1. Dwyer, Johanna DSc, RD

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The new Dietary Guidelines 2010 Committee will be meeting soon. For the past few months at Nutrition Today, we have focused on some vexing issues that committee members will need to consider as they fulfill their charge to provide food-based guidance about what people should eat to stay healthy and reduce disease risk. In this and the next few issues, we will continue to feature reviews of some of the relevant questions. In the meantime, here is some food for thought on some other issues that guideline formulators and implementers must keep in mind.


Evidence-Based Dietary Guidelines

For more than 25 years, some of the finest minds in nutrition, medicine, and food science have devoted themselves to thorough reviews of new science to update the Dietary Guidelines. Increasingly, there is a call for recommendations based on even more systematic, evidence-based reviews that leave even less room for bias.1 The 2005 committee did its best and produced such reviews on several critical questions that arose in its deliberations, such as questions on intakes of sugars and alcohol.2 However, the volunteers found the process inordinately time-consuming, and only a few such reviews could be done in the time available. The US Department of Agriculture and the US Department of Health and Human Services, who sponsor the guidelines, are struggling to provide more support for the evidence reviews needed for the guidelines, and abstractors are being trained to help do so. Another innovation that might be considered is including in the recommendations a grading system that helps the reader to evaluate the strength of the evidence supporting each of the various recommendations. The US Preventive Services Task Force grades the evidence by how strong it is in making recommendations: A, improves health outcomes, and benefits substantially outweigh risks or harms; B, fair evidence that health outcomes are improved and fair evidence that benefits substantially outweigh risks or harms; C, same as B, except that the value of the benefits and harms is too close to justify a recommendation; and I, incomplete and no recommendation. The task force also takes into account how much evidence there is in making its recommendations on various public health issues.3



There is a great deal of interest and potential in individualization of nutrition recommendations such as the Dietary Guidelines.4 Are age-segmented dietary guidelines in order?5 Are nutritegenomic guidelines ready for prime time? Someday, dietary guidelines specific to our genes may be possible. At present, genetic profiling is not precise enough to personalize dietary recommendations.6


Matching the Food Supply to Dietary Guidelines

Beyond any specific recommendations that the committee may make, it is important to ensure that it is easy for Americans to put the guidelines into action, and thus, food availability and affordability enter the picture. To be eaten, foods must taste and look good and also be affordable. Consumers need to put the new Dietary Guidelines into action with food that is available at a reasonable price.


To accomplish this, the public health recommendations must be in synch with a suitable food supply. For many years, the US Department of Agriculture has tracked trends in the US food supply, and some progress is being made in that direction.7,8 Some examples are more fruits and vegetables and more whole grains. Nutrition-based decisions that result in products in line with the Dietary Guidelines are also essential within the food industry. Some examples include new and improved food products that emphasize whole grains, low sodium, and other formulations.9 However, it is important to remember that food science cannot achieve the impossible, and the committee needs to recognize the limitations of technology. A case in point is trans-fat. Trans-fats in food products have decreased significantly over the past few years, particularly in margarines and also in many other foods. However, trans-fat-free diets are virtually impossible to create without the use of tropical oils and other saturated fats and other fats needed for structural purposes. It makes no nutritional sense to increase saturated fats at the very time we are decreasing trans-fats; both need to go down! A more realistic approach than the outright ban of all trans-fats in eating establishments that went into effect in New York City in July of 2008 is a gradualist approach including small downward changes in trans-fats, such as what the province of Ontario has implemented with respect to trans-fat content over the past 2 years.


We wish the 2010 Dietary Guidelines Committee members all the best as they begin their work, and we will keep our readers abreast on its exciting progress.




1. Cooper MJ, Zlotkin SH. An evidence based approach to the development of national dietary guidelines. J Am Diet Assoc. 2003:103:S28-S33. [Context Link]


2. Dietary Guidelines Advisory Committee. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans 2005 to the Secretary of Health and Human Services and Secretary of Agriculture. Washington, DC: US Department of Agriculture, Agricultural Research Service; 2005. [Context Link]


3. Harris RP, Helford M, Woolf SH, et al. Current methods of the US Preventive Services Task Force: a review of the process. Am J Prev Med. 2001;20:21-35. [Context Link]


4. Hoolihan LE. Individualization of nutrition recommendations and food choices. Nutr Today. 2003;38:225-231. [Context Link]


5. McBean LD, Jarvis JK. Improving age-segmented dietary guidance. Nutr Today. 2003;38:218-224. [Context Link]


6. Janssenss ACJW, Gwinn M, Bradley A, Oostra BA, Duijn CM, Khoury MJ. A critical appraisal of the scientific basis of commercial genomic profiles used to assess health risks and personalize health interventions. Am J Hum Genet. 2008;82:593-599. [Context Link]


7. Sloan AE. Top 10 functional food trends. Food Technol. 2008;54:25-44. [Context Link]


8. Wells HF, Buzby JC. Dietary Assessment of Major Trends in US Food Consumption 1970-2005. US Department of Agricultures Economic Research Service, Economic Information Bulletin, No. 33. Washington, DC: US Department of Agriculture, Economic Research Service; March 2008. [Context Link]


9. Hiza HA, Berke L, Fingme T. Nutrient Content of the US Food Supply 2005. Home Economics Research Report, No. 58. Washington, DC: US Department of Agriculture, Economic Research Service; March 2008. [Context Link]