Health and environmental impacts of plant-rich dietary patterns: a US prospective cohort study

BACKGROUND

Diets that are rich in animal-based foods threaten planetary and human health, but plant-rich diets have varied health and environmental effects. We aimed to characterise a healthy dietary index and three plant-based indices by their environmental impacts and associations with risk of cardiovascular disease.

METHODS

In this prospective cohort study, we used data from a food-frequency questionnaire in the US-based Nurses' Health Study II. Participants were categorised by quintiles of four dietary indices, including the alternative healthy eating index-2010 (AHEI), plant-based diet index (PDI), unhealthy PDI, and healthy PDI. We calculated environmental impacts (greenhouse gas emissions and irrigation water, nitrogenous fertiliser, and high-quality cropland needs), and relative risks (RRs) of cardiovascular disease from 1991-2017, comparing quintiles.

FINDINGS

We included 90 884 participants in the health-impact analysis and 65 625 participants in the environmental-impact analysis. Comparing the top and bottom quintiles, higher AHEI scores were associated with a decreased cardiovascular disease risk (relative risk 0·77 [95% CI 0·66-0·89]); 30% lower greenhouse gas emissions (Q5 2·6 kg CO₂ equivalent vs Q1 3·7 kg CO₂ equivalent); and lower fertiliser, cropland, and water needs (all p_trends<0·0001). Similarly, the highest healthy PDI and PDI quintiles were associated with a decreased cardiovascular disease risk (healthy PDI 0·71 [0·60-0·83] and PDI 0·74 [0·63-0·85]) and lower environmental impacts (PDI water needs p_trend=0·0014; all other p_trends<0·0001). Conversely, the highest unhealthy PDI quintile had a higher cardiovascular disease risk compared with the lowest unhealthy PDI quintile (1·15 [1·00-1·33]; p_trend=0·023) and required more cropland (p_trend<0·0001) and fertiliser (p_trend=0·0008).

INTERPRETATION

Dietary patterns that are associated with better health had lower greenhouse gas emissions and nitrogenous fertiliser, cropland, and irrigation water needs. Not all plant-based diets conferred the same health and environmental benefits. US dietary guidelines should include nuanced consideration of environmental sustainability.

FUNDING

US National Institutes of Health.

Processed and Packed: How Refined Are the Foods That Children Bring to School for Snack and Lunch?

BACKGROUND

Increasing consumption of highly processed foods has been associated with adverse health outcomes among children. In the US, children consume up to half of their daily energy intake at school.

OBJECTIVES

We sought to characterize foods that children bring from home to school according to processing level and to evaluate the effectiveness of a school-based intervention, Great Taste Less Waste (GTLW), in reducing the proportion of energy brought from highly processed foods from home compared with control.

DESIGN

Secondary data analysis of a 7-month school-based, cluster-randomized trial.

PARTICIPANTS/SETTING

Third- and fourth-grade students (n = 502, mean age: 9.0 ± 0.62 years) at 10 public elementary schools in Eastern Massachusetts (school year 2012-2013).

INTERVENTION

GTLW included a 22-lesson classroom curriculum, homework activities, monthly parent newsletters, a food shopping and packing guide for parents, food demonstrations, school-wide announcements, and a poster contest.

MAIN OUTCOME MEASURES

The energy content of foods brought to school was estimated from digital photographs, and foods were assigned to 1 of 3 processing levels (less processed or unprocessed, moderately processed, or highly processed) based on an established classification system.

STATISTICAL ANALYSES PERFORMED

The percentage of energy brought from foods categorized into each processing level was calculated and compared pre- and postintervention using hierarchical linear models.

RESULTS

Most of the food brought from home to school was highly processed (70% of food energy brought). Foods categorized as snack foods and desserts contributed the greatest percentage of total energy to the highly processed category at baseline and follow-up (72% and 69%, respectively). Energy from foods brought for snack tended to be more highly processed than those brought for lunch. No significant differences were observed from pre- to postintervention in the GTLW group compared with control for the percentage of energy brought from highly processed foods in adjusted models (β: -1.1, standard error: 2.2, P = .6) or any other processing level.

CONCLUSIONS

Highly processed foods were prevalent in home-packed lunches and snacks, and these patterns persisted after a targeted intervention. Further research is needed to identify strategies to improve the healthfulness of foods brought from home to school.

Environmental and Economic Effects of Changing to Shelf-Stable Dairy or Soy Milk for the Breakfast in the Classroom Program

OBJECTIVES

To estimate economic and environmental effects of reducing milk waste from the US Breakfast in the Classroom (BIC) School Breakfast Program by replacing conventional milk with shelf-stable dairy or soy milk.

METHODS

We estimated net greenhouse gas emissions (GHGE; kg CO2 equivalents [e]) from replacing conventional milk with shelf-stable dairy or soy milk by adapting existing life cycle assessments and US Environmental Protection Agency Waste Reduction Model estimates to BIC parameters. We estimated net cost with school meal purchasing data.

RESULTS

Replacing conventional dairy milk with shelf-stable dairy or soy milk would reduce milk-associated GHGE by 28.5% (0.133 kg CO2e) or 79.8% (0.372 kg CO2e) per student per meal, respectively. Nationally, this equates to driving 248 million or 693 million fewer miles annually, respectively. This change would increase milk costs 1.9% ($0.005) or 59.4% ($0.163) per student per meal, respectively.

CONCLUSIONS

Replacing conventional milk with shelf-stable dairy or soy milk could substantially reduce waste and concomitant GHGE in BIC; switching to shelf-stable dairy has low net costs. Pilot tests of these options are warranted to optimize the nutritional value, cost, and sustainability of BIC.

Behavioral Correlates of Empirically-Derived Dietary Patterns among University Students

Given the importance of young adulthood in establishing lifelong dietary habits, it is imperative to better understand potential underlying drivers of dietary behavior in the university-age population. Dietary patterns have been associated with disease risk, but behavioral predictors of dietary pattern adherence are poorly understood, especially among emerging adults. This study aims to evaluate health-related behaviors associated with dietary pattern scores among freshmen participating in the Tufts Longitudinal Health Study (TLHS; n = 630). We previously derived dietary patterns using principal components analysis and orthogonal rotation from dietary intake data. Health-related behavior data were collected via survey. All data were collected during the Spring semesters of 1998⁻2007. Unadjusted linear models were used to determine associations between dietary pattern scores and health-related behaviors. Significant correlates were retained in multivariable regression models, which were adjusted for demographic characteristics. We found that never eating meals away from home was associated with higher adherence to the Prudent and lower adherence to the Western and Alcohol patterns. Intention to lose weight was negatively associated with the Western pattern, while intention to gain weight was positively associated with all dietary patterns. These findings suggest that intervention efforts aimed at improving eating out behaviors and engaging in healthy weight management strategies may promote healthier dietary patterns among university students.

Factors Influencing Fluid Milk Waste in a Breakfast in the Classroom School Breakfast Program

OBJECTIVE

To determine predictors of fluid milk waste in a Breakfast in the Classroom School Breakfast Program.

DESIGN

Cross-sectional with 3 repeated measures/classroom.

SETTING

Elementary schools in a medium-sized, low-income, urban school district.

PARTICIPANTS

Twenty third- through fourth-grade classrooms across 6 schools.

MAIN OUTCOMES

Dependent variables include percentage of total and served milk wasted. Independent variables included observed daily menu offerings, program factors, and teacher and student behavior.

ANALYSIS

Descriptive statistics were used to characterize variables across classrooms and schools. Multilevel mixed-effects models were used to test associations between predictors and outcomes of interest. P ≤ .05 was considered statistically significant.

RESULTS

Total milk waste increased 12% when juice was offered and 3% for each additional carton of unserved milk. Teacher encouragement to take and/or consume breakfast was associated with a 5% and 9% increase in total and served milk waste, respectively. When students were engaged in other activities in addition to eating breakfast, total milk waste decreased 10%.

CONCLUSIONS AND IMPLICATIONS

Beverage offerings were predictive of greater total milk waste. Teacher and student behavior also appeared to influence milk consumption. Findings suggest that specific changes to School Breakfast Program implementation policies and practices could have an important role in waste mitigation.

Nutritional, Economic, and Environmental Costs of Milk Waste in a Classroom School Breakfast Program

OBJECTIVES

To measure fluid milk waste in a US School Breakfast in the Classroom Program and estimate its nutritional, economic, and environmental effects.

METHODS

Fluid milk waste was directly measured on 60 elementary school classroom days in a medium-sized, urban district. The US Department of Agriculture nutrition database, district cost data, and carbon dioxide equivalent (CO₂e) emissions and water footprint estimates for fluid milk were used to calculate the associated nutritional, economic, and environmental costs.

RESULTS

Of the total milk offered to School Breakfast Program participants, 45% was wasted. A considerably smaller portion of served milk was wasted (26%). The amount of milk wasted translated into 27% of vitamin D and 41% of calcium required of School Breakfast Program meals. The economic and environmental costs amounted to an estimated $274 782 (16% of the district's total annual School Breakfast Program food expenditures), 644 893 kilograms of CO₂e, and 192 260 155 liters of water over the school year in the district.

CONCLUSIONS

These substantial effects of milk waste undermine the School Breakfast Program's capacity to ensure short- and long-term food security and federal food waste reduction targets. Interventions that reduce waste are urgently needed.

Breakfast consumption and adiposity among children and adolescents: an updated review of the literature

BACKGROUND

Breakfast consumption has been associated with reduced risk of overweight and obesity among children, but previous evidence reviews fail to confirm a causal relationship.

OBJECTIVES

To review recent literature on breakfast consumption and adiposity among children and discuss potential underlying mechanisms.

METHODS

A comprehensive literature search of studies published since the 2010 US National Evidence Library review (January 2010-January 2015) was conducted.

RESULTS

Twelve studies met inclusion criteria. All were conducted in industrialized countries: six in Europe, four in the USA, one in China and one in Australia. Ten of the studies used observational longitudinal designs, with follow-up periods ranging from 1 to 27 years (median: 3, mean: 7.4); of these, eight reported inverse associations between breakfast consumption and excess adiposity, while two found no association. The other studies (1 case-control, 1 experimental) each reported a protective effect of breakfast consumption on overweight and obesity among children.

CONCLUSIONS

Findings corroborate results from previous reviews, adding support for a possible, protective role for breakfast consumption in preventing excess adiposity during childhood and adolescence. However, drawing a causal conclusion from the collective evidence is curtailed by methodological limitations and inconsistencies, including study design, follow-up duration and frequency, exposure and outcome assessment, as well as limited consideration of confounding, mediating and effect-modifying variables. More rigorous study designs employing valid and standardized measurement of relevant variables are needed.

Cross-Sectional Associations between Empirically-Derived Dietary Patterns and Indicators of Disease Risk among University Students

The transition from adolescence to adulthood is a unique period during which lifelong dietary habits are shaped. Dietary patterns (DPs) among young adults attending college have not been adequately described, and associations between DPs and indicators of disease risk are not well understood in this age group. Dietary data were collected from undergraduates participating in the Tufts Longitudinal Health Study (TLHS; 1998-2007) by Food Frequency Questionnaire (FFQ; n = 1323). DPs were derived using principal components analysis with varimax rotation. Scree plots; eigenvalues; factor loadings; and previous studies were used to determine and label the DPs retained. Cross-sectional relationships between DP scores and anthropometric measures (percent body fat (PBF) and (BMI) and lipid biomarkers (total; HDL and LDL cholesterol; and triglycerides) were assessed with multivariable regression models; adjusted for demographics; physical activity; smoking; intention to gain/lose weight; and total energy intake. Effect modification by sex was tested. Three DPs were identified: Prudent; Western; and Alcohol. Greater adherence to the Prudent DP was associated with favorable anthropometric outcomes. The Alcohol DP was associated with a favorable lipid profile. Associations between the Western DP and blood lipids differed by sex; with unfavorable impact observed only among males. Our findings add to the literature linking DPs in young adults with measurable adiposity and cardiometabolic outcomes; suggesting that improving nutrition among college students could reduce chronic disease risk.

Serum Retinol and Carotenoids in Association with Biomarkers of Insulin Resistance among Premenopausal Women

Objective. The aim of this study was to investigate how serum retinol and carotenoids (β-carotene, β-cryptoxanthin, lutein/zeaxanthin, lycopene) are associated with biomarkers of insulin resistance. Research Methods and Procedures. The BioCycle Study (2005–2007) is a prospective cohort of 259 healthy premenopausal women. Fasting serum samples were collected at up to sixteen clinic visits, from which retinol, carotenoids, insulin, glucose, and sex hormone-binding globulin (SHBG) were measured. Insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). Linear mixed models were used to determine associations adjusting for age, race, body mass index (BMI), education, smoking, physical activity, triglycerides, and energy intake. Results. Retinol was positively associated with HOMA-IR (β = 0.19 (95% CI: 0.07, 0.32)) units per ug/mL increase in retinol; the relationship was driven by insulin (β = 0.20 (95% CI: 0.08, 0.31)). Retinol was inversely associated with SHBG (β = −0.22 (95% CI: −0.28, −0.16)). Although no significant associations were found between serum carotenoids and HOMA-IR, β-carotene was positively associated with SHBG and β-cryptoxanthin inversely with fasting plasma glucose. Conclusion. Results indicate a possible role for serum retinol in the pathogenesis of type 2 diabetes. However, they do not support a strong association between individual or total serum carotenoids and insulin resistance.