How to Choose a Vegan Vitamin D3 K2 Supplement UK: Form, Dose and Source

Quick answer: choose lichen-derived vitamin D3 (cholecalciferol, not D2/ergocalciferol) with vitamin K2 as MK-7 (menaquinone-7, not MK-4). Lichen D3 is unambiguously vegan and halal. MK-7 has significantly longer half-life in the body than MK-4 — once daily dosing is effective. Take with a fat-containing meal. PHE recommends 10μg (400 IU) D3 for all UK adults October to March; adults with confirmed deficiency or darker skin tones typically need 1,000–2,000 IU/day.

D3 vs D2: why the form matters

Two forms of vitamin D are used in supplements:

• Vitamin D3 (cholecalciferol): the form produced by human skin in response to UV-B. Significantly more effective than D2 at raising and maintaining serum 25-OH vitamin D levels. A 1998 comparison study in the American Journal of Clinical Nutrition (Trang et al.) found D3 raised serum 25-OH vitamin D approximately 87% more effectively per IU than D2. Commonly derived from lanolin (sheep wool wax) — the source relevant for halal and vegan compliance.
• Vitamin D2 (ergocalciferol): plant-derived (from yeast or fungi exposed to UV light). Historically used in vegan products because it avoids lanolin. Less effective than D3 at comparable doses. Shorter half-life — serum levels decline faster between doses.

The vegan and halal solution: lichen-derived D3. Lichen is a symbiotic organism (algae + fungi) that naturally produces vitamin D3 when exposed to UV light — making it the only plant-origin source of D3. Lichen D3 is chemically identical to lanolin D3 (same molecule) but derived entirely from plant-kingdom organisms. It is unambiguously vegan and unambiguously halal across all scholarly positions. Our Lipovita D3+K2 uses lichen-derived D3.

K2 forms: MK-7 vs MK-4

Vitamin K2 (menaquinone) exists in multiple chain lengths. The two most relevant for supplements:

• MK-7 (menaquinone-7): naturally derived from natto (fermented soybeans) or via fermentation. Has a plasma half-life of approximately 72 hours — meaning a single daily dose maintains active K2 levels around the clock. Better studied for bone and cardiovascular outcomes. Most evidence for D3+K2 supplementation is in MK-7 form.
• MK-4 (menaquinone-4): synthesised in the body from K1, or produced synthetically for supplements. Has a plasma half-life of approximately 1–2 hours — requires multiple daily doses or high single doses to maintain levels. Used in Japanese pharmaceutical bone density trials at very high doses (45mg/day — far above supplement levels). The evidence base for MK-4 at supplement doses is less robust than MK-7.

For daily supplementation, MK-7 is the preferred form — longer half-life, better suited to once-daily dosing and the form with more human trial evidence at supplement-range doses.

Why D3 and K2 should be taken together

Vitamin D3 significantly increases intestinal calcium absorption — this is its primary bone health mechanism. But without vitamin K2, that additional absorbed calcium may not be appropriately directed to bone. K2 activates two key calcium-routing proteins:

• Osteocalcin (vitamin K2-dependent): draws calcium into bone matrix, increasing bone density
• Matrix Gla protein (MGP) (vitamin K2-dependent): prevents calcium depositing in arterial walls (soft tissue calcification)

What research supports: A 2015 meta-analysis in Nutrients (Maresz, 7 RCTs) confirmed MK-7 supplementation significantly improved lumbar spine bone mineral density in postmenopausal women. A 2017 study in Thrombosis and Haemostasis found MK-7 at 180mcg/day for 3 years significantly improved carboxylation of MGP — the protein preventing arterial calcification. This is the scientific basis for the recommendation to combine D3 with K2 rather than D3 alone.

Dose: what the evidence supports

Vitamin D3:

• PHE recommendation: 10μg (400 IU) for all UK adults October to March
• Maintenance for adults with adequate baseline: 400–1,000 IU/day
• People with confirmed deficiency (25-OH vitamin D below 25 nmol/L): 1,000–4,000 IU/day to restore levels. A 2011 meta-analysis in the American Journal of Clinical Nutrition (Autier and Gandini) found 400 IU/day insufficient to restore adequate levels in many deficient adults; 1,000 IU was the minimum effective maintenance dose.
• Darker skin tones and those who cover up outdoors year-round: 1,000–2,000 IU/day year-round
• EU safe upper level: 100μg (4,000 IU)/day from supplements. Toxicity (hypercalcaemia) is extremely rare below 10,000 IU/day in healthy adults.

Vitamin K2 MK-7:

• EU NRV: 75μg/day
• RCT doses for bone outcomes: 90–200mcg/day MK-7
• MGP carboxylation benefit (arterial calcium): 180mcg/day MK-7 (Thrombosis and Haemostasis 2017)
• No established upper safe limit for K2 MK-7; doses up to 360mcg/day have not shown adverse effects in trials
• Caution with warfarin: K2 counteracts warfarin’s mechanism. People on anticoagulants must discuss K2 supplementation with their GP or anticoagulant clinic before starting.

Fat-soluble absorption: the most important practical note

Both D3 and K2 are fat-soluble — they require dietary fat for absorption via micelle formation in the gut. A 2010 RCT (Mulligan and Bhatt, JBMR, n=17) found vitamin D3 absorption improved by 56% when taken with the largest fat-containing meal of the day vs fasted. Liposomal formulations (like our Lipovita D3+K2) encapsulate the nutrients in phospholipid spheres, bypassing the dietary fat requirement and producing higher plasma levels without needing to coordinate with a fat-containing meal.

Practical guidance: take D3+K2 with breakfast including eggs, nut butter, avocado or full-fat dairy; or with dinner containing oily fish, olive oil or nuts; or use a liposomal format that removes the fat requirement. Do not take on a completely empty stomach.

Halal and vegan compliance summary

• D3 source: lichen-derived (unambiguously vegan and halal) vs lanolin-derived (permissible under majority UK scholarly positions but some prefer lichen)
• K2 MK-7 source: typically from natto fermentation or synthetic — both vegan and halal. Check manufacturing environment certification.
• Capsule/delivery: HPMC capsule or liquid format — avoid standard gelatine capsules

Our Lipovita D3+K2 — 4,000 IU lichen-derived D3 + 100mcg MK-7 K2, liposomal liquid, fully halal certified, vegan, kosher. Three drops daily directly or into food.