Application of a Modified Healthy Eating Index (HEI-Flex) to Compare the Diet Quality of Flexitarians, Vegans and Omnivores in Germany

Abstract

Interest in plant-based nutrition has steadily increased in the western world in the recent years. The number of people following a meat-reduced, flexitarian diet is growing continuously. However, little is known about the diet quality of flexitarians compared to vegans or omnivores. Therefore, in this cross-sectional study, the food intake of 94 participants aged between 25–45 years was recorded via a validated food frequency questionnaire and 28 self-designed questions about the consumption of plant-based alternatives. An adapted Healthy Eating Index, HEI-flex, was developed to evaluate the diet quality of flexitarians, vegans and omnivores. Higher score points (SP) of the HEI-flex are associated with higher compliance with the official diet recommendations (Vmax = 100 SP). Finally, flexitarians scored significantly more highly when compared to omnivores (54 ± 8 vs. 47 ± 9 SP; p = 0.008) but lower than vegans (54 ± 8 vs. 61 ± 10 SP; p = 0.010). The results showed that the HEI-flex is a useful tool for assessing and comparing the diet quality of flexitarians, vegans and omnivores. Despite the consumption of highly processed plant-based alternatives, reduction in meat and meat products seems to be accompanied by increased overall diet quality.

Differences in dietary intake between Turkish vegans and omnivores: a cross-sectional study

“…Similar to our results, Clarys et al 4 reported higher scores for vegans compared to omnivores (65.4 ± 8.3 vs 54.2 ± 9.0, respectively) when using the older HEI -2010. Bruns et al 47 found that vegans scored significantly higher when compared to omnivores (61 ± 10 vs 47 ± 9; p < 0.001) in their study when assessed by another adapted version of HEI -2015 47 . Our results have shown to be in line with other studies in the literature, that a reduction in animal-derived foods appears to be accompanied by increased overall diet quality.…”

A scoping review of approaches used to develop plant-based diet quality indices

“…Of the 137 included articles, 31 articles described the original development of 35 plant-based diet quality indices ( Table 1 [ [13] , [14] , [15] , 18 , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] ] and Table 2 [ 15 , 18 , [40] , [41] , [42] , [43] , [45] , [46] , [47] , [48] , [49] , [51] , [52] , [53] , 55 ]), and the remaining 106 articles applied the 35 plant-based diet quality indices in an independent sample to the original development population ( Supplemental Table 2 ). The 137 included articles were published from 2007 to 2022, with most published in 2022 ( n = 39), 2021 ( n = 41), 2020 ( n = 20), and 2019 ( n = 11).…”

“… 0–6 N HEI-flexible (HEI-flex) Bruns et al. 2022 Germany [ 56 ] 1 ) HEI-2015 (39) 2 ) Food intake data from the FFQ 3 ) Questions regarding plant-based alternatives 4 ) Recommendations of the German Nutrition Society guidelines 5 ) WHO guidelines 6 ) Dietary guidelines for Americans FFQ, plant-based alternative products questionnaire, 3-d diet diary 14 Beverages, vegetables, fruit, protein sources, carbohydrate sources, whole meal, nuts and seeds, processed meat and plant-based meat alternatives, milk and dairy products and plant-based dairy alternatives, alcohol, high-energy density foods (sweet), high-energy density foods (fat), drinks with high-energy density, and fats and oils and plant-based fat substitutes Mean daily intake was calculated for each food group by a formula. Ratio between intake and intake recommendation calculated for each food group to create a unique HEI-flex score on the basis of adequacy and moderation principles.…”

“…The sample sizes of the development studies ranged from 54 [ 47 ] to 212,142 [ 55 ], with almost all conducted in samples of men and women ( n = 32) [13,14,15,18, 41–50,52,53,55–63,65,68,69) ( Table 2 ). About half of the indices ( n = 21) were developed using data from prospective cohort studies [ 13 , 14 , 15 , 18 , 41 , 42 , 46 , [51] , [52] , [53] , [54] , [55] , 59 , 60 , 62 , 63 , 68 ] followed by cross-sectional studies ( n = 9) [ 45 , [47] , [48] , [49] , [50] , 56 , 57 , 66 , 69 ].

FIGURE 2 Number of original plant-based diet quality indices published, and the number of publications applying them per year.

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“…The basis of development for each index was identified and categorized into 4 groups: 1 ) previously published diet quality indices; 2 ) epidemiological evidence for associations between food groups and health outcomes; 3 ) country-specific dietary guidelines; and 4 ) traditional dietary patterns. Almost half (46%, n = 16) of the indices used a previously published diet quality index as part of their basis for development [ 13 , 15 , 42 , 43 , 50 , 54 , [56] , [57] , [58] , 60 , 63 , 66 ]. Of these, most plant-based indices were developed on the basis of well-established diet quality indices, such as the HEI [ 23 ], AHEI [ 24 ], or previously published plant-based diet quality indices, such as PDI [ 15 ] and the provegetarian food pattern [ 14 ].…”