Friday, August 11, 2006

Vegan Diet - Part Deux; Still Wrong for Diabetes

On the heels of the recently published findings from Dr. Dean Ornish in July, we have another study claiming a vegan diet is better for those with diabetes than the diet recommended by the American Diabetes Association (ADA). This one, A Low-Fat Vegan Diet Improves Glycemic Control and Cardiovascular Risk Factors in a Randomized Clinical Trial in Individuals, was published this month in Diabetes Care.

Yesterday, the findings were highlighted in MedPage Today with the following statement as part of the "action points" for healthcare professionals:

Explain to patients with type 2 diabetes and their families that this study shows that both an ADA diet and a low fat vegan diet can significantly improve glycemic control, reduce the risk for cardiovascular and other risk factors, and prevent or delay the need for insulin injections. Further, this study suggests that the vegan diet may produce better results than the ADA diet.
It's disturbing to read such garbage, especially when you know it's targeting healthcare providers who are going to communicate this bunk to their patients!

Nowhere in the article do you read about the fact that among all participants, regardless of dietary intervention, they remained obese, with fasting blood sugars above the diabetic threshold, with HbA1C levels remaining above the ADA's 7% or lower target, and they experienced a decline in HDL levels while triglycerides remained elevated above the target of less than 100mg/dL for those with diabetes.

There is also no mention that the researchers didn't see fit to publish data showing effect of either diet on fasting insulin or post-prandial insulin; or post-prandial blood glucose. The researchers also failed to provide data separately for men and women for HDL, even though, for HDL levels, the targets are different.

To promote the vegan diet as "better" for those with diabetes is misleading as neither diet achieved the target of what is considered the critical marker for glycemic control over time - HbA1c. The target for those with diabetes is to reduce to and maintain their HbA1c at or below 7%. Anything above that level is considered poor glycemic control.

On its Medline site, the National Institutes of Health (NIH) states "If the HbA1c value is above 7%, it means your diabetes is poorly controlled."

Poorly Controlled!

Yet here we have findings where HbA1c persisted above 7% being touted as a better option for those with diabetes.

Those following the ADA diet for 22-weeks had HbA1c levels of 7.4%; those following the Vegan diet had HbA1c levels of 7.1%.

Even though both groups did have improvement from baseline, both groups remained above the level established to indicate good glycemic control after 22-weeks of compliance with both dietary interventions!

If the goal is to reduce the risk of complications from diabetes, then we must be sure we are promoting only those interventions shown to specifically make significant improvements and stop with this "hey, this is better than that" when neither are in fact helping those with diabetes reach the targets established to reduce the long-term risks from complications of poor glycemic control.

To say the Vegan diet was better is to consider less than acceptable results as better than less than acceptable results.

Neither diet acheived the 7% or less target for HbA1c!

So then, we need to know - are there any studies, of similar duration that indicate there may be a more effective dietary approach to achieving the risk marker targets for those with diabetes?

We find in the literature another dietary intervention study, of much longer length (22-months duration) that DID show significant improvements in those with diabetes; and resulted in better improvements when compared with this study in both the Vegan Group and the ADA Group.

Yes, there really is a study out there, that was longer than this one, that not only found greater improvements when followed; but achieved the ADA target of less than 7% for HbA1c!

In the study above, after the 22-weeks of dietary compliance, all participants in the Vegan Group had an average HbA1c of 7.1%; all participants in the ADA Group had an average HbA1c of 7.4%.

Compare that with the study from Sweden following a low-carb diet (20% of calories from carbohydrates) for 22-months - their HbA1c averaged 6.9%.

They achieved an HbA1c below the target of 7% when sticking with the diet.

Of particular interest is the results from those participating who originally followed the low-fat diet for the first six months of the study. After seeing the results for those following the low-carb diet they abandon the low-fat diet and started following the low-carb diet. At the 22-month mark, their HbA1c averaged 5.7%!

Oh, and did I mention the low-carb dieters (both those who followed it continuously for 22-months or jumped on it after six months) didn't have intensive counseling or support to maintain compliance.

As I wrote in my June 17th column, ADA Acknowledges Low-Carb Diets Help Control Blood Sugar, when results are contrary to the accepted dogma, we find those who communicate recommendations are "purposely avoiding evidence-based medicine standards."

In their presentation of this study and their actions points to healthcare professionals, MedPage Today failed the basic rules of evidence-based medicine. As I've said before, "Those with type II diabetes, those with pre-diabetes, and those at risk for developing insulin resistance which will lead to diabetes must be given all the facts so they can make a decision based on the full data available - anything less fails the standard of informed consent."

Search MedPage Today for news, information, a teaching brief or CME spotlight and the 22-month low-carbohydrate trial. Go ahead, I'll wait.

Yup, nothing. Nada, zip, zilch.

Now try the American Diabetes Association - search for anything related to the 22-month low-carbohydrate diet trial. Go ahead, I'll wait.

Again, nothing. Nada, zip, zilch.

Yet, here we have the media jumping on this study comparing a Vegan diet to the ADA diet, with unimpressive results after 22-weeks. We find MedPage Today touting the Vegan diet as "better"; Medical News Today reporting "low-fat vegan diet treats type 2 diabetes more effectively than a standard diabetes diet..."; and The Australian proclaiming "a low-fat vegan diet is the most effective treatment for type 2 diabetes - better than the current recommended diet..."

What's disturbing here isn't just the lack of enthusiasm after the publication of the findings from the low-carbohydrate diet trial; it's also troubling that both journalists and medical information sites are publishing articles that are out-of-synch with the published data in this new trial and seem intent on promoting a dietary approach that was not able to bring HbA1c to 7% or less!

Add to that the problematic decline in HDL with a persistent elevation of triglycerides.

What we have here is a widespread habit of dismissing incovenient data; disregarding facts; and simply ignoring compelling findings to maintain the status quo. The numbers in the study comparing a Vegan diet to the ADA diet are accurate and reflect how the dietary interventions effected those with type II diabetes.

The correct definition of "success" - reaching established targets - however leaves little to be desired with either the vegan 0r ADA diet since neither resulted in improvement to or below targets; thus this renders the findings meanlingless as a long-term dietary appraoch to improve glycemic control to the established target of an HbA1c of 7% or less.

Just don't expect the establishment to admit it is continuing to fail patients because they won't even consider the efficacy of a low-carbohydrate diet.

5 comments:

  1. Thank you so much for your comprehensive analysis of the evidence!
    -Bella and Blessing at
    http://360.yahoo.com/roseanchorage

    ReplyDelete
  2. Hi!

    My name is Brad and I run the blog "Fast Weight loss" located here:

    http://fast-weightloss.blogspot.com/

    I recently found your site http://weightoftheevidence.blogspot.com/ and am very interested in exchanging links. Let me know if you are interested in trading links with me.



    Thank you very much!






    Cheers
    Brad
    http://fast-weightloss.blogspot.com

    ReplyDelete
  3. I just wanted to say AWESOME JOB! I cannot wait to forward your report back to every knucklehead "high carb killer" trying to get poeple to follow this vegan diet! Without even looking into the evidence.

    tntpop

    ReplyDelete
  4. This comment has been removed by a blog administrator.

    ReplyDelete
  5. Refer to Diabetes for
    useful information

    ReplyDelete