Re: Critical review of the Dietary Guidelines for Americans

On Mon, 11 Oct 2010 07:03:46 +0200, "GysdeJongh" <jongh711@xxxxxxxxx>
wrote:

Nutrition. 2010 Oct;26(10):915-24.

In the face of contradictory evidence: report of the Dietary Guidelines for
Americans Committee.

Full Text:
http://download.journals.elsevierhealth.com/pdfs/journals/0899-9007/PIIS0899900710002893.pdf

This is not the DGAC report, it is a critical commentary on the report
of the Dietary Guidelines for Americans Committee.

I suggest reading it in full. It is fascinating. I noticed a comment
already from someone who is going to regret writing "Thanks for
posting this" before actually reading it.

A snippet to whet the appetite; I inserted the quotation marks for
clarity:

"Strong recommendations, weak evidence

Important aspects of the recommendations remain unproven. The DGAC
Report provides several examples in the summary of ?Needs for Future
Research? in each section.

In the carbohydrates section, a goal of that research would be to:

'Develop and validate carbohydrate assessment methods. Explore and
validate new and emerging biomarkers to elucidate alternative
mechanisms and explanations for observed effects of carbohydrates on
health [p. D5-43 [4]]... Studies of carbohydrates and health outcomes
on a macronutrient level are often inconsistent or ambiguous due to
inaccurate measures and varying food categorizations and definitions.'

However, the DGAC Report?s summary statement on carbohydrates is
unambiguous in the face of these inconsistencies:

'Healthy diets are high in carbohydrates [p. D5-42].'

In the absence of research that can explain the mechanisms
that would account for a beneficial effect of high carbohydrates
on health outcomes, the recommendation must be considered
premature.

The protein section includes a call for future research that
will:

'Develop standardized definitions for vegetable proteins and improve
assessment methods for quantifying vegetable protein intake to help
clarify outcomes in epidemiologic studies in this area. . Assessing
vegetarian eating patterns and their protein content is complex and
current methodologies do not capture critical variations. Therefore,
investigators? ability to quantify any possible association with
health benefits is limited [p. D4-31].'

Yet the DGAC Report?s recommendations suggest no such
limitations. Americans are told to:

'Shift food intake patterns to a more plant-based diet that emphasizes
vegetables, cooked dry beans and peas, fruits, whole grains, nuts, and
seeds [p. B3-3].'

The admission that health benefits from such a shift remain unknown
and the acknowledgement of ?potential limitations of [a] plant-based
diet for key nutrients? (p. D4-31) would suggest that such a
recommendation be made with more circumspection.

The DGAC Report calls for a general increase in whole grain
consumption:

Whole-grain versions of many grain products (such as plain white
bread, rolls, bagels, muffins, pasta, breakfast cereals) should be
substituted to meet the recommendation that half of grains consumed be
whole grains [p. B2-8].

However, theDGAC Report also calls for additional research to:

Develop definitions for whole grain foods... there is no consistent
way that whole grain foods are defined and determined. Without clear
definitions for whole grain foods, it is difficult to compare research
studies examining the effectiveness of various whole grains on
biomarkers of interest in CVD [cardiovascular disease], diabetes, and
obesity [p. D5-43].

Urging an increase in whole grain consumption before the term is
consistently defined stymies any practical attempts to apply this
recommendation.

These examples illustrate the general pattern of the DGAC Report:
strong recommendations are made with weak and inconclusive evidence to
support them. Conclusions rest on evidence-based methodology, embodied
in the creation of the Nutrition Evidence Library (NEL). In practice,
the methodology and the utilization of the NEL demonstrate several
critical weaknesses:

1. Research questions are formulated in a way that precludes a
thorough investigation of the scientific and medical literature.

2. Answers to research questions are based on an incomplete body of
relevant science; relevant science is frequently excluded due to the
nature of the question.

3. Science is inaccurately represented, interpreted, and/or
summarized.

4. Conclusions do not reflect the quantity and/or quality of relevant
science.

5. Recommendations do not reflect the limitations, controversies,
and uncertainties existing in the science."

The initial Dietary Goals for Americans (1977) proposed that Americans
increase carbohydrate intake and decrease fat, saturated fat,
cholesterol, and salt consumption, recommendations that are carried
further in the proposed 2010 guidelines. Thirty years ago, critics
argued ?that the value of dietary change remains controversial and
that science cannot at this time insure that an altered diet will
provide improved protection from certain killer diseases? [5]. The
proposed recommendations raise these same concerns. What remains of
value in the current DGAC Report is substantially undermined by a
failure to address these ongoing criticisms."

Cheers, Alan, T2, Australia.
d & e; metformin 1500mg
--
Everything in Moderation - Except Laughter.
http://loraldiabetes.blogspot.com (To Medicate - Or Not?)
http://loraltravel.blogspot.com (Buenos Aires, Argentina)
.

Relevant Pages

  • Re: Critical review of the Dietary Guidelines for Americans
    ... :>: This is not the DGAC report, it is a critical commentary on the report ... :>: Important aspects of the recommendations remain unproven. ... :>: mechanisms and explanations for observed effects of carbohydrates on ... :>: way that whole grain foods are defined and determined. ...
    (alt.support.diabetes)
  • Re: Critical review of the Dietary Guidelines for Americans
    ... Americans Committee. ... Concerns that were raised with the first dietary recommendations 30 y ago ... methodology, the DGAC Report demonstrates several critical weaknesses, ... evidence in the DGAC Report does not suggest a conclusive proscription ...
    (alt.support.diabetes)
  • Re: Critical review of the Dietary Guidelines for Americans
    ... Americans Committee. ... Concerns that were raised with the first dietary recommendations 30 y ago ... methodology, the DGAC Report demonstrates several critical weaknesses, ... evidence to conclude that increases in whole grain and fiber and decreases ...
    (alt.support.diabetes)