question re: a presentation by Dr. Barnard

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question re: a presentation by Dr. Barnard

Postby Birdy » Thu Jun 20, 2019 8:52 pm

Hi Jeff,
Here is a link to a presentation given by Dr. Neal Barnard published on YouTube in December, 2018:
https://www.youtube.com/watch?v=lSwL73evUdA

At about minute 14:30 he shows a graph of results for a vegan group and a control group in a clinical trial conducted on diabetics and dietary interventions. In the first graph, the results at 22 weeks are shown indicating a statistically significant decrease in A1C in the vegan group, with much less improvement in the control group that was following the ADA dietary recommendations for diabetics. My question concerns the second graph at about minute 15:10 that shows results after a one-year follow up period. The control group had returned to baseline A1C levels. The vegan group returned to within an A1C that was only 0.42 below baseline. At no time were either group below the threshold for reversal of their diabetes. Since I have T2DM, I've followed Dr. Barnard's work, yet I'd never seen the data of the one-year follow up until now. My question is, how can a very low fat, plant based diet be touted as able to reverse diabetes when clearly this study did not show that? I know that you aren't involved in that study and so can't speak specifically about it, but can you make general comments about this topic? Thank you.
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Re: question re: a presentation by Dr. Barnard

Postby JeffN » Thu Jun 20, 2019 10:45 pm

the study sounded very familiar and I checked my files and not only had it but also had a discussion with Dr Barnard about it back when it came out

Here is a link to the full text.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2677007/

Before I respond, I would be interested in any further comments you may have after reading the full text

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Re: question re: a presentation by Dr. Barnard

Postby Birdy » Sat Jun 22, 2019 1:11 pm

Jeff,
I got a chance to read the study. Thank you for the link.

I'm a lay person with a master's degree in a field that trained me to interpret research papers using basic understanding. However, I'm not trained in statistical analysis. That said, after reading the study twice, these are my observations:

The vegan diet group adhered to not only a vegan diet, but one that recommended very low-fat intake (no animal foods, no added oils, no avocado, nuts, seeds, coconut), a low glycemic diet, and minimal added sugars. The control group followed the American Diabetes Association (ADA) dietary recommendations. Both groups reduced energy intake. The study duration was a 22 week intervention period, followed by 52 weeks of follow up, to total a 74 week study.

At 74 weeks the following results were reported:


Weight loss was not significantly different between the two groups (only a 3 pound difference).

A1C in the vegan group = -0.34 (+ or - 0.19) and in the ADA group -0.14 (= or -) 0.17

Fasting plasma glucose changed by -19.5 in the vegan group and -14.0 in the ADA group

The largest effects were reductions in cholesterol measures among the vegan group = -20.4 as compared to the ADA group -6.8

C-reactive protein (a marker for inflammation) was reduced most in the ADA group.

At 74 weeks, the adherence rate = 51% in the vegan group and 48% in the ADA group.

So my question remains as to why this study is cited as showing reversal of type 2 diabetes when clearly neither group showed A1C values below the threshold for a diagnosis of diabetes and, after 72 weeks, both groups were essentially back to baseline A1C values. It would seem that what the study most strongly showed was a reduction in cholesterol among the people in the vegan group. It puzzles me that Dr. Barnard, who was the principal researcher involved in this study, wrote a book based on this study titled Reversing Diabetes.

I appreciate you taking the time to post your thoughts.
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Re: question re: a presentation by Dr. Barnard

Postby Birdy » Mon Jun 24, 2019 1:49 pm

Edit to my post on 6/22/19: A1C in the vegan group = -0.34 (+ or - 0.19) and in the ADA group -0.14 (= or -) 0.17

This should say " A1C changed in the vegan group....etc."
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Re: question re: a presentation by Dr. Barnard

Postby JeffN » Mon Jun 24, 2019 2:28 pm

I agree with you.

While there are no standard definitions of reversal yet (yes, even this is controversial), one should at least have numbers which have improved and are now good to excellent numbers. And in regard to blood sugars, that would be an A1c 5.6 or less, or at least under 6. After all, treatment goals are under 7. And a blood sugar under 100, if not at least under 126 (pre diabetes)

A few other points

- I am always concerned when a study attributes its benefit to a vegan diet without being very specific in regard to what about the vegan diet made the difference. Just eliminating animal products is not enough.

- Those on the vegan diet averaged 36 mg of cholesterol per 1000 calories, or about 50 mg/day so the diet wasn't even vegan. Even their definition of dietary adherence to the vegan group allowed the vegan group to not be vegan.

"For statistical purposes, dietary adherence for the vegan group was defined by 3 criteria: 1) the absence of meat, poultry, fish, dairy, or egg intake in any 24-h recalls, 3-d dietary records, or incidentally at any point; 2) saturated fat ≤5% and total fat ≤25% of energy on 3-d dietary records at 22 and 74 wk; and 3) mean daily cholesterol intake ≤50 mg on 3-d dietary records at 22 and 74 wk. Adherence for the conventional diet group was defined, based on the 22- and 74-wk 3-d dietary records, as 1) mean daily energy intake ≤200 kcal in excess of the prescribed intake and 2) saturated fat ≤10% of energy. Individuals who attended <10 of the first 22 weekly sessions were also considered nonadherent on either diet. These adherence criteria were used for descriptive purposes (not for participant teaching) and were not used in the primary outcome analysis."

When defining the details of a vegan diet to someone, do you allow for the intake of cholesterol? If so, where do they think the allowed cholesterol would come from? And, consider that, only 67% in the “vegan” group meet the “vegan” adherence criteria at 22 weeks and only 51% at 74 weeks.

- Both diets dropped caloric intake about 420 cal/day which is a 24% drop and both groups lost weight with the vegan group losing a little more.

- The vegan group doubled their intake of fruits and veggies.

Now, when I first saw this study and read through, I said, it is clear the "vegan" group ate less calories, much less fat, much more fiber and much more fruits and vegetables. This means they also lowered the energy density of their diet too (less fat, more low density foods). All of these are very good things. These are all the reasons they did somewhat better and would be expected, vegan or not.

In the discussion, this gets one sentence

"Much of the effect of the intervention diets on glycemia appears to be mediated by weight reduction. However, the 2 diets appear to have altered energy intake by different mechanisms. Although overweight individuals in the conventional diet group were prescribed an explicit energy deficit, a low-fat vegan diet typically elicits significant weight loss in the absence of prescribed energy intake limits (2). This is likely because reduced dietary fat and increased dietary fiber reduce dietary energy density (15, 16)."

Yet the conclusion makes no mention of these things and instead states....

"In conclusion, in individuals with type 2 diabetes participating in a research study, both a low-fat vegan diet and a diet based on 2003 ADA guidelines facilitated long-term weight reduction. In analyses controlling for medication changes, the vegan diet appeared to be more effective for control of glycemia and plasma lipid concentrations. Whether the observed differences provide clinical benefit for the macro- or microvascular complications of diabetes remains to be established."

So, the Vegan Diet was not very effective (as those who often refer to this study claim), and not very vegan either.

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Re: question re: a presentation by Dr. Barnard

Postby Birdy » Mon Jun 24, 2019 7:05 pm

Thanks a lot Jeff for your reply. That will give me something to think about for a while. I didn't pick up at all on the points you made about cholesterol or the vegan diet "not being very vegan". Go figure.
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