B-Complex contains 8 water-soluble vitamins (B1, B2, B3, B5, B6, B7, B9, B12) that act as cofactors in 100+ enzyme systems. The form matters — standard (cyanocobalamin B12 + folic acid) is fine for most people, but ~40% of the population has MTHFR variants that need activated (methylated) forms like methylcobalamin and 5-MTHF. This page ranks 10 popular B-complex products on absorption, evidence, and the methylated vs standard question.
Last updated: August 23, 2026 · Sources: NIH ODS B-Vitamins, Kennedy 2016, Kennedy 2010, Examine.com
At a glance
Best absorption (methylated)
Thorne B-Complex #1
NSF Certified for Sport. Activated forms (5-MTHF folate + methylcobalamin B12). High doses of B1, B3, B6. Bypasses MTHFR enzyme — works for ~40% of population with MTHFR variants.
Best AU mass-market
Swisse Ultiboost B-Complex with Vitamin C
100 tablets, standard cyanocobalamin + folic acid. Widely stocked at Watsons and Boots in Thailand. The default AU pharmacy choice for daily maintenance.
Best Thailand-available
Vistra B-Plus 30 caps
Thai pharmacy B-complex combined with probiotics and inulin. Targets the gut-brain axis. Stocked at Watsons, Boots, and Lazada.
Product comparison
Compare 10 popular B-complex products on form, dose of major B-vitamins, absorption score, GI tolerance, and price per dose. The "Form" column shows whether the product uses standard (cyanocobalamin/folic acid) or activated/methylated forms. B1-B6 doses are in mg, B7-B9-B12 in mcg.
Form column: "Standard" uses cyanocobalamin B12 + folic acid; "Activated Methylated" uses methylcobalamin B12 + 5-MTHF folate (works for MTHFR variants). Absorption 5/5 = highest bioavailability. GI tolerance 5/5 = fewest side effects. Evidence score 5/5 = strongest clinical-trial support.
Price column: prices marked "price not verified" indicate the author could not confirm a current retail price at write time. Use the retailer link to check the live price. We do not invent prices.
The 6 forms of B-complex, explained
1
Standard B-Complex
Daily maintenance
Absorption: 3/5 · GI tolerance: 5/5
The cheapest option per dose. Contains all 8 B-vitamins at RDA-level doses (typically 25-50 mg). Uses cyanocobalamin (B12) and folic acid (B9) — the standard, well-studied forms. Adequate for most people without genetic variations.
Cyanocobalamin is cheaper but less bioavailable than methylcobalamin. Folic acid must be converted by the MTHFR enzyme — ~40% of population has reduced MTHFR activity per NIH ODS.
Best for: Daily maintenance, general wellness, anyone without genetic variation in MTHFR, budget-conscious users.
2
Activated B-Complex (Methylated)
Best for MTHFR
Absorption: 5/5 · GI tolerance: 5/5
Uses the active, methylated forms: 5-MTHF (folate) and methylcobalamin (B12). Bypasses the MTHFR enzyme — works for ~40% of population with MTHFR polymorphisms. Higher doses of B1, B3, B6 per Thorne formulation. The form used in most clinical trials.
Most expensive per dose. The "extra" methylation is only beneficial for those with MTHFR variants — others see no advantage over standard B-complex.
Best for: Anyone with MTHFR mutation, chronic fatigue, depression with low B12/folate, anyone on a high-stress protocol, athletes in heavy training.
3
High-Potency B-Complex
Stress protocol
Absorption: 3/5 · GI tolerance: 4/5
High doses (100 mg of B1, B2, B3, B5, B6) for stress and nervous system support. Useful for short-term stress protocols. The dose most practitioners use for chronic stress or burnout recovery.
B6 at 100 mg exceeds the 60 mg/day UL for adults — long-term use risks peripheral neuropathy (per NIH ODS). Niacinamide (B3) at high doses can cause flushing.
Best for: Short-term stress protocols (4-8 weeks), chronic fatigue, anyone with documented B-vitamin deficiency, post-illness recovery.
4
Stress-Formulated B-Complex
AU pharmacy classic
Absorption: 3/5 · GI tolerance: 5/5
Standard B-complex + extra B12 (50 mcg) marketed for stress, energy, and fatigue. The "Blackmores B Complex + B12" pattern. Available over-the-counter at any AU pharmacy. Adequate for daily maintenance.
The "extra B12" is rarely enough to make a clinical difference for deficiency. Uses cyanocobalamin (not methylcobalamin) — no advantage for MTHFR variants.
Best for: Daily maintenance, general fatigue, anyone wanting a recognizable heritage pharmacy brand.
5
B-Complex + Iron
For women
Absorption: 2/5 · GI tolerance: 3/5
Combines B-complex with iron (often 5-10 mg). Useful for menstruating women, pregnancy, anemia protocols. The B12-folate-iron combination is the classic "blood-building" protocol.
Iron causes GI side effects (constipation, nausea) in many users. Not appropriate for men or post-menopausal women (iron overload risk).
Best for: Menstruating women with documented iron deficiency, pregnancy support, anemia protocols with practitioner guidance.
6
B-Complex + Probiotic
Gut-brain axis
Absorption: 4/5 · GI tolerance: 5/5
Combines B-complex with probiotics and prebiotics (inulin, FOS). Targets the gut-brain axis — many B-vitamins are produced by gut bacteria. Useful for those with gut-related fatigue or malabsorption.
Lower B-vitamin doses (15-20 mg) — not as potent as standalone high-dose B-complex. The "two-in-one" rarely matches the dose of either single product.
Best for: Gut-related fatigue, IBS, anyone with documented malabsorption, Thailand-available option for gut + energy.
How much B-vitamins do you actually need?
Per the US Institute of Medicine (IOM 1998, updated 2006) and the Australian NHMRC. Water-soluble B-vitamins have a low toxicity ceiling — excess is excreted in urine. The UL applies only to B6 (pyridoxine) and niacin (B3 as nicotinic acid).
B-Vitamin
Adult RDA
UL (supplement only)
Clinical-use dose
B1 Thiamine
1.1-1.2 mg
Not set
50-100 mg (stress)
B2 Riboflavin
1.1-1.3 mg
Not set
25-100 mg (migraines)
B3 Niacin
14-16 mg
35 mg (nicotinic acid)
50-500 mg (cholesterol)
B5 Pantothenic
5 mg
Not set
100-300 mg (adrenal)
B6 Pyridoxine
1.3-1.7 mg
100 mg
25-50 mg (PMS, nausea)
B7 Biotin
30 mcg
Not set
2,500-10,000 mcg (hair)
B9 Folate
400 mcg
1,000 mcg (synthetic)
400-800 mcg (pregnancy)
B12 Cobalamin
2.4 mcg
Not set
500-1,000 mcg (deficiency)
Source: NIH ODS B-Vitamin Fact Sheets · UL = tolerable upper intake level for supplements only. B6 is the only B-vitamin with a strict UL — chronic doses >100 mg/day cause peripheral neuropathy.
Top picks by use case
Best overall
Thorne B-Complex #1
NSF Certified for Sport. Activated methylated forms (5-MTHF + methylcobalamin). High doses of B1, B3, B6. Works for ~40% of population with MTHFR variants. Best for anyone who can afford premium pricing.
Best AU mass-market
Swisse Ultiboost B-Complex with Vitamin C
100 tablets at 30-50 mg daily values. Standard cyanocobalamin + folic acid. Widely stocked at Watsons and Boots in Thailand. The default AU pharmacy choice for daily maintenance.
Best Thailand-available
Vistra B-Plus 30 caps
Thai pharmacy B-complex + probiotics + inulin. Lower B-vitamin doses (15-20 mg) but adds gut-brain axis benefit. Stocked at Watsons, Boots, and Lazada. Best for gut-related fatigue.
Best budget AU
Nature's Own B Complex 60 tablets
Standard formulation at 30 mg daily values. CHEAP per tablet. Best budget option for daily maintenance. Frequently discounted at Australian pharmacies.
Best short-term stress protocol
Herbs of Gold B Complex 100
100 mg of B1, B2, B3, B5, B6. For SHORT-TERM stress protocols (4-8 weeks) only. The high B6 dose (100 mg) borders the UL — not for daily long-term use.
Best Thailand-domestic
Mega We Care Mega B Complex
50 mg doses of the major B-vitamins. The Thai-domestic option stocked at Watsons, Boots, and independent TH pharmacies. Cheap, accessible, and adequate for daily maintenance during stress.
Side effects & drug interactions
B-complex vitamins are water-soluble and generally safe at RDA doses. The main risks are B6 peripheral neuropathy at high doses (>100 mg/day chronic), and niacin flushing at >50 mg/day nicotinic acid.
Proton pump inhibitors (omeprazole) — long-term use depletes B12
Metformin — chronic use depletes B12 and folate
Anticonvulsants (phenytoin, carbamazepine) — deplete folate over time
B6 peripheral neuropathy risk: chronic B6 (pyridoxine) supplementation above 100 mg/day causes peripheral neuropathy — numbness, tingling, and ataxia in the hands and feet. Cases have been reported at 200-500 mg/day for months, but the EU food safety authority sets the UL at 25 mg/day to be conservative. Symptoms are usually reversible if caught early. Per NIH ODS, anyone taking >25 mg/day B6 long-term should monitor for neurological symptoms.
Methylated vs standard: The "you need methylated B12 and folate" trend is partly evidence-based, partly overhyped. NIH ODS confirms that ~40% of population has MTHFR variants that reduce conversion of folic acid to 5-MTHF. For these people, methylated forms are genuinely better. For others, the difference is negligible. A 23andMe or genetic test can confirm MTHFR status; suspected deficiency based on blood tests is also a reasonable trigger.
Kennedy DO. (2016). B Vitamins and the Brain: Mechanisms, Dose and Efficacy — A Review. Nutrients 8(2):68. PMID 26824326
Kennedy DO, et al. (2010). Effects of high-dose B vitamin complex with vitamin C and minerals on subjective mood and performance in healthy males. Psychopharmacology 211(1):55-68. PMID 20354725
Tardy AL, et al. (2020). Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review. Nutrients 12(1):228. PMID 31948027
Calderon-Ospina CA, Nava-Mesa MO. (2020). B Vitamins in the nervous system: Current knowledge of the biochemical modes of action. CNS & Neurological Disorders - Drug Targets 19(1):31-46.
Examine.com — B-Complex research review. examine.com
Thorne, Swisse, Blackmores, BioCeuticals, Ethical Nutrients, Herbs of Gold, Nature's Own, Vistra, Mega We Care, Interpharma — product pages and dose information cited per row above (date column).
Trusted brands we rate
These 10 brands are featured on every vitfacts.com comparison page. We track them
for ingredient transparency, third-party testing, and Thailand availability.
A heritage naturopathic brand spanning over 90 years, known for rigorous ingredient sourcing and massive pharmacy presence throughout the Asia-Pacific region.
A premium, practitioner-only brand (owned by Blackmores) offering highly concentrated, clinical-strength formulas that are frequently recommended by healthcare professionals.
A high-quality pharmacy brand heavily focused on evidence-based ingredients, widely known for its "Inner Health" probiotic range and highly absorbable magnesium powders.
Born in Australia, this brand formulates therapeutic herbal and nutritional supplements with a strict focus on purity, offering many vegan-friendly options.
One of Australia's longest-running and most accessible vitamin brands, providing a massive, budget-friendly range found in most major supermarkets and pharmacies.
A dominant local brand in Thai retail pharmacies (such as Watsons and Boots), highly popular for its acerola cherry, collagen, and beauty-focused supplements.
A leading pharmaceutical-grade supplement brand in Southeast Asia, widely trusted by Thai consumers for its fish oil and targeted clinical nutrition products.
While based in the US, Thorne is heavily imported and highly sought after by functional medicine practitioners globally—including in both Australia and Thailand. It is considered a gold standard due to its strict four-round testing protocol and complete absence of unnecessary fillers or binders.
Why these 10? See the VitFacts editorial policy page (forthcoming) for the criteria — minimum
10 years of documented safety record, public certificate-of-analysis policy, and verifiable
Thailand distribution.
