Effects of a 3-month dietary intervention with a lacto-ovo-vegetarian diet on vitamin B12 levels in a group of omnivores: results from the CARDIVEG (Cardiovascular Prevention with Vegetarian Diet) study

Previous studies have suggested that vegetarianism can result in a reduction of vitamin B-12 circulating levels. The aim of the present study was to investigate the effects of a 3-month dietary intervention with a lacto-ovo-vegetarian diet (VD) on the levels of circulating vitamin B-12 in a group of omnivores. We analysed fifty-four omnivorous subjects who followed a VD as a first dietary intervention within the CARDIVEG (Cardiovascular Prevention with Vegetarian Diet) study, a dietary intervention study. VD resulted in a significant reduction (P<0 center dot 001) of 51 center dot 2 % of vitamin B-12 intake and in a significant reduction (P=0 center dot 005) of 6 center dot 2 % of the circulating levels of vitamin B-12 (-24 center dot 5 pg/ml). Changes in vitamin B-12 intake were significantly correlated with changes in circulating levels of vitamin B-12 (R 0 center dot 61, P<0 center dot 001). Subgroup analyses showed that reduction in circulating vitamin B-12 levels was more evident in participants who were younger, overweight, non-smokers and had hypercholesterolaemia. A logistic regression analysis showed that a reduction in vitamin B-12 intake greater than the first quartile of the delta changes obtained in the study population (-28 center dot 5 %) conferred a significantly higher risk of experiencing a decrease in circulating vitamin B-12 levels (OR 10 center dot 1; 95 % CI 1 center dot 3, 76 center dot 1). In conclusion, a 3-month VD period determined a significant reduction in circulating levels of vitamin B-12, being significantly correlated with the reduction in vitamin B-12 intake. Although a well-planned VD can provide adequate nutrition across all life stages, special care must be taken to ensure adequate vitamin B-12 intake and to help prevent deficiency.