17 Years of Nutritional Advice

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JAMA reports a new study from the National Health and Nutrition Examination Survey (NHANES) looking at the changes in our national diet. The information comes from the self-reported dietary recall of roughly 44,000 US adults over age 20; mean age 47, 52% women. Since the study considered NHANES data over time, the population subtly shifted with an increasing number of over 60, more people with “some college education,” and more racial/ethnic diversity. (Except for education these changes were roughly 3%, college 15%)

Because food recall surveys are soft data posing as numbers, NHANES has tried to improve the quality of the data with follow up phone calls that “probe for foods forgotten,” and generally adding overlooked data. That said, it does remain self-reported, memory-based, so statistical reporting may give the information more gravitas than is warranted. The researchers also calculated the Healthy Eating Index (HEI) for our national diet; HEI looks at how much of the “good” food we eat and the “bad” food we avoid. [1] The caveat here is that HEI has no minimal difference in score associated with clinical outcomes.  

Results

  • Energy intake from carbohydrates declined by 2%. Most of the decline was in low-quality carbs, e.g., added sugar and fruit juice; which compensated for a slight increase in their high-quality brethren, e.g., whole grains and fruits.
  • Energy from proteins rose by 1%. The percentage increase from both plant and animal sources were about the same. We ate more poultry and eggs, whole grains, nuts, and soy.
  • Energy from fats rose by a little more than 1%. Saturated fats accounted for a third of that increase
  • The HEI score improved from 55.7 to 57.7 (100 is best)
  • While these trends were seen in each demographic grouping, higher income, greater education, and younger age, all were associated with greater change.

After seventeen years of scientific papers, education, regulation, labeling, subsidies to producers and consumers, and media attention the best that can be reported is a slight decrease in our intake of low-quality carbohydrates and a similar slight increase in whole grain, poultry, and nuts. Really? After seventeen years of effort?

The authors do try for a bit of spin calling these significant findings while at the same time bemoaning a real lack of improvement in reducing our consumption of animal proteins and saturated fats. They also point out that a majority of our carbohydrates remain of low quality. So, significance refers is statistical, not any measurable outcome.

If the definition of insanity is “doing the same thing over and over and expecting a different result” than our national “policy” towards healthful nutrition may qualify. There has been, in my view, negligible change in our diet. Around the edges perhaps a fewer empty calories, an occasional salad, and do we want to believe that McChicken is somehow better than a Quarter Pounder? But it seems that altering the national diet has not responded to our collective efforts. If you are looking for a silver lining, take heart in the finding that the younger generation seems to have gotten at least a part of the memo, showing a greater improvement in their overall diet.

What this study shows is how difficult it is to untie the Gordian knot that we call our diet and the social structures we have erected to support it.

[1] The good – “fruit, whole fruit, total vegetables, greens and beans, whole grains, dairy, total protein foods, seafood, and plant protein, and fatty acids.” The bad – “refined grains, sodium, percentage of energy from added sugar or saturated fatty acids.”

Source Trends in Dietary Carbohydrate, Protein, and Fat Intake and Diet Quality Among US Adults, 1999-2016 JAMA DOI: 10.1001/jama.2019.13771

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