Abstract: The Dietary Guidelines for Americans dictates the federal nutrition programs, policies, and recommendations of the United States. Corresponding nutrition guides have been established to help educate the public about the dietary intake patterns recommended in these guidelines as well as to ameliorate the US obesity epidemic and its health-related outcomes. The purpose of this systematic review was to summarize population adherence to and knowledge of these guiding US nutrition guides issued since 1992, including the Food Guide Pyramid, MyPyramid, and MyPlate. Of the 31 studies included in the review, 22 examined adherence, 6 examined knowledge, and 3 examined both adherence and knowledge. Across studies, adherence to nutrition guides was low, with participants consuming inadequate levels of fruit, vegetables, and dairy in particular. Knowledge of nutrition guides increased over time since publication and decreased with age of the participants. An association between knowledge of and adherence to nutrition guides was not found. Disparities in knowledge and adherence existed across demographic groups. Based on these findings, it is suggested that federal dietary guidance can be strengthened by increasing dissemination of nutrition guides to the public and tailoring promotional activities to specific demographic and socioeconomic groups.
Alex’s Notes: If you are as huge a fan of the USDA dietary guidelines for Americans (DGA) as I am (please note the sarcasm) then the very brief study at hand will hopefully amuse you. The authors clearly demonstrate a disconnect from reality when they state in the introduction that,
“These guidelines have evolved to meet population needs in accordance with current research.”
Regardless, the review at hand was conducted to see how familiar Americans were with the DGA since 1992, and how well they followed the recommendations. As it turns out, 1992 was the year in which the first Food Guide Pyramid was published, followed by MyPyramid in 2005, and the most recent MyPlate DGA in 2010. Since food group terminology has changed throughout the DGA evolution, for the purpose of this review,
““grains” refers to the bread, cereal, rice, and pasta group in the Food Guide Pyramid as well as to the grains groups in MyPyramid and MyPlate; “proteins” refers to the meat, poultry, fish, dry beans, eggs, and nuts group in the Food Guide Pyramid, to the meat and beans group in MyPyramid, and to the protein foods group in MyPlate; and “dairy” refers to the milk, yogurt, and cheese group in the Food Guide Pyramid. Fruit and vegetable groups were nominally the same.”
Overall, 31 studies were included and all but one were observational in nature, utilizing 24-hour dietary recalls or food frequency questionnaires. A high-frequency of knowledge about both the Food Guide Pyramid and MyPyramid was apparent with 80-90% being the typical range of familiarity across the reviewed studies. Knowledge of MyPlate was much less familiar (about 20-40%), and overall there was a decreasing knowledge of the DGA as age increased, which may unfortunately be explained to the pervasive nature of these recommendations within the school systems.
Despite the knowledge of the DGA, adherence to it was typically very low. This isn’t as good as it sounds, because the shortcomings of Americans were in the dairy, vegetable, and fruit categories, while they tended to over-consume grains and proteins. Notably, children consistently consumed less grains and vegetables and more dairy than adults. There were some studies that looked at both adherence to the DGA and knowledge of it, and amusingly it was found that there was an inverse relationship (i.e. the more people knew, the less they adhered). I can vouch for that one; I am familiar with MyPlate and don’t follow its advice; in fact, I actively try to avoid its recommendations. The authors wouldn’t agree with me here, however, as they write,
“The trends in adherence to and knowledge of federal dietary guidelines that were identified in this review among the populations examined point to shortcomings in public health education and implementation of otherwise scientifically sound nutrition guidelines.” [Emphasis mine]
There is that disconnect again. Although, they do deserve a hat-tip when they point out that fruit and vegetables should be half of one’s diet and yet production of these crops receives less than 2% of funding from the 2008 Farm Bill. But then they ruin it again by mentioning that obesity rates for 2-5 year olds have declined recently in those who participate in the federal nutrition programs, and take this to mean that these programs can play a beneficial role in affecting health status and outcomes. Really?