Tuesday, November 30, 2021

Dietary and nutrition guidance for the holidays and beyond

 - Kenny Lin, MD, MPH

Still feeling the aftereffects of Thanksgiving dinner? You're hardly alone. As the days get shorter and people look forward to holiday celebrations, three recent dietary and nutrition guidelines provide practical advice for physicians and patients.

The 2020-2025 Dietary Guidelines for Americans, summarized in Practice Guidelines in the November issue of AFP, are the latest iteration of a scientific collaboration between the U.S. Departments of Agriculture (USDA) and Health and Human Services dating back to 1980. The current report provides guidance for healthy eating across a person's lifespan, emphasizing dietary patterns with nutrient-dense foods and beverages:

At least one-half of food eaten should be fruits and vegetables, especially whole fruits and vegetables of a variety of colors. The core elements of the other half of food that should be eaten include grains, dairy, protein, and oils with lower saturated fat. At least one-half of grain servings should be whole grains. Minimize alcohol use and consumption of foods with added sugar, saturated fat, and sodium.

In an accompanying editorial, Drs. Amy Locke and Rachel Goossen observed that "although many of the recommendations are widely accepted, ... criticisms revolve around the authors' reported financial ties to the food industry and the discrepancies between the published guidelines and the recommendations submitted to the authors by the scientific advisory committee." Examples of such discrepancies include the Dietary Guidelines' overemphasis on consuming dairy and animal-based proteins and insufficient limits on alcohol use. Drs. Locke and Goossen suggested that "the most accessible way to use the information included in the report is through the USDA's MyPlate website and app" that organize advice by food groups and subgroups.

Recognizing that nearly 9 in 10 adults consume more sodium than the National Academy of Medicine's Chronic Disease Risk Reduction (CDRR) intake of 2,300 mg/day, the U.S. Food and Drug Administration recently finalized voluntary guidance for industry that aims to reduce the average American's daily sodium intake by 12% (from 3,400 to 3,000 mg/day) over the next two and a half years. Industry cooperation is critical because more than 70% of sodium intake comes from packaged food and food prepared away from home. Whether these goals will be achieved in the absence of an enforcement mechanism is unclear, as the sodium content of popular commercially processed and restaurant foods has changed little over the past decade.

Finally, the U.S. Preventive Services Task Force reiterated its 2014 recommendation that found insufficient evidence to assess the benefits and harms of screening for vitamin D deficiency in asymptomatic adults. In a Putting Prevention into Practice case study in AFP, Drs. Howard Tracer and Robert West noted that due to individual variability, "no one serum vitamin D level cutoff point defines deficiency, and no consensus exists regarding the precise serum levels of vitamin D that represent optimal health or sufficiency." In a previous editorial, I observed that frequent measurement of vitamin D levels in clinical practice is inconsistent with the evidence. As for supplementation, "family physicians should also counsel patients on the recommended dietary allowance for vitamin D (600 IU per day in adults 70 years and younger, and 800 IU per day in adults older than 70 years), and discourage most patients from using supplements, especially in dosages near or above the tolerable upper limit of 4,000 IU per day."