Electrolyte Sponsorships Don't Improve Reading Comprehension: A Case Study of Joseph Everett
Updated: May 3
Firstly, I'd like to thank all of the people who volunteered days of their time in order to make this article possible!
Some time ago, the YouTube channel, What I've Learned, release the video called "Vegan diets don't work. Here's why", wherein the channel's host, Joseph Everett, tells a cautionary tale regarding the health-related pitfalls of so-called "vegan" diets. In this article, Joseph will be exposed as the shameless fabulist that he is. Most of the references are taken out of context or cherry-picked, while others actually directly contradict the claims that they were cited to support.
In order to save on characters, I'm forced to truncate my introduction. So, I'll just take this time to say that you, Joseph, are a complete sophist, and you should be utterly ashamed for misleading the millions of people who consume your content. The effort that it took to write this article is more than you deserve, but its contents are more than deserved by your viewers. Your viewers deserve the truth— not cringey narratives about maverick dentists and cave paintings. With that, let's begin.
Claim #1 (00:00):
It’s well understood that each of these vitamins have many functions in the body, but what does this have to do with nice teeth or looking attractive? Well, research later confirmed that along with things like protein and calcium, these vitamins indeed work together to transport minerals to support proper formation of the bones.  And of course your facial structure which includes the dental arch depends on proper development of your facial bones.
This is incredibly unscientific evidence on this hypothesis. The potential for selection bias with this particular body of evidence is enormously high, and on multiple levels. Of course we do not want to assume bad faith on the part of the researcher himself, but no credible scientific establishment would consider this evidence to be anything above laughable on the hypothesis specified. The specified hypothesis is that vitamin K2 (presumably in conjunction with other fat soluble vitamins) is responsible for teeth being straight rather than crooked.
It's not clear at all how the evidence presented even interacts with the hypothesis. These traditional peoples were not screened for vitamin K2 status or intake. There were no prospective analysis. No intake measurements. No biomarker measurements. Just storytelling. In fact, four years ago Joseph published a video that present a far more plausible hypothesis for the appearance of strong jaws and straight teeth in traditional populations eating traditional diets. In the video he cites a researcher named Clark Spencer Larson from Ohio State University, who claims that stronger jaws and straighter teeth seen in ancestral populations are a consequence of the repetitive chewing of tough, fibrous plant material.
There is also evidence that straighter teeth tend to be more worn down in traditional populations, which supports the chewing hypothesis.  In fact, Joseph references the pictures from Weston A Price's Nutrition and Physical Degeneration as evidence for the chewing hypothesis. He remarks that the straight teeth in the traditional populations appear more worn down.
Has Joseph changed his view? It's unclear why, as this is a far more plausible hypothesis, and can actually subsume the vitamin K2 hypothesis. If vitamin K2 intake is a correlate for traditional diets, and traditional diets are more likely to be high in fibrous, tough plant foods, and straighter teeth tend to be more worn then crooked teeth, then the chewing hypothesis would appear to be more parsimonious.
Also, if insufficiency of K2 and the other fat soluble vitamins are to blame for crowded teeth due to their role in bone formation, why is there no mention of any of these people have any other issues associated with those sorts of nutritional insufficiencies? Like rickets, blindness, poor skin, or even haemophilia? It doesn't make sense.
Claim #2 (01:01):
If eating zero animal foods improves health so much, why would a 2016 study find that 84% of vegans eventually quit their diet? 
First of all, the claim of 84% of vegans quitting is just blatantly incorrect according to his own citation, which found a 70% dropout rate for vegans. Second of all, this is a ridiculous question. People stop doing health promoting things for all sorts of reasons, and it probably would have been a good idea for him to read the goddamn reference instead of resorting to conspiracy theories. The study includes an inventory of explanations for participant recidivism, and the craving of animal products only occurred in the minority of recidivists.
Furthermore the study includes a table of motivations for pursuing veganism. Only a measly 1-3% of participants had motivations that were purely ethical in nature. While most motivations were health related. So, it seems like people are generally going on plant-based diets for health related reasons, and abandoning the diets without generally suffering health related costs. This isn't the only reason the question is stupid. Plenty of health promoting behaviours have high recidivism rates, such as exercise.
The Faunalytics study from the previous year actually explicitly stated that health did not present a noticeable difficulty for study participants, with the exception of vitamin B12 monitoring. Very few people actually reported any health issues at all, and it's not clear how many of them were actually supplementing B12.
The study had 54 current vegans and 129 former vegans. Of those 129 former vegans, 123 gave reasons. Of those 123, 104 reported no health issues. Of the remaining 19, 7 had no health issues, but rather just "felt" like they weren't getting enough nutrients or were concerned for no particular reason. One seemed to quit because they doubted the benefits. Only 11 reported actual health issues.
Of those 11, 6 were vague like "sick", "lightheaded", "not healthy", and "health issues", and doctors and/or dietitians were rarely, or never, involved to actually confirm that the diet was the issue. In conclusion, if we're being outrageously generous to his position, 6% of those who tried a vegan diet reported any health issues at all. But as we discussed above, it's unclear if this is just a result of poor supplementation practices.
It's not clear why we should accept the implication that a diet is healthy if and only if it can be generally adhered to. There are many examples of diets with poor adherence rates that I don't think Joseph would sign off on being unhealthy, and there are plenty of examples of diets with high adherence rates that Joseph wouldn't consider healthy at all.
D := (x) diet is great
G := people generally adhere to (x) diet
s := Standard American Diet
k := Ketogenic Diets
P1) A diet is great if and only if people generally adhere to it.
P2) People generally adhere to SAD and not keto.
C) Therefore, SAD is great and keto isn't.
Claim #3 (04:59):
So it’s interesting to observe that the Dutch are competing with Montenegrins for the tallest people in the world title (animation source: USA data) and they happen to be 2nd and 3rd on the list for the most milk consumed per capita in the world. A study of 105 countries in the journal Economics & Human Biology noted that animal food, particularly dairy, most correlated with increases in height. 
This is actually the first claim where he actually starts citing peer reviewed research and not just the 1930s equivalent of a blog article with no citations.
Firstly, this is an ecological fallacy. Essentially, Joseph is looking at two temporally concurrent variables and implying a causal relationship. Specially, the research that Joseph cites does not look at individuals, their animal food/dairy consumption in childhood, nor their attained height in adulthood. These heights aren't compared to height projections or heights of peers consuming different diets.
Instead, this research is just looking at the average height of each entire country and the average intake of said foods. Such studies are susceptible to something called the ecological fallacy, meaning what applies on a country average level may not apply on an individual level.
In this graph on average as X increases, so does Y. But if you look at each cluster separately, as X increases Y decreases. A real life example of this is the relationship between smoking and longevity.
If you plot each country's smoking rate and lifespan you'll see that the more people smoke the longer they live. This correlation, of course, breaks at an individual level.
I very much doubt that Joseph would approve of this ecological study. 
The study makes no attempt to adjust for socioeconomic or genetic differences in the countries involved. Richer countries tend to have access to more expensive sources of calories, but also have fewer infections and cleaner water, among many other things conducive to better health. They also tend to eat meat. This doesn't tell us what's happening within each of those populations across the spectrum of meat consumption.
Also it's likely that the reason animal protein correlates strongly with height in Joseph's reference is that it's the main source of protein calories in most diets around the world. For example, in Europe where they essentially consume no plant protein (most plant foods consumed lack significant protein), highly correlated protein (defined by the authors as milk, eggs, pork, beef and potatoes), as well as animal protein and total meat associate more with height than total calories and total protein. If you look at Asia where people eat more plants protein, you'll see total protein and total calories correlate better. Also, inequality adjusted human development index unsurprisingly was more strongly correlated with height than any food.
Claim #4 (05:30):
I recently interviewed Yovana Mendoza who had essentially made a career based around her vegan lifestyle when she had health issues she tried her best to solve them while staying on the diet, using all kinds of supplements and troubleshooting strategies but she eventually had to prioritize her health and quit the diet after 6 years … even though she had every motivation to keep being vegan. Reintroducing animal foods fixed her health issues. Yovana’s case is a peak at how complex it can be to replace animal foods in your diet.
Yovana Mendoza was a so-called "raw" vegan. As you can see from the picture he flashed, she was on a meme starvation diet of only raw food averaging an abysmal ~1000 calories a day.
Raw food diets are associated with many stupid beliefs revolving around self-purification, including extensive fasting periods (49% of study participants), not supplementing B12 (7% took any supplement at all), and enemas (16% of them). 
Some believe once you are "purified" you lose your period which is a sign you're clean, for example. As you approach 100% raw food, pretty much half of them complain of amenorrhea, probably due to insufficient calories.
As you can see, raw diets associate with considerably low BMI scores.
Rawvana also made a video telling us how since she's gotten healthier on her raw vegan diet her "eyes have become greener", so I don't know how much stock we should put in her health advice, Joseph.
As illustrated by Anna's analysis, this seems to be an extremely common pipeline. People go raw vegan, influenced by social media morons, they don't eat enough calories, because their diets aren't formulated correctly, and then they return to some omnivorous diet and claim that veganism failed them. No. Veganism didn't fail you. You played a stupid game and you won a stupid prize.
Claim #6 (06:18):
Take Vitamin A - you might think the average vegan has way more vitamin A because it comes from vegetables like carrots or sweet potatoes - but that’s not vitamin A, that’s beta carotene that has to be converted into vitamin A …and the conversion rate is very poor - about 12:1.  Though it’s more like 21:1 when you account for the hampering effect of fiber in the diet.  Not only that, the more you eat, the worse the conversion rate becomes. Further, depending on your genes, your conversion rate could be even lower - this is the case for me and for potentially as much as 37% of people of European descent (See also, 57% lower.  Actual vitamin A only comes from animal foods or synthetic supplements.
Firstly, let's cut to the chase. Is there a risk of vitamin A deficiency among those only relying on non-retinol sources of vitamin A? That's the question. We'll get to the mechanistic speculation, and why it's so dumb, but for now let's focus on actual outcomes. To my knowledge there are two studies assessing retinol status in vegans after excluding those who supplement. 
Both studies showed that vegans had statistically significantly lower retinol status than omnivores, but the differences were not clinically significant. We're free to speculate all we want, but at the end of the day there is no reason to believe that the differences in status actually amount to any differences in expected health outcomes between the two groups.
Now, let's get to the mechanistic fuckery. Joseph claims that there are genetic differences in carotenoid to retinol conversion capacity that could lead to deficiency in some who are relying on carotenoids over retinol. Right off the bat, Joseph's own reference contradicts his claim, as the entire variance in the population sample had fasting plasma retinol within the reference range.
...the lowest plasma concentration was 963.8 nM, indicating that all volunteers had adequate serum vitamin A concentrations.
Even the people with the worst impairments maintain adequate retinol status, despite only getting an average of a measly 133mcg/day of retinol. The only thing that changes is that the ratio of beta-carotene to retinol is increased based on the severity of the impairment in conversion rates. That's all.
But, we can take this a step further and actually see what happens when we try to correct vitamin A deficiency using dietary carotenoids in human subjects.  On the whole, eating foods rich in carotenoids reliably improves and/or normalizes vitamin A status. Even foods that have been genetically engineered to have higher levels of carotenoids reliably improve vitamin A status in humans.  In fact, a newer study published in 2020 found no differences in retinol status between BCO1 genotypes in a population consuming low amounts of preformed retinol. 
Let me explain what's happening here. These genetic variants likely aren't changing the total amount of retinol converted from carotenoids. Likely the only thing that's happening here is that the conversion curve is changing shape without a change to the area under that curve. Meaning that across these genetic variants, people are capable of converting the same amount of retinol from carotenoids, but the rate at which they make that conversion is slightly longer in those with the so-called impairments. In my opinion, this is the most parsimonious way to reconcile the data.
As a side note, the only cases of vitamin A toxicity (hypervitaminosis A) from whole foods that I could find in the literature involved the consumption of preformed retinol from liver.  In one case, a child died from consuming chicken liver pate sandwiches. I could find no case reports of such vitamin A toxicity related to carotenoids.
Claim #7 (06:58):
A 2021 study found vegan Finnish children had insufficient vitamin A and a 2020 German study found vegans to have a lower vitamin A level than omnivores. 
In both studies, vegan participants had lower vitamin A status, but again, this seemed to be clinically irrelevant. With the authors of the Finnish study concluding that none of the vegans could be classified as deficient, and the the authors of the German study reporting that Vitamin A status among vegans was still well within the reference range.
We should be starting to see a pattern here, and this should lead us to question the utility of having higher vitamin A status as a consequence of consuming preformed retinol. Even if we granted that you will boast a higher vitamin A status as an omnivore, it's not clear that possessing a higher status actually has any clinical benefit or advantage. I don't know why it would be desirable. Is Joseph prepared to resign himself to affirming that more is simply better? Shall we coin this the Everett Fallacy?
Claim #8 (07:26):
Vitamin D is pretty much only found in animal foods with some exceptions like some mushrooms and some algae. Some people can get enough vitamin D from the sun, but if you live at latitudes above 37 degrees, your skin barely makes any vitamin D from the sun except for in summer. 
This is one of those times where I won't say anything I will just let his citation speak for itself.
"Lack of sun exposure would be less of a problem if diet provided adequate vitamin D. But there aren't many vitamin D–rich foods (see chart, below), and you need to eat a lot of them to get 800 to 1,000 IU per day...For these and other reasons, a surprising number of Americans — more than 50% of women and men ages 65 and older in North America — are vitamin D–deficient, according to a consensus workshop held in 2006."
His own citation notes that a massive portion of the population is deficient and the treatment for that is sun exposure or supplementation, not goose liver.
Claim #9 (07:40)
A 2016 Finnish study found vegans’ levels of vitamin D to be 34% lower than omnivores. 
They had lower intake and therefore lower levels. According to Joseph's previous reference, they should probably be supplementing more.
Claim #10 (07:52):
Unless you’re eating fermented foods, you’ll only find vitamin K2 in animal foods. The richest sources of K2 are going to be animal livers (especially goose liver), egg-yolks, hard cheese and full-fat dairy. Unfortunately New York City made it illegal for schools to serve whole milk in 2006.  The fermented soybean dish natto does in fact have a ton of K2 and sauerkraut has some too. Vitamin K2 helps put calcium into the right places like your bones and keeps it out of your heart which is thought to be one reason higher vitamin K2 strongly correlated with reduced risk of heart disease. 
Here's a quick intro for vitamin K2. There are many different vitamin K isomers (or vitamers). We have vitamin K1 from plants and vitamin K2, primarily from fermented foods or animal products. There is only one vitamin K1, but vitamin K2 has many forms, including MK4 and MK7, which have been studied most. The form of K2 you can not obtain from fermented foods is MK4, but it doesn't appear to be bioavailable at nutritional doses.
First, we'll look at bioavailability of MK4. He mentions animal livers (especially goose liver), egg-yolks, hard cheese and full-fat dairy. I couldn’t find any study on bioavailability of MK4 from foods rather than supplements. But, we can look at studies with doses one could plausibly obtain from diet alone. In probably the best study on this subject, researchers assessed 420 μg of MK-4 compared to 420 μg of MK-7.  As you can see from this chart, the only reasonable way to obtain this is with goose liver. 
The other things he recommended simply don’t have enough. To get this amount it would take 8.9 kilograms of hard cheese, 52.5 liters of whole milk, or 52.4 average eggs. The amount of goose liver it would take to get this dose of MK-4 is roughly 115g of liver, however this has over 10,000μg of retinol, the upper limit is 3000μg and hypervitaminosis A is no joke.
But regardless, let’s say someone managed to eat this amount of MK-4 regularly. Is it actually absorbed? It wouldn't appear so.
At no time point after the oral administration of 420μg of MK4 is it actually detectable in the blood.
In summary, Joseph suggests food items like hard cheese and whole milk for vitamin K2 when they have abysmal amounts that probably aren't even absorbed. Worth noting that the natto he dismissed contains MK7 which is actually bioavailable, as evidenced by the same reference. Natto also contains it in concentrations over 700 times that of hard cheese, which is the richest source of MK7 out of the foods he listed.
Claim #11 (08:25):
Speaking of all these nutrients for the skeleton, a 2021 polish study found vegan children to have weaker bones and were 3cm shorter than their meat eating counterparts. 
What Joseph didn't mention was that 29% of the vegan children did not consume vitamin B12 supplements or fortified foods, and only 32.7% used vitamin D supplements. Those who did actually consume vitamins B12 and D had comparable B12 and D status to omnivores. It's entirely plausible, if not probable, that this high percentage of non-supplementing participants was enough to drag down the average for the entire group.
I mention this because it's clear that a large chunk of the cohort was not actually supplementing vitamin B12 and vitamin D. Both of which are nutrients that are strongly associated with normal growth. There was also little to no consideration for other dietary variables, and the analysis itself is cross-sectional with extremely small sample-sizes.
Perhaps also worth noting are the similar lean mass, lower fat mass, and preferable LDL-C and hs-CRP values of the vegans. But he didn't mention that.
Claim #12 (08:27):
A British study and a Dutch study also found vegan children to be shorter. 
Let's start with the British study. These results are trivially explainable by the lower caloric intakes for vegans in his reference.
Also, while the vegans tended to fall below the 50th percentile for weight, the vast majority experienced normal growth, and the lower weight (and in some cases height) may be attributable to the lower caloric intake. The authors actually take note of this, but Joseph didn't mention it.
The authors also suggest that the lower fat intake may be the reason they had a lower caloric intake, and go on to state that dense fat sources can be important for children for that reason (eat your avocados, kids). They concluded that children can grow up to be "normal" and that there's no evidence of impairment to cognitive development.
Just as a side note, it's also funny to mention that the vegan diets were more nutrient dense than the average omnivorous UK diet. Even more hilariously, they explicitly state that there are healthy and unhealthy versions of vegan diets and that clowns will run with the occasional case reports on unhealthy vegan kids fed inappropriate diets. These authors were calling out Joseph in 1988.
On to the Dutch study. Firstly, the so-called "vegan" diet was actually a type of meme "vegan" diet called the macrobiotic diet. This diet is highly restrictive and often very low in protein. This is not representative of what a well-balanced "vegan" diet would look like.
Thus far, the studies he cited either haven't supported his claim or provide clear reasons for why there may be differences in growth. With the reasons provided not being intractable characteristics of vegan diets themselves. He also left out the studies where we do see similar growth between vegan and omnivorous kids with adequate diets.
In the Farm Study was a 1989 study involving children ages four months to ten years residing in a community in Tennessee.  75% of mothers were vegan through pregnancy and 73% of children were vegan since birth. These mothers consumed well balanced diets with fortified foods (soy milk and nutritional yeast), which they fortified themselves!
The Farm community was generally well informed regarding issues related to vegetarianism, including complementing different protein sources, for example, grains and legumes and nonanimal sources of vitamins and minerals. Until 1983, the population followed a vegan diet, with soybeans being their primary source of protein. Supplements of vitamins A, D, and B12 were added to the soy milk produced on The Farm. Nutritional yeast (containing vitamin B12) and other vitamin and mineral supplements were also used. In the fall of 1983, some members of the community introduced eggs and dairy products into their diets.
Across vegan children, growth was skirting the 50th percentile on average. This is exactly where these growth trajectories should be.
Same for weight.
We also have the VeChi Diet Study.  Vegan and omnivorous children had similar caloric intakes. Omnivores had the highest protein, fat, and added sugar intake, while vegans had the highest total carb and fibre intake. In fact, the vegans were still able to consume a median of 2.25g of protein per kg bodyweight. While there were a few outliers in each group, growth was generally very similar overall.
There are explanations for the children who may have been stunted or wasted, and they're nothing that is necessarily inherent to vegan diets themselves. These reasons include: short parents, inadequate caloric intake, exclusively breastfeeding longer than recommended (probably due to hippie vegan parents doing dumb hippie things).
Regarding these eight children classified as stunted, two had very low reported energy intakes (534 kcal/day and 598 kcal/day, respectively), and both were exclusively breastfed >6 months (7 and 9 months, respectively). An overly long period of exclusively breastfeeding can result in an insufficient intake of complementary foods and inadequate low TEI because, after a certain age, human milk alone cannot supply energy and all nutrients in adequate amounts to meet a child’s requirements . Furthermore, one of the two children as well as three other children classified as stunted had parents with a BH (mother: 161 cm, father: 170 cm) below the German average (167 cm and 180–181 cm of 25–55-year-old women or men, respectively) that might have influenced the child’s BH. The other child with low energy intake was also categorized as SGA, which is considered a risk factor for stunting . Another stunted child was categorized as SGA, and its birthweight was only slightly above 2500 g (2545 g). The seventh child was exclusively breastfed for twelve months (the eighth child was breastfed for eight months), and it had parents with BHs (mother: 160 cm, father: 178 cm) below the German average.
We also have data on intake of micronutrients and fatty acids in the 1-3 year olds in this cohort.  All diet groups had low iodine intake, and the vegans had the lowest intakes of saturated fat, cholesterol, and DHA (although omnivores had low intakes too), but higher intakes of ALA and LA. They also mention that vegan and vegetarian children had the more favourable intakes of several micronutrients and fatty acids.
In addition to evaluating nutrient intake, they also measured status in 6-18 year olds.  Ultimately, the results are very similar to the those of the VeChi Diet Study that was previously mentioned, with preferable blood lipids in the vegans.
A further study on mothers consuming various dietary patterns supports that a vegan diet can support "normal and physiological growth" through pregnancy and the first year of life. Also of note, 95.2% (20/21) of the vegan mothers took supplements through pregnancy. 
So some of Joseph's own references suggest vegan diets can support growth and development, and that is consistent with other research where vegans are consuming a balanced and appropriately supplemented diet.
Claim #13 (09:34):
Most vegans know they need to supplement B12 which is very important for proper brain function. Yet, one study looking at B12 status in vegetarians and vegans found that 7% of vegetarians and 52% of vegans were not getting enough B12.  However, in another study with a more sensitive testing method - they found a whopping 77% of vegetarians and 92% of vegans had insufficient B12 whereas only 11% of omnivores did.  Perhaps these B12 supplements don’t work exactly like animal foods do. Also it can take years to deplete the body’s B12 store, so people can be lacking B12 for a while without realizing it.
Right off the bat, 81% of vegans did not supplement in the first study. In the second, the authors did not assess how many of them were supplementing, but we know 59% supplemented "B vitamins".
Joseph then concludes (from two studies were the majority did not supplement B12) that B12 supplements "don’t work exactly like animal foods do". If Joseph wanted to know if B12 supplements work at all he could've simply read his previous reference, Elorinne, et al. (2016).  Had he done so, he would have noticed that 91% of that cohort took B12 supplements, and as you'd expect they were not B12 deficient.
If Joseph wanted to know if B12 supplements work differently than animal foods, he could turn his attention to this interventional study that found that fortified cereal was more effective at raising B12 than pork. 
Also, various doses of cheapo, vanilla-ass cyanocobalamin rescue vitamin B12 deficiency in clinically deficient vegans.  This is confirmed by clinically meaningful reductions in both methylmalonic acid and total homocysteine. If Joseph knows of any better biological correlates for B12 absorption and utilization, as well as evidence that they're uniquely affected by animal foods, I'd love to hear from him about it.
Claim #14 (11:38):
...another possibility is the vegan diet has impaired digestion.
The term "digestion" here is so unclear and nebulous, that it is uncertain what exactly to look for in the literature in order to test the hypothesis. However, if we assume that the hypothesis is referring to any symptoms related to digestion, we should expect to see increased rates of digestion-related symptoms, as reported as adverse events, in any of the randomized controlled trials that have been done on so-called "vegan" diets. But we can find close to none, which calls into question whether or not this is even an effect, let alone a generalizable effect.
Claim #15 (12:25):
...many [vegans] do quit the diet because of health issues.
If "many" is meant to be some sort of generalization, then his claim is straightforwardly contradicted by a study discussed in one of his own references on vegan recidivism rates, the 2015 Faunalytics study.
Interestingly, health did not present a noticeable difficulty for study participants, with the exception of vitamin B12 monitoring. 2) Consider increasing awareness about the importance of B12: a far greater percentage of former (76%) than current (42%) vegetarians/vegans never had their B12 levels checked while they were adhering to the diet.
His only evidence for this claim is a montage of ex-vegan YouTubers who already have a demonstrable history of lying to people's faces. What the fuck are we even doing here, Joseph? These people were telling their audiences that they had newfound health on a vegan diet, and now they are once again telling their audiences that they have newfound health, but on a non-vegan diet. Joseph expects us to believe them. I can only guess that's because he is an idiot and doesn't understand what evidence is.
Claim #16 (13:21):
A 2012 study found in 63 patients with constipation, reducing fiber intake improved symptoms but eating a zero fiber diet completely eliminated all symptoms. 
This is a category mistake. Constipation isn't indigestion. Digestion precedes stool formation and colonic transit. Also, there is no mention of vitamin B12 deficiency or its related symptoms among the subjects in the reference Joseph provided. It's not clear how this is interacting with the claim.
I'll briefly entertain the tangent, though. The trial that Joseph references is not easily generalizable, because the subjects had idiopathic constipation. It's also not clear at all what this has to do with "vegan" diets. Additionally the researchers did not actually assess fibre intake. Fibre intake was assumed based on the researchers instructions to the subjects, which naturally is a very poor measurement to fibre intake.
Meanwhile, we see very consistently that increased consumption of fibre associates with a decrease in bowel transit time and improving symptoms of constipation. 
Claim #17 (13:46):
As for B12, you need to have strong enough stomach acid to properly absorb it and dietary fiber is known to weaken the stomach acid. 
For the former claim, there is no reference. But what Joseph is probably referring to here is the requirement for a lower stomach pH in digesting food normally in general. Without a sufficiently acidic stomach acid, it is true that vitamin B12 may not be adequately liberated from a given food matrix.
However, this doesn't apply to supplements (as supplements do not have a food matrix that requires a particularly low pH stomach acid to digest), and therefore doesn't apply to "vegan" diets. Also, we can easily see from previously cited research that vegans can achieve and maintain normal B12 status on high fibre diets.
In fact, you can even absorb B12 adequately and rescue frank B12 deficiency syndromes by shoving it directly up your ass.  Sublingual B12 supplements are effective in rescuing B12 deficiency.  Both of these methods bypass the stomach completely.
Claim #18 (13:56):
So the context matters - what else are you getting with the nutrients? For example, there are plenty of plant sources of iron, but plant foods like whole grains, legumes and nuts contain phytic acid that impairs iron absorption.  Spinach is thought to be a great source of iron but you can only absorb 2% of it because of the oxalate in it. 
Once again, Joseph shows that he either doesn't read the studies he cites or ignores where they contradict him. From the first study:
Iron deficiency anemia appears to be no more prevalent among vegetarian women than among nonvegetarian women...Thus, although several reports indicate that vegetarians in Western societies have lower iron stores and may have lower hemoglobin concentrations, they do not indicate a greater incidence of iron deficiency anemia...Lowering iron stores without increasing the risk of iron deficiency anemia may confer a health advantage when vegetarian diets are chosen from an abundant food supply.
Joseph further shows that he is really good at constructing strawmen. What official public health authority in any developed country actually recommends spinach as a significant source of iron? Regardless, it's also a non-sequitur that just because spinach has a particularly poor bioavailability of iron that there exist no vegan sources of iron with good bioavailability. There even exist other green vegetables with good bioavailability, such as broccoli and cabbage. 
Claim #19 (14:00)
Then, where the heme-iron in animal foods is very easily absorbed, the non heme iron in plants and supplements is quite poorly absorbed. Two different literature reviews suggest that vegans are at greater risk for iron deficiency than omnivores .
No citation was provided for this claim and he says it as if it follows logically from what he said beforehand. Which it doesn't. Phytic acid in isolation impairing iron absorption in some plant foods high in phytic acid having low bioavailability of iron also doesn't imply that iron is poorly absorbed from all plant sources.
Firstly, despite whole wheat flour being higher in phytic acid than white wheat flour, it has better bioavailability of iron.  Granted this is in animal models, but this is evidence Joseph has been known to accept in the past.
Secondly, other compounds that are common in plant foods but are absent (or virtually absent) from animal foods may have pleiotropic effects that mitigate or even overcome the effect of phytates on iron absorption, with vitamin C probably being the most prominent example. In regards of counteracting phytic acid, 50mg (less than an orange worth) does more than 50g of meat. 
It also doesn't follow that one needs to consume animal products to meet iron needs, which Joseph heavily implies. Increased intake through diet and/or supplementation are clearly possible.
First of all, both the literature reviews Joseph cites are looking at vegetarians, not vegans. I thought his video was on so-called "vegan" diets, not vegetarianism. Even the authors of his own references disagree with his interpretation. Here's a quote from Pawlak, et al. (2017):
Findings regarding individuals who adhere to specific vegetarian diet type, such as vegans, were underrepresented and thus, conclusions regarding iron status among such individuals were not possible.
And from another of Joseph's references, Pawlak, et al. (2018):
Considering the limitations, it is reasonable to conclude that the findings are most likely not representative of the entire vegetarian populations nor are they representative of any one specific vegetarian subgroup. 3 of the studies were published in the 1990s and one in 1982. It is reasonable to assume that iron fortification practices have changed since the time of food availability has improved due to globalization. Consequently, this makes the generalization of the findings difficult
So, what is the point in wrongly applying or generalizing these findings with already questionable external validity from vegetarians onto vegans? That being said, just because the studies Joseph cites don't appropriately support his claim does not imply that his claim is wrong. For that, we need to go deeper.
There are three studies that were published before the two reviews that Joseph cited that differentiate between vegans and vegetarians, while also comparing them to omnivores with measurements of plasma ferritin. There are four that were published afterward. It would be valuable to go through them one by one.
In Schüpbach, et al. (2017), omnivores had higher plasma ferritin, but there was a lower percentage of vegans than omnivores in the range of deficiency, while vegans had almost double the iron intake of omnivores. 
The more curious finding with respect to iron was that for omnivores and vegetarians, the correlation between iron intake and plasma ferritin was fairly strong and statistically significant (r = 0.247, p = 0.030; r = 0.331, p = 0.030, respectively), but not so for vegans (r = 0.168, p = 0.281).
The more concerning finding outside of iron was that despite