DIET

 

ANCOVA was used to compare the food and nutrient intake of vegetarians and non-vegetarians while controlling for age, sex, ethnicity, education of mother, education of father, total energy intake, BMI z-score, and physical activity level. Intakes of total fat, SFA, monounsaturated fatty acids (MUFA), LA:ALA ratio, total protein, vitamin D, and sodium were lower for both groups compared to the US adolescents, but zinc intake was only lower for vegetarians. On the other hand, a larger proportion of non-vegetarians met the zinc recommendations compared to their vegetarian counterparts (77 vs. Comparison of the intake of selected nutrients by vegetarians and non-vegetarians.

As seen in Table 4, at least 75% of both vegetarians and non-vegetarians in the study population met the recommended intake amounts for carbohydrates, protein, vitamin B12, riboflavin, vitamin C, thiamine, folate, and iron, and had adequate intakes of the omega-3 fatty acid, alpha linolenic acid (ALA). Vegetarians significantly ate more fruits, vegetables, and other plant-based foods, but significantly less foods of animal origin, sugar-sweetened beverages, and coffee/tea compared to non-vegetarians. All study protocols, including data collection and informed consent, were approved by the Institutional Review Boards of Andrews University in Michigan (IRB#12-113) and Loma Linda University in Southern California (IRB#5120014).

Assessment of Dietary Intake

Dietary intake was measured using a validated 151-item self-administered semi-quantitative web-based food frequency questionnaire designed for the study (27). Dietary intake was measured with a validated 151-item self-administered web-based food frequency questionnaire; weight and height were measured during school visits. In the web-based survey, participants also self-reported their weight and height after measuring themselves. A sizable proportion of this population are vegetarians, 4.2% being vegan and ~32% being left-over vegetarian (23). About 77% of vegetarians reported adequate intake of linoleic acid compared to about 72% of non-vegetarians. More vegetarians (49%) than non-vegetarians (25%) had <10% of their caloric intake from SFA. Intake of dairy products by non-vegetarians was higher by just a small amount (between 0.07 to 0.30 of a serving) compared to vegetarians. Not surprisingly, non-vegetarians ate slightly over one serving more of animal protein foods than the non-vegetarians, but their egg intake amounted to approximately one-third of a serving compared to about one-fourth of a serving for their vegetarian counterparts. The parents' educational levels were used as surrogate for socio-economic status. The informed consent was made official and printed for record-keeping only after the parent had confirmed his/her identity and consent, and the child's assent to participate. Comparison of the intake of selected foods by diet groups.

Table 3 shows a comparison of the nutrient intakes between the two diet groups. Percentage who met age-and-gender specific recommendations for intake of selected nutrients and food groups.

Table 4 also shows the percentage of study participants who met the recommendations for vegetables, fruits, grains, dairy, and protein foods. The nutrients assessed in the study were: energy, total carbohydrates, added sugar, total fat, saturated fatty acids (SFA), mono-unsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), linoleic acid (LA), alpha linolenic acid (ALA), total protein, animal protein, vegetable protein, total dietary fibber, insoluble fibber, soluble fibber, vitamin B12, vitamin C, thiamine, riboflavin, vitamin D, vitamin E, folate, calcium, iron, potassium, magnesium, sodium, and zinc.

Intake Comparisons With the US Adolescent Population

Food intakes of the study population were compared with their counterparts in the general US population using the values for those aged 14–18 years old in the 2007–2010 published estimates for the US population in the National Cancer Institute's Epidemiology and Genomics Research Program website (30). 62%), and nuts/soy products (98 vs. In a 2016 national poll conducted in the United States among a representative sample of adults ages 18 years and above, 3.3% were self-reported vegetarians, half of whom claimed to be vegans (20).

Vegetarian and vegan diets are associated with a lower risk of chronic diseases among adults (21, 22). Increased portion sizes of marketplace foods (10) have contributed to increased caloric consumption (11, 12) and low diet quality among US adolescents (13). Compared to their non-vegetarian counterparts, a larger percentage of vegetarians ate more vegetables (80 vs. On the contrary, intake of nutrient-dense foods (i.e., fruits and vegetables), remains below recommendations (15–18).

With a growing trend toward plant-based diets, there is an increasing movement toward vegetarian eating in different population groups, including adolescents. Intakes of dairy, fruits, total vegetables, non-starchy vegetables, and protein foods were relatively greater (ranging from about 25% to 300% more), whereas intakes of breads/grains/pastas, starchy vegetables, and fish were relatively lower (ranging from about 20 to 90%) for both diet groups than average US adolescents. High diet quality is also imperative to prevent depression (6), an increasing mental health problem among the youth and young adults (6–8).

Increased independence during adolescence and other factors, such as the family's socio-economic condition and education of parents (9), may influence dietary habits. Although both groups had parents with college education or higher, the vegetarians had a significantly greater proportion of parents with higher education, especially at the graduate level. The final analytical dataset included 534 participants.

Descriptive and univariate analyses for all participants and by dietary preference (vegetarian vs. Vegetarian was defined as the combined intake of meat, meat derivatives, poultry, and fish of <1 serving per week. Our objective was to describe and compare the dietary intake of vegetarian adolescents with their non-vegetarian counterparts in a population known to espouse healthy living. non-vegetarian) were conducted using either independent t-test or Chi-square test to check differences between vegetarians and non-vegetarians. Vegetarian was defined as intake of less than one combined portion (<3 ounces) of meat, meat derivatives, poultry, and fish per week.

Assessment of Other Measures

During school visits, trained personnel measured weight and height of the participants. Vegan diets eliminate all animal products. Vegetarians ate about one-half serving more of fruits, nearly serving more of vegetables, and over one serving more of nut/nut butters and meat alternatives than their non-vegetarian peers. A website was especially created for the study that served as the interface in the enrolment of potential participants and their parents, completing informed consent, and providing information on demographics, lifestyle habits, physical development, and dietary intake using the web-survey. Non-vegetarians, however, spent significantly more time in vigorous physical activity compared to their vegetarian counterparts.

TABLE 1

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Table 1. 39%) than vegetarians. Overall, vegetarian adolescents have a more favourable dietary intake profile than non-vegetarians, but both vegetarians and non-vegetarians in this study population have a more adequate diet than the general US adolescent population. In the same manner as for foods, percent differences between the mean intakes of the vegetarians and non-vegetarians were then calculated against the general US population/NHANES values.

Intake Comparisons With Dietary Guidelines and Dietary Reference Intakes

The US Dietary Guidelines Recommendations and Nutritional Goals for Age-Sex Groups Based on Dietary Reference Intakes and Dietary Guidelines Recommendations found in Appendix 7 of the 2015–2020 Dietary Guidelines for Americans (2015DGA) (32) was used to determine what proportions of the study population met the recommended intake amounts for selected nutrients. 36%), and magnesium (56 vs. Since mean intake values were separated for male and female adolescents, weighted means were computed to represent the whole group. Almost 50% of the vegetarians consumed <10% of their total caloric intake from saturated fatty acids (SFA) whereas only half of that proportion (~25%) met the SFA intake recommendation among non-vegetarians. Given that our weft was semi-quantitative, i.e., has fixed serving sizes, intake of these food groups was determined based on the sum of the intake frequency per day of the foods under each group, where frequency per day is equivalent to serving per day.

The nutrient profile of each food in the FFQ was determined using the Nutrition Data System for Research (29) database. A majority (75% or more) of both groups met the 2015 Dietary Guidelines' age-and-gender-specific recommendations for most nutrients but only 16–18% of vegetarians/non-vegetarians did not exceed the upper limit for sodium. Girls were more likely to be vegetarians compared to boys and more than half (52%) of the vegetarians were non-Hispanic whites. 48%) recommendations. Of the non-vegetarians, only 7% and 44% met the fish and meats/poultry/eggs recommendation, respectively, which none of the vegetarians met. Table 2 displays the estimated marginal means with their 95% confidence intervals after controlling for relevant covariates. 38%) and protein foods (61 vs. Demographic characteristics according to vegetarian status.

As shown in Table 2, there were significant differences in the food intakes of vegetarians and non-vegetarians. Some of these variables were controlled for when dietary intake comparisons were made between vegetarians and non-vegetarians.

Data Management and Analysis

Of the 601 original participants, 13 were excluded due to completely missing diet or demographic data and 54 were excluded due to implausible energy intake (<500 calories and >3,500 calories for girls, <800 calories and >4,500 calories for boys). Supplementary Table 1 shows the list of foods under each of the food groups. A vegetarian diet excludes meat, seafood, and products containing both, but may include eggs and dairy. Compared to the general US adolescent population, both diet groups ate more fruits, vegetables, dairy and protein foods, and also consumed more micronutrients but less macronutrients. On the other hand, non-vegetarians significantly consumed more total (~6 g more), saturated (~5 g more) and monounsaturated (~3 g more) fats, animal protein (~23 g more), and zinc (1 mg more) compared to vegetarians.

TABLE 3

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Table 3. Adolescents (n = 534) aged 12–18 years old from middle and high schools near major Adventist universities in Michigan and Southern California provided dietary, demographic, and anthropometric data. Thus, our objectives were to describe and compare the dietary intake of Adventist vegetarian and non-vegetarian adolescents, determine if their reported intakes meet the recommend intakes for their age group, and compare their dietary profile with those of the general US adolescent population.

Methods

Study Design and Participants

In previous reports, we have described a cross-sectional study—the Teen Food and Development Study—that we conducted among adolescents to examine associations between dietary intake and certain health outcomes, particularly physical growth and pubertal development (24–26). Although intakes of sugar-sweetened beverages and coffee/tea were small for both groups (much less than a serving), the non-vegetarians significantly consumed more of these beverages than the vegetarians.

TABLE 2

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Table 2. However, while plant-based or vegetarian diets and their health effects are well studied in adults, reports on vegetarian children and adolescents are scarce. Descriptive statistics and ANCOVA were used to compare the intake of vegetarians and non-vegetarians. Vegetarians were also leaner compared to non-vegetarians. A healthy diet during adolescence predisposes to better physical health since it is associated with lower weight gain (1) and lower risk of developing cardiovascular risk factors (5) during adulthood. Vegetarians had significantly higher intakes of carbohydrates and total protein but lower intakes of fats, animal protein, and zinc compared to their counterparts. Although there has been a decrease in sugar- sweetened beverages intake since 1999 (14), high-calorie-low nutrient-density foods have remained major sources of calories among the youth (12–14). Participants reported frequency of their intake of a food item using a drop-down list: never/rarely, 1–3 times per month, once per week, 2–4 times per week, 5–6 times per week, once per day, 2–3 times per day, and 4 or more times per day.

Assessment of Vegetarian Status

Vegetarian status was determined based on self-reported intake of foods that differentiate vegetarians from non-vegetarians. 77%), legumes (88 vs. Very small proportions (≤10%) of both vegetarians and non-vegetarians met the dietary recommendations for vitamins D and E and potassium, and <20% consumed sodium below the upper limit. A national online survey conducted by Harris Poll for the Vegetarian Resource Group in 2014 indicated that 4% of youth ages 8–18 years are vegetarians while a total of 32% eat at least one vegetarian meal per week (19). Intakes of ALA, dietary fibre, vitamin B12, vitamin C, thiamine, vitamin E, folate, iron, potassium, and magnesium were higher for both groups (ranging from ~10 to ~290%) except for zinc, which was only higher for the non-vegetarian group compared to the US adolescent population. However, only vegetarians reported lower intake of fish while non-vegetarians had a fish intake similar to that of US adolescents. Only vegetarians had higher intakes of polyunsaturated fatty acids (PUFA), linoleic acid (LA), and calcium. More than 90% of both groups met dairy recommendations, but greater proportions of vegetarians met recommendations for vegetables, fruits, nuts/soy products, and legumes than non-vegetarians. 36%), calcium (44 vs. Anthropometrics were measured during school visits.

Parents of potential participants 17 years old and younger provided their consent for their children's participation in the study by checking a box and providing their name and at least one telephone number at which they could be reached. Compared to non-vegetarians, a larger proportion of vegetarians met the dietary fibber (53 vs. Clinical data for the anthropometrics were used for the statistical analysis; however, for participants who were absent during the school visits (about 4%), self-reported measures were used in the analysis since self-reported weight and height were found to be highly correlated to the clinic-measured values (28).

A section of the self-administered web survey included items on demographics and lifestyle (time spent on vigorous physical activity and sleep). Before analysis, the food and nutrient variables were log-transformed due to non-normal distributions.

Food Groupings and Nutrient Calculations

Foods were grouped according to the following categories: (1) breads, grains and pastas; (2) cereals; (3) fresh fruits; (4) 100% fruit juices, canned and dried fruits; (5) non-starchy vegetables; (6) starchy vegetables; (7) legumes; (8) meats (red meats, processed meats, and poultry); (9) fish; (10) meat alternatives; (11) nuts and nut butters; (12) eggs; (13) dairy cheese; (14) dairy milk; (15) dairy substitutes; (16) dairy desserts; (17) water; (18) sugar-sweetened beverages; (19) coffee and tea; and, (20) pastries and chips. To ascertain that a parent actually provided the consent, a call was made at the telephone number provided. Vegetarians had significantly higher intakes of carbohydrates (~27 g more), polyunsaturated fatty acids (~3 g more PUFA and LA, and ~2 g more ALA), LA:ALA ratio, vegetable protein (~21 g more), dietary fibber (~8 g more), vitamin C (~20 mg more), thiamine (~1.7 mg more), vitamin E (~1.4 mg more), folate (~135 mcg more), calcium (~130 mg more), iron (3.6 mg more), potassium (~296 mg more), magnesium (~72 mg more), as well as sodium (~150 mg more) and phosphorus (57 mg more). In the same manner, the children indicated their assent to be part of the study by checking the assent box and providing their name on the same consent form. Although several studies have been published on Adventist adults, only very few have been reported on young people and none of these investigated their dietary intakes. No vegetarian participants met the meat/poultry/eggs and fish intake recommendations.

Figures 1, 2 show comparisons of percent intake differences for food groups (Figure 1) and nutrients (Figure 2) between the two diet groups and the general US adolescent population. 70%). We used the dietary data from this study in this report. To determine if the participants met the recommended food groups intake, Healthy U.S.-Style Eating Pattern: Recommended Amounts of Food from Each Food Group at 12 Calorie Levels found in Appendix 3 of the 2015DGA was used. Briefly, we collected data on 601 adolescents (262 males and 339 females) aged 12–18 years old from selected Adventist and public middle and high schools near major Adventist universities in Michigan and Southern California. Nutrient intake per day was computed using the sum-product method, i.e.,

A=∑i=1nFiai (1)

where A = total intake of nutrient A per day; Fi = frequency of food i intake per day; and ai = amount of nutrient A in food i. Briefly, the questionnaire included 8 food groups: convenience foods (32 items), protein-rich foods (29 items), starches/cereals (17 items), vegetables/fruits (21 items), dairy products (10 items), beverages (24 items), snacks/sweets (11 items), and soups/legumes (7 items). 64%).

TABLE 4

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Table 4. Nutrient and energy demands increase to support the accelerated growth and development during adolescence, thus, it is crucial to establish or maintain healthy dietary habits during this period since this tends to persist through adulthood (4). 74%), fruits (72 vs. Dietary intake of adult vegetarians from large prospective studies has been well-characterized but is rarely reported in vegetarian adolescents. Comparisons were made according to age and gender group recommendations for nutrients and calorie levels of 1,600 kcal (for female participants ages 12–13 years old), 1,800 kcal (for male participants ages 12–13 years old and female participants ages 14–18 years old), and 2,200 kcal (for male participants ages 14–18 years old).

Results

The demographic profile of the study population is presented in Table 1 for both vegetarians and non-vegetarians. The first 16 food groups were further re-categorized into breads/grains/pastas/cereals, total fruits, total vegetables, total protein foods, total dairy. Weighted mean intake values for selected foods were computed since mean intakes were reported separately for males (n = 808) and females (n = 727). We have access to the Adventist population, a group of people known to espouse a healthy lifestyle that includes a plant-based diet. Percent differences between the mean intakes of the vegetarians and non-vegetarians in the study population were then calculated against the weighted means of the US adolescent population.

Nutrient intakes of the study population were also compared with the general US population ages 12–19 years using What We Eat in America, NHANES 2011–2012 (31) values from the Nutrient Intakes from Food and Beverages table. Only a small proportion of both groups met the recommendations for starchy vegetables, while more non-vegetarians met the recommendations for grains (41 vs. The influence of the Adventist plant-based diet culture that is translated both at home and at school is evident in our findings.

Introduction

Dietary habits formed during childhood and adolescence have both short- and long-term impacts on health (1–3). 68%), non-starchy vegetables (85 vs.