What is the question?

• What is the relationship between beverage consumption and growth, size, body composition, and risk of overweight and obesity?

What is the answer to the question?

• Milk: 
  • Limited evidence suggests that milk intake is not associated with adiposity in children. 
  • Insufficient evidence is available to draw a conclusion about the relationship between the type of milk (i.e., milk fat content, flavor) and adiposity in children.
  • Limited evidence suggests that higher milk intake is associated with a greater increase in height compared to lower intake in children.
  • Limited evidence suggests that milk intake is not associated with adiposity in adults.  
• 100% Juice: 
  • Limited evidence suggests 100% juice intake in children is not associated with adiposity or height in children. 
  • Limited evidence suggests 100% juice consumption is not associated with measures of adiposity in adults.
• Sugar-sweetened beverages: 
  • Moderate evidence suggests that higher sugar-sweetened beverage intake is associated with greater adiposity in children. 
  • Limited evidence suggests that higher sugar-sweetened beverage intake is associated with greater adiposity in adults. 
  • Insufficient evidence is available to determine the relationship between sugar-sweetened beverages compared with low- and no- calorie sweetened beverages on adiposity in children.
  • Limited evidence suggests no association between sugar-sweetened beverages compared with low- and no- calorie sweetened beverages on adiposity in adults.
• Low and no-calorie sweetened beverages:
  • Limited evidence suggests no association between low- and no-calorie sweetened beverage consumption and adiposity in children.
  • Limited evidence suggests that low- and no- calorie sweetened beverage consumption is associated with reduced adiposity in adults.

Why was this question asked?

• This important public health question was identified by the U.S. Departments of Agriculture (USDA) and Health and Human Services (HHS) to be examined by the 2020 Dietary Guidelines Advisory Committee.

How was this question answered?

• The 2020 Dietary Guidelines Advisory Committee, Beverages and Added Sugars Subcommittee conducted a systematic review to answer this question with support from the Nutrition Evidence Systematic Review (NESR) team.

What is the population of interest? 

• Healthy people and/or those at risk for chronic disease, ages 2 and older were included in this evidence.

What evidence was found? 

• This review includes 152 articles that examined drinking milk (62 articles), 100% juice (42 articles), sugar-sweetened beverages (SSBs, 76 articles), or low- and no-calorie sweetened beverages (LNCSBs, 37 articles). Some articles examined more than one type of beverage.
• Most studies examined outcomes related to adiposity. Examples of these outcomes are: BMI, BMI above a cutoff (i.e., overweight, obesity), waist circumference, and body fat.
• Milk: Few studies reported significant associations, which suggests that the amount of milk children and adults drink is not associated with adiposity. However, children who drank more milk tended to grow taller than children who drank less milk. The articles did not provide enough evidence to draw conclusions about the type of milk children drink (i.e., milk fat levels, flavored milk) and adiposity.
• 100% Juice: Evidence from the highest-quality studies suggests that the amount of 100% juice children and adults drink is not associated with adiposity.
• SSBs: Most studies compared drinking SSBs with drinking less SSBs or drinking water instead of drinking SSBs. These studies tended to find that children and adults who drink SSBs have higher adiposity than children and adults who drink less SSBs or drink water instead. A small number of studies compared drinking SSBs with drinking LNCSBs. This evidence tended to be inconsistent. In children, there was not enough evidence to draw a conclusion about drinking SSBs compared with LNCSBs and adiposity. In adults, the evidence suggested that there is no association.
• LNCSBs: Few studies in children reported significant associations, which suggests that the amount of LNCSBs children drink is not associated with adiposity. In contrast, most studies in adults (including the highest-quality studies) reported that adults who drink more LNCSBs have lower adiposity than adults who drink less LNCSBs.
• The evidence has several limitations. The studies differed from one another in some important ways, such as the outcomes that were measured and the way the beverage exposure was defined. Some studies may not have been long enough or may not have studied enough participants to detect associations. Factors other than beverage consumption may impact the outcomes, and these factors were not always carefully addressed in the studies’ analyses.

How up-to-date is this systematic review?

• This review searched for studies from January 2000 to June 2019, with the exception of evidence on sugar-sweetened beverage consumption compared to a different amount of sugar-sweetened beverage consumption or water, in which the search included studies from January 2012 to June 2019. 

Background

• This important public health question was identified by the U.S. Departments of Agriculture (USDA) and Health and Human Services (HHS) to be examined by the 2020 Dietary Guidelines Advisory Committee.
• The 2020 Dietary Guidelines Advisory Committee, Beverages and Added Sugars Subcommittee conducted a systematic review to answer this question with support from the Nutrition Evidence Systematic Review (NESR) team.
• The goal of this systematic review was to examine the following question: What is the relationship between beverage consumption and growth, size, body composition, and risk of overweight and obesity?

Conclusion statements and grades

• Milk: 
  • Limited evidence suggests that milk intake is not associated with adiposity in children. (Grade: Limited)
  • Insufficient evidence is available to draw a conclusion about the relationship between the type of milk (i.e., milk fat content, flavor) and adiposity in children. (Grade: Grade not assignable)
  • Limited evidence suggests that higher milk intake is associated with a greater increase in height compared to lower intake in children. (Grade: Limited)
  • Limited evidence suggests that milk intake is not associated with adiposity in adults. (Grade: Limited)
• 100% Juice: 
  • Limited evidence suggests 100% juice intake in children is not associated with adiposity or height in children. (Grade: Limited)
  • Limited evidence suggests 100% juice consumption is not associated with measures of adiposity in adults. (Grade: Limited)
• Sugar-sweetened beverages: 
  • Moderate evidence suggests that higher sugar-sweetened beverage intake is associated with greater adiposity in children. (Grade: Moderate)
  • Limited evidence suggests that higher sugar-sweetened beverage intake is associated with greater adiposity in adults. (Grade: Limited)
  • Insufficient evidence is available to determine the relationship between sugar-sweetened beverages compared with low- and no- calorie sweetened beverages on adiposity in children. (Grade: Grade not assignable)
  • Limited evidence suggests no association between sugar-sweetened beverages compared with low- and no- calorie sweetened beverages on adiposity in adults. (Grade: Limited)
• Low and no-calorie sweetened beverages:
  • Limited evidence suggests no association between low- and no-calorie sweetened beverage consumption and adiposity in children. (Grade: Limited)
  • Limited evidence suggests that low- and no- calorie sweetened beverage consumption is associated with reduced adiposity in adults. (Grade: Limited)

Methods 

• A literature search was conducted using 3 databases (PubMed, Cochrane, Embase) to identify articles that evaluated the intervention or exposure of non-alcoholic beverage consumption and the outcomes of growth, size, body composition, and risk of overweight and obesity. A manual search was conducted to identify articles that may not have been included in the electronic databases searched. Articles were screened by two NESR analysts independently for inclusion based on pre-determined criteria. 
• Data extraction and risk of bias assessment were conducted for each included study, and both were checked for accuracy. The Committee qualitatively synthesized the body of evidence to inform development of a conclusion statement(s), and graded the strength of evidence using pre-established criteria for risk of bias, consistency, directness, precision, and generalizability.

Summary of the evidence

Milk: 

• The body of evidence includes 62 papers: 30 papers on children and 32 papers on adults. Of the evidence on children, there were 4 papers from randomized controlled trials (RCTs) and 26 papers from longitudinal cohort studies. Of the evidence on adults, there were 7 papers from RCTs; 24 papers from prospective cohort studies; and 1 paper using a Mendelian Randomization design. 
• To discern healthy growth from excessive growth in children, weight status (i.e., prevalence or incidence of overweight or obesity), BMI and BMI z-scores, and body composition measures (e.g., waist circumference and body fat), were considered to reflect “adiposity.” 
  • The majority of the findings for these outcomes were not significant. The few findings that were significant were not consistent in direction. 
• To assess healthy growth in children, outcomes such as height and lean mass were considered. Four studies reported height as an outcome: 3 cohort studies reported a significant positive association between milk intake and height in children, and 1 RCT found no effect of milk intake on height compared to drinking water though this study’s duration was only 12 weeks.
• Seven cohort studies specifically examined types of milk (i.e. milk fat levels, flavored milk) and adiposity outcomes in children; however, the results were not consistent. 
• The majority of the studies in adults found no significant association between milk intake and adiposity; there were some significant associations; however, these were inconsistent in direction. 
• The body of evidence from children and adults has several significant limitations including lack of specificity and consistency in definition of the exposure, the use of non-validated methods for assessing beverage intake, uncontrolled confounding, and inconsistencies in findings. More research is needed to address these issues. 

100% Juice: 

• 42 papers examining the relationship between 100% juice intake and outcomes related to growth, size, body composition, and risk of overweight or obesity were included in this body of evidence.
• Studies published between January 2000 and June 2019 were synthesized by age group
  • Children: 23 studies, including 1 RCT and 22 prospective cohort studies 
  • Adults: 19 studies, including 4 RCTs, 1 NRCT, and 14 prospective cohort studies 
• Evidence in children
  • The 1 RCT and the majority of the higher quality prospective cohort studies found no statistically significant relationship between 100% juice intake and adiposity.  
  • The few studies that were significant were not consistent in direction.
  • The evidence in children was limited by lack of clarity in defining the juice exposure; inconsistent quantification of juice consumption, inconsistent measures of adiposity, lack of evidence from stronger study designs, and inadequate adjustment for confounders.
• Evidence in adults
  • The 4 RCTs and 1 NRCT found no statistically significant relationship between 100% juice intake and adiposity. 
  • The prospective cohort studies found inconsistent evidence depending on the specific measure of adiposity.  For example, roughly half of the studies (n=4) found that greater consumption of 100% juice intake was related to a greater increase in weight, while the others (n=3) found no significant relationship. Studies examining waist circumference were more consistent, with 5 of the 6 studies finding no significant association with 100% juice intake. Further, all studies (n=3) examining body fat or prevalence of (abdominal) obesity found no significant associations with 100% juice intake. 
  • The evidence from the RCTs and NRCT were limited by the short durations small sample sizes.
  • The evidence from the prospect cohort studies were limited by the single measurement of the exposure, reliance on self-reported outcome data, inadequate adjustment for confounders, and limited generalizability of the experimental data.

Sugar-sweetened beverages: 

• 76 studies identified via a literature search from June 2012 to June 2019 were included in this systematic review. Studies were synthesized based on comparator (no/different amount of sugar-sweetened beverage or low/no-calorie sweetened beverage) and age of participants (children or adults). 
• Sugar-sweetened beverage (SSB) consumption compared to different amounts or water
  • Children: 46 articles
    • RCTs: 2 articles
    • NRCTs: 1 article
    • Prospective cohort studies: 43 articles 
  • Adults: 27 articles
    • RCTs: 3 articles
    • NRCTs: 1 article
    • Prospective cohort studies: 23 articles 
• Sugar-sweetened beverage consumption compared to low- or no-calorie sweetened beverages (LNCSB)
  • Children: 2 articles 
    • RCTs: 2 articles
  • Adults: 6 articles 
    • RCTs: 5 articles
    • Prospective cohort studies: 1 article
• In studies examining SSB intake in children, the majority of studies (~80%) reported a significant effect or association between SSB intake and adiposity, however this was not always consistent within studies that reported multiple outcome measures. There were additional concerns related to risk of bias and generalizability. 
• In studies examining SSB intake in adults, the majority of studies (~70%) reported a significant effect or association between SSB intake and adiposity; however, this was not always consistent within studies that reported multiple outcome measures. The 3 included RCTs had significant risk of bias concerns related to the methodology, particularly around the comparator, and concerns with generalizability.   
• Two articles from one RCT addressed the relationship between SSB compared to LNCSB intake in children and there was insufficient evidence to draw a conclusion. 
• In studies comparing intake of SSBs and LNCSB in adults, there was inconsistency in findings and in methodology. Of the 5 RCTs, 3 did not find a significant difference between groups, however 2 of these studies had small sample sizes and may have been underpowered. Of the 2 studies that did report a significant effect, there was not a significant effect across all reported outcomes. For example, one study reported differences based on the type of sweetener within LNCSB and the other did not find a difference in weight or BMI between groups, but did report that those who consumed LNCSB were more likely to achieve 5% weight loss.

Low and no-calorie sweetened beverages: 

• There were 37 studies identified via literature search from January 2000 to June 2019 included in this systematic review that examined the relationship between LNCSB and outcomes related to growth, size, body composition, and risk of overweight and obesity.
  • Of the 17 papers in children, all were prospective cohort studies.
  • Of the 20 papers in adults, 6 were from RCTs and 14 were from prospective cohort studies.
• In studies examining LNCSB intake in children, the majority of studies (~75%) reported no association for the main outcome measure(s) of adiposity among the study populations. The remaining studies had mixed associations and methodologic concerns.
  • 3 papers with findings of increased adiposity measures
  • 1 paper with findings of decreased adiposity measures
  • 1 paper only reported height-related outcomes
• The body of evidence from children had several limitations
  • Inadequate adjustment for confounders
  • Inconsistency in methods for assessing beverage intake
  • Short study duration
  • High attrition
• In studies examining LNCSB intake in adults, the majority of studies (72%) reported a significant effect or association between LNCSB intake and adiposity; however, this was not always consistent within studies that reported multiple outcome measures.
  • One well-designed RCT and two large prospective cohort studies reported an association between LNCSB and reduced adiposity.
• The body of evidence from adults had several limitations
  • Experimental studies: short study duration, no assessment of compliance, and difference in comparators
  • Cohort studies: confounding, difference in assessment methods, poor generalizability, and high attrition