Type and length of vegetarian diet and serum vitamin B₁₂ concentrations

Introduction: Avoiding animal products is the basic principle of a vegetarian diet. Deficiency of vitamin B₁₂ is its classic negative effect. The assessment of vitamin B₁₂ resources is necessary to introduce supplementation in case of deficiency. A modern vegetarian diet includes the intake of semi-ready and ready-to-use products.
Aim: Assessment of the influence of a modern vegetarian diet on vitamin B₁₂ resources.
Material and methods: The study comprised 118 vegetarians (40 vegans, 24 lacto vegetarians and 54 lacto-ovo vegetarians) and 90 omnivores. 53 vegetarians had been on the diet for less than 5 years and 65 for more than 5 years. Serum vitamin B₁₂ concentrations were analyzed in all studied subjects.
Results: Long-term vegetarians had lower vitamin B₁₂ concentrations (Xśr. ± SEM: 254±10 pg/ml) than healthy subjects (364±14 pg/ml). Levels of vitamin B₁₂ were highest in lacto-ovo vegetarians (336±10 pg/ml) and lowest in vegans (281±37 pg/ml). Vitamin B₁₂ deficiency was found in 24 (60%) vegans and in 1 (4.2%) lacto-vegetarian.
Conclusions: In modern vegetarians a significant decrease of vitamin B₁₂ concentration is found. The type of diet and length of its application has a crucial role for vitamin B₁₂ body resources. A vegan diet is the most restrictive in this respect. Thus a vegetarian diet, especially a vegan one, demands systematic control of serum vitamin B₁₂ concentrations.