Onnit Vitamin D3 Spray delivers 1,000 IU of lichen-sourced (plant-based) vitamin D3 plus vitamin K2 per serving, in a fast-absorbing sublingual spray with an MCT oil carrier. D3 raises vitamin D levels more effectively than D2, and the paired K2 helps direct absorbed calcium to bone. 30 servings per 24ml bottle, in two flavours.

Vitamin D3 and K2 in a sublingual spray. Lichen-sourced, plant-based, MCT oil carrier.

Ireland gets an average of 1,400 hours of sunlight per year - less than half the European average. Combined with the angle of the sun between October and March (too low for meaningful UVB synthesis at this latitude), the result is that most Irish adults cannot produce adequate vitamin D from sunlight for roughly six months of the year. The Irish Longitudinal Study on Ageing (TILDA) found that over 40% of Irish adults over 50 have insufficient vitamin D levels - and that's before accounting for the majority who spend most daylight hours indoors.

Vitamin D deficiency doesn't announce itself clearly. The effects - reduced immune function, low mood, fatigue, disrupted sleep, and impaired calcium absorption - overlap with a dozen other common complaints, which is part of why it goes unaddressed for so long.

Why D3, not D2

There are two supplemental forms of vitamin D: D2 (ergocalciferol, typically from mushrooms) and D3 (cholecalciferol). D3 is the form your skin produces in response to UVB exposure, and it raises and maintains blood levels of 25(OH)D more effectively than D2. A meta-analysis published in the American Journal of Clinical Nutrition confirmed that D3 is significantly more potent at raising serum vitamin D levels - the relevant measure of sufficiency.

Most vitamin D3 on the market is derived from lanolin (sheep's wool). Onnit's D3 is sourced from lichens - one of the few plant-based sources of D3 - making this formulation suitable for vegans and those avoiding animal-derived supplements.

Why K2 is in the formula

Vitamin D3 increases calcium absorption. Vitamin K2 determines where that calcium actually goes. Without adequate K2, absorbed calcium can accumulate in soft tissue and arterial walls rather than being directed to bones and teeth where it's needed. Research published in Thrombosis and Haemostasis found that K2 (specifically MK-7) activates the proteins that direct calcium to bone matrix - a meaningful functional pairing with D3 supplementation.

Spray format and the MCT oil carrier

Sublingual and buccal delivery bypasses first-pass metabolism in the liver. Because D3 is a fat-soluble vitamin, the fractionated MCT oil carrier in this spray improves absorption directly - fat-soluble compounds are absorbed more efficiently in the presence of dietary fat. A study on fat-soluble vitamin absorption confirmed significantly greater uptake when taken alongside dietary fat. The spray format also removes the need to time D3 with meals for those using it fasted.

1,000 IU per serving - in line with standard maintenance dosing for adults. 30 servings per 24ml bottle.

Available in Passion Fruit Guava and Grapefruit.

24ml | 30-day supply
1,000 IU Vitamin D3 (lichen-sourced) + Vitamin K2 per serving. Plant-based. MCT oil carrier.

Not suitable for those on anticoagulant medications (warfarin/Coumadin) without medical supervision - Vitamin K2 can affect clotting. Consult your doctor if pregnant, nursing, or taking medications.

Stocked and shipped from Dublin. Order before 4pm for same-day dispatch.

Frequently Asked Questions

Why does Ireland's climate make vitamin D supplementation important?

Between roughly October and March the sun sits too low in Ireland for meaningful UVB skin synthesis, so most adults can't make enough vitamin D from sunlight for about half the year. Research has found a large share of Irish adults have insufficient levels.

What's the difference between vitamin D3 and D2?

D3 (cholecalciferol) is the form your skin makes from sunlight and raises blood vitamin D levels more effectively than D2 (ergocalciferol). This spray uses D3.

Is this vitamin D3 suitable for vegans?

Yes. Most D3 is sourced from lanolin (sheep's wool), but this is lichen-sourced — one of the few plant-based sources of D3 — so it's suitable for vegans.

Why is vitamin K2 included with the D3?

D3 increases calcium absorption, and K2 helps direct that calcium to bone rather than soft tissue. The two are a well-studied functional pairing.

How do I use the spray?

One spray under the tongue per serving delivers 1,000 IU. The sublingual format bypasses the need to time it with meals, and the MCT oil carrier supports absorption of this fat-soluble vitamin. Available in Passion Fruit Guava and Grapefruit.

Who should avoid it?

Anyone on anticoagulant medication (such as warfarin) should not take added K2 without medical supervision, as K2 can affect clotting. Consult your doctor if pregnant, nursing, or on medication.