B-Vitamin Forms Evaluation

Comprehensive B-Vitamin Forms Evaluation

Vitamins Evaluated

8 Essential B Vitamins

Forms Analyzed

35+ Supplemental Forms

Evidence Sources

90+ Clinical Studies

Standard

NTRPX Evidence Hierarchy

The definitive reference for B-vitamin form selection — evidence over theory, proven over promising, independent replication required. The B-vitamin complex represents eight chemically distinct water-soluble vitamins essential for energy metabolism, methylation, neurotransmitter synthesis, and cellular function. However, not all supplemental forms are created equal. This evaluation systematically analyzes every available form of each B vitamin, comparing bioavailability data, clinical evidence, mechanisms of action, safety profiles, and practical considerations. The goal: identify the optimal forms for NTRPX Systems integration based on rigorous evidence standards. For each vitamin, we answer the fundamental question: which form delivers the greatest biological benefit with the highest confidence?

NTRPX Evidence Standards Applied: This evaluation prioritizes (1) human clinical trials over preclinical data, (2) replicated findings over single studies, (3) objective biomarkers over subjective endpoints, and (4) safety-validated forms over theoretical advantages. Where evidence is limited, we state so explicitly.

Quick Reference: Optimal Forms Summary

B1 Thiamine

Benfotiamine (peripheral) TTFD (CNS)

B2 Riboflavin

Riboflavin-5’-Phosphate (R5P)

B3 Niacin

Nicotinamide Riboside (NR)

B5 Pantothenic

D-Calcium Pantothenate (Standard)

B6 Pyridoxine

Pyridoxal-5’-Phosphate (P5P)

B7 Biotin

D-Biotin (Only active form)

B9 Folate

L-5-MTHF (Quatrefolic®)

B12 Cobalamin

Methyl + Adenosyl (Both coenzymes)

Evaluation Methodology

NTRPX Evidence Hierarchy

Form Selection Criteria

Criterion	Weight	Description
Bioavailability	30%	Absorption, tissue distribution, cellular uptake
Clinical Evidence	25%	Human RCTs demonstrating superiority
Safety Profile	20%	Adverse effects, toxicity thresholds, interactions
Mechanism Validation	15%	Understanding of how form confers advantage
Practical Factors	10%	Stability, cost, availability, formulation

Standards Applied

Evidence Over Theory

Mechanistic plausibility alone is insufficient. Human clinical data required.

Proven Over Promising

Replicated findings prioritized over novel discoveries awaiting confirmation.

Safety Non-Negotiable

Forms with established safety profiles preferred over theoretical advantages.

Vitamin B1: Thiamine

Active Form

Thiamine Diphosphate (ThDP)

Key Enzymes

PDH, α-KGDH, Transketolase

Primary Function

Glucose → ATP

RDA

1.1-1.2 mg/day

Form Comparison & Recommendation

Thiamine Form Hierarchy

Head-to-Head Comparison

Form	Plasma Bioavailability	BBB Penetration	Tissue Distribution	Mechanism	Evidence Tier
Thiamine HCl	1× (baseline)	Poor	Limited	Active transport (THTR1/2)	N/A
Benfotiamine	11.5×	Uncertain/Delayed	Peripheral excellent	Enzymatic cleavage	TIER 2
TTFD	~5×	✓ Confirmed	CNS + peripheral	Non-enzymatic reduction	TIER 3
Sulbutiamine	High	✓ Confirmed	CNS emphasis	Non-enzymatic reduction	TIER 3

NTRPX Recommendation

Peripheral/Metabolic Support

Benfotiamine 150-300mgPrimary choice for metabolic support, diabetic complications, AGE inhibition. Superior peripheral tissue distribution with excellent safety profile.

CNS/Cognitive Support

TTFD 50-100mgPrimary choice for neurological applications. Confirmed BBB penetration via PET imaging. Start low (50mg), titrate to avoid paradoxical reaction.

Dual-Form Strategy: For comprehensive thiamine support, consider combining Benfotiamine (peripheral) + TTFD (central). Include 10-25mg thiamine HCl as baseline insurance.

Mechanism of Action

Thiamine Coenzyme Function

Critical Distinction: Thioesters vs Disulfides

Property	Thioesters (Benfotiamine)	Disulfides (TTFD, Sulbutiamine)
Chemical structure	S-acyl derivative	Open-ring disulfide
Membrane crossing	Requires alkaline phosphatase	Non-enzymatic reduction at membrane
BBB penetration	Controversial/delayed	Confirmed (PET imaging)
Peak plasma	1-2 hours	Rapid
Primary target	Peripheral tissues (blood, liver, kidney)	CNS + peripheral
Non-coenzyme effects	AGE inhibition	Anti-inflammatory, antioxidant

Benfotiamine Mechanism

TTFD Mechanism

Why This Matters: Benfotiamine requires enzymatic processing (alkaline phosphatases) which may limit BBB penetration. TTFD’s non-enzymatic reduction allows direct membrane crossing, including the blood-brain barrier — confirmed by PET imaging studies showing rapid brain and spinal cord entry.

Clinical Evidence

Benfotiamine Clinical Trials

Study	Design	N	Population	Intervention	Primary Outcome	Result	Reference
Stracke et al. 1996	RCT, DB	24	Diabetic neuropathy	320mg/day, 3 weeks	Neuropathy symptoms	Significant improvement	Exp Clin Endocrinol Diabetes
Haupt et al. 2005	RCT, DB, PC	165	Diabetic polyneuropathy	300-600mg/day, 6 weeks	Neuropathy Score	Significant improvement	Int J Clin Pharmacol Ther
Stirban et al. 2006	RCT, crossover	13	Type 2 diabetes	1050mg/day, 3 days	Postprandial endothelial dysfunction	Prevented dysfunction	Diabetes Care
Gibson et al. 2020	Open-label pilot	5	Mild Alzheimer’s	300mg/day, 18 months	ADAS-cog	Improved (no placebo)	J Alzheimers Dis
Pan et al. 2010	Preclinical	—	APP/PS1 mice	—	Amyloid pathology	Reduced plaques	Brain

Bioavailability Studies

Study	Design	Comparison	Finding	Reference
Schreeb et al. 1997	Crossover, 12 subjects	Benfotiamine vs Thiamine HCl	Plasma: 1,147% / Erythrocyte ThDP: 196%	Int J Clin Pharmacol Ther
Loew 1996	Review	Multiple derivatives	Benfotiamine superior tissue penetration	Int J Clin Pharmacol Ther

TTFD Clinical Trials

Study	Design	N	Population	Intervention	Primary Outcome	Result	Reference
Mimori et al. 1996	RCT	17	Mild cognitive impairment	100mg/day, 12 weeks	Cognitive function	Significant improvement	Metab Brain Dis
Lonsdale 1987-2013	Case series	100s	Various neurological	Variable doses	Clinical outcomes	Consistent benefit, no toxicity	Evid Based Complement Alternat Med
Bitsch et al. 1991	Human pharmacokinetics	12	Healthy	Single dose	Tissue distribution	Superior to HCl	Ann N Y Acad Sci

BBB Penetration Evidence

Study Type	Method	Finding	Reference
PET imaging	[¹¹C]-TTFD	Rapid brain and spinal cord accumulation	Volvert et al.
Tissue analysis	Post-mortem	Higher brain thiamine with lipophilic derivatives	Multiple
Benfotiamine BBB	Multiple methods	Negative/Uncertain — Limited acute brain penetration	Volvert et al.; Sambon et al.

Benfotiamine BBB Controversy: Multiple studies have failed to demonstrate significant acute brain penetration with benfotiamine. Some data suggests possible accumulation with chronic dosing (30+ days), but TTFD remains the preferred form when CNS effects are the primary goal.

Evidence Summary

Benfotiamine

Evidence Tier: TIER 2 (Probable)Strong RCT evidence for diabetic neuropathy. Superior bioavailability well-established. AGE inhibition demonstrated. BBB penetration remains uncertain.

TTFD

Evidence Tier: TIER 3 (Possible)BBB penetration confirmed via PET. Limited RCT replication. Extensive clinical use (Lonsdale, 40 years). Unique non-coenzyme mechanisms.

Safety Profile

Adverse Events

Form	Common AEs	Serious AEs	Special Considerations
Benfotiamine	Minimal; rare GI upset	None reported	Produces hippuric acid (no accumulation)
TTFD	Garlic odor possible; paradoxical reaction	None reported	Start low, titrate up
Sulbutiamine	Brain fog, mood changes	None reported	Requires other B vitamins
Thiamine HCl	Extremely rare	None	Anaphylaxis with IV (rare)

Paradoxical Reaction (TTFD)

Important: Some individuals experience temporary symptom worsening when initiating TTFD. This “paradoxical reaction” is thought to result from rapid mobilization of thiamine-dependent enzymes. Management: Start at 33-50mg, increase gradually over 1-2 weeks to target dose.

Toxicity Thresholds

Form	UL	Maximum Studied	Safety Margin
Thiamine HCl	None established	3g/day	Very wide
Benfotiamine	None established	2g/day	Very wide
TTFD	None established	300mg/day	Wide

Drug Interactions

Drug	Interaction	Severity	Action
Loop diuretics	Increased thiamine excretion	Moderate	Consider supplementation
Fluoroquinolones	May reduce thiamine levels	Minor	Monitor
Alcohol (chronic)	Depletes thiamine	Major	Supplement required

NTRPX Systems Fit

Systems Integration

System	Recommended Form	Dose	Rationale
Sustain	Benfotiamine	150-300mg	Metabolic support, AGE inhibition
Boost	Benfotiamine	100-150mg	Energy metabolism foundation
Recover	Benfotiamine	150-300mg	Tissue repair, antioxidant
Sprint	TTFD	50-100mg	CNS penetration, cognitive support

Specification

Parameter	Specification
Primary Form	Benfotiamine ≥98% purity
Secondary Form	TTFD (Fursultiamine) ≥98%
Baseline Insurance	Thiamine HCl 10-25mg
Avoid	Sulbutiamine (mood concerns without full B-complex)

Vitamin B2: Riboflavin

Active Forms

FMN + FAD

Key Function

Electron Transport

Dependencies

Required for B6, B9, B3

RDA

1.1-1.3 mg/day

Form Comparison & Recommendation

Riboflavin Form Analysis

Form	Structure	Absorption	Conversion Required	Practical Difference
Riboflavin	Free vitamin	~95% up to 27mg	Yes (flavokinase)	Standard
Riboflavin-5’-Phosphate (R5P/FMN)	Phosphorylated	~95% up to 27mg	Dephosphorylated, then rephosphorylated	Minimal for most
FAD	Adenylated FMN	~95% up to 27mg	Fully hydrolyzed first	No advantage

Critical Insight

All forms have similar bioavailability because FAD and FMN are hydrolyzed to free riboflavin by intestinal phosphatases before absorption. Free riboflavin is then re-phosphorylated intracellularly. The theoretical advantage of “active forms” is largely negated by intestinal processing.

When R5P May Provide Advantage

Population	Rationale	Evidence Level
Impaired flavokinase activity	Bypasses phosphorylation step	Theoretical
MTHFR polymorphisms	FMN required for MTHFR function	Indirect support
Liver dysfunction	Primary phosphorylation site	Theoretical

NTRPX Recommendation

Recommended: Riboflavin-5'-Phosphate (R5P)

Dose: 10-25mgSelected based on precautionary principle — provides active coenzyme form with better solubility, no disadvantage vs free riboflavin, marginal cost increase. For migraine prevention, either form at 400mg/day is acceptable.Evidence Tier: TIER 4 (Theoretical) for R5P superiority — no direct clinical trials comparing forms, but no downside to active form.

Mechanism of Action

FMN/FAD Coenzyme Function

Critical B-Vitamin Dependencies

Riboflavin deficiency impairs B6, B9, and B3 status. This makes adequate B2 essential for the entire B-complex to function optimally. In NTRPX formulations, B2 serves as a foundational cofactor.

Clinical Evidence

Migraine Prevention (Primary Clinical Application)

Study	Design	N	Intervention	Outcome	Reference
Schoenen et al. 1998	RCT, DB, PC	55	400mg/day, 3 months	↓59% migraine frequency	Neurology
Boehnke et al. 2004	Open-label	23	400mg/day, 3 months	↓50% migraine days	Eur J Neurol
MacLennan et al. 2008	RCT, DB, PC	48	200mg/day, 12 weeks	Trend toward improvement	J Child Neurol

Status Assessment

Marker	Method	Interpretation
EGRAC	Erythrocyte Glutathione Reductase Activity Coefficient	<1.2 adequate; 1.2-1.4 marginal; >1.4 deficient
Urinary riboflavin	24-hour collection	<40 μg/day indicates deficiency

Form Comparison Studies

Evidence Gap: No published RCTs directly compare riboflavin vs R5P for clinical outcomes. The recommendation for R5P is based on theoretical advantages (active form, better solubility) without documented superiority.

Safety & Specification

Safety Profile

Parameter	Value
UL	None established
Toxicity	No known toxicity even at high doses
Common AE	Yellow-orange urine discoloration (harmless)
Half-life	~1 hour (rapid turnover)

NTRPX Specification

Parameter	Specification
Form	Riboflavin-5’-Phosphate Sodium
Dose	10-25mg (all systems)
Purity	≥98%
Migraine protocol	400mg (either form acceptable)

Vitamin B3: Niacin

Active Forms

NAD+ / NADP+

Enzymatic Reactions

400 Enzymes

Age-Related Decline

~50% NAD+ by Age 60

RDA

14-16 mg NE/day

Form Comparison & Recommendation

NAD+ Precursor Hierarchy

Comprehensive Form Comparison

Form	NAD+ Boosting	Flush	Lipid Effects	Sirtuin Concern	Regulatory	Evidence Tier
Nicotinic Acid	High	YES	✓ ↑HDL ↓LDL/TG	None	GRAS	TIER 1
Nicotinamide	Highest	No	None	High doses may inhibit	GRAS	TIER 1
NR (Niagen®)	Moderate-High	No	Minimal	None	GRAS	TIER 2
NMN	Moderate	No	Minimal	None	⚠️ Not legal as supplement	TIER 3
Inositol Hexanicotinate	None/Minimal	No	None proven	N/A	GRAS	TIER 4

Biosynthesis Pathways

NR Advantage: Nicotinamide riboside bypasses the rate-limiting NAMPT enzyme, providing a more direct route to NAD+. This also avoids the potential sirtuin inhibition concern of high-dose nicotinamide, which can cause product inhibition of NAMPT.

NTRPX Recommendation

Primary: Nicotinamide Riboside

Dose: 250-500mgEfficient NAD+ elevation without flush. Bypasses NAMPT rate-limitation. No sirtuin inhibition concern. GRAS status, well-tolerated to 2g/day. Clean regulatory profile.Evidence Tier: TIER 2 (Probable)

Alternative: Nicotinamide

Dose: 100-500mgMore cost-effective. Highest NAD+ boost per mg. Sirtuin concern only at very high doses (>1g). Appropriate for budget formulations.Evidence Tier: TIER 1 (Proven) for NAD+ elevation

Forms to Avoid:

Inositol hexanicotinate (“flush-free niacin”): Clinical data shows no NAD+ elevation at 1g dose
NMN: FDA ruled (November 2022) may not be legally marketed as dietary supplement
High-dose nicotinic acid: Hepatotoxicity risk, uncomfortable flush

Clinical Evidence

Nicotinamide Riboside Human Trials

Study	Design	N	Dose	Duration	Primary Finding	Reference
Martens et al. 2018	RCT, DB, PC, crossover	24	1g/day	6 weeks	↑NAD+ 60%, ↓SBP 2-4mmHg trend	Nat Commun
Dollerup et al. 2018	RCT, DB, PC	40	1g/day	12 weeks	↑NAD+, insulin sensitivity unchanged	Am J Clin Nutr
Elhassan et al. 2019	RCT	12	1g/day	21 days	↑NAD+ in skeletal muscle	Cell Rep
Conze et al. 2019	Safety, dose-escalation	140	Up to 2g/day	8 weeks	Well-tolerated, dose-dependent NAD+	Sci Rep
Remie et al. 2020	RCT, DB, PC	13	1g/day	6 weeks	↑NAD+ in obese adults, no metabolic changes	Obesity

NAD+ Precursor Comparison Study

Study	Design	Finding	Reference
Pencina et al. 2023	RCT, head-to-head, 1g doses	NAD+ boosting: Nicotinamide > Niacin > NR > NMN > IHN (ineffective)	J Clin Endocrinol Metab

Nicotinic Acid Lipid Trials (Historical)

Study	N	Finding	Reference
Coronary Drug Project 1975	8,341	↓27% nonfatal MI; long-term ↓11% mortality	JAMA
AIM-HIGH 2011	3,414	No benefit adding niacin to statin	N Engl J Med

Context: High-dose nicotinic acid was historically used for lipid modification but has largely been replaced by statins. Current interest in niacin forms focuses on NAD+ boosting for longevity and mitochondrial function rather than lipid effects.

Safety Profile

Form-Specific Safety

Form	Key Concern	UL	Maximum Safe Dose
Nicotinic Acid	Hepatotoxicity (especially sustained-release); flush	35mg (as niacin)	2-3g/day with monitoring
Nicotinamide	Hepatotoxicity at very high doses	35mg (as niacin)	3g/day
NR	Well-tolerated	None established	2g/day in trials

The Flush Phenomenon

The flush is harmless but can be uncomfortable. Nicotinamide and NR do not cause flush because they do not activate GPR109A.

NTRPX Specification

Parameter	Specification
Form	Nicotinamide Riboside (as Niagen® or equivalent)
Dose	250-500mg (Recover); 100-250mg (Sustain/Boost)
Alternative	Nicotinamide 100-500mg
Avoid	Inositol hexanicotinate, NMN

Vitamin B5: Pantothenic Acid

Active Form

Coenzyme A (CoA)

Key Function

Acyl Group Transfer

Deficiency

Extremely Rare

AI

5 mg/day

Form Comparison & Recommendation

Available Forms

Form	Structure	Primary Use	CoA Conversion
D-Calcium Pantothenate	Calcium salt	Standard supplementation	5 enzymatic steps
D-Pantothenic Acid	Free acid	Less stable	5 enzymatic steps
Pantethine	Disulfide of pantetheine	Lipid modification	2 steps (direct CoA precursor)
Dexpanthenol	Alcohol form	Topical/injectable	5+ steps

Critical Distinction

PANTETHINE ≠ PANTOTHENIC ACID clinically. Pantethine has unique lipid-lowering effects not seen with pantothenic acid. They are not interchangeable for therapeutic purposes.

NTRPX Recommendation

Recommended: D-Calcium Pantothenate

Dose: 25-100mgStandard form is sufficient for CoA synthesis. Deficiency virtually impossible with any reasonable intake. Stable, cost-effective, well-tolerated.Evidence Tier: N/A — No evidence that any form is superior for general B5 support

Pantethine Add-On: For lipid-focused formulations only, consider Pantethine 300-600mg. Not necessary for general B-vitamin support due to significant cost increase.

Clinical Evidence

Pantethine Lipid Modification

Study	Design	N	Dose	Duration	Findings	Reference
Meta-analysis 2005	28 trials pooled	646	600-1200mg/day	4 months	↓TG 32.9%, ↓TC 15.1%, ↓LDL 20.1%, ↑HDL 8.4%	Nutr Res
Rumberger et al. 2011	RCT, DB, PC	32	600mg/day	16 weeks	↓TC 8.4%, ↓LDL 11.8%	Nutr Res
Evans et al. 2014	RCT	120	600mg/day	16 weeks	↓TC, ↓LDL, improved ratios	Vasc Health Risk Manag

Mechanism of Pantethine Lipid Effects

Pantothenic acid (standard form) does NOT produce these lipid effects. The unique benefits of pantethine appear related to its direct CoA precursor status and cysteamine release.

Safety & Specification

Safety Profile

Parameter	Value
UL	None established
Toxicity	No known toxicity
High-dose effects	Mild GI upset at 10g+
Drug interactions	None significant

NTRPX Specification

Parameter	Specification
Form	D-Calcium Pantothenate
Dose	25-100mg (all systems)
Purity	≥99%
Optional add-on	Pantethine 300-600mg (lipid formulas only)

Vitamin B6: Pyridoxine

Active Form

Pyridoxal-5’-Phosphate (PLP)

Enzymatic Reactions

140 Enzymes (~4% of all)

Key Functions

Neurotransmitter Synthesis

RDA

1.3-2.0 mg/day

Form Comparison & Recommendation

The Pyridoxine Paradox

CRITICAL SAFETY FINDING: High-dose pyridoxine (B6) supplementation can cause the very symptoms it should prevent — sensory neuropathy and nerve damage. This “pyridoxine paradox” occurs because inactive pyridoxine competitively inhibits active PLP at enzyme binding sites.

Form Comparison

Form	Conversion Required	Neurotoxicity Risk	Retention	Cost
Pyridoxine HCl	Yes (multiple steps)	HIGH at >50mg chronic	Moderate	Low
Pyridoxal-5’-Phosphate (P5P)	No — active form	MINIMAL	Higher	Higher
Pyridoxamine	Yes	Lower	Moderate	Moderate

Clinical Evidence for Neurotoxicity

Study	Findings	Reference
Vrolijk et al. 2017	Cell viability studies: Pyridoxine causes concentration-dependent neuronal death; P5P does not	Toxicol In Vitro
Hadtstein & Vrolijk 2021	Comprehensive review: >50 cases pyridoxine neuropathy since 2014	Adv Nutr
Dalton & Dalton 1987	Original report: Neuropathy at 50-500mg/day	Acta Neurol Scand

NTRPX Recommendation

MANDATORY: Pyridoxal-5'-Phosphate (P5P)

Dose: 10-25mgP5P is the only acceptable form for NTRPX formulations. Active coenzyme form requires no conversion. Avoids neurotoxicity risk entirely. Higher retention and utilization. Supports individuals with impaired conversion (MTHFR, liver issues).Evidence Tier: TIER 2 (Probable) for safety advantage

DO NOT USE Pyridoxine HCl in any NTRPX formula. The neurotoxicity risk at moderate-to-high doses is unacceptable when a safe alternative exists.

Mechanism of Action

PLP Coenzyme Functions

Conversion Pathway

B2 Dependency: The conversion of pyridoxine to PLP requires FMN (from riboflavin B2). Riboflavin deficiency impairs B6 activation, reinforcing the need for adequate B2 in any B-complex formula.

Safety Profile

Neurotoxicity Data

Dose	Risk	Timeframe	Reversibility
<10mg/day	Negligible	—	—
10-50mg/day	Low	Chronic use	Usually reversible
50-200mg/day	Moderate	Months	Variable
>200mg/day	High	Weeks-Months	May be permanent

Drug Interactions

Drug	Interaction	Action
Levodopa	B6 increases peripheral conversion (reduces efficacy)	Use only with carbidopa
Phenytoin, phenobarbital	Increased B6 catabolism	Monitor, may need supplementation
Isoniazid	B6 antagonist	Supplement required

NTRPX Specification

Parameter	Specification
Form	Pyridoxal-5’-Phosphate (P5P) exclusively
Dose	10-25mg (all systems)
Purity	≥98%
PROHIBITED	Pyridoxine HCl

Vitamin B7: Biotin

Active Form

D-Biotin (only one)

Key Enzymes

5 Carboxylases

Deficiency

Very Rare

AI

30 mcg/day

Form Analysis

Only One Active Form Exists

SIMPLE DECISION: There is only ONE biologically active form of biotin — D-Biotin. Eight structural varieties exist, but only D-biotin has biological activity. No form selection required beyond ensuring D-biotin (not DL-racemic).

Form	Activity	Notes
D-Biotin	✓ Active	The only form to use
L-Biotin	✗ Inactive	Enantiomer, no biological activity
DL-Biotin (racemic)	50% active	Avoid — half is inactive L-form
Biocytin	Precursor	Protein-bound in food; cleaved to D-biotin

NTRPX Recommendation

Recommended: D-Biotin

Dose: 30-300 mcgEnsure product specifies D-biotin (not DL-racemic). Deficiency extremely rare; low doses sufficient. Avoid high-dose biotin (>1000 mcg) due to lab test interference.

Hair/Nail Claims Assessment

Evidence Status: NOT SUPPORTED

Marketing vs Evidence: Biotin is heavily marketed for hair and nail health. The clinical evidence does not support these claims in non-deficient individuals.

Study Type	Findings	Reference
Patel et al. 2017	Systematic review: Insufficient evidence for hair/nail benefits	Skin Appendage Disord
Study limitations	No baseline biotin measurement, varied diagnoses, conditions can resolve spontaneously	Multiple

NTRPX Position

Do NOT market biotin for hair/nail health. Deficiency is extremely rare in developed countries, and supplementation in non-deficient individuals shows no benefit for hair or nail quality.

Lab Test Interference

Critical Clinical Consideration

High-dose biotin interferes with common lab tests using streptavidin-biotin immunoassay methodology. This can cause clinically dangerous misdiagnosis.

Affected Test	Direction	Clinical Impact
TSH, T3, T4	False positive/negative	Thyroid misdiagnosis
Troponin	False negative	Missed heart attack
PSA	False negative	Missed cancer
Pregnancy tests	Variable	Incorrect result
Vitamin D	Variable	Incorrect supplementation

Clinical Guidance

Biotin Dose	Action Before Lab Work
<300 mcg/day	No action needed
300-1000 mcg/day	Inform lab
>1000 mcg/day	Discontinue 48-72 hours before testing

Reference	Finding
Li et al. 2020	Comprehensive review of biotin interference	J Appl Lab Med
FDA Safety Communication 2017	Warning about biotin interference	FDA

Safety & Specification

Safety Profile

Parameter	Value
UL	None established
Toxicity	No known toxicity at any dose
Adverse effects	None (except lab interference)
Drug interactions	Anticonvulsants may deplete

NTRPX Specification

Parameter	Specification
Form	D-Biotin only (not DL-racemic)
Dose	30-300 mcg (all systems)
Maximum	1000 mcg (lab interference concern above)
Purity	≥99%

Vitamin B9: Folate

Active Form

5-MTHF (L-Methylfolate)

Key Function

One-Carbon Transfer

MTHFR Variants

~40% Population Affected

RDA

400 mcg DFE/day

Form Comparison & Recommendation

Form Hierarchy

The MTHFR Problem

~40% of the global population has MTHFR gene variants that reduce the ability to convert folic acid to active 5-MTHF. For these individuals, folic acid supplementation may be suboptimal or even counterproductive.

MTHFR Genotype	Prevalence	Enzyme Activity	Folic Acid Conversion
CC (wild-type)	~45%	100%	Normal
CT (heterozygous)	~45%	~65%	Reduced
TT (homozygous)	~10%	~30%	Severely impaired

Conversion Pathway

Unmetabolized Folic Acid (UMFA)

Concern	Evidence	Reference
UMFA detectable at >200 mcg folic acid	Kinetic studies	Am J Clin Nutr
UMFA detected in cord blood	Observational	Am J Clin Nutr
May compete with 5-MTHF for receptors	Theoretical	Multiple
Long-term health effects unknown	Research gap	—

5-MTHF Branded Forms

Brand	Salt Form	Bioavailability	Notes
Quatrefolic®	Glucosamine salt	Highest	Most soluble, most stable
Metafolin®	Calcium salt	High	Well-established
Generic L-5-MTHF	Various	Variable	Ensure (6S) isomer specified

Isomer Matters: Only the L- and (6S)- forms are biologically active. D- and (6R)- forms are not. Always verify the product specifies the correct stereochemistry.

NTRPX Recommendation

MANDATORY: L-5-MTHF (Quatrefolic® preferred)

Dose: 400-800 mcgActive form bypasses entire metabolic pathway. Benefits ~40% of population with MTHFR variants. No UMFA accumulation. Superior bioavailability. No B12 masking concern.Evidence Tier: TIER 2 (Probable) for superiority in MTHFR populations

DO NOT USE Folic Acid in NTRPX formulas.Exception: CDC/WHO still recommend folic acid for pregnancy/neural tube defect prevention because only folic acid has RCT evidence for NTD prevention. For pregnancy-specific products, consider regulatory guidance.

Clinical Evidence

5-MTHF vs Folic Acid Studies

Study	Design	N	Finding	Reference
Prinz-Langenohl et al. 2009	RCT, crossover	37	5-MTHF raises plasma folate more effectively than folic acid in TT genotype	Br J Pharmacol
Lamers et al. 2006	RCT	147	5-MTHF equivalent to folic acid for reducing homocysteine	Am J Clin Nutr
Venn et al. 2002	RCT	104	5-MTHF sustained homocysteine reduction at 6 months	Eur J Clin Nutr

Depression Adjunctive Therapy

Study	Design	N	Dose	Finding	Reference
Papakostas et al. 2012	RCT, DB, PC	75	15mg L-methylfolate + SSRI	Significant improvement vs placebo + SSRI	Am J Psychiatry
Shelton et al. 2013	RCT, DB, PC	123	15mg L-methylfolate + SSRI	Response rate: 32.3% vs 14.6%	J Clin Psychiatry

Bioavailability Studies

Study	Finding	Reference
Scaglione & Panzavolta 2014	Comprehensive review: 5-MTHF pharmacologically distinct from folic acid	Xenobiotica

Safety & Specification

Safety Profile

Form	Safety Concerns
5-MTHF	Generally well-tolerated; may cause overmethylation in sensitive individuals
Folic Acid	UMFA accumulation; may mask B12 deficiency
Folinic Acid	Well-tolerated; may be better for methylation-sensitive

NTRPX Specification

Parameter	Specification
Form	(6S)-5-Methyltetrahydrofolate glucosamine salt (Quatrefolic®)
Dose	400-800 mcg (all systems)
Stereochemistry	(6S)- or L- form ONLY
PROHIBITED	Folic acid

Vitamin B12: Cobalamin

Active Forms

Methylcobalamin + Adenosylcobalamin

Key Functions

Methylation + Energy

Absorption

Requires Intrinsic Factor

RDA

2.4 mcg/day

Form Comparison & Recommendation

B12 Form Hierarchy

Why BOTH Active Forms?

Methylcobalamin and adenosylcobalamin serve DIFFERENT biochemical functions. Using only one form provides incomplete B12 support.

Function	Methylcobalamin	Adenosylcobalamin
Location	Cytoplasm	Mitochondria
Enzyme	Methionine synthase	Methylmalonyl-CoA mutase
Reaction	Homocysteine → Methionine	Methylmalonyl-CoA → Succinyl-CoA
Supports	Methylation, DNA synthesis	Energy production, fatty acid metabolism

NTRPX Recommendation

Primary: Methylcobalamin

Dose: 500-1000 mcgActive coenzyme for methylation reactions. Primary form in blood, liver, brain. Higher retention than cyanocobalamin. No conversion required.

Secondary: Adenosylcobalamin

Dose: 250-500 mcgActive coenzyme for energy production. Primary form in mitochondria. Required for propionate/odd-chain FA metabolism. Completes B12 support.

Use BOTH forms together for comprehensive B12 support. Alternatively, hydroxocobalamin (which converts to both active forms) is an acceptable single-form option.

DO NOT USE Cyanocobalamin as primary B12 source. Lower retention, greater urinary losses, and requires multiple conversion steps. Contains cyanide molecule (safe but unnecessary when active forms are available).

Clinical Evidence

Form Comparison Studies

Study	Design	Finding	Reference
Paul & Brady 2017	Review	Methylcobalamin and adenosylcobalamin may be preferable for genetic polymorphisms affecting B12 metabolism	Integr Med
Obeid et al. 2015	Review	All forms effective for raising serum B12; tissue-specific differences exist	Mol Nutr Food Res
Thakkar & Billa 2015	Review	Methylcobalamin shows unique neuroprotective properties	Expert Opin Drug Deliv

Retention Studies

Study	Finding	Reference
Adams et al. 1971	Hydroxocobalamin retained better than cyanocobalamin after injection	Lancet
Okuda et al. 1973	Methylcobalamin shows higher tissue retention	J Lab Clin Med

Absorption Considerations

Factor	Impact on B12 Absorption
Intrinsic factor	Required for ileal absorption; absent in pernicious anemia
Gastric acid	Required to release B12 from food protein
Age	Absorption decreases (atrophic gastritis)
Metformin	Reduces B12 absorption
PPIs, H2 blockers	Reduce gastric acid, impair B12 release
Passive diffusion	~1% absorbed without IF (high-dose relevant)

High-Dose Strategy: At doses >500 mcg, passive diffusion becomes significant (~1% = 5+ mcg), which can bypass intrinsic factor requirement. This is why high-dose oral B12 can be effective even in pernicious anemia.

Safety & Specification

Safety Profile

Parameter	Value
UL	None established
Toxicity	No known toxicity at any dose
Adverse effects	Rare: acne/rosacea flare (high-dose methylcobalamin)
Drug interactions	See absorption factors

NTRPX Specification

Parameter	Specification
Primary Form	Methylcobalamin ≥98%
Secondary Form	Adenosylcobalamin ≥98%
Methylcobalamin Dose	500-1000 mcg
Adenosylcobalamin Dose	250-500 mcg
Alternative	Hydroxocobalamin 1000 mcg
PROHIBITED	Cyanocobalamin as primary source
Storage	Protect from light (methylcobalamin sensitive)

Cross-Cutting Analysis

Methylation Pathway Integration

The Methylation Cycle Requires B2, B6, B9, B12

Critical Dependencies

Vitamin	Role in Methylation	Form Required
B2 (Riboflavin)	FAD is cofactor for MTHFR	R5P
B6 (Pyridoxine)	P5P is cofactor for CBS (transsulfuration)	P5P
B9 (Folate)	5-MTHF is methyl donor	L-5-MTHF
B12 (Cobalamin)	Methylcobalamin is cofactor for methionine synthase	Methylcobalamin

All four vitamins must be in active forms for optimal methylation support. Deficiency or suboptimal form of any one impairs the entire cycle.

Energy Metabolism Integration

B1, B2, B3, B5 Coordinate Energy Production

Energy B-Vitamin Summary

Vitamin	Coenzyme	Energy Role
B1	ThDP	PDH, α-KGDH (TCA cycle entry points)
B2	FAD/FMN	ETC Complex I & II, SDH
B3	NAD+/NADP+	>400 redox reactions, TCA cycle, ETC
B5	CoA	Acetyl-CoA formation, fatty acid metabolism

Synergy & Ratio Considerations

Recommended Ratios

Vitamin	RDA	NTRPX Range	Ratio to B2
B1	1.2 mg	25-100 mg (benfotiamine)	2-8×
B2	1.3 mg	10-25 mg (R5P)	1× (baseline)
B3	16 mg	100-500 mg (NR/NAM)	8-40×
B5	5 mg	25-100 mg	2-8×
B6	1.7 mg	10-25 mg (P5P)	1-2×
B7	30 mcg	100-300 mcg	—
B9	400 mcg	400-800 mcg (5-MTHF)	—
B12	2.4 mcg	500-1000 mcg (methyl+adenosyl)	—

Key Synergies

Synergy	Mechanism	Importance
B2 + B6	FMN required for pyridoxine oxidase	Essential
B2 + B9	FAD required for MTHFR	Essential
B9 + B12	Methylation cycle partners	Always supplement together
B6 + B9 + B12	Homocysteine metabolism	Cardiovascular relevance
B1 + B2 + B3 + B5	Energy metabolism	Performance relevance

NTRPX Systems Integration

All Systems Go — Sustain

B-Vitamin Specification

Vitamin	Form	Dose	Rationale
B1	Benfotiamine	150-300 mg	Peripheral metabolic support, AGE inhibition
B2	R5P	15-25 mg	Active form, supports B6/B9 function
B3	NR or Nicotinamide	250-500 mg	NAD+ maintenance
B5	D-Calcium Pantothenate	50-100 mg	CoA synthesis
B6	P5P	15-25 mg	Active form, avoids neurotoxicity
B7	D-Biotin	100-300 mcg	Carboxylase support
B9	L-5-MTHF (Quatrefolic)	400-800 mcg	Methylation support
B12	Methylcobalamin + Adenosylcobalamin	500 + 250 mcg	Both coenzyme forms

All Systems Go — Boost

B-Vitamin Specification

Vitamin	Form	Dose	Rationale
B1	Benfotiamine	100-150 mg	Energy metabolism
B2	R5P	10-15 mg	Electron transport
B3	Nicotinamide	100-250 mg	NAD+ for acute energy
B5	D-Calcium Pantothenate	25-50 mg	CoA availability
B6	P5P	10-15 mg	Neurotransmitter synthesis
B7	D-Biotin	100 mcg	Standard support
B9	L-5-MTHF	400 mcg	Methylation
B12	Methylcobalamin	500 mcg	Cognitive support

All Systems Go — Recover

B-Vitamin Specification

Vitamin	Form	Dose	Rationale
B1	Benfotiamine	150-300 mg	Tissue repair, antioxidant
B2	R5P	15-25 mg	Glutathione recycling
B3	NR	250-500 mg	NAD+ for cellular repair
B5	D-Calcium Pantothenate	50-100 mg	Wound healing support
B6	P5P	15-25 mg	Protein metabolism
B7	D-Biotin	100-300 mcg	Standard support
B9	L-5-MTHF	600-800 mcg	Cell turnover, DNA repair
B12	Methylcobalamin + Adenosylcobalamin	750 + 500 mcg	Elevated for recovery

Sprint (Cognitive Focus)

B-Vitamin Specification

Vitamin	Form	Dose	Rationale
B1	TTFD	50-100 mg	Confirmed BBB penetration
B2	R5P	10-15 mg	Neural metabolism
B3	Nicotinamide	100-250 mg	Brain NAD+
B5	D-Calcium Pantothenate	25-50 mg	Acetylcholine precursor
B6	P5P	10-25 mg	Neurotransmitter synthesis
B7	D-Biotin	100 mcg	Standard support
B9	L-5-MTHF	400 mcg	Neural methylation
B12	Methylcobalamin	1000 mcg	Cognitive, methylation

Final Specifications Summary

Approved Forms

Vitamin	Approved Form(s)
B1	Benfotiamine, TTFD
B2	Riboflavin-5’-Phosphate
B3	Nicotinamide Riboside, Nicotinamide
B5	D-Calcium Pantothenate
B6	Pyridoxal-5’-Phosphate
B7	D-Biotin
B9	L-5-MTHF (Quatrefolic)
B12	Methylcobalamin + Adenosylcobalamin

Prohibited Forms

Vitamin	DO NOT USE
B1	Sulbutiamine (mood concerns)
B3	Inositol hexanicotinate, NMN
B6	Pyridoxine HCl (neurotoxicity)
B7	DL-Biotin (racemic)
B9	Folic acid (MTHFR, UMFA)
B12	Cyanocobalamin (as primary)

Quality Standards

Parameter	Specification
Identity	HPLC confirmation of stated forms
Purity	≥98% for all vitamins
Heavy metals	USP <232>/<233> limits
Microbial	USP <2021> standards
Stability	24-month shelf life
Third-party testing	Required for all batches

References

B1 Thiamine References

B2 Riboflavin References

Schoenen J, et al. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology. 1998;50(2):466-70.
Boehnke C, et al. High-dose riboflavin treatment is efficacious in migraine prophylaxis: an open study in a tertiary care centre. Eur J Neurol. 2004;11(7):475-7.
Powers HJ. Riboflavin (vitamin B-2) and health. Am J Clin Nutr. 2003;77(6):1352-60.

B3 Niacin References

Nicotinamide Riboside Studies

Martens CR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9:1286.
Dollerup OL, et al. A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects. Am J Clin Nutr. 2018;108(2):343-53.
Elhassan YS, et al. Nicotinamide Riboside Augments the Aged Human Skeletal Muscle NAD+ Metabolome and Induces Transcriptomic and Anti-inflammatory Signatures. Cell Rep. 2019;28(7):1717-28.
Conze D, et al. Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults. Sci Rep. 2019;9:9772.

Comparative Studies

Pencina KM, et al. Nicotinamide Adenine Dinucleotide Augmentation in Overweight or Obese Middle-Aged and Older Adults: A Physiologic Study. J Clin Endocrinol Metab. 2023;108(8):1968-80.

B5 Pantothenic Acid References

Rumberger JA, et al. Pantethine, a derivative of vitamin B5 used as a nutritional supplement, favorably alters low-density lipoprotein cholesterol metabolism in low- to moderate-cardiovascular risk North American subjects: a triple-blinded placebo and diet-controlled investigation. Nutr Res. 2011;31(8):608-15.
Evans M, et al. Pantethine, a derivative of vitamin B5, favorably alters total, LDL and non-HDL cholesterol in low to moderate cardiovascular risk subjects eligible for statin therapy: a triple-blinded placebo and diet-controlled investigation. Vasc Health Risk Manag. 2014;10:89-100.
McRae MP. Treatment of hyperlipoproteinemia with pantethine: A review and analysis of efficacy and tolerability. Nutr Res. 2005;25(4):319-33.

B6 Pyridoxine References

Neurotoxicity Studies

Vrolijk MF, et al. The vitamin B6 paradox: Supplementation with high concentrations of pyridoxine leads to decreased vitamin B6 function. Toxicol In Vitro. 2017;44:206-12.
Hadtstein F, Vrolijk M. Vitamin B-6-Induced Neuropathy: Exploring the Mechanisms of Pyridoxine Toxicity. Adv Nutr. 2021;12(5):1911-29.
Dalton K, Dalton MJ. Characteristics of pyridoxine overdose neuropathy syndrome. Acta Neurol Scand. 1987;76(1):8-11.

B7 Biotin References

Patel DP, et al. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord. 2017;3(3):166-9.
Li D, et al. Biotin interference with diagnostic immunoassays: problem and solutions. J Appl Lab Med. 2020;5(3):452-61.
FDA Safety Communication. The FDA Warns that Biotin May Interfere with Lab Tests. 2017.

B9 Folate References

5-MTHF vs Folic Acid

Prinz-Langenohl R, et al. (6S)-5-methyltetrahydrofolate increases plasma folate more effectively than folic acid in women with the homozygous or wild-type 677C→T polymorphism of methylenetetrahydrofolate reductase. Br J Pharmacol. 2009;158(8):2014-21.
Lamers Y, et al. Red blood cell folate concentrations increase more after supplementation with [6S]-5-methyltetrahydrofolate than with folic acid in women of childbearing age. Am J Clin Nutr. 2006;84(1):156-61.
Scaglione F, Panzavolta G. Folate, folic acid and 5-methyltetrahydrofolate are not the same thing. Xenobiotica. 2014;44(5):480-8.

Depression Studies

Papakostas GI, et al. L-methylfolate as adjunctive therapy for SSRI-resistant major depression: results of two randomized, double-blind, parallel-sequential trials. Am J Psychiatry. 2012;169(12):1267-74.
Shelton RC, et al. Assessing effects of l-methylfolate in depression management: results of a real-world patient experience trial. J Clin Psychiatry. 2013;74(4):377-81.

B12 Cobalamin References

Paul C, Brady DM. Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms. Integr Med (Encinitas). 2017;16(1):42-9.
Obeid R, et al. Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency. Mol Nutr Food Res. 2015;59(7):1364-72.
Thakkar K, Billa G. Treatment of vitamin B12 deficiency — methylcobalamin? Cyanocobalamin? Hydroxocobalamin? — clearing the confusion. Expert Opin Drug Deliv. 2015;12(1):129-40.

Document Control

Version	Date	Author	Changes
1.0	2026-01-24	NTRPX R&D	Initial comprehensive evaluation

B-Vitamin Forms Evaluation Summary: This document establishes evidence-based form selection for all 8 essential B vitamins. Key principles: (1) Active coenzyme forms preferred where evidence supports safety advantage (P5P, 5-MTHF, methylcobalamin); (2) Safety concerns override theoretical benefits (pyridoxine neurotoxicity, folic acid UMFA); (3) Bioavailability advantages must be clinically demonstrated (benfotiamine, TTFD); (4) Some vitamins have only one active form (D-biotin). All recommendations are subject to revision as new evidence emerges.

Start Here

Method

Systems

Formulations

Ingredient Manual

Evaluations

Community

​Comprehensive B-Vitamin Forms Evaluation

Vitamins Evaluated

Forms Analyzed

Evidence Sources

Standard

​Quick Reference: Optimal Forms Summary

B1 Thiamine

B2 Riboflavin

B3 Niacin

B5 Pantothenic

B6 Pyridoxine

B7 Biotin

B9 Folate

B12 Cobalamin

​NTRPX Evidence Hierarchy

​Form Selection Criteria

​Standards Applied

Evidence Over Theory

Proven Over Promising

Safety Non-Negotiable

​Vitamin B1: Thiamine

Active Form

Key Enzymes

Primary Function

RDA

​Thiamine Form Hierarchy

​Head-to-Head Comparison

​NTRPX Recommendation

Peripheral/Metabolic Support

CNS/Cognitive Support

​Thiamine Coenzyme Function

​Critical Distinction: Thioesters vs Disulfides

​Benfotiamine Mechanism

​TTFD Mechanism

​Benfotiamine Clinical Trials

​Bioavailability Studies

​TTFD Clinical Trials

​BBB Penetration Evidence

​Evidence Summary

Benfotiamine

TTFD

​Adverse Events

​Paradoxical Reaction (TTFD)

​Toxicity Thresholds

​Drug Interactions

​Systems Integration

​Specification

​Vitamin B2: Riboflavin

Active Forms

Key Function

Dependencies

RDA

​Riboflavin Form Analysis

​Critical Insight

​When R5P May Provide Advantage

​NTRPX Recommendation

Recommended: Riboflavin-5'-Phosphate (R5P)

​FMN/FAD Coenzyme Function

​Critical B-Vitamin Dependencies

​Migraine Prevention (Primary Clinical Application)

​Status Assessment

​Form Comparison Studies

​Safety Profile

​NTRPX Specification

​Vitamin B3: Niacin

Active Forms

Enzymatic Reactions

Age-Related Decline

RDA

​NAD+ Precursor Hierarchy

​Comprehensive Form Comparison

​Biosynthesis Pathways

​NTRPX Recommendation

Comprehensive B-Vitamin Forms Evaluation

Quick Reference: Optimal Forms Summary

NTRPX Evidence Hierarchy

Form Selection Criteria

Standards Applied

Vitamin B1: Thiamine

Thiamine Form Hierarchy

Head-to-Head Comparison

NTRPX Recommendation

Thiamine Coenzyme Function

Critical Distinction: Thioesters vs Disulfides

Benfotiamine Mechanism

TTFD Mechanism

Benfotiamine Clinical Trials

Bioavailability Studies

TTFD Clinical Trials

BBB Penetration Evidence

Evidence Summary

Adverse Events

Paradoxical Reaction (TTFD)

Toxicity Thresholds

Drug Interactions

Systems Integration

Specification

Vitamin B2: Riboflavin

Riboflavin Form Analysis

Critical Insight

When R5P May Provide Advantage

NTRPX Recommendation

FMN/FAD Coenzyme Function

Critical B-Vitamin Dependencies

Migraine Prevention (Primary Clinical Application)

Status Assessment

Form Comparison Studies

Safety Profile

NTRPX Specification

Vitamin B3: Niacin

NAD+ Precursor Hierarchy

Comprehensive Form Comparison

Biosynthesis Pathways

NTRPX Recommendation

Nicotinamide Riboside Human Trials

NAD+ Precursor Comparison Study

Nicotinic Acid Lipid Trials (Historical)

Form-Specific Safety

The Flush Phenomenon

NTRPX Specification

Vitamin B5: Pantothenic Acid

Available Forms

Critical Distinction

NTRPX Recommendation

Pantethine Lipid Modification

Mechanism of Pantethine Lipid Effects

Safety Profile

NTRPX Specification

Vitamin B6: Pyridoxine

The Pyridoxine Paradox

Form Comparison

Clinical Evidence for Neurotoxicity

NTRPX Recommendation

PLP Coenzyme Functions

Conversion Pathway

Neurotoxicity Data

Drug Interactions

NTRPX Specification

Vitamin B7: Biotin

Only One Active Form Exists

NTRPX Recommendation

Evidence Status: NOT SUPPORTED

NTRPX Position

Critical Clinical Consideration

Clinical Guidance

Safety Profile

NTRPX Specification

Vitamin B9: Folate

Form Hierarchy

The MTHFR Problem

Conversion Pathway

Unmetabolized Folic Acid (UMFA)

5-MTHF Branded Forms