Long-Term Vegetarian and Vegan Diets in Older Adults Are Associated With Inadequate Intakes of Protein and...

Plant-based diets are linked to health benefits but may challenge adequate nutrient intake in older adults.

This study aimed to analyze the nutrient, particularly protein intake, of Dutch older adults with decades-long adherence to vegetarian or vegan diets.

In this cross-sectional study, dietary intake was assessed using 3-d food records and compared with a Dutch reference group. Protein quality was assessed using the Meal Protein Quality Score (MPQS) and Protein Adequacy and Quality Score (PAQS). Group comparisons utilized Kruskal-Wallis tests.

The study included 20 vegetarians and 6 vegans aged 76 (72-80) y. Median dietary adherence was 42 y for vegetarians and 10 y for vegans, preceded by 31 y of vegetarian diet. Compared with omnivores, vegans had lower energy intake, higher proportion of energy from carbohydrate and fat, and higher fiber intake. In contrast, vegetarians had comparable energy intake to omnivores but lower proportion of energy from carbohydrates and higher fat and fiber intake. Protein intake below the recommended daily allowance occurred in 83% of vegans, 40% of vegetarians, and 25% of omnivores. Foods contributing to protein intake were dairy products for vegetarians and dairy replacers for vegans, combined with gluten- and soy-based products. Protein quality over the day, expressed as PAQS, was <1 in most vegans (100%) and vegetarians (83.3%), indicating lower protein quality. Inadequate protein quality per meal (MPQS <100) was observed across all meals, except dinner in vegetarians. Both plant-based diets failed to meet the recommended intakes for calcium, zinc, vitamin B-12, and vitamin D, as well as iron and folate in vegans.

Our findings indicate that long-term vegetarian and vegan diets in older adults are associated with inadequate micronutrient intake and insufficient protein intake, adequacy, and quality, especially in vegans. Although inadequacies are common, well-composed plant-based meals can provide adequate protein quality, highlighting opportunities for targeted nutritional guidance.