Need assistance

[DarlBundren]

Hi guys,

Long time no see.

Some days ago I debated veganism with a medical student. Her claims were that 1) There is a special kind of B12 that can only be obtained from animals (according to her this has to do with the fact that B12 turns into something else when it's digested by mammals) and not getting this vitamin can result in cardiovascular diseases. (" supplements only provide the 'weaker' form" 2) Oncological patiens should abstain from eating too many vegetables. Meat apparently is OK 3) she didn't believe that the scientific consensus was that both vegan and vegetarian diets are suitable for people of any age.

I'm not used to debating nutrition and I was especially baffled by her second claim. She promised to send me papers on the matter. In the meantime I told her that I'd prove her that I was right about the scientific consensus. Can you help me? What sources should I cite? I have something in my own language, but I wanted to prove that it is far from being a fringe opinion.

Cheers

[Margaret Hayek]

The best source I know on the scientific consensus is the 2016 literature review and position statement of the Academy of Nutrition and Dietics, the largest dietic organization in North America (and I believe the world), which is by no means a vegan organization and has actually been criticized for being too influenced by animal agriculture:

https://www.ncbi.nlm.nih.gov/pubmed/27886704

Here is the abstract:

It is the position of the Academy of Nutrition and Dietetics that appropriately planned
vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide
health benefits for the prevention and treatment of certain diseases. These diets are
appropriate for all stages of the life cycle, including pregnancy, lactation, infancy,
childhood, adolescence, older adulthood, and for athletes. Plant-based diets are more
environmentally sustainable than diets rich in animal products because they use fewer
natural resources and are associated with much less environmental damage. Vegetarians
and vegans are at reduced risk of certain health conditions, including ischemic
heart disease, type 2 diabetes, hypertension, certain types of cancer, and obesity. Low
intake of saturated fat and high intakes of vegetables, fruits, whole grains, legumes, soy
products, nuts, and seeds (all rich in fiber and phytochemicals) are characteristics of
vegetarian and vegan diets that produce lower total and low-density lipoprotein
cholesterol levels and better serum glucose control. These factors contribute to reduction
of chronic disease. Vegans need reliable sources of vitamin B-12, such as fortified
foods or supplements.
J Acad Nutr Diet. 2016;116:1970-1980.

I seem to be having trouble finding free online versions of the full text; I'll try to PM you the paper.

[carnap]

Some days ago I debated veganism with a medical student. Her claims were that 1) There is a special kind of B12 that can only be obtained from animals (according to her this has to do with the fact that B12 turns into something else when it's digested by mammals) and not getting this vitamin can result in cardiovascular diseases.

Yes, but we are animals and we can synthesize the the forms used by the body form cyanocobalamin (the most common form of B-12 supplement). But there are 4 naturally according forms of B-12 and we can create supplements of all of them so what they are claiming isn't correct. The most common form found in animal products is hydroxocobalamin which is also the form typically found in B-12 shots.

Though its possible that some people have deficits that prevent them from fully utilizing cyanocobalamin. Not sure if that is documented or not.

I'm not used to debating nutrition and I was especially baffled by her second claim.

Claiming "scientific consensus" is difficult, scientists usually don't go around and vote on various topics. So on this I think she is right, its by no means clear what the "scientific consensus" is on vegan diets. Though at least from what I've experienced the medical community is rather skeptical of vegan diets but that shouldn't be mistaken as representative of the scientific community.

The best source I know on the scientific consensus is the 2016 literature review and position statement of the Academy of Nutrition and Dietics,

Academic of Nutrition and Dietetics isn't a scientific group but instead a trade group representing the trade of Dietetics in the United States. Their position paper by no means represents a scientific consensus; it was authored by a few people and voted on by a small panel of Academy members. The paper wasn't reviewed by the scientific community. I don't think it helps that almost all the authors and reviewers were vegan/vegetarian.

[DarlBundren]

Thanks everyone for your reply.

Yes, but we are animals and we can synthesize the the forms used by the body form cyanocobalamin (the most common form of B-12 supplement).

I'm still waiting for her reply on this, but that day she told me that it's not the same. Her claim was that this particular form of B12 had to be already digested by a mammal in order to be as effective as she claimed it was.

But there are 4 naturally according forms of B-12 and we can create supplements of all of them so what they are claiming isn't correct. The most common form found in animal products is hydroxocobalamin which is also the form typically found in B-12 shots.

So, If I understand you correctly, "hydroxocobalamin" is the form to which she was referring. Is it only found in B-12 shots? Are there any real advantages in getting this kind of B-12 over common cyanocobalamin?

Academic of Nutrition and Dietetics isn't a scientific group but instead a trade group representing the trade of Dietetics in the United States

Thanks for the clarification. If you go to pubmed and take a look at that abstract you can find a similar paper by the "Dieticians of Canada". What do you think of it? The Autralian dietary guidilines seem to see vegetarianism favourably too.

[carnap]

So, If I understand you correctly, "hydroxocobalamin" is the form to which she was referring. Is it only found in B-12 shots? Are there any real advantages in getting this kind of B-12 over common cyanocobalamin?

I'm not sure what she has in mind but hydroxocobalamin is the most common form in meat but adenosylcobalamin also is found in animal products. And as far as humans go, the active forms of the vitamin are methylcobalamin and adenosylcobalamin both of which you can supplement with.

The only benefit to supplementing with natural forms of B-12 instead of cyanocobalamin is that they are more directly metabolized but they are also less stable as supplements and don't appear to be absorbed as well as supplements. There may be some people that don't metabolize cyanocobalamin but generally people are able to convert it into methylcobalamin and adenosylcobalamin.

But regardless of what form of B-12 she has in mind her claim is wrong, you can create supplements of both of the forms of B-12 that the human body utilizes.

Thanks for the clarification. If you go to pubmed and take a look at that abstract you can find a similar paper by the "Dieticians of Canada". What do you think of it? The Autralian dietary guidilines seem to see vegetarianism favourably too.

Yes, there are other trade groups with similar views but that doesn't tell us much about the "scientific consensus". Not only are these Dietetics groups not scientific organizations but they represent a very similar block of people (the world's scientists aren't isolated to English speaking nations).

When you look beyond English speaking nations the view of vegan diets tends to be more negative. For example, neither the German nor Swiss counter party to the English speaking organizations claim that vegan diets are appropriate for "all stages of life" and instead note the lack of research in the cases of pregnancy and child development. In contrast the Academy of Nutrition claims its appropriate for "all stages of life" but the paper fails to provide any compelling evidence in the case of pregnancy and children (if you haven't, I'd suggest you read the entire paper and not just the abstract).

[brimstoneSalad]

1) There is a special kind of B12 that can only be obtained from animals (according to her this has to do with the fact that B12 turns into something else when it's digested by mammals) and not getting this vitamin can result in cardiovascular diseases. (" supplements only provide the 'weaker' form"

Maybe she means only "naturally" obtained from animals. E.g. that spirulina has pseudo-b12 forms.
But that's not where most vegans are getting their B-12, we get it from supplements... so that's a terrible argument.

Like carnap said, all of these forms ARE available as supplements. However, there's little to no evidence that anybody needs forms other than cyanocobalamin.

There are reports of people getting deficient while eating large amounts of meat, too, so animal products are no guarantee if you have digestive or absorption issues. In fact, in those cases a supplement is probably better since it is capable of providing much larger doses.

There are also transdermal options, although I'm unsure how well studied they are. Those would overcome any digestive issues.

2) Oncological patiens should abstain from eating too many vegetables. Meat apparently is OK

Vegetables tend to be low in calories and can promote weight loss, which is something you don't want in cancer patients.
That's a kind of asinine argument against veganism, though, I don't know what her point was. A high vegetable diet is more helpful for prevention of cancer than treatment, although for some cancers a low methionine diet may help which would probably be mostly vegan since most animal products are high in it (Obviously, talk to your oncologist). Not all vegan diets are low methionine though, and not all are low calorie. No reason people with cancer shouldn't eat a well planned vegan diet to suit their needs.

3) she didn't believe that the scientific consensus was that both vegan and vegetarian diets are suitable for people of any age.

It's about well planned vegan diets, and that has to do with the fact that:

1. People need nutrients, not particular sources of nutrients.
2. Those nutrients are all available from non-meat sources.
3. A well planned & B12 supplemented vegan diet can contain all needed nutrients, and be modified or augmented with supplements for people who have specific problems (like those who have higher iron needs).

There are fair questions to ask as to whether most vegan advocacy really promotes well planned vegan diets (there is a bad trend of high carb diet advice being promoted which may be harmful), but it's unreasonable at this point to suspect that there are magical nutrients people need that only come from meat and that we just haven't discovered yet despite evidence from use of lab produced diets, TPN etc.

This is a work in progress, but there's some good information on there about why it's inappropriate to cherry pick the DGE, etc.
wiki/index.php/Adequate_Nutrition

[Margaret Hayek]

Academic of Nutrition and Dietetics isn't a scientific group but instead a trade group representing the trade of Dietetics in the United States. Their position paper by no means represents a scientific consensus; it was authored by a few people and voted on by a small panel of Academy members. The paper wasn't reviewed by the scientific community. I don't think it helps that almost all the authors and reviewers were vegan/vegetarian.

From where are you getting your information on this?

(1) The paper was published in the Journal of the JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS, which is a peer reviewed journal, and the paper lists a set of reviewers. What is your evidence that the paper was not reviewed by a standard reputable peer review process? (Note by the way that the paper is a literature review in support of its conclusions; it is not a bare assertion of a position.)

(2) What is your evidence that "almost all the authors and reviewers were vegan / vegetarian"

(3) What is the basis of your assessment that the paper does not present sufficient evidence of the nutritional adequacy of well planned vegan diets with adequate supplementation during pregnancy and childhood? I am pasting what the paper actually says about this below.

(4) What is your evidence that the current position statements of certain continental European countries say different things?


Here is what the paper says about pregnancy and children:

"Pregnant and Lactating Women
Limited research indicates that where food access is adequate, vegetarian pregnancy outcomes, such as birth weight and pregnancy duration, are similar to those in nonvegetarian pregnancy.7,86,87 Use of a vegetarian diet in the first trimester resulted in lower risk of excessive gestational weight gain in one study.88 Maternal diets high in plant foods may reduce the risk of complications of pregnancy, such as gestational diabetes.88,89 The Academy of Nutrition and Dietetics’ position and practice papers on “Nutrition and Lifestyle for a Healthy Pregnancy Outcome”90,91 provide appropriate guidance for pregnant vegetarians. Special consideration is required for iron, zinc, vitamin B-12, and EPA/DHA.87,89 Depending on dietary choices, pregnant vegetarians may have higher iron intakes than nonvegetarians and are more likely to use iron supplements.92 Because of the potential for inadequate intakes and the adverse effects of iron deficiency, a low-dose (30 mg) iron supplement is recommended in pregnancy.93 The recommended amount of iron could be provided via a prenatal supplement, a separate iron supplement, or a combination of these.
There is insufficient evidence that zinc intake and status in vegetarian pregnancies differ from nonvegetarian pregnancies.87,89 Due to the increased zinc requirements of pregnancy and the lower bioavailability in diets based on high-phytate grains and legumes, increasing zinc intake and using food preparation techniques that improve bioavailability are recommended.7,8,29 Pregnant and lactating vegetarians need regular and adequate dietary and/ or supplemental sources of vitamin B-12.7,8,89,91 Infants of vegetarian women have lower plasma DHA concentrations and
breast milk of vegetarians is lower in DHA.7,8 These n-3 fatty acids can be synthesized to some extent from a-linolenic acid, but conversion rates
are low (though somewhat enhanced in pregnancy).8,89 Pregnant and lactating vegetarians may benefit from direct sources of EPA and DHA derived
from microalgae.8,91

Infants, Children, and Adolescents
Exclusive breastfeeding is recommended for the first 6 months.94 If breastfeeding is not possible, commercial infant formula should be used as
the primary beverage for the first year. Complementary foods should be rich in energy, protein, iron, and zinc, and may include hummus, tofu, well-cooked legumes, and mashed avocado.8 Full fat, fortified soy milk, or dairy milk can be started as early as 1 year of age for toddlers who are growing normally and eating a variety of foods.95 Vegetarian children and teens are at lower risk than their nonvegetarian peers for overweight and obesity. Children and adolescents with BMI values in the normal range are more likely to also be within the normal range as adults, resulting in significant disease risk reduction.96 Other benefits of a vegetarian diet in childhood and adolescence include greater consumption of fruits and vegetables, fewer sweets and salty snacks, and lower intakes of total and saturated fat.97 Consuming balanced vegetarian diets early in life
can establish healthful lifelong habits.8 The peak age of onset for the most common eating disorders is in the adolescent years. Eating disorders have a complex etiology and prior use of a vegetarian or vegan diet does not appear to increase the risk of an eating disorder, though some with preexisting disordered eating may choose these diets to aid in their limitation of food intake.7,8 Nutrients that may require attention in the planning of nutritionally adequate diets for young vegetarians include iron, zinc, vitamin B-12, and for some, calcium and vitamin D. Mean protein intakes of vegetarian children generally meet or exceed recommendations.7 Protein needs of vegan children may be slightly higher than those of nonvegan children because of differences in protein digestibility and amino acid composition.7 Recommendations of 30% to 35% more protein for 1- to 2-year-old vegans, 20% to 30% more for 2 to 6 year olds, and 15% to 20% more for children older than 6years have been suggested.7,95 While
dietary factors may limit absorption of iron and zinc, deficiencies of these minerals are uncommon in vegetarian children in industrialized countries.98 Iron and zinc status of children on very restricted plant-based diets should be monitored. Supplemental iron and zinc may be needed in such cases.98 Vitamin B-12 intake of vegan infants and children should be assessed and fortified foods and/or supplements used as needed to insure adequacy.7

Full set of references
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[brimstoneSalad]

Some more specific references courtesy of Avi which are useful in understanding consensus on the adequacy of properly planned vegan diets, and how it wasn't pulled out of the air:

https://obgyn.onlinelibrary.wiley.com/d ... 0528.13280

...The lack of randomised studies prevents us from distinguishing the effects of diet from confounding factors. Within these limits, vegan–vegetarian diets may be considered safe in pregnancy, provided that attention is paid to vitamin and trace element requirements.

https://academic.oup.com/ajcn/article-a ... 22/4716540

...Most parents were aware of the need to supplement the diet with vitamin B-12. It is concluded that provided sufficient care is taken, a vegan diet can support normal growth and development.

https://www.ncbi.nlm.nih.gov/pubmed/7288184

...Their diets, however, were generally adequate but a few children had low intakes of riboflavin and vitamin B12. It is concluded that, provided sufficient care is taken, a vegan diet can meet the nutritional requirements of the preschool child.

As to the unfounded anti-vegan assertions of some kind of survivorship bias passing on special vegan genes to these kids, Avi had this to say which was really a great response:

Well that would just be an unsubstantiated assertion. I can do the same thing the other way around, watch: even though the vegan pregnancy and children results were normal, this actually means that veganism is super healthy and better than normal because the sample is biased with people who have bad genes and are only sticking to veganism because veganism is such a great diet it's the only diet to keep them normal and alive.

Bias can go either way. If he wants to make the case that the results are biased in favor of veganism and not against veganism, the burden of proof is on him. Until then the appropriate conclusion is agnosticism. His assertions are just speculations and any vegan can speculate in favor of veganism the same exact way.

[carnap]

From where are you getting your information on this?

From them, they are the organization that regulates and certifies who can call themselves a "dietitian" in the United States which would make them a trade group by definition. They aren't a scientific organization, that is, they aren't in the business of conducting research and the vast majority of their members are dietitians and not researchers.

(1) The paper was published in the Journal of the JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS, which is a peer reviewed journal, and the paper lists a set of reviewers.

Right, that is their journal that they run which is used to position their various positions and commentary. That is much different than an independent science journal.

(2) What is your evidence that "almost all the authors and reviewers were vegan / vegetarian"

Simply look up their names. There are three authors:

https://en.wikipedia.org/wiki/Vesanto_Melina
https://www.amazon.com/Nutrition-Wellne ... B0006RG71I
https://www.forksoverknives.com/contrib ... gs.u=_ymU0

Not only are all three authors vegan/vegetarian, but they have careers created around promoting vegetarian diets. Now that doesn't mean, in itself, that the position paper is wrong but it does create an environment for bias. Even the vast majority of the reviewers for the position were vegetarian (again, just look them up). Why didn't the Academy have the article written and reviewed by a more diverse group?

(3) What is the basis of your assessment that the paper does not present sufficient evidence of the nutritional adequacy of well planned vegan diets with adequate supplementation during pregnancy and childhood?

That they fail to cite research that supports what they claim. I'll give an example below.

Limited research indicates that where food access is adequate, vegetarian pregnancy outcomes, such as birth weight and pregnancy duration, are similar to those in nonvegetarian pregnancy.7,86,87

Let's look at this specific example in detail. Firstly note the language, they note themselves that the research is "limited" yet are making widespread dietary recommendations on them. That is the first red-flag. How about the citations? Let's look at them.

7. Mangels R, Messina V, Messina M. The Dietitian’s Guide to Vegetarian Diets. 3rd ed. Sudbury, MA: Jones and Bartlett; 2011.

This appears to be a case of someone citing themselves as evidence. This is a book used to instruct dietitians about vegetarian diets and is co-authored by one of the authors of the position paper. There is no indication what specifically in the book they are referring (no page reference) to and if it was a study why didn't 'they cite the study directly? So there is no way to evaluate this citation.

86. Evidence Analysis Library. Pregnancy and nutrition-vegetarian nutrition. 2007. http://andevidencelibrary.com/ topic.cfm?cat¼4322. Accessed June 23, 2016.

This isn't a study but instead an analysis by the academy but its behind a pay-wall so I cannot evaluate it. But again I wonder why primary research wasn't cited but instead another review.

87. Piccoli GB, Clari R, Vigotti FN, et al. Vegan-vegetarian diets in pregnancy: Danger or panacea? A systematic narrative review. BJOG. 2015;122(5):

This also isn't a study but a literature review. This is the conclusion of the author:

"The evidence on vegan-vegetarian diets in pregnancy is heterogeneous and scant. The lack of randomised studies prevents us from distinguishing the effects of diet from confounding factors. Within these limits, vegan-vegetarian diets may be considered safe in pregnancy, provided that attention is paid to vitamin and trace element requirement"

This review was recent (2015) yet the authors found that the "evidence on vegan-vegetarian diets in pregnancy is heterogeneous and scant". There doesn't seem to be anything cited specifically for vegan diets either.

So as I claimed, the Academy's position in the case of children and pregnancy aren't well supported by the evidence. The idea of the paper seems to be that because there is currently no evidence of harm then that means that the diets "may be considered safe" but that is a tremendously weak argument when the research is "heterogeneous and scant".

[carnap]

It's about well planned vegan diets, and that has to do with the fact that:

1. People need nutrients, not particular sources of nutrients.
2. Those nutrients are all available from non-meat sources.
3. A well planned & B12 supplemented vegan diet can contain all needed nutrients, and be modified or augmented with supplements for people who have specific problems (like those who have higher iron needs).

This argument fails on a few points:

#1. In the abstract people just need nutrients, but we are biological systems and specific nutrients don't magically go from our month into our body. The source of the nutrients is important on a number of fronts, for example:

i.) The source of the nutrient can impact how the nutrient is absorbed
ii.) Nutrients come packaged with other other compounds and those compounds can have positive and/or negative impacts on human health.
iii.) Source can determine the form of nutrient present, for example, supplements are often made with synthetic versions of nutrients because
the natural form isn't stable outside of food. The synthetic versions typically have different metabolic pathways and as a result can have
differential health outcomes.

#2. The form of nutrients in plants and meat are often different and, as above, how the nutrients are packaged impacts how they are utilized. And while its true that all essential nutrients (other than B-12) are found in plants there is question about whether everyone can adequately synthesis the down-stream compounds from their plant-based precursors. For example, the case of synthesis rates of long-chain omega-3 fatty acids (e.g., DHA) from the short-chain versions contained in plants (ALA).


Now its certainly possible ( and I like very plausible) that with the appropriate knowledge you could craft individualized vegan diets that work for nearly everyone but we don't have that knowledge yet. Currently vegan diets are based on very general guidelines that may or may not be appropriate for most people. But many people report issues with vegan diets and there has been little done to understand the nature of those problems. There are also many people that report that they are doing well on vegan diets.