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Specific guide to this web site for:


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      Educators 
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 2.  Medical Students

 3.  Science media writers

 4.  High School & College
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   Misadventures:


1. Harvard led MI study

2. JACC study 

   (J. of Amer. Coll.
   Cardio.)


3. NEJM cath study

4. Amer. J. of Cardio.
    review of literature

5.
ALLHAT
    controversy
 

6.
Oat bran study

7.
Pregnancy & Alcohol

8.
Are Geminis really
   
different?
      
9. Columbia 'Miracle' Study  
                                                 

Additional Topics:

Celebrex

Limitations of Meta-Analyses

Large Randomized Clinical Trials

Tale of Two Large
Trials

Advocate meta-analyses

Network meta-analyses






 

 

 

 

The Death of the oat bran fad. 
(Murdered by a poorly conceived study.)    
download pdf format

Problems with the study which incorrectly concluded that oat bran did not significantly lower cholesterol:

On closer examination, The New England Journal of Medicine article1 was a seriously flawed study.

1.  The primary problem with this study is that there were insufficient numbers of participants to exclude a cholesterol lowering effect. There were only 20 participants. To prove an effect is not present, a large number of participants need to be studied.  A trial demonstrating a positive effect generally requires fewer participants than a trial trying to reliably prove that no difference exists.

2. Cholesterol lowering drug interventions tend to have a lesser effect on patients who have a very low cholesterol intake  and start out with low cholesterol levels. The individuals in this trial had a low dietary intake of fat and cholesterol compared to the rest of the U.S. population.    The baseline cholesterol and LDL cholesterol levels of the subjects of this study were low. Many of the participants for this trial were dieticians who followed a low fat diet quite different from the average diet of an older individual at high risk for heart disease. 

1. Swain JF, Rouse,IL, Curley CB, Sacks FM.  Comparison of the effects of oat bran and low-fiber wheat on serum lipoprotein levels and blood pressure. N Engl J Med 1990; 322:147-52

The oat bran fad passed with the  publication of a flawed study:

There was an article1 in the medical literature which received wide media attention that effectively killed the oat bran craze. Years back, many people were making and eating oat bran muffins to lower cholesterol.  details  The fad aspect of oat bran ended when  an article was published claiming to indicate that oat bran (high fiber vs. low fiber) did not significantly lower cholesterol.  This article was a significantly flawed study. (see right column)

See right column for details of problems in this study.
 
Letters written pointing out the flaws in this study:

Subsequent letters to The New England Journal of Medicine (NEJM)  (citations) noted the inadequacy of the study. A letter2 by the Robenoubonoffs, M.D. and R.D. suggests, “The authors have managed to confuse the American public further with a poorly designed and underpowered  trial that draws erroneous conclusions.”  A letter3 by James Burrous, M.D. published in the same issue of The New England Journal of Medicine asked, “What does a small … study of dietitians with desirable cholesterol levels … tell us about the population of the American public at risk?"

A later different study documents the cholesterol lowering effect of oat bran:

A subsequent study4 was performed on 84 middle aged men and women who were placed on metabolic diets comparing oat bran to wheat bran. This study showed a statistically significant 5% reduction in total cholesterol for oat bran beyond what was found for wheat bran.  details

Multiple studies were later combined and analyzed to further assess the effects of oat bran on cholesterol:

There were at least two subsequent meta-analyses  (analyses combining multiple other studies).

    One meta-analysis5 concluded that oat bran modestly reduced cholesterol. details

    A second meta-analysis6, this one written by the senior author of the initial flawed oat bran study, illustrates how the conclusions of a meta-analysis can be slanted.
   
This meta-analysis presented the conclusions of the meta-analysis in a way as consistent as possible with the initial suboptimal study.  details.

1. Swain JF, Rouse,IL, Curley CB, Sacks FM.  Comparison of the effects of oat bran and low-fiber wheat on serum lipoprotein levels and blood pressure. N Engl J Med 1990; 322:147-52

2. Roubenoff RA, Roubenoff R. Letter to the Editor, Oat Bran and Serum Cholesterol.  New England Journal of Medicine 1990; 320:1746-47.

3. Burris, J. Letter to the Editor, Oat Bran and Serum Cholesterol. New England Journal of Medicine 1990; 320:1746-47.

4. Wheat-bran and oat-bran supplements' effects on blood lipids and lipoproteins.  Kashtan H, Stern H, Jenkins D, Jenkins A, Hay K, Marcon N, Minkin S, Bruce WR. Am J Clin Nutr 1992;55:976-80.

5. Oat Products and Lipid Lowering. A Meta-analysis. Ripsin CM, Keenan J, Van Horn L, et al. JAMA 1992; 267:3317-25.

6. Brown L, Rosner B, Lillett W, Sacks F. Cholesterol-lowering effects of dietary fiber: a meta-analysis. Am. J. Clin. Nutr. 1999; 69:30-42

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