Overview of the 2020 Dietary Guidelines Advisory Committee Report
By Hadley Turner
The USDA recently made available the scientific report of the 2020 Dietary Guidelines Advisory Committee (the Committee), which will advise the development of the 2020–2025 Dietary Guidelines for Americans. Today’s Dietitian provides a summary of some of the Committee’s key additions, changes, and recommendations.
This edition of the scientific report pays special attention to the impact of nutrition and dietary patterns on each life stage: pregnancy, lactation, birth to 24 months, childhood, adolescence, and adulthood. The Committee cites the Agricultural Act of 2014—which mandates including recommendations for infants, toddlers, and pregnant and lactating women in the 2020–2025 Dietary Guidelines—and the fact that nutrition status in one life stage affects nutrition status in the next as the primary reasons for the life stage focus.
What’s There, What’s Not
Unlike the 2015 scientific report, the 2020 report doesn’t include discussion of dietary patterns’ environmental sustainability, nor their sustainability for individuals; food insecurity, hunger, and other economic realities of food access are absent. The Committee states it considers these topics to be beyond the scope of its report.
However, in its opening letter to Sonny Perdue and Alex Azar, Secretaries of Agriculture and Health and Human Services, respectively, the Committee acknowledges increasing food insecurity amid the COVID-19 pandemic and urges the USDA and Department of Health and Human Services to investigate and address social, economic, and environmental concerns related to dietary patterns and access to healthful foods. These topics also are suggested as issues for future Committees to address.
Despite these omissions, the scientific report includes detailed recommendations for pregnancy, lactation, and infants and toddlers, a new and likely welcome addition for RDs. Key points in each section include the following.
The Committee cites the association between maternal diet prepregnancy and pregnancy complications, as well as the connection between maternal diet before and throughout pregnancy and neonate health. Its recommendations here align with current guidelines: Pregnant women should consume an overall healthful dietary pattern and be sure to include seafood high in omega-3s for the child’s cognitive development, as well as folic acid supplementation to prevent neural tube defects. While folic acid and folate are emphasized, the scientific report also examined the effects of other nutrients of concern during pregnancy, including iron, choline, magnesium, vitamin D, dietary fiber, and iodine.
Maternal diet is systematically reviewed in its relationship to maternal weight, infant birthweight, maternal complications such as gestational diabetes and preeclampsia, infant neurocognitive development, and infant food allergies and allergic diseases, among other conditions. The Committee states that diets generally higher in vegetables, fruits, whole grains, nuts and seeds, legumes, and seafood and lower in red and processed meats may modestly reduce the risk of complications such as gestational diabetes and hypertension for pregnant women and their infants. In addition, including common allergens such as dairy milk and peanut products in the maternal diet doesn’t increase the risk of children’s food allergy and allergic disease, a conclusion in line with the evolution over the past decade of guidelines for preventing food allergy.
Questions on the effect of maternal diet during lactation are similar to those during pregnancy: In short, how do these choices affect child development and maternal health outcomes? Topics of focus include lactation’s impact on postpartum weight status, maternal diet’s effect on breastmilk quality, and breastmilk quality’s influence on infant development.
Maternal micronutrient status is of concern during lactation as well as pregnancy, especially for folate/folic acid, magnesium, vitamin D, zinc, dietary fiber, potassium, calcium, copper, thiamin, vitamin A, and choline. Of note, the Scientific Report states that iron may be overconsumed by almost one-third of lactating women taking supplements.
The Committee couldn’t adequately evaluate the relationship between infant development and maternal seafood consumption during lactation, as no studies met its inclusion criteria, but it’s recommended that seafood consumption fall within recommendations set by the 2015–2020 Dietary Guidelines. Lactating women shouldn’t be encouraged to avoid common food allergens, and, of course, a generally healthful dietary pattern is recommended. The Committee states that any duration of breast-feeding is better than none for lowering risk of long-term infant overweight and obesity, but there was limited evidence for breast-feeding lowering risk of CVD and type 1 or type 2 diabetes.
Infancy and Toddlerhood
The focus of the scientific report’s first chapter on infancy and toddlerhood is the introduction of complementary foods. The Committee doesn’t recommend parents introduce complementary foods before 4 months of age and concurs with guidelines that suggest beginning complementary feeding between 4 and 6 months of age. These foods should be higher in fat and nutrient dense, and sugar-sweetened beverages should be avoided.
However, the Committee doesn’t weigh in on the widely covered recommendations from several nutrition organizations to limit 100% juice consumption (ie, no juice up to 12 months of age and no more than 4 oz per day between ages 1 and 3 years), instead suggesting that the next Committee look into this further.
Supplementation for infants and toddlers also is covered in the scientific report, and the Committee doesn’t support a blanket recommendation for vitamin D or iron supplementation in this population. However, caregivers may consider providing iron-fortified infant cereals or other fortified foods for those fed primarily breastmilk or formula from ages 6 to 12 months.
Another question the Committee addressed is whether a certain food pattern can be recommended for infants and toddlers based on current evidence. For those aged 6 to 12 months, this couldn’t be established, nor for those older than 12 months whose diets consisted of at least 20% breastmilk or formula.
But for others older than 12 months who aren’t fed breastmilk or formula, a food pattern is recommended that’s consistent with healthful food patterns for those older than 2 years. The Committee doesn’t recommend the inclusion of fortified toddler-specific foods that have grown in popularity over the last several years. There’s little or no room for added sugars in this eating pattern.
Other Areas of Examination
In reevaluating evidence for recommendations for those older than 2 years, the Committee’s conclusions mostly aligned with those of previous Committees. One addition was the Committee’s review of evidence surrounding Acceptable Macronutrient Distribution Ranges (AMDR) due to increased interest in this topic, especially in low- and very low-carbohydrate diets, throughout the nation.
To that end, most of the studies evaluated distributions wherein the carbohydrate proportion was below the AMDR, fat was above the AMDR, and protein was within the AMDR. Because of the poor quality of many studies and a lack of consistency of macronutrient distribution among these investigations, the Committee couldn’t make a recommendation as to the effects of nontraditional macronutrient distributions on health outcomes.
The Committee also revisited evidence on dietary fats and CVD, beverages, alcohol, and added sugars. No surprises for fats, nonalcoholic beverages, and added sugars: Replace saturated fats with unsaturated fats in the diet to protect against CVD, be mindful of intake of all caloric beverages but especially limit sugar-sweetened beverages, and reduce intake of added sugars (ideally to less than 6% of calories).
However, the Committee concludes that there’s justification for tightening alcohol recommendations (currently at two drinks per day for men and one drink per day for women) for men to one drink per day, especially for those who drink every day, due to an increase in all-cause mortality risk at two drinks per day. Overall, the report states, the less alcohol consumed, the better, citing alcohol’s association with all-cause mortality and several types of cancer.
Another new area examined is the frequency of eating and the number of eating occasions, including meals and snacks. There’s limited evidence, but the Committee suggests that dietary patterns that reduce snacking and largely keep to three meals per day are likely to encourage alignment with dietary guidelines.
The full report can be viewed here.
— Hadley Turner is the associate editor of Today’s Dietitian and RDLounge.com.