even listing all the possibilities, and hence no way of assessing whether the potential huge costs outweigh the potential huge benefits.