A randomized crossover trial comparing Mediterranean and low-fat vegan diets found that the vegan diet significantly reduced dietary advanced glycation end-products and led to greater weight loss.

in the study, published in Frontiers in Nutrition, researchers recruited 62 adult patients with overweight aged 30 to 76 years who had a body mass index (BMI) of 28 to 40 and spanned 36 weeks. The participants were randomized to follow a Mediterranean (n = 32) or low-fat vegan diet (n = 30) for 16 weeks, followed by a 4-week washout period, then crossed over to the other diet for 16 weeks. Body weight and composition were measured as primary outcomes. Three-day diet records were collected at weeks 0, 16, 20, and 36, and analyzed using the Nutrition Data System for Research software. Dietary advanced glycation end-products (AGEs) were estimated using an established database, calculating kilounits AGE/g of food multiplied by grams consumed per day.

The Mediterranean diet followed the PREDIMED protocol, emphasizing vegetables, fruits, legumes, fish, nuts, and olive oil. The vegan diet consisted of fruits, vegetables, grains, and legumes, excluding animal products and added fats. Both diets were ad libitum with no meals provided.

Among the key findings were:

• AGEs decreased by 73% (9,413 kilounits AGE/d) on the vegan diet vs no change on the Mediterranean diet.
• Participants lost an average of 6.0 kg on the vegan diet vs no change on the Mediterranean diet.
• Changes in dietary AGEs correlated with changes in body weight (r = 0.47, P < .001), independent of energy intake (r = 0.39, P = .003).

Dietary AGEs decreased from 12,939 to 3,526 kilounits AGE/d on the vegan diet (P < .001), while no significant change occurred on the Mediterranean diet (10,943 to 11,833 kilounits AGE/d). The treatment effect was –10 303 kilounits AGE/d (95% confidence interval [CI] = –13,090 to –7,516, P < .001).

Detailed AGE changes by food group (kilounits AGE/d):

• Meat: –4,896 on vegan diet vs –677 on Mediterranean diet
• Dairy: –2,327 on vegan diet vs –935 on Mediterranean diet
• Added fat: –1,071 on vegan diet vs 1,716 on Mediterranean diet
• Eggs: –528 on vegan diet vs 114 on Mediterranean diet
• Seafood: –711 on vegan diet vs 457 on Mediterranean diet.

The reduction in dietary AGEs on the vegan diet came primarily from:

• Excluding meat consumption (41%): Red meat = –1,027 (95% CI = –1,500 to –554, P < .001), white meat = –3,504 (95% CI = –4,322 to –2,685, P < .001)
• Minimizing added fats (27%)
• Avoiding dairy products (14%): Full-fat dairy = –1,172 (95% CI = –1,940 to –404, P < .01).

Other notable changes (kilounits AGE/d):

• Vegetables: 114 on vegan diet vs 18 on Mediterranean diet
• Grains: –115 on vegan diet vs –239 on Mediterranean diet
• Nuts & Seeds: –425 on vegan diet vs 494 on Mediterranean diet
• Meat alternatives: 478 on vegan diet vs 66 on Mediterranean diet.

Body weight decreased by 6.0 kg on the vegan diet vs no change on the Mediterranean diet (treatment effect –6.0 kg, 95% CI = –7.5 to –4.5, P < .001). Fat mass decreased by 3.4 kg (95% CI = –4.7 to –2.2, P < .001) and visceral fat volume by 314.5 cm³ (95% CI = –446.7 to –182.4, P < .001) on the vegan diet.

Changes in dietary AGEs correlated with changes in body weight (r = 0.48, P < .001 for period 1) and remained significant after adjustment for total energy intake (r = 0.39, P = .003).

A statistically significant carryover effect was observed for total AGEs (P = .01). An additional ANOVA for repeated measures assessing treatment effect from the first study period alone showed a reduction of –9,578 kilounits AGE/d (95% CI = –13,014 to –6,143, P < .001) on the vegan diet.

The study had 99.99% power to detect an 8,000-point difference in AGEs with 62 participants. Carryover effects were assessed using 2-sample t tests comparing treatment effects by first diet received. Period-specific estimates of treatment effects were determined because of the detected carryover effect.

This study was one of the first to directly compare the effects of Mediterranean and low-fat vegan diets on dietary AGEs and body weight. The significant reduction in dietary AGEs on the vegan diet aligned with previous studies showing benefits of plant-based diets for metabolic health. The association between changes in dietary AGEs and body weight, independent of energy intake, suggested a potential mechanism for the weight loss benefits of vegan diets.

The high retention rate (84%) suggested that both diets were feasible and acceptable to participants. Self-reported adherence to both diets was high, although specific percentages were not provided.

Limitations of the study included the possibility of false positive findings caused by multiple comparisons, although the primary outcomes remained significant after conservative correction. Self-reported dietary intake and the detected carryover effect for total AGEs were also noted limitations.

The authors declared that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.