Our read is that taking vitamin B12 is well supported, particularly for those on plant-based diets or with specific health concerns.
✓WELLSUPPORTED
⚠
High-risk intervention — consult a physician before acting.Drug-drug interactions, dose-dependence, and screening contraindications apply.
Consensus
88%
broad agreement
Evidence quality
45/100
limited
Risk
High
specialist only
Cost / month
$
estimated
Effort
Low
time & habit
Abstract
Our read is that vitamin B12 supplementation is well supported, especially for individuals on plant-based diets, to prevent deficiencies and support cognitive health.
Experts suggest that B12, often alongside other B vitamins and omega-3s, can help reduce homocysteine levels, which is linked to slowing cognitive decline and brain atrophy.
However, the form of B12 and potential interactions with other supplements are important considerations.
Method
Bryan Johnson suggests that vitamin B12 supplementation at 5000% of the daily value may be necessary to reliably raise serum levels due to low bioavailability in supplement form. Paul Saladino recommends taking B12 in forms other than cyanocobalamin, such as methylcobalamin, hydroxocobalamin, or adenosylcobalamin.
Evidence detail
01Reducing homocysteine levels with B vitamin supplementation (B12 and folate) can slow cognitive decline and brain atrophy (Peter Attia).
02B complex vitamins (B12, B6), folic acid, and omega-3s can slow brain shrinkage and improve memory in individuals with high homocysteine (Peter Attia, Rhonda Patrick).
03Supplementation with B6, B12, and folate can lower homocysteine levels, improve cognition, and benefit the blood-brain barrier (Rhonda Patrick, Paul Saladino).
04Humans require essential nutrients such as B12, K2, choline, taurine, creatine, and carnitine, which are not adequately obtained from plant foods alone (Paul Saladino).
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A vegan diet can lead to nutritional deficiencies in B12, creatine, carnitine, choline, carnosine, anserine, taurine, and vitamin K2 (Paul Saladino).
06Higher levels of Vitamin B12, Coenzyme Q10, and Vitamin E, and lower levels of oxidized LDL and CRP are observed in individuals consuming more meat compared to traditional lab reference ranges (Paul Saladino).
07For female androgenetic alopecia, optimal hair growth potential exists when B12 levels are between 300-1000 ng/L, hemoglobin is >13 g/dL, and serum ferritin is >70 ng/mL (Paul Saladino).
08Nutritional deficiencies, such as B12 deficiency, can explain psychiatric symptoms and may be identifiable through biomarkers (Peter Attia, Andrew Huberman).
Caveats
Paul Saladino cautions that vitamin B12 should be taken in forms other than cyanocobalamin, such as methylcobalamin, hydroxocobalamin, or adenosylcobalamin, as cyanocobalamin contains cyanide, a mitochondrial toxin. He also notes that large doses of vitamin C may contribute to vitamin B12 deficiency. Paul Saladino also states that there is no evidence humans can obtain sufficient Vitamin B12 from soil not fertilized with human manure, and that obtaining B12 from lake water is unfounded. Metformin can lead to Vitamin B12 deficiency, which can cause anemia and potentially irreversible neurological damage (Paul Saladino, Rhonda Patrick).
What would change this verdict
New evidence demonstrating that plant-based diets reliably provide sufficient bioavailable B12 without supplementation, or that cyanocobalamin is a safe and effective form of B12, would change the verdict.
69Advocates
54Skeptics
37Neutral
⌕
Sort
Advocates
69
Evidence ScoreEvidence Score
DR
Daniel Roth· MD/PhD
MD/PhD ·48 claims
97
TH
Tomás Hofstadter· Founder
Founder ·90 claims
97
HA
Hannah Achebe· MS
MS ·56 claims
95
HM
Henrik Mendoza· Author
Author ·30 claims
95
VB
Vera Bhatia· RD
RD ·44 claims
95
BB
Bilal Bautista· MD
MD ·84 claims
95
MY
Mei Yusuf· Investor
Investor ·95 claims
94
Skeptics
54
Evidence ScoreEvidence Score
RM
Renu Mwangi· Author
Author ·28 claims
83
AL
Anders Larsson· RD
RD ·23 claims
82
AR
Aaron Roth· MS
MS ·37 claims
81
WW
Wei Whitlock· Author
Author ·50 claims
80
IK
Imani Khoury· RN
RN ·56 claims
80
IT
Iris Toledo· DO
DO ·7 claims
79
CB
Camila Becker· DO
DO ·49 claims
77
Neutral
37
Evidence ScoreEvidence Score
JM
Júlia Mendoza· Author
Author ·49 claims
87
RH
Roald Hoffman· Coach
Coach ·51 claims
85
PM
Priya Mendoza· RN
RN ·12 claims
83
RT
Renu Toledo· DO
DO ·85 claims
81
LB
Lina Bauer· Engineer
Engineer ·31 claims
81
DP
Daniel Park· PhD
PhD ·25 claims
79
AB
Asha Bhatia· PA
PA ·44 claims
77
Verdict
Sort
From advocates
2026-04-04
The intervention improves the primary outcome at standard doses in healthy adults.
JLCMEO+1Júlia Larsson, Clare Mwangi +2
JLCMEO+14 creators
✓WELLSUPPORTED
2026-04-04
The effect size is large enough to matter clinically, not just statistically.
MPRPTQ+1Mei-Lin Petrov, Rhonda Patrick +2
MPRPTQ+14 creators
✓WELLSUPPORTED
2026-05-23
Mechanistic and trial evidence converge on a real, replicable effect.
TQYNFWTomás Quinn, Yuki Nakashima +1
TQYNFW3 creators
✓WELLSUPPORTED
2026-05-13
Benefits hold across the populations where it's been tested.
MNFLIHMei Nakamura, Felix Lindgren +1
MNFLIH3 creators
✓WELLSUPPORTED
2026-02-17
The effect size is large enough to matter clinically, not just statistically.
THFWHMTomás Hofstadter, Felix Wexler +1
THFWHM3 creators
✓WELLSUPPORTED
From skeptics
2026-02-10
The headline effect shrinks once you account for trial quality.
ITMRTCIris Tanaka, Mei Rodriguez +1
ITMRTC3 creators
◐PARTIALLYSUPPORTED
2026-05-22
Animal-model results don't translate to the human protocol being recommended.
ZLWMZaynab Lindgren, Wei Marchetti
ZLWM2 creators
◐PARTIALLYSUPPORTED
2026-01-15
The headline effect shrinks once you account for trial quality.
WMWei Marchetti
WM1 creator
◐PARTIALLYSUPPORTED
2026-04-22
The headline effect shrinks once you account for trial quality.
⚠ High-risk claim
SOTKIYSana Olsson, Theo Khoury +1
SOTKIY3 creators
?LIMITEDRESEARCH
2026-05-27
Animal-model results don't translate to the human protocol being recommended.