Effects of a 3-month dietary intervention with a lacto-ovo-vegetarian diet on vitamin B-12 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 B12 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 B12 in a group of omnivores. We analyzed 54 omnivorous subjects who followed a VD as a first dietary intervention within the CARDIVEG study, a dietary intervention study. VD resulted in a significant reduction (p<0.001) of 51.2% of vitamin B12 intake and in a significant reduction (p=0.005) of 6.2% of the circulating levels of vitamin B12 (-24.5 pg/mL). Changes in vitamin B12 intake were significantly correlated with changes in circulating levels of vitamin B12 (R=0.61, p<0.001). Subgroup analyses showed that reduction of circulating vitamin B12 levels was more evident in participants who were younger, overweight, non-smokers, and with hypercholesterolemia. A logistic regression analysis showed that a reduction of vitamin B12 intake greater than the 1st quartile of the delta changes obtained in the study population (-28.5%) conferred a significantly higher risk of experiencing a decrease in circulating vitamin B12 levels (OR 10.1; 95% CI 1.3-76.1). In conclusion, a 3-month VD period determined a significant reduction in circulating levels of vitamin B12, being significantly correlated with the reduction in vitamin B12 intake. Although a well-planned VD can provide adequate nutrition across all life stages, special care must be taken to ensure adequate vitamin B12 intake, and to help prevent deficiency.

Previous studies have suggested that vegetarianism can result in a reduction of vitamin B12 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 B12 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<0·001) of 51·2 % of vitamin B12 intake and in a significant reduction (P=0·005) of 6·2 % of the circulating levels of vitamin B12 (-24·5 pg/ml). Changes in vitamin B12 intake were significantly correlated with changes in circulating levels of vitamin B12 (R 0·61, P<0·001). Subgroup analyses showed that reduction in circulating vitamin B12 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 B12 intake greater than the first quartile of the delta changes obtained in the study population (-28·5 %) conferred a significantly higher risk of experiencing a decrease in circulating vitamin B12 levels (OR 10·1; 95 % CI 1·3, 76·1). In conclusion, a 3-month VD period determined a significant reduction in circulating levels of vitamin B12, being significantly correlated with the reduction in vitamin B12 intake. Although a well-planned VD can provide adequate nutrition across all life stages, special care must be taken to ensure adequate vitamin B12 intake and to help prevent deficiency.