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Alyssa Luck

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Is it Possible to be Healthy on a Vegan Diet? [Part Two]

Alyssa Luck · Jul 15, 2013 · Leave a Comment

Note: this is one of my oldest posts, written when I was 19. I’m sure there are FAR better and more comprehensive summaries out there of the nutritional risks of a vegan diet, but this post (along with part one) do cover the high points, so I’ve left them up!

In part one, I discussed whether it’s possible to get enough vitamin D, calcium and vitamin K2 – three nutrients that are vital to bone health – on a vegan diet, without using supplements. We discovered that it is possible, but only if you get lots of sunlight, eat plenty of greens, properly prepare your nuts and seeds, and eat natto. In this post I’ll wrap it up by looking at iron, zinc, vitamin A, and vitamin B12. Then we can finally answer the question: Is it possible to be healthy on a vegan diet without the use of supplements?

Iron and Zinc

Iron and zinc, like vitamin D, are significantly more bioavailable in animal products than in plants. Iron comes in two forms: non-heme iron, which is found in plants, and heme-iron, which is found in animals. (‘Heme’ refers to ‘hemoglobin,’ which is the molecule that binds to iron in the blood.) On average, serum ferritin (a measure of iron status) tends to be lower in those following a vegan diet than in those following an omnivorous diet, although the risk of iron deficiency anemia appears to be similar. (1)

Unsurprisingly, whole vegans and raw vegans will likely fare much better than SAD vegans because their higher intake of unprocessed fruits and vegetables will afford them much higher levels of vitamin C, which markedly increases the absorption of non-heme iron. (2) However, there are several factors even in a seemingly healthy ‘whole vegan’ diet that could be cause for concern: vegan diets can be high in phytates from whole grains and soy, which have been shown to significantly reduce the absorption of non-heme iron. (3) Phytates have similar inhibitory effects on zinc absorption. (4)

Zinc also tends to be better absorbed when accompanied by higher levels of protein, so the relatively low-protein diet of a vegan might reduce the efficiency of zinc absorption. (5) Fermentation and sprouting of grains and legumes significantly lower their phytate content, so in addition to improving calcium absorption, these traditional practices could be extremely important in making sure vegans get enough iron and zinc.

Vitamin A

The next nutrient I want to address is vitamin A. If you think vitamin A is found in carrots and sweet potatoes, your high school nutrition class did you a disservice. These vegetables (and other plant foods) are actually high in beta-carotene, which is a precursor to vitamin A, but is not the real thing. Retinol is the ‘real’ vitamin A, the biologically active form that protects your eyesight and other good stuff. Unfortunately, retinol is only found in animal products.

The absorption of beta-carotene in humans varies widely, and the conversion of that beta-carotene into retinol isn’t very efficient. (6) Factors that influence this process include the fiber content and processing of the food, digestive health, and nutrient deficiencies, as well as some genetic factors that are completely beyond our control.

In a vegan who is gloriously healthy and who is eating a variety of beta-carotene rich vegetables (along with a healthy amount of fat to increase absorption), I wouldn’t worry about vitamin A status, so I definitely think it’s possible to maintain healthy vitamin A levels on a vegan diet without supplementation. However, for someone with a compromised absorption-conversion pathway, supplementation is probably necessary to avoid problems. It’s also worth noting that iron and zinc are necessary for converting beta-carotene to vitamin A, so if you’re deficient in those two minerals, you might be deficient in vitamin A as well. (7)

DHA (Docosahexaenoic acid)

That’s an impressive name, isn’t it? Maybe one of these days I’ll actually be able to pronounce it correctly on the first try. Anyways, DHA is a long-chain omega-3 fatty acid that is vital to the proper functioning of the immune system, and it likely played a role in the evolutionary development of the modern human brain. (8) You’ll find some great information on the importance of DHA here and here.

There are a few different omega-3 fatty acids, including DHA, EPA, and ALA. ALA is the kind found in plant foods like flax, while EPA and DHA are found only in seafood and algae. Thus, vegans don’t get any DHA in their diet unless they’re taking an algae supplement. The current belief is that ALA is the only omega 3 fat we must get from our food, but evidence is mounting that DHA is the true ‘essential fatty acid.’

The conversion of ALA into DHA is much lower than previously thought: only 2-5% of dietary ALA is converted into DHA, and that conversion rate is even lower in people with micronutrient deficiencies. (9) One study shows that the level of DHA in the blood, tissues, and breast milk of vegans is much lower than in omnivores, and that the level of omega-6 fats is much higher. (10) Additionally, ALA supplements did not increase tissue levels of DHA, while pre-formed DHA supplements increased tissue DHA dramatically.

In his report on essential fatty acids, Chris Masterjohn makes the case that in order to be optimally healthy, humans must get pre-formed DHA from their diet. This would mean that vegans must take an algae-derived DHA supplement, because there are no vegan food sources of DHA.

I think this is another instance where your mileage may vary. Someone with an extremely efficient ALA to DHA conversion pathway, no micronutrient deficiencies, and a low intake of the omega-6 fat linoleic acid (which can impede DHA formation) may be able to maintain health on a vegan diet without a DHA supplement, but I think the vast majority of vegans would probably see health improvements if they started taking DHA.  

Vitamin B12

Alright folks, here’s the kicker. So far, we haven’t run into any nutrients that would render a vegan diet (sans supplementation) completely unsustainable. If you live near the equator, eat plenty of greens, regularly consume natto, always soak your seed-like edibles, liberally slather your sweet potatoes with coconut oil, and have an abnormally efficient ALA conversion pathway, you should be fine with regards to vitamin D, calcium, vitamin K2, iron, zinc, vitamin A, and essential fatty acids. But I don’t think you’re going to be able to escape vitamin B12.

This innocent little B-vitamin is frequently used as ammo against the vegan community, leaving them with little to defend themselves but trembling teaspoons of nutritional yeast. Not to beat a dead horse, but really – vitamin B12 is only found in animal foods. You can’t get it from plants. Vegans have been shown to have much lower levels of vitamin B12 than vegetarians or omnivores, likely with serious consequences. (11, 12) The “vitamin B12” found in plant-based supplements such as yeast and spirulina is not true vitamin B12. In fact, it looks like those B12 analogues could potentially make a B12 deficiency worse. (13) If you are a vegan, you really, really, really should supplement with vitamin B12.

A Note About Gut Bacteria

I believe that the ability of a person to stay healthy on a vegan diet is closely tied to the state of their intestinal flora. Take vitamin K2, for example: some of our gut bacteria can produce vitamin K2, which some people absorb. (14, 15) Between that and the limited conversion of K1 to K2, I wouldn’t be surprised to find a vegan who could avoid K2 deficiency without supplementing and without suffering through bowls of natto. This is especially true if they don’t have other nutrient deficiencies or health issues.

The same might be said for vitamin B12. In some populations, the production of vitamin B12 by intestinal bacteria appears to contribute significantly to B12 status, but in communities with different populations of gut flora, B12 production by intestinal flora is negligible or not well absorbed. (16) So maybe, just maybe, not all vegans need to supplement with B12, but since one study found that half of vegans were B12 deficient, and another using more sensitive testing methods found that 83% of vegans were deficient, I’d say supplementing is still the smart thing to do. (17, 18)

If a vegan is able to stay healthy while avoiding B12 supplementation, I give credit to their gut bacteria and superior genetics. However, in modern, westernized societies where antibiotics and hand sanitizer reign supreme, I doubt most of our gut bugs are up to the task of efficient K2 and B12 production.

Conclusion

My purpose with this post isn’t to prove that you shouldn’t be vegan because it’s bad for your health. If you’re careful and you have the genes (and gut bugs) for it, I don’t think it is. Rather, it’s a response to anyone who claims that a) humans are meant to be vegans; b) the healthiest diet is a vegan diet; or c) all humans should be vegan. None of these things can be true, because for the vast majority of people, it is not possible to be healthy on a vegan diet without the use of supplements. And how can you claim any of those things for a diet that requires scrupulous planning and an arsenal of pills in order to work properly? Plus, for many people with compromised digestive systems, it wouldn’t be possible to be a healthy vegan even with all the supplements in the world.

A person’s ability to thrive on a vegan diet hinges on their ability to absorb the plant forms of nutrients (which are less bioavailable than their animal forms), as well as their genetically and environmentally programmed ability to convert compounds such as beta-carotene and ALA into their bioactive forms. But even if all those factors are in line, vegans would need an extremely unique population of intestinal flora in order to avoid the need for B12 supplementation.

So to give a straight answer to the question: Yes, it’s probably possible for a very small percentage of people to be healthy on a vegan diet without the use of supplements. I’ve seen people claim to be healthy, long-term vegans who don’t supplement. I take people at their word, so if you tell me you’ve been a thriving vegan for 50 years with nary a B12 supplement, I’ll believe you. (I’ll also be intensely jealous of your gut bacteria.) But based on the evidence presented here, I’d say you’re in the lucky minority.

That’s it! Hopefully I covered all the important points. Here are all the posts in the series:

Veg*n is Not a Curse Word
Plant-Based Diet or Plant-Based Diet?
Are Humans Herbivores?
Is it Possible to be Healthy on a Vegan Diet? [Part One]
Is it Possible to be Healthy on a Vegan Diet? [Part Two]
A word on raw meat, carnivory, and compassion towards animals

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Hi! I’m Alyssa. I like thunderstorms and cats, hate wearing shoes, and enjoy devising extensive research projects for myself in my free time. This is me in Bali with a monkey on my shoulder. And this is my blog, where I muse about health-related topics and document my relentless self-guinea pigging. If you want to know more about me, click here!

alyssa.luck

alyssa.luck
Photo dump from the last year. Thanks to everyone Photo dump from the last year. Thanks to everyone who made 28 the best yet - excited for 29🥰

(PS. In case anyone wants to know what it’s like in my head, I was going to write something like “year 28” or “my 28th year” but then I realized that the year between your 28th and 29th birthdays is not your 28th year of life, it’s your 29th year. I am turning 29 because I have been alive for 29 years. So then I had a whole thing about how to word it without being inaccurate and ended up going with what you see above which is vague and weird but the point is it was a good year and I love all the people in my life dearly)
Biology of Belief (2005) was written by Bruce Lipt Biology of Belief (2005) was written by Bruce Lipton, who earned a PhD in developmental biology in 1971 and was an anatomy professor and academic researcher in the 70s and 80s. Despite the book's presentation and Lipton's background, this is not a science book. It is an exposition of an ideology, supported by haphazard and poorly contextualized nuggets of evidence, rhetorical leaps, and a mind-boggling overuse of analogies. 

The book largely failed to deliver on its promised content. What it does is argue for the primacy of the environment over DNA in controlling life; propose that the cell membrane rather than the nucleus is the "brain" of the cell; invoke quantum physics to explain why modern medicine fails; explain that our behavior is largely controlled by our subconscious mind; inform parents that they therefore have a great deal of control over the destiny of their children; and conclude that humans must become nonviolent protectors of the environment and of humanity because Everything Is Connected.

It’s not that these points aren’t relevant to the topic at hand - they are. But they were not connected in a coherent way that would explain how “belief” actually works (like…biologically), and the treatment of scientific concepts throughout was careless, or perhaps disingenuous.

I think he's correct about many things, some of them being common knowledge. For instance, the "new" science of epigenetics is now old news, as is the critical role of parenting and early environment in shaping a child’s future. But however important these and attendant concepts may be, the book did not do a good job explaining, supporting, or connecting them. 

As far as practical guidance, he refers the reader to a list of resources on his website, which is fine, but I expected some scientific insight into how/why those modalities work. None was given. 

On the plus side, the book was quite thought-provoking, and I came away with loads of references and topics to follow up on. My favorite line? "There cannot be exceptions to a theory; exceptions simply mean that a theory is not fully correct."
Friedrich Nietzsche, The Gay Science (section 382) Friedrich Nietzsche, The Gay Science (section 382), as quoted in the introduction to Thus Spoke Zarathustra because I like the translation better.
This paper totally changed the way I think about e This paper totally changed the way I think about early nervous system development and the relationship between physiology and sociality. 

The authors propose that newborn babies are not inherently social, and have just one goal in life: physiological homeostasis. I.e. staying alive. This means nutrients, warmth, and regulation of breath and heart rate, i.e. autonomic arousal (it’s well-accepted that newborns sync their breathing and heart rate with caregivers through skin to skin contact). 

All these things are traditionally provided by a loving caregiver. So what the baby experiences during the first weeks of life, over and over, is a shift from physiological perturbation to homeostasis (a highly rewarding event inherently) REPEATEDLY PAIRED with things like the sound of a caregiver’s voice and seeing their face. Thus, over time, the face/voice stimuli become rewarding as well. 

The authors argue that THIS is the beginning of humans’ wiring for sociality, and may explain why loving social interactions can have such a profound regulating effect on physiology throughout life: because the brain was trained for it at an early age. 

This framework holds all kinds of fascinating implications for what happens if that initial “training” isn’t so ideal. What if the return to nutritional homeostasis via feeding is paired with negative expressions and vocalizations rather than loving ones, perhaps as could occur with PPD? What happens if the caregiver has poor autonomic regulation, such that social stimuli become paired with cardiorespiratory overexcitement in the baby? Could that have potential for influencing later introversion vs extroversion? (Because if social interaction is paired with autonomic overexcitement, that could lead to social interaction literally being more energetically draining, which is what introverts experience. Thoughts?)

For my energy metabolism enthusiasts: Table 1 in the paper draws a link between metabolic rate and sociality across species. Swipe for a screenshot. 

Anyway, check out the paper! It’s free, just google “growing a social brain pdf.”
I’ll be under general anesthesia in a couple day I’ll be under general anesthesia in a couple days to have two tooth implants placed, and I think I’ll take the opportunity to have a little heart-to-heart with my subconscious mind. A bit of medically-assisted self-hypnosis, if you will. 

I randomly stumbled upon these papers a couple months ago - an RCT showing reduced post-op pain in patients who listened to recorded positive messages while under general anesthesia, plus a post-hoc analysis of the same data that found reduced post-op nausea and vomiting in a subset of high-risk patients. 

The full review paper from the first slide is unfortunately in German, but it has long been recognized that even when unconscious, the patient is listening (for better or for worse). 

It boggles my mind that it isn’t standard of care to have patients listen to recordings like this while under sedation, considering that almost nothing could be easier, safer, or cheaper, and we have at least some evidence of significant efficacy. I mean c’mon, what more could you want from an intervention? 

(Yeah, I know. Profit. If anyone still thinks that our medical system operates with patient well-being as the foremost goal, you’re deluding yourself.)

“There should be a fundamental change in the way patients are treated in the operating room and intensive care unit, and background noise and careless conversations should be eliminated.”

“Perhaps it is now time to finally heed this call and to use communication with unconscious patients that goes beyond the most necessary announcement of interventions and is therapeutically effective through positive suggestions. When in doubt, assume that the patient is listening.”
If you've seen "vagus nerve exercises" that have y If you've seen "vagus nerve exercises" that have you moving your eyes or tilting your head, you've probably encountered the work of Stanley Rosenberg. The exercises he created and introduced in his 2017 book now appear in instructional videos all over the internet. 
 
The book itself has much to recommend it: it's accessible, it's practical, it's inspiring. But it has one major flaw: the solid practical and informational content regarding the cranial nerves is framed in terms of the scientifically dubious polyvagal theory. 
 
I particularly enjoyed the book as an introduction to the therapeutic arena of bodywork, of which Rosenberg is a skilled practitioner. His book is full of case reports that demonstrate how immensely powerful extremely subtle movements and physical manipulations can be. These do need to be kept in perspective: it's a small sample size of the most remarkable cases, and the results were achieved within the supportive clinical environment of a skilled practitioner. You can tell from his descriptions how refined his technique is. But nevertheless, it was a paradigm-shifting read for me, and the exercises give you something concrete to play around with. 
 
The book also brought the cranial nerves and the concept of “social engagement” to the fore as arbiters of health. Rosenberg has a solid background in cranial nerve anatomy and shares many interesting tidbits and considerations that you don’t typically hear; for instance, the potential impact of dental and orthodontic work on cranial nerve function.
 
So, is it worth reading? If any of the above piques your interest, go for it! Just read my post on polyvagal theory first – you can use the book to practice separating the wheat (solid informational content) from the chaff (pseudoscientific framing). If nothing else, the book is a nice reminder that genuine healers who get lasting results for their patients do exist.

But if you just want to try the exercises, you can easily find them all on YouTube. 

“You learn techniques to understand principles. When you understand the principles, you will create your own techniques.” -Stanley Rosenberg
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