The Evolution of Science and Regulation of Dietary Supplements: Past, Present, and Future.

Dietary supplement use in the United States is widespread and increasing, especially among certain population groups, such as older Americans. The science surrounding dietary supplements has evolved substantially over the last few decades since their formal regulation in 1994. Much has been learned about the mechanisms of action of many dietary supplement ingredients, but the evidence on their health effects is still building. As is true of much nutrition research, there are many studies that point to health effects, but not all are at the level of scientific evidence (e.g., randomized controlled interventions), rigor, or quality needed for definitive statements of efficacy regarding clinical endpoints. New technologies and approaches are being applied to the science of dietary supplements, including nutrigenomics and microbiome analysis, data science, artificial intelligence, and machine learning - all of which can elevate the science behind dietary supplements. Products can contain an array of bioactive compounds derived from foods as well as from medicinal plants, which creates enormous challenges in data collection and management. Clinical applications, particularly those aimed at providing personalized nutrition options for patients, have become more sophisticated as dietary supplements are incorporated increasingly into clinical practice and self-care. The goals of this paper are to provide historical context for the regulation and science of dietary supplements, identify research resources, and suggest some future directions for science in this field.

Dietary Quality and Diet-Related Factors Among U.S. Emerging Adults (18-23y) Are a Cause for Concern, NHANES 2015-2018.

BACKGROUND: Poor dietary quality is a risk factor for diet-related chronic disease and suboptimal nutritional patterns often begin early in the life course. While the dietary intakes of young children, adolescents, and middle-aged and older adults are well established, much less is known about emerging adults, who represent a unique timepoint in life, as they are undergoing significant changes in food environments, autonomy, finances, and caregiver and parental involvement. OBJECTIVE: To examine dietary quality, as assessed via the Healthy Eating Index (HEI), by demographic, socioeconomic, and health-related characteristics among U.S. emerging adults (18-23y) who participated in the 2015-2018 National Health and Nutrition Examination Survey (NHANES). METHODS: NHANES data were collected via a household interview and 2 24-hour dietary recalls (24HR). Usual dietary intakes from the 24HRs were approximated using the multivariate National Cancer Institute Method to compute mean HEI-2015 overall and component scores (range 0-100, higher scores indicating higher dietary quality). RESULTS: Overall dietary quality among U.S. emerging adults [HEI-2015: 50.3±1.3] was significantly lower than other U.S. adults (≥24y) [HEI-2015: 56.3±0.5; p<0.0001], with differences primarily driven by lower intakes of whole fruit, vegetables, and whole grains, and higher intakes of sodium, refined grains, and saturated fat. Few differences in HEI-2015 scores were noted across population subgroups by sex, food security, family income, and food assistance program participation, except for added sugar; intakes of added sugar were significantly higher among women, food insecure, and food assistance program participants as compared to their counterparts, respectively. CONCLUSIONS: Dietary quality is poor among U.S. emerging adults and persists across all population subgroups, suggesting a significant need for tailored public health interventions to improve dietary quality among this population. Future research investigating to what extent emerging adults prioritize healthful behaviors and exploring other indicators for identifying nutritionally vulnerable subgroups may be impactful for identifying disparities among this life stage.

Improvements in dietary intake, behaviors, and psychosocial measures in a community-randomized cardiovascular disease risk reduction intervention: Strong Hearts, Healthy Communities 2.0.

BACKGROUND: Cardiovascular disease (CVD) prevalence has disproportionately risen among midlife and older female adults of rural communities, partly due to poor diet and diet-related behaviors and psychosocial factors that impede healthy eating. OBJECTIVES: This study aimed to evaluate the impact of Strong Hearts Healthy Communities 2.0 (SHHC-2.0) on secondary diet-related outcomes between intervention and control participants that align with the dietary goal and behavioral aims of the SHHC-2.0, a CVD risk reduction program. METHODS: A community-randomized controlled trial was conducted in rural, medically underserved communities. Participants were female adults ≥40 y who were classified as obese or both overweight and sedentary. Communities were randomized to SHHC-2.0 intervention (n = 5 communities; n = 87 participants) or control (with delayed intervention) (n = 6 communities; n = 95 participants). SHHC-2.0 consisted of 24 wk of twice-weekly experiential nutrition education and group-based physical activity classes led by local health educators. Changes between baseline and end point (24 wk) in dietary intake (24-h recalls), dietary behaviors (e.g., Rapid Eating Assessment for Participants-Short Version [REAP-S] scores) and diet-related psychosocial measures (e.g., Three Factor Eating questionnaire) between groups were analyzed using linear mixed-effects multilevel models. RESULTS: At 24 wk, participants from the 5 intervention communities, compared with controls, consumed fewer calories (mean difference [MD]= -211 kcal, 95% CI: -412, -110, P = 0.039), improved overall dietary patterns measured by REAP-S scores (MD: 3.9; 95% CI: 2.26, 5.6; P < 0.001), and improved psychosocial measures (healthy eating attitudes, uncontrolled eating, cognitive restraint, and emotional eating). CONCLUSIONS: SHHC-2.0 has strong potential to improve diet patterns and diet-related psychosocial wellbeing consistent with improved cardiovascular health. This trial was registered at www. CLINICALTRIALS: gov as NCT03059472.

Snack frequency, size, and energy density are associated with diet quality among US adolescents.

OBJECTIVE: To evaluate snacking and diet quality among US adolescents. DESIGN: Cross-sectional analysis examined snack frequency (snacks/day), size (kcal/snack) and energy density (kcal/g/snack) as predictors of diet quality using the mean of two 24-h dietary recalls. Diet quality was assessed using the Healthy Eating Index (HEI-2015, 0-100), a mean adequacy ratio (MAR, 0-100) for under-consumed nutrients (potassium, fibre, Ca, vitamin D) and mean percentage of recommended limits for over-consumed nutrients (added sugar, saturated fat, Na). Linear regression models examined total snacks, food only snacks and beverage only snacks, as predictors of diet quality adjusting for demographic characteristics and estimated energy reporting accuracy. SETTING: 2007-2018 National Health and Nutrition Examination Survey. PARTICIPANTS: Adolescents 12-19 years (n 4985). RESULTS: Snack frequency was associated with higher HEI-2015 (ß = 0·7 (0·3), P < 0·05) but also with higher intake of over-consumed nutrients (ß = 3·0 (0·8), P ≤ 0·001). Snack size was associated with lower HEI (ß = -0·005 (0·001), P ≤ 0·001) and MAR (ß = -0·005 (0·002), P < 0·05) and higher intake of over-consumed nutrients (ß = 0·03 (0·005), P ≤ 0·001). Associations differed for food only and beverage only snacks. Food only snack frequency was associated with higher HEI-2015 (ß = 1·7 (0·03), P ≤ 0·001), while food only snack size (ß = -0·006 (0·0009), P ≤ 0·001) and food only snack energy density (ß = -1·1 (0·2), P ≤ 0·001) were associated with lower HEI-2015. Conversely, beverage only snack frequency (ß = 4·4 (2·1) P < 0·05) and beverage only snack size (ß = 0·03 (0·01), P ≤ 0·001) were associated with higher intake of over-consumed nutrients. CONCLUSIONS: Smaller, frequent, less energy-dense food only snacks are associated with higher diet quality in adolescents; beverages consumed as snacks are associated with greater intake of over-consumed nutrients.

Precision Nutrition: The Hype Is Exceeding the Science and Evidentiary Standards Needed to Inform Public Health Recommendations for Prevention of Chronic Disease.

As dietary guidance for populations shifts from preventing deficiency disorders to chronic disease risk reduction, the biology supporting such guidance becomes more complex due to the multifactorial risk profile of disease and inherent population heterogeneity in the diet-disease relationship. Diet is a primary driver of chronic disease risk, and population-based guidance should account for individual responses. Cascading effects on evidentiary standards for population-based guidance are not straightforward. Precision remains a consideration for dietary guidance to prevent deficiency through the identification of population subgroups with unique nutritional needs. Reducing chronic disease through diet requires greater precision in (a) establishing essential nutrient needs throughout the life cycle in both health and disease; (b) considering effects of nutrients and other food substances on metabolic, immunological, inflammatory, and other physiological responses supporting healthy aging; and (c) considering healthy eating behaviors. Herein we provide a template for guiding population-based eating recommendations for reducing chronic diseases in heterogenous populations.

Neurobiology of eating behavior, nutrition, and health.

Eating behavior and food-related decision making are among the most complex of the motivated behaviors, and understanding the neurobiology of eating behavior, and its developmental dynamics, is critical to advancing the nutritional sciences and public health. Recent advances from both human and animal studies are revealing that individual capacity to make health-promoting food decisions varies based on biological and physiological variation in the signaling pathways that regulate the homeostatic, hedonic, and executive functions; past developmental exposures and current life-stage; the food environment; and complications of chronic disease that reinforce the obese state. Eating rate drives increased calorie intake and represents an important opportunity to lower rates of food consumption and energy intake through product reformulation. Understanding human eating behaviors and nutrition in the context of neuroscience can strengthen the evidence base from which dietary guidelines are derived and can inform policies, practices, and educational programs in a way that increases the likelihood they are adopted and effective for reducing rates of obesity and other diet-related chronic disease.

Usual nutrient intakes and diet quality among United States older adults participating in the Supplemental Nutrition Assistance Program compared with income-eligible nonparticipants.

BACKGROUND: The proportion of older adults with food insecurity at 8% has increased faster than that of the general United States population from 2001 to 2017. Many low-income food-insecure older adults rely on food-assistance programs, such as the Supplemental Nutrition Assistance Program (SNAP), for meeting energy and nutrient needs, whereas others are eligible but do not participate. Neither updated nutrient intake estimates nor potential differences in meeting the Dietary Reference Intakes from foods alone and with dietary supplements (DS) among low-income older adults using or eligible for SNAP are known. OBJECTIVES: This study assessed and compared national estimates of usual nutrient adequacy and dietary quality of United States older adults using SNAP and income-eligible nonparticipants. METHODS: Usual dietary intake was estimated among older adults (≥60 y; n = 2582) in the 2007-2016 NHANES cross-sectional national survey. Data on food-assistance participation and eligibility (poverty-income-ratio ≤130%), DS use, and ≥24-h dietary recalls were used. The NCI method (Markov Chain Monte Carlo approach) was applied to estimate mean usual nutrient intakes, proportion of inadequate nutrient intake, and dietary quality using the 2015 Healthy Eating Index. RESULTS: Neither usual nutrient intake from dietary and total sources nor dietary quality differed between older adult SNAP participants and eligible nonparticipants. Low dietary quality and high percentage of inadequate intake for several nutrients were apparent among both groups, especially from food sources alone, including vitamins A (56%), C (55%), D (97%), E (99%), calcium (73%), and magnesium (74%), but rates were attenuated when DS were also considered (i.e., 36% reduced risk for vitamin D inadequacy). CONCLUSIONS: Diet quality and usual nutrient intake among older adult SNAP participants and eligible nonparticipants were poor, but DS lowered the risk of nutrient inadequacy. Future policies and programs should focus on improving the intake of vitamins A, C, D, E, calcium, and magnesium and dietary quality for all older adults.

Moderate consumption of freeze-dried blueberry powder increased net bone calcium retention compared with no treatment in healthy postmenopausal women: a randomized crossover trial.

BACKGROUND: Preclinical studies suggest that blueberry consumption is associated with improved bone health. OBJECTIVES: We conducted a blueberry dose-response study in ovariectomized (OVX)-rats that informed a study in postmenopausal women using the urinary appearance of calcium (Ca) tracers from prelabeled bone to reflect changes in bone balance. We hypothesized that blueberry consumption would reduce bone loss in a dose-dependent manner compared with no treatment. METHODS: OVX rats were fed 4 doses of blueberry powder (2.5%, 5%, 10%, and 15%) in randomized order to determine bone 45Ca retention. Fourteen healthy, nonosteoporotic women ≥4 y past menopause were dosed with 50 nCi of 41Ca, a long-lived radioisotope, and equilibrated for 5 mo to allow 41Ca deposition in bone. Following a 6-wk baseline period, participants were assigned to a random sequence of 3 6-wk interventions, a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 0.75, 1.5, or 3 cups of fresh blueberries incorporated into food and beverage products. Urinary 41Ca:Ca ratio was measured by accelerator mass spectrometry. Serum bone resorption biomarkers and urinary polyphenols were measured at the end of each control and intervention period. Data were analyzed using a linear mixed model and repeated measures analysis of variance. RESULTS: In both OVX rats and postmenopausal women, blueberry interventions benefited net bone calcium balance at lower but not at higher doses. In women, net bone calcium retention increased by 6% with the low (95% CI: 2.50, 8.60; P < 0.01) and 4% with the medium (95% CI: 0.96, 7.90; P < 0.05) dose compared with no treatment. Urinary excretion of hippuric acid increased dose-dependently with blueberry consumption. No significant relationships were found between bone resorption biomarkers, 25-hydroxyvitamin D, and interventions. CONCLUSIONS: Moderate consumption (<1 cup/d) of blueberries may be an effective strategy to attenuate bone loss in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT02630797.

Major Gaps in Understanding Dietary Supplement Use in Health and Disease.

Precise dietary assessment is critical for accurate exposure classification in nutritional research, typically aimed at understanding how diet relates to health. Dietary supplement (DS) use is widespread and represents a considerable source of nutrients. However, few studies have compared the best methods to measure DSs. Our literature review on the relative validity and reproducibility of DS instruments in the United States [e.g., product inventories, questionnaires, and 24-h dietary recalls (24HR)] identified five studies that examined validity (n = 5) and/or reproducibility (n = 4). No gold standard reference method exists for validating DS use; thus, each study's investigators chose the reference instrument used to measure validity. Self-administered questionnaires agreed well with 24HR and inventory methods when comparing the prevalence of commonly used DSs. The inventory method captured nutrient amounts more accurately than the other methods. Reproducibility (over 3 months to 2.4 years) of prevalence of use estimates on the questionnaires was acceptable for common DSs. Given the limited body of research on measurement error in DS assessment, only tentative conclusions on these DS instruments can be drawn at present. Further research is critical to advancing knowledge in DS assessment for research and monitoring purposes.

Selecting a dietary supplement with appropriate dosing for 6 key nutrients in pregnancy.

BACKGROUND: Most pregnant women in the United States (US) are at risk of inadequate intake of key nutrients during pregnancy from foods alone. Current dietary supplement practices reduce risk of inadequacy for only some nutrients and induce excessive intake of other nutrients. OBJECTIVES: Our study aimed to estimate the doses of supplementation needed to help most pregnant women achieve the recommended intake without exceeding upper limits for key prenatal nutrients and to identify US dietary supplements providing these doses. METHODS: We conducted 24-h dietary recalls in 2450 pregnant participants aged 14-50 y from 2007 to 2019. We estimated the usual intake of vitamins A and D, folate, calcium, iron, and ω-3 FAs from foods alone. We calculated the target doses of supplementation needed to shift 90% of participants to consume above the estimated average requirement and keep 90% below the tolerable upper limit. We identified products in the Dietary Supplement Label Database providing these target doses of supplementation. RESULTS: The target dose for supplementation was ≥198 mcg retinol activity equivalents of total vitamin A (with ≤2063 mcg preformed retinol); 7-91 mcg vitamin D; 169-720 mcg dietary folate equivalents of folic acid; 383-943 mg calcium; 13-22 mg iron; and ≥59 mg ω-3 FAs. Out of 20,547 dietary supplements (including 421 prenatal products), 69 products (33 prenatal) contained all 6 nutrients; 7 products (2 prenatal) contained target doses for 5 nutrients. Only 1 product (not a prenatal) contained target doses for all 6 nutrients, but it currently costs ∼USD200/mo and requires 7 tablets per daily serving. CONCLUSIONS: Almost no US dietary supplements provide key nutrients in the doses needed for pregnant women. Affordable and convenient products that fill the gap between food-based intake and estimated requirements of pregnancy without inducing excess intake are needed to support pregnant women and their offspring. Am J Clin Nutr 20XX;xx:xx-xx.

A narrative review of nutrient based indexes to assess diet quality and the proposed total nutrient index that reflects total dietary exposures.

A priori dietary indices provide a standardized, reproducible way to evaluate adherence to dietary recommendations across different populations. Existing nutrient-based indices were developed to reflect food/beverage intake; however, given the high prevalence of dietary supplement (DS) use and its potentially large contribution to nutrient intakes for those that use them, exposure classification without accounting for DS is incomplete. The purpose of this article is to review existing nutrient-based indices and describe the development of the Total Nutrient Index (TNI), an index developed to capture usual intakes from all sources of under-consumed micronutrients among the U.S. population. The TNI assesses U.S. adults' total nutrient intakes relative to recommended nutrient standards for eight under-consumed micronutrients identified by the Dietary Guidelines for Americans: calcium, magnesium, potassium, choline, and vitamins A, C, D, E. The TNI is scored from 0 to 100 (truncated at 100). The mean TNI score of U.S. adults (≥19 y; n = 9,954) based on dietary data from NHANES 2011-2014, was 75.4; the mean score for the index ignoring DS contributions was only 69.0 (t-test; p < 0.001). The TNI extends existing measures of diet quality by including nutrient intakes from all sources and was developed for research, monitoring, and policy purposes.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.1967872.

A Randomized Intervention of Supplemental Nutrition Assistance Program-Education Did Not Improve Dietary Outcomes Except for Vitamin D Among Lower-Income Women in Indiana.

BACKGROUND: The goal of US Department of Agriculture Supplemental Nutrition Assistance Program-Education (SNAP-Ed) is to improve the likelihood that those eligible for SNAP will make healthy choices aligned with the Dietary Guidelines for Americans, 2020-2025. OBJECTIVE: The objective of the study was to evaluate the long-term effects of a direct SNAP-Ed intervention in which participants actively engage in learning with educator instruction about dietary quality and usual intake of key nutrient and food groups among Indiana SNAP-Ed-eligible women participants as an example sample in the context of no similar existing evaluation. DESIGN: The study design was a parallel-arm, randomized controlled, nutrition education intervention, with follow-up at 1 year. PARTICIPANTS/SETTING: Participants (18 years and older; n = 97 women) eligible for SNAP-Ed and interested in receiving nutrition education lessons were recruited from 31 Indiana counties from August 2015 to May 2016 and randomized to an intervention (n = 53) or control (n = 44) group. INTERVENTION: The intervention comprised core lessons of Indiana SNAP-Ed delivered between 4 and 10 weeks after baseline assessment. Each participant completed a baseline and 1-year follow-up assessment. Dietary intake was assessed using repeated 24-hour dietary recalls (up to 2). MAIN OUTCOME MEASURES: Mean usual nutrient, food group intake, diet quality (ie, Healthy Eating Index-2010 scores), and proportion of intervention and control groups meeting Dietary Guidelines for Americans, 2020-2025 recommendations and Dietary Reference Intake indicators of requirement or adequacy, were determined using the National Cancer Institute method and the simple Healthy Eating Index-2010 scoring algorithm method. Dietary changes between intervention and control groups were examined over time using mixed linear models. STATISTICAL ANALYSES PERFORMED: Bonferroni-corrected significance levels were applied to the results of the mixed linear models for comparisons of usual intake of nutrients and foods. RESULTS: No differences in diet quality, intake of food group components, food group intake, or nutrients were observed at 1-year follow-up, except that vitamin D intake was higher among those who received SNAP-Ed compared with the control group. CONCLUSIONS: A direct SNAP-Ed intervention did not improve diet quality, food group intake, or key nutrient intake, except for vitamin D, among Indiana SNAP-Ed-eligible women up to 1 year after the nutrition education.

Maternal Periconceptional Folic Acid Supplementation and DNA Methylation Patterns in Adolescent Offspring.

BACKGROUND: Folate, including the folic acid form, is a key component of the one-carbon metabolic pathway used for DNA methylation. Changes in DNA methylation patterns during critical development periods are associated with disease outcomes and are associated with changes in nutritional status in pregnancy. The long-term impact of periconceptional folic acid supplementation on DNA methylation patterns is unknown. OBJECTIVES: To determine the long-term impact of periconceptional folic acid supplementation on DNA methylation patterns, we examined the association of the recommended dosage (400 µg/d) and time period (periconceptional before pregnancy through first trimester) of folic acid supplementation with the DNA methylation patterns in the offspring at age 14-17 y compared with offspring with no supplementation. METHODS: Two geographic sites in China from the 1993-1995 Community Intervention Program of folic acid supplementation were selected for the follow-up study. DNA methylation at 402,730 CpG sites was assessed using saliva samples from 89 mothers and 179 adolescents (89 male). The mean age at saliva collection was 40 y among mothers (range: 35-54 y) and 15 y among adolescents (range: 14-17 y). Epigenome-wide analyses were conducted to assess the interactions of periconceptional folic acid exposure, the 5,10-methylenetetrahydrofolate reductase (MTHFR)-C677T genotype, and epigenome-wide DNA methylation controlling for offspring sex, geographic region, and background cell composition in the saliva. RESULTS: In the primary outcome, no significant differences were observed in epigenome-wide methylation patterns between adolescents exposed and those non-exposed to maternal periconceptional folic acid supplementation after adjustment for potential confounders [false discovery rate (FDR) P values < 0.05]. The MTHFR-C677T genotype did not modify this lack of association (FDR P values < 0.05). CONCLUSIONS: Overall, there were no differences in DNA methylation between adolescents who were exposed during the critical developmental window and those not exposed to the recommended periconceptional/first-trimester dosage of folic acid.

Trends in Overall and Micronutrient-Containing Dietary Supplement Use in US Adults and Children, NHANES 2007-2018.

BACKGROUND: Dietary supplement (DS) use is widespread in the United States and contributes large amounts of micronutrients to users. Most studies have relied on data from 1 assessment method to characterize the prevalence of DS use. Combining multiple methods enhances the ability to capture nutrient exposures from DSs and examine trends over time. OBJECTIVES: The objective of this study was to characterize DS use and examine trends in any DS as well as micronutrient-containing (MN) DS use in a nationally representative sample of the US population (≥1 y) from the 2007-2018 NHANES using a combined approach. METHODS: NHANES obtains an in-home inventory with a frequency-based dietary supplement and prescription medicine questionnaire (DSMQ), and two 24-h dietary recalls (24HRs). Trends in the prevalence of use and selected types of products used were estimated for the population and by sex, age, race/Hispanic origin, family income [poverty-to-income ratio (PIR)], and household food security (food-secure vs. food-insecure) using the DSMQ or ≥ 1 24HR. Linear trends were tested using orthogonal polynomials (significance set at P < 0.05). RESULTS: DS use increased from 50% in 2007 to 56% in 2018 (P = 0.001); use of MN products increased from 46% to 49% (P = 0.03), and single-nutrient DS (e.g., magnesium, vitamins B-12 and D) use also increased (all P < 0.001). In contrast, multivitamin-mineral use decreased (70% to 56%; P < 0.001). In adults (≥19 y), any (54% to 61%) and MN (49% to 54%) DS use increased, especially in men, non-Hispanic blacks and Hispanics, and low-income adults (PIR ≤130%). In children (1-18 y), any DS use remained stable (∼38%), as did MN use, except for food-insecure children, whose use increased from 24% to 31% over the decade (P = 0.03). CONCLUSIONS: The prevalence of any and MN DS use increased over time in the United States. This may be partially attributed to increased use of single-nutrient products. Population subgroups differed in their DS use.

Association of weight status with the types of foods consumed at snacking occasions among US adolescents.

OBJECTIVE: This study aimed to evaluate snack food-group composition by weight status among United States adolescents. METHODS: Cross-sectional analysis of adolescent food-group-component intake from snacking occasions using two 24-hour dietary recalls from the 2007 through 2018 National Health and Nutrition Examination Survey (NHANES; n = 5264; 12-19 years) was conducted. ANCOVA models evaluated food intakes by BMI percentile (BMI%; normal weight [NW]: <85th BMI%; overweight [OW]: 85th-95th BMI%; and obesity [OB]: ≥95th BMI%), adjusting for energy misreporting and key covariates. RESULTS: Adolescents with OB consumed greater total daily energy from snacks (mean [SE]: NW = 424 [10] kcal; OW = 527 [16] kcal; OB = 603 [22] kcal; p < 0.001) than adolescents with OW and NW. Adolescents with OW or OB consumed higher amounts of refined grains, dairy, protein, oil, solid fat, and added sugar from snacks than adolescents with NW (p < 0.05-0.001). CONCLUSIONS: Adolescents with OW or OB consume more calories and higher levels of overconsumed dietary components, i.e., added sugar, solid fats, and refined grains, from snacks than adolescents with NW. Age-specific snacking recommendations to inform dietary guidance are needed to prevent excess intake of overconsumed nutrients and calories.

Frequency of Eating in the US Population: A Narrative Review of the 2020 Dietary Guidelines Advisory Committee Report.

Background: A person's daily nutrient intake and overall nutritional status are determined by a complex interplay of the types and amounts of foods ingested in combination with the timing and frequency of eating. Objectives: The aim was to summarize frequency of eating occasion data examined by the 2020 Dietary Guidelines Advisory Committee, the macronutrient contributions they provide, and meal frequency relative to dietary quality among the US population (≥2 y), with a focus on sex, age, race/Hispanic origin, and income. Methods: Demographic and 24-h recall data from the 2013-2016 NHANES were examined. An eating occasion was defined as "any ingestive event (e.g., solid food, beverage, water) that is either energy yielding or non-energy yielding"; all eating occasions were further divided into discrete meals and snacks. Frequency of meals and snacks was defined as "the number of daily EOs [eating occasions]," respectively. Diet quality was assessed via the Healthy Eating Index (HEI)-2015. Results: Most Americans consume 2 (28%) to 3 (64%) meals on a given day and >90% consume 2 to 3 snacks on that day. Adult, Hispanic, and non-Hispanic Black and lower-income (<131% family poverty-to-income ratio) Americans had a lower frequency of eating than children or adolescents, non-Hispanic White, and non-Hispanic Asian Americans and higher-income Americans, respectively. Americans who reported 3 meals on a given day consumed a diet higher in dietary quality than Americans who consumed 2 meals on a given day (HEI-2015: 61.0 vs. 55.0), regardless of population subgroup. Conclusions: The frequency of the types of eating occasions differs according to age, race and Hispanic origin, and income. Dietary quality is associated with the number of meals consumed. Healthy dietary patterns can be constructed in a variety of ways to suit different life stages, cultural practices, and income levels; improved diet quality and careful consideration of nutrient density when planning meals are warranted.