Dietary Guidelines Advisory Committee: The Science

With the politics out of the way (see yesterday’s post), let’s talk about what’s superb in the Dietary Guidelines Advisory Committee Report: the scientific review and analysis.

This was based on reviews produced by the Nutrition Evidence Library (NEL), which apparently recruited dozens of people to identify articles, assess their quality by uniform criteria, and rank the overall evidence as limited, moderate, or strong and consistent or inconsistent.

I particularly like the way the report organizes the research review by questions (of which there are 56, if I counted right).  The questions cover a great range of topics.  Examples:

• What nutrients and dietary components are overconsumed by the general public?
• Can a daily multivitamin/mineral supplement prevent chronic disease?
• What is the role of prebiotics and probiotics in health?
• What are health effects related to consumption of nuts?
• What are the health effects related to consumption of chocolate?
• How do the health outcomes of a vegetarian diet compare to those of a diet which customarily includes animal products?
• How are non-caloric sweeteners related to energy intake and body weight?
• What amount of water is recommended for health?

Questions are followed immediately by Conclusions, Implications, and Review of the Evidence. All of this is written with great clarity, accompanied by thoughtful comments, and packed with useful information.

Here is just one example (I’ve emphasized the evaluative words):

What is the Relationship between Vegetable Protein and/or Soy Protein and Selected Health Outcomes? Few studies are available, and the limited body of evidence suggests that vegetable protein does not offer special protection against type 2 diabetes, coronary heart disease, and selected cancers. Moderate evidence from both cohort and cross-sectional studies show that intake of  vegetable protein is generally linked to lower blood pressure. Moderate evidence suggests soy protein may have small effects on total and low density lipoprotein cholesterol in adults with normal or elevated blood lipids, although results from systematic reviews are inconsistent. A moderate body of consistent evidence finds no unique benefit of soy protein on body weight. A limited and inconsistent body of evidence shows that soy protein does not provide any unique benefits in blood pressure control.

Readers may disagree with the committee’s research interpretations, but its conclusions deserve serious consideration.

And, if anyone wants to know the state of the available science on any of a large number of questions in nutrition, this report is the place to look first.

Student alert: I will be using this report in classes.