Protein and Amino Acid Adequacy and Food Consumption by Processing Level in Vegans in Brazil

Abstract

Importance: Major concerns regarding individuals who adhere to a vegan diet are whether they meet protein and essential amino acid recommendations and how reliant they are on ultraprocessed foods.

Objectives: To investigate whether individuals who adhere to a vegan diet meet protein and essential amino acid recommendations and, as secondary objectives, to determine ultraprocessed food intake and potential factors associated with inadequate protein intake in this population.

Design, setting, and participants: This cross-sectional survey study was conducted between September 2021 and January 2023 in Brazil among male and female adults (aged 18 years or older) who adhered to a vegan diet recruited from social media platforms.

Exposure: Adherence to a vegan diet and unprocessed and minimally processed foods and ultraprocessed food consumption.

Main outcomes and measures: Protein and essential amino acid intake and food consumption by processing level were assessed using a 1-day food diary. Nutrient adequacy ratios were calculated by dividing nutrient intake by its recommendation (using scores truncated at 1) for each participant and then finding the mean across participants for each nutrient. The mean adequacy ratio was the mean of all nutrient adequacy ratios.

Results: Of 1014 participants who completed the survey, 774 individuals (median [IQR] age, 29 [24-35] years; 637 female [82.3%]) were confirmed as adhering to a vegan diet and provided adequate food recalls, among whom 558 individuals reported body weight and so had relative protein and amino acid intake values available. The median (IQR) body mass index (calculated as weight in kilograms divided by height in meters squared) of participants was 22.6 (20.3-24.8). The nutrient adequacy ratio of protein was 0.93 (95% CI, 0.91-0.94); for essential amino acids, ratios ranged from 0.90 (95% CI, 0.89-0.92) for lysine to 0.98 (95% CI, 0.97-0.99) for phenylalanine and tyrosine. The mean adequacy ratio for protein and all amino acids was 0.95 (95% CI, 0.94-0.96). The median intake level was 66.5% (95% CI, 65.0%-67.9%) of total energy intake for unprocessed and minimally processed food and 13.2% (95% CI, 12.4%-14.4%) of total energy intake for ultraprocessed food. Adjusted logistic regression models showed that consuming protein supplements (odds ratio [OR], 0.06 [95% CI 0.02-0.14]; P < .001) or textured soy protein (OR, 0.32 [95% CI, 0.17-0.59]; P < .001) was associated with decreased odds of inadequate protein intake. Higher ultraprocessed food intake levels were also associated with decreased odds of inadequate protein intake (eg, fourth vs first quartile of intake: OR, 0.16 [95% CI, 0.07-0.33]; P < .001), and higher unprocessed and minimally processed protein intake levels were associated with increased odds of inadequate protein intake (eg, fourth vs first quartile of intake: OR, 12.42 [95% CI, 5.56-29.51]; P < .001).

Conclusions and relevance: In this study, most individuals who adhered to a vegan diet attained protein and essential amino acid intake recommendations, largely based their diet of unprocessed and minimally processed food, and had a significantly lower proportion of ultraprocessed food intake compared with previous reports. Participants consuming less ultraprocessed food were more likely to have inadequate protein intake, suggesting a significant reliance on ultraprocessed proteins for this population.

Figure 1.. Nutrient Intake and Adequacy Ratios and Proportion Meeting Recommendations

A, Violin plots show the distribution of essential amino acid and protein intake relative to body mass. Dots indicate medians; whiskers, 95% CIs; red dashed lines, respective recommendations. B, Nutrient mean adequacy ratios (presented as ratios, ranging from 0-1, left axis) and the proportion of individuals above and below recommendations for essential amino acids and protein (presented as percentages, ranging from 0%-100%, right axis) are shown.

Figure 2.. Caloric and Protein Intake by Nova Food Processing Category

A, Violin plots show the distribution of relative caloric contribution of each food processing category. Dashed lines indicate reference values from the Brazilian population living in metropolitan areas. B, The relative contribution of each food processing category to protein intake is shown. Dots indicate medians; whiskers, 95% CIs.

Figure 3.. Logistic Regression Models for Association of Variables With Protein Inadequacy

A, The association between binary variables (consuming protein supplements and consuming textured soy protein) with inadequate protein intake is shown. B, The association between quartiles of continuous variables and inadequate protein intake is shown. Results are presented as odds ratio coefficients and 95% CIs for having inadequate protein intake given the variable in comparison with the reference level. NA indicates not applicable.