Adequate vitamin B12 and folate status of Norwegian vegans and vegetarians

Authors: HENJUM, SIGRUN - Oslomet - Oslo Metropolitan University; GROUFH-JACOBSEN, SYNNE - University Of Agder; Allen, Lindsay - A; RAAEL, ELLEN - Oslomet - Oslo Metropolitan University; ISRAELSSON, ANNA MARIA - Oslomet - Oslo Metropolitan University; Shahab-Ferdows, Setti; HAMPEL, DANIELA - University Of California, Davis

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2022
Publication Date: 9/27/2022
Citation: Henjum, S., Groufh-Jacobsen, S., Allen, L.H., Raael, E., Israelsson, A., Shahab-Ferdows, S., Hampel, D. 2022. Adequate vitamin B12 and folate status of Norwegian vegans and vegetarians. British Journal of Nutrition. 129(12):2076-2083. https://doi.org/10.1017/S0007114522002987.
DOI: https://doi.org/10.1017/S0007114522002987

Interpretive Summary: Vegetarian or vegan diets could be a cause for vitamin B12 deficiency due to the low or no intake of animal-source foods, which are the main B12-dietary sources. On the otehr hand, dietary folate increases when adhering to plant-based diets due to consumption of fruits and vegetables. Thus, we examined the B12 and folate status of Norwegian vegans and vegetarians using dietary B12 intake, B12- and folate supplement use, and biomarkers (serum B12 [B12], plasma total-homocysteine [tHcy], plasma-methylmalonic acid [MMA], and serum-folate). Healthy vegans (n=115) and vegetarians (n=90) between 18 and 60 years of age were recruited. They completed a 24-hour recall and a food-frequency questionnaire and provided a non-fasting blood sample. cB12 status, a combined indicator for evaluation of B12 status, was calculated. The cB12 indicator suggested that the B12 status was adequate for the veangs and vegetarians in this study. Further, we found comparable blood values for B12, tHcy, and MMA concentrations (overall median: 357pmol/L, 9.0µmol/L, 0.18µmol/L) between the two groups, but not folate (vegans: 25.8nmol/L, vegetarians: 21.6nmol/L, p=0.027). When only examining the measured B12 concentrations, 14% of all participants had B12 concentration <221pmol/L, indicative of B12 insufficiency. More vegetarians than vegans had a B12 intake below the RDI, including supplements (40 vs. 18%, p<0.001). 24-hour B12 supplement use and higher age were predictors of higher B12 concentrations. As expected, folate deficiency was overall low (<2.5%). Our results showed that most participants are adequate in B12 and folate, indicating that the dietary intake and supplement use is sufficient to maintain adequate B12 and folate levels in Norwegian vegetarians and vegans.

Technical Abstract: Background: Plant-based diets may increase the risk of vitamin B12 deficiency due to limited or no intake of animal-source foods, the main B12-dietary source, while dietary folate sources as fruits and vegetables increases when adhering to plant-based diets. Objective: We evaluated the B12 and folate status of Norwegian vegans and vegetarians using dietary B12 intake, B12- and folate supplement use, and biomarkers (serum B12 [B12], plasma total-homocysteine [tHcy], plasma-methylmalonic acid [MMA], and serum-folate). Methods: Healthy vegans (n=115) and vegetarians (n=90), 18-60 years, completed a 24-hour recall and a food-frequency questionnaire and provided a non-fasting blood sample. cB12 status, a combined indicator for evaluation of B12 status, was calculated. Results: B12 status were found to be sufficient in vegans and vegetarians according to the cB12 indicator. No differences were found between vegans and vegetarians for B12, tHcy, and MMA concentrations (overall median: 357pmol/L, 9.0µmol/L, 0.18µmol/L), unlike for folate (vegans: 25.8nmol/L, vegetarians: 21.6nmol/L, p=0.027. 14% of all participants had B12 concentration <221pmol/L, indicative of B12 insufficiency. Vegetarians revealed highest share of participants below the RDI of 2 µg/day including supplements (40 vs. 18%, p<0.001). Predictors for higher B12 concentrations was found to be 24-hour B12 supplement use and higher age. Folate deficiency (<10 nmol/L) was overall low (<2.5%). Conclusion: Based on multiple approaches of B12 assessment, most participants revealed adequate status, supported by the high percentage who used B12 supplementation. Folate concentrations were adequate, indicating sufficient folate supply for maintaining adequacy in Norwegian female and male vegans and vegetarians.