- Adventist Health Study-2 (2020)
- Polish Clinical Trial (2012)
- EPIC-Oxford (2001 & 2010)
- Studies on Adult Vegans Not Supplementing with B12
- Vegans Taking B12 Supplements
Vegan adults who do not supplement with vitamin B12 tend to have lower serum B12 levels than non-vegetarians, larger red blood cells indicative of anemia, and elevated methylmalonic acid levels. They sometimes have overt B12 deficiency symptoms such as neuropathy. In contrast, vegans who supplement their diets with vitamin B12 tend to have serum B12 levels in the normal range and no symptoms of B12 deficiency. Additional studies of B12 status in vegans are in Homocysteine and Mild B12 Deficiency in Vegans.
Adventist Health Study-2 (2020)
As part of Adventist Health Study-2, Haddad et al. (2020) compared the B12 intakes, levels, and biomarkers in 76 vegans, 221 lacto-ovo-vegetarians, and 488 nonvegetarians who were over 30 years old.
After including fortified foods and supplements, the median daily B12 intake among vegans (9.4 µg) wasn’t significantly different from the lacto-ovo-vegetarians (6.6 µg) or nonvegetarians (7.3 µg). A higher prevalence of vegans (15.2%) didn’t meet the Estimated Average Requirement (EAR) of 2.0 µg/day when compared to lacto-ovo-vegetarians (10.6%) or nonvegetarians (6.5%).
On average, serum B12, holotranscobalamin, methylmalonic acid, and homocysteine didn’t differ between the diet groups. A higher percentage of vegans had MMA levels ≥270 nmol/l (10.8%) and ≥370 nmol/l (4.1%) than the other diet groups, but the difference wasn’t statistically significant. Homocysteine levels were relatively high in this study (vegans = 12.0 µmol/l, lacto-ovo-vegetarians = 11.1 µmol/l, and nonvegetarians = 11.4 µmol/l).
Polish Clinical Trial (2012)
A group of 20 omnivores agreed to follow a vegan diet for 5 years. Half the group ate B12 fortified foods and the other half did not. Neither group took B12 supplements. The amount of B12 received via fortified foods was not measured. After 5 years, B12 levels in the group using fortified foods went from about 340 to 310 pg/ml. B12 levels went from about 290 to 220 pg/ml in the group not using fortified foods. Only two participants had B12 levels fall below 200 pg/ml, traditionally considered the cutoff for B12 deficiency, and they were both from the unfortified foods group (Mądry, 2012).
EPIC-Oxford (2001 & 2010)
An abstract from EPIC-Oxford reported plasma vitamin B12 levels of a subset of men (Lloyd-Wright, 2001). Results are in the table below. The vegan men had the lowest levels, and many weren’t supplementing with vitamin B12.
|B12 Status of Men in EPIC-Oxford (2001)|
|B12 intake – from food only (µg/day)||9.6||2.4||.4|
|B12 intake – including supplements (µg/day)||9.6||2.7||3.0|
|Plasma B12 (pmol/l)||~296||~170||~122|
|Number with levels < 96 pmol/l||1||50||150|
A 2010 report from EPIC-Oxford found almost the exact same results: 232 vegan men had an average serum B12 level of 122 pmol/l (95% CI 117-127) (Gilsing, 2010). There might have been a substantial overlap with participants in Lloyd-Wright et al., 2001.
The 2010 study included a blood sample from 65 vegan men obtained 6 years after baseline. Among those 65 vegan men, about 10% appeared to have a significant B12 deficiency. There was no association between vegan men reporting taking B12 supplements and serum vitamin B12 levels, suggesting the men were probably not consistently taking the supplements.
Studies on Adult Vegans Not Supplementing with B12
Australians have a lifestyle similar to North Americans, but with limited B12 fortified foods. Hokin and Butler (1999) examined Australian Seventh-day Adventist ministers, aged 22-80, who did not take B12 supplements. The results as seen in Table 2, showed vegans to have significantly lower B12 levels (Hokin,1999).
|Table 2. B12 Status of Australians in Hokin and Butler Study|
|#||B12 (range)||Malabsorption / IF deficiency|
|Non-Veg||53||394A ± 196 (181-973)||NR|
|Lacto-Ovo||234||NRB||20% / 10%|
|Vegans||11||224A ± 100 (99-420)||NR|
|A – Statistically significant difference between groups with same letters
B – Not significantly different from the Non-Veg
NR – Not reported
Crane et al. (1998, USA) studied 2 families (9 people) who were vegan for over 1 year and who did not regularly take B12 supplements or fortified foods:
- They ate food from their gardens or local grocery stores.
- Serum B12 (sB12) was below 200 pg/ml in 8 members; average sB12 was 190 ± 65 pg/ml.
- The only family member over 200 pg/ml, with a B12 level of 331 pg/ml, was also the only one with signs of deficiency (mild numbness in one hand and easy fatigue). These cleared up after starting oral B12, so her high levels might be attributable to inactive B12 analogues.
- 8 had high urinary MMA.
- Homocysteine levels were in the normal range, but dropped after B12 therapy.
- The subjects were given 500 µg B12/day, which they chewed before swallowing.
After 2 months:
- Average red blood cell count increased.
- Average total cholesterol decreased by 10.3% and LDL cholesterol decreased by 19.6%. (Note: This is the only study that observed a cholesterol reduction in vegans because of B12 supplementation.)
- Serum MMA levels dropped dramatically (from .65 ± .61 to .13 ± .06 µmol/l).
- Average sB12 rose to 553 ± 113 pg/ml.
Crane et al. write:
The laboratory evidence in these two families is too strong to believe that they had an adequate amount of [B12]. It is remarkable that they had been on a total vegetarian diet for so long, yet with little or no clinical symptoms or signs of an insufficiency of cobalamin. In this study none of the family members were aware of symptoms of easy fatigability, tingling in the extremities, or frequent upper respiratory infections. (Crane, 1998)
Crane et al. (1994, USA) measured the sB12 of healthy adult vegans (1-28 years on the diet) who had not used B12 supplements or fortified foods in the previous year or more. See Table 3 for results.
|Table 3. B12 Status in Non-supplementing Vegans in Crane et al. Study 1994|
|#||sB12 < 200 pg/ml||sB12 < 100 pg/ml||sB12 range|
|no FF or SUP for 1 yr||76||47 (62%)||19%||41-615|
|fortified soymilk for 1 yr||20A||304-540|
|A – 8 were children
FF – Fortified foods
sB12 – Serum B12
SUP – supplements
Participants with low B12 levels were given oral B12. The B12 levels of some of these participants did not increase, which led to the study about chewing B12 tablets mentioned under Chewing or Swallowing Whole in Vitamin B12: Vegan Sources.
Crane et al. also examined urinary MMA levels in 29 vegan adults who had not used B12 supplements or fortified foods in the previous year (Crane, 1994):
- 11 had B12 levels < 200 pg/ml. Their average MCV (95.9 ± 5.5 fl) was significantly higher than those with higher B12 levels.
- 7 of these 11 had high MMA.
- None with normal B12 levels had elevated MMA.
- One vegan of 5 years had no symptoms of B12 deficiency despite a sB12 of 90 pg/ml. However, after 1 month of oral B12, he noticed that his chronic indigestion after meals had disappeared.
Medkova et al. (2001, Russia) studied a vegan settlement in Siberia in 1993 (Mądry, 2012, Medkova, 2013). They reported that the vegans had been vegan an average of 2.2 years and that their vitamin B12 levels were normal. This could have been due to having enough vitamin B12 stored in their system, and exact measurements were not given.
Tungtrongchitr et al. (1993, Thailand) studied 132 Thai adult vegetarians (64 males, 68 females) and 47 healthy nonvegetarians. The vegetarians apparently ate no animal products. Serum B12 levels are shown in Table 4.
|Table 4. B12 Status of Thai Adults in Tungtrongchiter et al. Study 1993|
|Serum B12||Serum B12 range|
There were some blood cell differences between vegetarians and non-vegetarians. Serum B12 decreased as years as a vegetarian increased. Groups practicing vegetarianism for ≥ 6 years resulted in particularly low average sB12 levels (83-135 pg/ml) (Tungtrongchitr, 1993).
Bar-Sella et al. (1990, Israel) compared 36 vegans (5-35 years on diet) to 36 non-vegetarians. None of the vegans used supplements. Vegans had significantly lower levels of B12 (164 vs. 400 pg/ml). No non-vegetarian was deficient in B12, but 2 were borderline. No subjects had blood abnormalities. 4 vegans had a history of muscle pain, abnormal sensations in the legs, and difficulty concentrating. Their serum B12 levels are shown in Table 5.
|Table 5. B12 Levels in 4 Vegans with History of Nerve-related Problems|
|Serum B12 (pg/ml)||65||84||89||90|
3 of the 4 were followed and showed substantial clinical improvement after B12 injections which increased their B12 levels to over 200 pg/ml (Bar-Sella, 1990).
Areekul et al. (1988, Thailand) found a significant difference between B12 levels (62 ± 78 pg/ml) in 29 apparently healthy vegetarians and 60 omnivores (629 ± 160 pg/ml). 8 vegetarians had undetectable B12 levels, while only 2 had levels over 200 pg/ml. The researchers did not state whether any of the vegetarians were taking B12 supplements, but they appeared not to be doing so (Areekul, 1988).
Vegans Taking B12 Supplements
Table 6 shows the results of the Haddad et al. (1999, USA) study comparing vegans to non-vegetarians.
|Table 6. Results of Haddad et al.|
|#||yrs on diet||# taking B12 SUPA,B||B12 (pg/ml)||# with
B12 < 203
> .38 µmol/l
|Had 1 Indicator of
|Vegans||25||4.2 (1-25)||9||421 ± 169||3||5||10|
|Non-Veg||20||423 ± 134||0||0|
|A – Per correspondence with author
B – Some vegans ate B12 fortified foods
SUP – Supplements
There were no differences in homocysteine between the groups. There was a significant association between B12 supplementation and sB12 but no relation with sMMA. In private correspondence, Haddad suggested this was because some vegans did not regularly take the supplements and some had only recently begun. Blood will reflect recent higher B12 intake while MMA levels take longer to change (Haddad, 1999).
Harman & Parnell (1998, New Zealand) compared 24 adult vegetarian Seventh-day Adventists (SDA) (including some vegans; number not specified) to 23 non-vegetarian SDAs. Some vegetarians were taking B12 supplements and injections. Table 7 shows the results.
|Table 7. Results of Harman and Parnell|
|Male Vegetarians||220 ± 103|
|Female Vegetarians||282 ± 132|
|Male Non-Veg||331 ± 142|
|Female Non-Veg||331 ± 167|
B12 levels did not differ significantly between groups (Harman, 1998).
Alexander et al. (1994, New Zealand) looked at 18 vegetarians. B12 levels were as shown in Table 8.
|Table 8. B12 levels in Alexander et al.|
|#||Years on diet||sB12|
- 6 had B12 levels below the reference range: 82, 86, 182, 190, 197 (vegan or lacto-ovo wasn’t specified). None had macrocytosis. The woman with the lowest value was found to have an intrinsic factor deficiency.
- 7 vegetarians took B12 supplements and only one had low B12 levels, but their levels were not significantly different than those who did not take supplements.
- The vegans actually had a higher average sB12 than the Lacto-Ovo. (Alexander, 1994).
Sanders et al. (1978, UK) compared adult vegan (no animal products ≥ 1 year; average 8 yrs) members of The Vegan Society (UK) to age and sex-matched non-vegetarians. 18 of the vegans were taking B12 supplements or eating fortified foods. Results are shown in Table 9.
|Table 9. Sanders et al. (1978, UK)|
|Serum B12 (pg/ml)|
|22 Vegans||289 R 120-675|
|22 Non-Veg||371 R 250-775|
5 vegans were not taking B12 supplements or fortified foods. See Table 10.
|Table 10. Sanders et al. (1978, UK)|
|Years as vegan||2||4||6||6||13|
The results indicate that supplementing vegans had higher sB12 levels than non-supplementing (Sanders, 1978).
Gilsing, 2010. Gilsing AM, Crowe FL, Lloyd-Wright Z, Sanders TA, Appleby PN, Allen NE, Key TJ. Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study. Eur J Clin Nutr. 2010 Sep;64(9):933-9.
Haddad, 1999. Haddad EH, Berk LS, Kettering JD, Hubbard RW, Peters WR. Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr. 1999;70(suppl):586S-93S.
Haddad EH, Jaceldo-Siegl K, Oda K, Fraser GE. Associations of Circulating Methylmalonic Acid and Vitamin B-12 Biomarkers Are Modified by Vegan Dietary Pattern in Adult and Elderly Participants of the Adventist Health Study 2 Calibration Study. Curr Dev Nutr. 2020 Jan 22;4(2):nzaa008.
Harman, 1998. Harman SK, Parnell WR. The nutritional health of New Zealand vegetarian and non-vegetarian Seventh-day Adventists: selected vitamin, mineral and lipid levels. NZ Med J. 1998 Mar 27;111(1062):91-4.
Lloyd-Wright, 2001. Lloyd-Wright Z, Allen N, Key TJ, Sanders TB. How prevalent is vitamin B12 deficiency among British vegetarians and vegans? Proceedings of the Nutrition Society. University of Sheffield, Sheffield, UK. 2001(Jul):174A.
Mądry, 2012. Mądry E, Lisowska A, Grebowiec P, Walkowiak J. The impact of vegan diet on B-12 status in healthy omnivores: five-year prospective study. Acta Sci Pol Technol Aliment. 2012 Apr 2;11(2):209-12.
Medkova, 2001. Medkova IL, Mosiakina LI, Biriukova LS. [Results of a dynamic study on the status of health and nutrition of a Siberian vegan settlement]. Vopr Pitan. 2001;70(4):7-12. Russian. (Abstract)
Sanders, 1978. Sanders TA, Ellis FR, Dickerson JW. Studies of vegans: the fatty acid composition. of plasma choline phosphoglycerides, erythrocytes, adipose tissue, and breast milk, and some indicators of susceptibility to ischemic heart disease in vegans and omnivore controls. Am J Clin Nutr. 1978 May;31(5):805-13.
Tungtrongchitr, 1993. Tungtrongchitr R, Pongpaew P, Prayurahong B, Changbumrung S, Vudhivai N, Migasena P, Schelp FP. Vitamin B12, folic acid and haematological status of 132 Thai vegetarians. Int J Vitam Nutr Res. 1993;63(3):201-7.