Often, people say something like

"I'd love to be vegan, but I have low iron levels and a vegan diet would be unhealthy for me."

I'm not a physician and I can't just say

"I assure you, your iron intake will not suffer, but maybe even improve."

I still don't really know whether there are people who can't be vegan for health reasons.

What health conditions can people have such that a change to a vegan diet would be unhealthy?

Some examples I've witnessed (only personally):

  • The iron argument, multiple times, especially about adult women.
  • Someone claiming that he has a special kind of anaemia and he needed to eat beef because of it.
  • A vegetarian with Irritable Bowel Syndrom turning to meat eating because of his doctors recommendation.
  • Please do not answer in comments -- on a question, this space should be used for requesting clarification or suggesting changes :)
    – Erica
    Sep 8 '20 at 12:20

There are many medical conditions that call for dietary restrictions. For example:

  • irritable bowel syndrome
  • allergies
  • migraines
  • gluten sensitivity

When a person has a combination of medical conditions, it can be very hard to find foods that satisfy all the restrictions.

I have a friend with several allergies and migraines. After removing all allergens and the migraine triggers from his diet, he is very restricted. Considering that he doesn't have much time for complicated recipes, he decided to eat seafood.

Every specific case would need to be evaluated by a combination of a doctor and nutritionist, to determine, if it's really impossible or just very hard to be vegan.


Check the list of Potential migraine triggers

The article in medicalnewstoday says: Any food can cause an allergy, theoretically and As far as foods are concerned, nearly all allergens are proteins

Another good list of food allergens is foodallergy.org

healthline.com lists foods to avoid with irritable bowel syndrome.

  • I'm interested in know the list of restrictions your friend has found work for him.
    – ecc
    Feb 13 '17 at 16:59
  • 4
    actually these conditions make it more difficult, but still possible..
    – Attilio
    Feb 27 '17 at 23:47
  • 1
    Some allergies (soy or wheat) would make your CULINARY life far more difficult as a vegan, though :) Mar 13 '17 at 9:52
  • @Attilio has a point. I have two of the example conditions and it just takes a bit more of work
    – istepaniuk
    Jun 27 '19 at 15:21

One possibility: Omega-3 deficiency. Although omega-3 fatty acids can be found in non-meat sources, the best way to get them is by eating fish.

I knew someone once who was an on-again-off-again veg*an for this reason, because her body had trouble absorbing omega-3. She would stick to plant foods for a few weeks, then be forced (feeling horrible about it) back into eating fish for a while. Last I heard, she and her doctor had come up with a way for her to cut out fish on a more permanent basis (although I never found out what that was).


Besides celiac disease and allergies, the following can make a vegan diet difficult:


Autism. One of the main symptoms of autism is sensory processing disorder. This means that the brain perceives sensory input from the nerves incorrectly. This causes some senses to be very very pleasant, and others to be absolutely horribly unpleasant, and can even be erroneously perceived as physical pain. Every person is different, and thus the things different autistic people perceive as painful vary. Whilst one person can stand loud noise, another is in physical pain because of it. While one likes mac 'n' cheese, another may be in physical pain due to its scent, texture or taste. It's different for everyone, and as you can imagine this restricts some autistic people's diets very very much. There are some autistic people who can survive being vegan, but there are also some whose "safe foods" (foods that don't trigger pain) happen to be mostly non vegan foods. Since the diet is already limited, limiting it further to only the handful of vegan safe foods would have catastrophic affects on their health and safety as they would not have access to variety nor all the nutrients one needs to survive.


Trying to recover from a restrictive eating disorder.

  • 1
    Welcome. Maybe you could elaborate to improve this answer. I think a mental health reason is as valid as physical health. Someone with disordered eating may very well use veganism for the wrong reasons, but equally they might use it as a wholesome way back in to eating. Some references would be even better.
    – David S
    Aug 22 '19 at 13:24

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