Scientific Questions
The 2025 Dietary Guidelines Advisory Committee (Committee) is using three scientific approaches (data analysis, food pattern modeling, and systematic reviews) to examine the evidence on nutrition and health. As part of Step 1, HHS and USDA developed a list of proposed scientific questions to inform the Committee’s work. The Committee prioritized the questions and presented the list of questions it planned to address at Meeting 2. According to the Federal Advisory Committee Act, the Committee has up to two years to complete its work. Similar to all previous Committees, as the Committee conducts its work, it has taken steps to further prioritize the scientific questions to be reviewed to inform its advice to HHS and USDA in the time available to conduct its work.
The Committee is divided into subcommittees to conduct its evidence review, and the scientific questions being addressed by each subcommittee are listed below. In addition, a list of scientific questions that the Committee has discontinued work on is provided, with the rationale for why each question was deprioritized.
Finally, the Committee is developing a protocol for each of its scientific questions. The protocol is the plan for how each question will be examined using one of the three scientific approaches. The protocols for questions being addressed using systematic reviews can be found on the Nutrition Evidence Systematic Review’s (NESR) website , and the protocols for questions being answered using food pattern modeling can be found on DietaryGuidelines.gov. Protocols are now available for the majority of questions the Committee will examine during its evidence review. The remaining protocols will be posted after they are discussed by the Committee at a public meeting. The data analysis plan that outlines the process, strategy, and analyses is currently available on DietaryGuidelines.gov.
Subcommittee 1: Dietary Patterns and Specific Dietary Pattern Components Across Life Stages |
Systematic Review Questions: |
Dietary Patterns |
| What is the relationship between dietary patterns consumed and growth, body composition, and risk of obesity? |
| What is the relationship between dietary patterns consumed and risk of cardiovascular disease? |
| What is the relationship between dietary patterns consumed and risk of type 2 diabetes? |
| What is the relationship between consumption of dietary patterns with varying amounts of ultra-processed foods and growth, body composition, and risk of obesity? |
| What is the relationship between dietary patterns consumed and risk of breast cancer? |
| What is the relationship between dietary patterns consumed and risk of colorectal cancer? |
| What is the relationship between dietary patterns consumed and risk of cognitive decline, dementia, and Alzheimer's disease? |
| What is the relationship between dietary patterns consumed and bone health? |
Beverages |
| What is the relationship between beverage patterns consumed and growth, body composition, and risk of obesity? |
| What is the relationship between dairy milk and milk alternative consumption and growth, body composition, and risk of obesity? |
| What is the relationship between 100% juice consumption and growth, body composition, and risk of obesity? |
| What is the relationship between sugar-sweetened beverage consumption and growth, body composition, and risk of obesity? |
| What is the relationship between low- and no-calorie sweetened beverage consumption and growth, body composition, and risk of obesity? |
| What is the relationship between sugar-sweetened beverage consumption and risk of type 2 diabetes? |
| What is the relationship between low- and no-calorie sweetened beverage consumption and risk of type 2 diabetes? |
Food Sources |
| What is the relationship between food sources of saturated fat consumed and risk of cardiovascular disease? |
Subcommittee 2: Diet in Pregnancy and Birth through Adolescence |
Systematic Review Questions: |
| What is the relationship between dietary patterns consumed during pregnancy and risk of hypertensive disorders of pregnancy? |
| What is the relationship between dietary patterns consumed during pregnancy and risk of gestational diabetes mellitus? |
| What is the relationship between repeated exposure to foods and food acceptance? |
| What is the relationship between complementary feeding and growth, body composition, and risk of obesity? |
| What is the relationship between parental and caregiver feeding styles and practices during childhood and adolescence and growth, body composition, and risk of obesity? |
| What is the relationship between parental and caregiver feeding styles and practices during childhood and adolescence and consuming a dietary pattern that is aligned with the Dietary Guidelines for Americans? |
| What is the relationship between dietary patterns consumed during pregnancy and gestational age at birth? |
| What is the relationship between dietary patterns consumed during pregnancy and birth weight? |
Subcommittee 3: Food Pattern Modeling and Data Analysis |
Food Pattern Modeling Questions: |
| Should foods and beverages with lower nutrient density (i.e., those with added sugars, saturated fat, and sodium) contribute to item clusters, representative foods, and therefore the nutrient profiles for each food group and subgroup used in modeling the USDA Dietary Patterns? |
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For each food group, what are the implications for nutrient intakes within the USDA Dietary Patterns if: (1) the recommended daily or weekly quantity of the food group or subgroup is modified (e.g., between a range of 0 to a number above the current recommendation) and (2) if the proportion coming from each subgroup within a food group is modified? If the USDA Dietary Patterns do not meet nutritional goals after these food group and subgroup modifications, what other changes to the USDA Dietary Patterns could help meet nutritional goals for each life stage (e.g., young children, older adults, individuals who are pregnant or lactating, adolescents)? These analyses will examine hypothetical modifications to food groups and subgroups and the implications on meeting nutritional goals to more equitably represent the diverse scope of population subgroup norms, preferences, and needs. Results from these analyses will be synthesized with the results from the Committee’s other food pattern modeling analyses, data analyses, and systematic reviews to determine if the Committee’s advice to the Departments will include suggested changes to the USDA Dietary Patterns or recommend new dietary patterns. |
| What quantities of foods and beverages lower in nutrient density can be accommodated in the USDA Dietary Patterns while meeting nutritional goals within calorie levels? |
| Do simulated diets that meet the updated USDA Dietary Patterns and reflect variation in dietary intakes achieve nutrient adequacy? |
Data Analysis Questions: |
| What are the current patterns of food and beverage intake? |
| What are the current intakes of food groups, nutrients, and dietary components? |
| Which nutrients and/or dietary components present a substantial public health concern because of underconsumption or overconsumption? |
| What is the current prevalence of nutrition-related chronic health conditions? |
Subcommittee 4: Strategies for Individuals and Families Related to Diet Quality and Weight Management |
Systematic Review Questions: |
| What is the relationship between frequency of meals and/or snacks and growth, body composition, and risk of obesity? |
| What is the relationship between frequency of meals and/or snacks and energy intake? |
| What is the relationship between frequency of meals and/or snacks and consuming a dietary pattern that is aligned with the Dietary Guidelines for Americans? |
| What is the relationship between portion size and growth, body composition, and risk of obesity? |
| What is the relationship between portion size and energy intake? |
Evidence Scan Questions: |
| What evidence has been published on the relationship between culturally tailored dietary interventions and diet-related psychosocial factors, dietary intake, diet quality, and health outcomes? |
Discontinued Scientific Questions
Subcommittee 1: Dietary Patterns and Specific Dietary Pattern Components Across Life Stages |
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Systematic Review Questions: |
Rationale |
| Dietary Patterns | |
| What is the relationship between dietary patterns consumed and risk of depression? | The Committee consulted Federal subject matter experts on this topic and based on concerns from these experts about reverse causality and/or the plausibility of the relationship between dietary patterns and risk of depression, the Committee decided to discontinue this systematic review. |
| What is the relationship between dietary patterns consumed and risk of prostate cancer? | In consideration of project workload and timelines, the Committee discontinued this systematic review after determining it was lower priority due to there being fewer new studies published on this topic compared to dietary patterns and breast cancer or colorectal cancer. |
| Beverages | |
| What is the relationship between coffee and/or tea consumption and risk of type 2 diabetes? | In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to risk of type of 2 diabetes is higher priority than examining coffee and tea independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses. |
| What is the relationship between coffee and/or tea consumption and growth, body composition, and risk of obesity? | In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to growth, body composition, and risk of obesity is higher priority than examining coffee and tea independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses. |
| What is the relationship between dairy milk and milk alternative consumption and risk of type 2 diabetes? | In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to risk of type of 2 diabetes is higher priority than examining dairy milk and milk alternatives independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses. |
| What is the relationship between 100% juice consumption and risk of type 2 diabetes? | In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to risk of type of 2 diabetes is higher priority than examining 100% juice independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses. |
Subcommittee 4: Strategies for Individuals and Families Related to Diet Quality and Weight Management |
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Evidence Scan Question: |
Rationale |
| What evidence has been published on the relationship between home food availability in adults and diet-related psychosocial factors, dietary intake, diet quality, and health outcomes? | In consideration of project workload and timelines, the Committee discontinued this evidence scan after determining that the planned evidence scan on culturally tailored dietary interventions is higher priority. In addition, home food availability in infants, young children, children, and adolescents will be examined in other systematic reviews being conducted on caregiver feeding practices. |