Vitamin D and vitamin K are two important fat-soluble vitamins that play essential roles throughout the body. Both are well known for their contribution to bone health, but research suggests their functions extend beyond the skeleton to immune function, muscle health, cardiovascular health and more — and both can be low in certain populations.
Vitamin D insufficiency is a recognised public-health concern, particularly among older adults, people with darker skin tones, and those at northern latitudes such as the UK, where sunlight is often insufficient through autumn and winter. Vitamin K status may also be suboptimal in some individuals, especially those taking certain medications or eating limited amounts of vitamin K-rich foods.
What many people don't realise is that vitamin D3 and vitamin K2 have complementary roles: vitamin D helps increase calcium absorption from the gut, while vitamin K contributes to the activation of proteins involved in calcium utilisation and bone health. Neutrient D3 + K2 provides vitamin D3 and vitamin K2 as MK-7 in an MCT oil-based oral spray — a convenient alternative to traditional tablets and capsules.
QUICK FACTS
Neutrient D3 + K2 at a glance
What are vitamin D3 and vitamin K2?
Vitamin D is not technically a vitamin in the conventional sense — it is a secosteroid that functions in many ways like a hormone, with receptors in tissues throughout the body. Vitamin D3 (cholecalciferol) is produced in the skin following UVB exposure and is generally more effective than D2 at raising and maintaining blood levels of 25(OH)D, which is why it is the preferred form for supplementation. In the UK, UVB is typically insufficient for skin synthesis between October and March.
Vitamin K refers to a family of fat-soluble compounds. Vitamin K1 is found in green leafy vegetables, while vitamin K2 (menaquinones) occurs in certain fermented and animal-derived foods. K2 exists in several forms (MK-4 to MK-13); the body stores only limited amounts, which deplete rapidly without regular intake. The forms vary considerably in how long they remain in circulation, as shown below.
| Vitamin K2 form | Approx. half-life | Common use |
|---|---|---|
| MK-4 | ~3–6 hours | Short-term; found naturally in some foods and supplements |
| MK-7 (used in Neutrient) | ~72 hours | Optimal for daily supplementation |
| MK-9 | ~24 hours | Less studied; limited supplemental use |
How much do you need?
| Nutrient (per 2 sprays, adults) | Amount | NRV | EFSA upper level |
|---|---|---|---|
| Vitamin D3 (cholecalciferol) | 50mcg (2,000 IU) | 1,000% | 100mcg (4,000 IU) |
| Vitamin K2 (MK-7) | 50mcg | 66% | No upper level set |
| Children aged 7+ (1 spray) | 25mcg D3, 25mcg K2 | — | — |
The UK NHS recommends 10mcg (400 IU) of vitamin D per day, with particular emphasis during autumn and winter, though many practitioners consider this a minimum to prevent deficiency rather than an optimal level. Neutrient D3 + K2 provides 50mcg (2,000 IU) of D3 per adult dose — a level widely used in research and well within EFSA's tolerable upper intake of 100mcg (4,000 IU) per day. For K2 there is no set RDA, and the 50mcg of MK-7 offers a meaningful daily contribution.
Risk factors for vitamin D and K deficiency
Vitamin D deficiency is a global concern, with subtle, non-specific symptoms. Those at greatest risk include UK residents from October to March; older adults; people with darker skin; those with an indoor lifestyle or who cover the skin; routine high-factor sunscreen users; people with obesity; those with kidney, liver or malabsorption conditions; pregnant women; and those taking vitamin D-depleting medications such as steroids, anticonvulsants, metformin and PPIs.
Vitamin K stores are small and deplete rapidly — a low-K diet can lead to measurable deficiency in as little as seven days. Those at greatest risk include people with fat-malabsorption disorders, hospitalised patients after gastrointestinal surgery, those taking anticoagulants such as warfarin, people with significant liver disease, those on very low-fat diets, and anyone whose diet is low in fermented foods and grass-fed animal products.
Food sources of vitamin D and vitamin K2
Vitamin D and K2 occur naturally in a relatively limited range of foods. Vitamin D is found in oily fish, egg yolks and fortified foods, while K2 is most common in fermented foods and certain animal-derived foods such as natto and hard cheeses. Because some of the richest K2 sources (like natto) are rarely eaten in Western diets, and vitamin D synthesis is limited in winter, an oral spray can provide a convenient, consistent source of both alongside a balanced diet.
| Vitamin D source | D per 100g | Vitamin K2 source | K2 per 100g |
|---|---|---|---|
| Cod liver oil | ~250mcg/tsp | Natto (fermented soybeans) | ~900mcg |
| Salmon (cooked) | ~10–15mcg | Hard cheeses (e.g. Gouda) | ~75mcg |
| Mackerel (cooked) | ~8–13mcg | Soft cheeses | ~50mcg |
| Herring (cooked) | ~8–10mcg | Duck leg | ~35mcg |
| Tinned tuna | ~4–6mcg | Egg yolk | ~32mcg |
| Mushrooms (sun-exposed) | ~2–10mcg | Butter (grass-fed) | ~15mcg |
| Egg yolk | ~2mcg | Liver | ~10–15mcg |
| Fortified cereals | ~2mcg/serving | Kefir | ~10mcg |
| Full-fat milk | ~0.1mcg/100ml | Sauerkraut | ~5mcg |
D3 + K2 Benefits
What are vitamin D3 and K2 good for?
Both vitamins are best known for their roles in bone health, but the research of the past two decades reveals a far broader sphere of activity for each — and they are especially powerful taken together. The sections below cover the benefits of vitamin D3 and then vitamin K2.
Supplement forms: which D and K are best?
Vitamin D supplements come as D2 (ergocalciferol) or D3 (cholecalciferol). Research generally suggests D3 is more effective than D2 at raising and maintaining blood levels of 25(OH)D, which is why it is commonly selected for supplementation. D3 itself may be derived from lanolin, fish oils or algae — algae-derived D3 provides a vegan-friendly alternative to animal sources. The carrier medium matters too: MCT oil readily dissolves fat-soluble nutrients and provides a stable delivery system.
Vitamin K supplements are available as K1 (phylloquinone) or K2 in MK-4 or MK-7 form. One of the distinguishing features of MK-7 is its longer half-life — compared with MK-4, it remains available in the body for longer following supplementation, making it a popular choice for once-daily use. Neutrient D3 + K2 uses algae-derived D3 and K2 as MK-7.
"What most people don't realise is that D3 and K2 work closely together in the body. Vitamin D helps the body absorb calcium, while K2 helps activate proteins involved in how that calcium is utilised. We chose MK-7 because it remains available in the body for longer than several other forms of vitamin K2. It's a small detail that makes a real difference to how the formula works."
Jonathan Orchard — Founder, Neutrient™
Six things worth knowing about D3 + K2
What makes Neutrient D3 + K2 different?
Neutrient D3 + K2 has been developed around three key considerations: ingredient selection, nutrient pairing and delivery format. It provides vitamin D3 as cholecalciferol from algae and vitamin K2 as MK-7, balanced at 2,000 IU of D3 with 50mcg of K2, and delivered as an MCT-oil oral spray. The table below shows how the chosen forms compare with the alternatives.
| Supplement form | Bioavailability | Duration of activity | Vegan? | In Neutrient D3 + K2? |
|---|---|---|---|---|
| Vitamin D2 (ergocalciferol) | Lower | Shorter | Yes | No |
| Vitamin D3 from lanolin | Higher | Longer | No | No |
| Vitamin D3 from algae | Higher | Longer | Yes | ✔ Yes |
| Vitamin K2 as MK-4 | Good | ~3–6 hours | Depends | No |
| Vitamin K2 as MK-7 | Excellent | ~72 hours | Yes | ✔ Yes |
The chosen forms: algae D3 and MK-7
The formula provides vitamin D3 as cholecalciferol from algae and vitamin K2 as MK-7, two forms commonly used in nutritional research and supplementation. D3 is generally more effective than D2 at raising 25(OH)D levels, and the algae-derived source makes the product suitable for vegans.
The nutrient pairing: D3 and K2 together
2,000 IU of vitamin D3 balanced with 50mcg of K2 as MK-7 reflects the physiological relationship between the two: vitamin D contributes to calcium absorption, while vitamin K2 is required to activate the proteins involved in calcium utilisation and bone health. The formula combines both in amounts intended for meaningful daily supplementation.
MK-7: the longest-acting K2
With a half-life of approximately 72 hours, MK-7 remains in circulation far longer than MK-4 (around 3–6 hours), allowing it to stay available in the body between daily doses. This is one reason MK-7 is commonly selected for once-daily supplementation.
The oral spray format
Many vitamin supplements are tablets or capsules; Neutrient D3 + K2 is an oral spray. It is designed to be held briefly in the mouth before swallowing, allowing contact with the oral tissues, with an MCT oil carrier providing a suitable medium for these fat-soluble vitamins. The format is particularly appealing for people who find pills difficult to take.
Clean, vegan, free-from formula
The spray is free from gluten, glycerine, alcohol, animal derivatives, sweeteners and flavours. A natural vitamin E antioxidant (D-alpha tocopherol) protects the formula from oxidation to help maintain stability.
| Ingredient | Amount per 2 sprays | Role |
|---|---|---|
| Vitamin D3 (cholecalciferol from algae) | 50mcg (2,000 IU) — 1,000% NRV | Most bioavailable form of vitamin D; supports bone, immune, muscle and cardiovascular health. Algae-derived, vegan-suitable. |
| Vitamin K2 (menaquinone MK-7) | 50mcg — 66% NRV | Longest-acting K2 form (~72-hour half-life); supports activation of vitamin K-dependent proteins for bone and cardiovascular health. |
| MCT oil (from coconut) | Carrier oil | Medium-chain triglyceride carrier used to deliver the fat-soluble vitamins. |
| D-alpha tocopherol | Antioxidant | Natural vitamin E antioxidant that protects the spray formula from oxidation and helps maintain stability. |
Who is Neutrient D3 + K2 for?
Neutrient D3 + K2 is designed for adults seeking a convenient way to supplement vitamin D3 and vitamin K2 as part of a balanced diet and healthy lifestyle. It is particularly well suited for:
- UK residents and others in the northern hemisphere at risk of suboptimal vitamin D status during autumn and winter (October to March)
- Individuals looking to support bone health
- Post-menopausal women
- Older adults, who synthesise vitamin D less efficiently and may be at greater risk of both vitamin D and K deficiency
- People with darker skin, who require more sun exposure to synthesise adequate vitamin D
- Vegans, for whom the algae-derived D3 provides a plant-based source
- Those who dislike or cannot swallow tablets or capsules, for whom the spray is an effortless alternative
- Anyone already taking Neutrient Multi+ who wants a dedicated, higher-dose D3 + K2 product to pair with their multivitamin
How to take D3 + K2
Adults take 2 sprays daily into the mouth; children aged 7+ take 1 spray daily. Each 30ml bottle provides up to 100 adult servings — around three months' supply.
When to take
Any time of day, with or without food. Apply directly under the tongue or to the inside of the cheek for fastest absorption
After spraying
Wait 2–5 minutes before eating or drinking to maximise absorption through the oral mucous membranes
Storage
Store in a cool, dry place away from direct sunlight, upright with the cap replaced. Use within 6 months of opening, and shake gently if stored for some time
Safety and precautions
Vitamin D3 is safe at the recommended dose of 2,000 IU per day. EFSA has set the tolerable upper intake at 100mcg (4,000 IU) per day for adults, a generous margin above the 50mcg (2,000 IU) provided here. Vitamin D toxicity is associated only with very high doses over prolonged periods, well above this level.
Vitamin K2 is safe for most individuals even at higher doses. However, it should not be taken by people using anticoagulant medication such as warfarin without consulting their doctor, as vitamin K can influence INR stability — even small amounts can affect INR in a small proportion of rapid responders.
Individuals with sarcoidosis are abnormally sensitive to vitamin D and should not take supplementary vitamin D without medical supervision.
Disclaimer
If you are taking anticoagulants (blood thinners) such as warfarin, do not take this product without medical supervision. If pregnant, breastfeeding, taking medication or managing a medical condition, consult a healthcare professional before use. Not recommended for children under 7. Keep out of reach of children. Food supplements are not a substitute for a varied diet and a healthy lifestyle.
References
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