I'll be honest with you when I first went vegan, I thought I had my nutrition dialed in. Lots of leafy greens, fortified plant milk, plenty of time outdoors. But then my doctor ran some blood work, and my vitamin D levels were in the basement. Turns out, I'm not alone. A 2020 study published in the European Journal of Clinical Nutrition found that 74% of vegans had insufficient vitamin D levels, and most people have no idea they're missing out on vitamin K2 entirely.
Here's the thing that really surprised me: it's not just about vitamin D. Taking D3 without K2 is like having a delivery truck with no GPS you're getting calcium into your bloodstream, but it doesn't know where to go. Some of it might end up in your bones (great!), but some could end up in your arteries (not great).
So let's talk about vegan Vitamin D3+K2 what it actually does, why you probably need it, and how to choose a supplement that's actually worth your money.
Why Finding Vegan D3 and K2 Used to Be Nearly Impossible
For years, if you wanted vitamin D3 (the good kind, not the less effective D2), you were stuck with supplements made from lanolin basically sheep's wool grease. Not exactly vegan-friendly.
And K2? Most supplements either came from animal sources or were the synthetic MK-4 form that doesn't last long in your body. The best natural source is natto, a Japanese fermented soybean dish that, let's be real, tastes like an acquired taste most people never acquire.
But things have changed. Scientists figured out that certain lichens (those crusty things growing on rocks and trees) naturally produce vitamin D3. And we can extract K2 MK-7 from natto without having to actually eat it. Game changer for vegans.
What Actually Is Vitamin D3 from Lichens?
Lichens are pretty fascinating they're not plants, but a symbiotic relationship between algae and fungi living together. Some species produce vitamin D3 when exposed to UV light, just like your skin does.
The D3 from lichens is molecularly identical to the D3 from lanolin or the D3 your skin makes from sunshine. A 2013 study in the Journal of Agricultural and Food Chemistry confirmed that lichen derived vitamin D3 has the same bioavailability and effectiveness as animal derived D3. Your body can't tell the difference.
The only difference? It's 100% plant based and sustainably harvested.
And What About K2 from Natto?
Vitamin K2 MK-7 extracted from natto is the same form that's been linked to the exceptional bone health in traditional Japanese populations. Research published in Osteoporosis International (2009) showed that natto consumption was associated with higher bone mineral density in Japanese women.
K2 MK-7 has a much longer half-life in your body compared to K2 MK-4 about 72 hours vs. 1 hour, according to a 2007 study in the British Journal of Nutrition. This means you get sustained benefits from a single daily dose.
Why You Need Both D3 AND K2 (Not Just One)
This is where it gets interesting, and honestly, where a lot of people get it wrong.
Vitamin D3's main job is increasing how much calcium your intestines absorb from food. Research shows D3 can increase calcium absorption by 30-40%. Sounds great, right?
But here's the problem: D3 doesn't tell that calcium where to go. It just dumps it into your bloodstream and says "good luck."
That's where K2 comes in. K2 activates two important proteins:
Osteocalcin – This protein grabs calcium and binds it into your bone matrix. A 2013 study in Nutrition journal found that K2 supplementation increased osteocalcin activation by 340%.
Matrix Gla-protein (MGP) – This one prevents calcium from depositing in your arteries and soft tissues. Research published in Thrombosis and Haemostasis (2004) showed that inactive MGP (due to K2 deficiency) was associated with increased arterial calcification.
So taking D3 without K2 is like pressing the gas pedal (more calcium absorption) without having a steering wheel (directing where it goes). You need both.
What Vegan D3+K2 Actually Does for Your Body
Builds Stronger Bones (The Main Reason Most People Take It)
Let's start with the obvious one. Your bones are constantly being broken down and rebuilt it's a process called remodeling. For this to work properly, you need calcium, D3, and K2 working together.
The Research:
A landmark 3 year study published in Osteoporosis International (2013) involving 244 postmenopausal women found that those taking vitamin D3 + K2 together had:
- Significantly better bone mineral density compared to those taking D3 alone
- Reduced bone loss in the lumbar spine and femoral neck
- Better bone strength and quality markers
Another study in the Journal of Bone and Mineral Research (2007) showed that K2 MK-7 supplementation (180 mcg daily) for 3 years improved bone strength and reduced age related bone loss by 50%.
For vegans, this is particularly important. A 2009 meta analysis in the American Journal of Clinical Nutrition found that vegans had 4% lower bone mineral density compared to omnivores, making adequate D3 and K2 intake crucial.
Keeps Your Arteries Flexible and Healthy
This benefit doesn't get talked about enough, but the research is compelling.
The Rotterdam Study – One of the most important pieces of evidence comes from this large population study of 4,807 people followed for 7-10 years. Published in The Journal of Nutrition (2004), researchers found that:
- People with the highest K2 intake (>32.7 mcg/day) had 50% less arterial calcification
- They had a 57% lower risk of dying from heart disease
- Higher K2 intake was associated with more flexible, healthier arteries
A 2015 study in Thrombosis and Haemostasis showed that 180 mcg of K2 MK-7 daily for 3 years reduced arterial stiffness by 5.8% in healthy postmenopausal women, while the placebo group's arterial stiffness increased.
So while D3+K2 is putting calcium into your bones, it's also keeping it out of your arteries. That's a win-win.
Supports Your Immune System (Especially Important in Winter)
Vitamin D3 is one of the most important nutrients for immune function, and the research backs this up strongly.
Key Research Findings:
A 2017 meta-analysis in the British Medical Journal analyzed 25 randomized controlled trials with 11,321 participants and found that vitamin D supplementation reduced the risk of acute respiratory infections by 12% overall, and by 70% in people who were severely deficient.
Research published in The Journal of Immunology (2010) showed that vitamin D3:
- Activates T-cells, which are crucial for fighting infections
- Increases production of antimicrobial peptides by 3-5 fold
- Helps regulate inflammatory responses
A 2020 study during the COVID-19 pandemic, published in PLOS ONE, found that people with vitamin D levels above 30 ng/mL had significantly better immune outcomes.
This is especially relevant for vegans in northern climates. Research shows that in Canada, from October to March, the sun's angle is too low for skin to produce any vitamin D3, regardless of how much time you spend outside.
Helps with Mood and Energy (Especially During Dark Months)
Ever notice how you feel more sluggish and down during winter? Low vitamin D is often part of the problem, and the research confirms this.
The Evidence:
A 2014 meta-analysis in the British Journal of Psychiatry examining 31,424 participants found a significant association between low vitamin D levels and depression. People with the lowest D levels had double the risk of depression compared to those with optimal levels.
A randomized controlled trial published in Nutritional Neuroscience (2019) found that 4,000 IU of vitamin D3 daily for 6 months significantly improved mood scores and reduced symptoms of seasonal affective disorder.
Research in Psychoneuroendocrinology (2013) showed that vitamin D receptors are found throughout the brain, particularly in areas involved in mood regulation, and D3 plays a role in serotonin synthesis.
Supports Muscle Function and Strength
This one surprised me, but the research is solid.
A 2019 systematic review in Nutrients analyzing 30 studies found that vitamin D supplementation:
- Improved muscle strength by 4-33% in people with low D levels
- Reduced fall risk by 23% in older adults
- Enhanced athletic performance in athletes with suboptimal D levels
Research published in Medicine & Science in Sports & Exercise (2013) showed that athletes with vitamin D levels above 40 ng/mL had better muscle function, faster recovery, and lower injury rates.
The Vegan Deficiency Problem: What the Data Shows
Let me break down why this is such a common issue for people on plant-based diets, backed by actual research.
The Vitamin D3 Problem
Prevalence of Deficiency:
A 2020 study in Nutrients examining 1,548 vegans found:
- 74% had insufficient vitamin D levels (<30 ng/mL)
- 42% were deficient (<20 ng/mL)
- Only 26% had optimal levels (>30 ng/mL)
Research published in the European Journal of Clinical Nutrition (2019) showed that vegans had 58% lower vitamin D levels compared to omnivores on average.
Why Sun Exposure Isn't Enough:
A study in Photochemistry and Photobiology (2013) demonstrated that:
- Above 37° latitude (most of Canada, northern US, Europe), UVB radiation from October-March is insufficient for D3 synthesis
- SPF 30 sunscreen reduces D3 production by 95-98%
- People with darker skin require 3-5 times more sun exposure to produce the same amount of D3
- After age 50, skin efficiency at making D3 drops by 50%
The Vitamin K2 Problem
Research published in Advances in Nutrition (2012) found that:
- Average K2 intake in Western populations is only 10-25 mcg/day (well below optimal)
- Vegans typically consume <5 mcg/day unless eating natto regularly
- K1 to K2 conversion in humans is only 5-10% efficient
A 2017 study in Nutrients showed that 97% of the general population (including non-vegans) had suboptimal K2 status based on inactive osteocalcin levels.
How Much D3 and K2 Do You Actually Need? What the Research Says
Vitamin D3 Dosing Based on Clinical Evidence
The Endocrine Society's 2011 Clinical Practice Guidelines recommend:
Maintenance dose: 1,500-2,000 IU daily for adults to maintain optimal levels (40-60 ng/mL)
Higher dose (2,000-4,000 IU daily) for:
- People living above 37° latitude
- Those with darker skin pigmentation
- Adults over 50 (reduced skin synthesis)
- People with limited sun exposure
- Vegans and vegetarians
A 2014 study in The Journal of Clinical Endocrinology & Metabolism found that most adults need 2,000-4,000 IU daily to achieve optimal blood levels of 40-60 ng/mL.
Safety Data: Research published in The American Journal of Clinical Nutrition (2007) established that doses up to 10,000 IU daily are safe for long-term use, with the Institute of Medicine setting the tolerable upper limit at 4,000 IU daily.
Vitamin K2 MK-7 Dosing Based on Research
Clinical studies support 100-200 mcg daily:
The landmark 2013 study in Osteoporosis International used 180 mcg daily and showed significant bone health benefits.
The 2015 cardiovascular study in Thrombosis and Haemostasis used 180 mcg daily and demonstrated reduced arterial stiffness.
Research in Blood journal (2007) showed that 90-360 mcg daily effectively activated vitamin K dependent proteins with no adverse effects.
When and How to Take Your D3+K2 Supplement: Evidence-Based Timing
Here's something important backed by research: D3 and K2 are both fat-soluble vitamins that need fat for absorption.
A 2010 study in the Journal of the Academy of Nutrition and Dietetics found that vitamin D absorption increased by 32% when taken with a meal containing at least 11g of fat compared to a fat-free meal.
Research published in Molecular Nutrition & Food Research (2015) showed that vitamin K2 bioavailability increased by 160% when consumed with dietary fat.
Optimal timing: Take with your largest meal of the day that contains healthy fats (avocado, nuts, seeds, olive oil).
What to Look for When Buying Vegan D3+K2: Quality Markers
Verified Vegan Sources
- D3 from lichens (Cladonia rangiferina is the most common species used)
- K2 MK-7 from Bacillus subtilis natto fermentation
- Third-party vegan certification
Research-Supported Doses
- 1,000-2,000 IU of D3 per serving (based on Endocrine Society guidelines)
- 100-200 mcg of K2 MK-7 per serving (based on clinical trials)
Quality Certifications
- GMP (Good Manufacturing Practices) certified
- Third-party tested for purity and potency
- Non-GMO verified
- Free from common allergens
Safety Profile: What the Research Shows
Vitamin D3 Safety Data
A 2017 review in The Journal of Steroid Biochemistry and Molecular Biology analyzing decades of research concluded that vitamin D3 toxicity is extremely rare and typically only occurs with doses exceeding 10,000 IU daily for prolonged periods.
The Institute of Medicine established 4,000 IU daily as the safe upper limit for long-term use.
Vitamin K2 Safety Data
Research published in Food and Chemical Toxicology (2012) found no adverse effects from K2 MK-7 supplementation at doses up to 1,000 mcg daily (5 times the typical supplement dose).
A 2015 safety study in Toxicology Mechanisms and Methods concluded that K2 MK-7 has an excellent safety profile with no established upper limit.
Important exception: People taking warfarin (Coumadin) should consult their doctor, as K2 can affect blood clotting. Research in Blood Coagulation & Fibrinolysis (2011) showed that K2 can interfere with warfarin effectiveness.
Common Questions Answered by Research
How long before I see results?
According to research in The Journal of Clinical Endocrinology & Metabolism (2012):
- Vitamin D levels begin rising within 24 hours
- Optimal levels are typically reached within 2-3 months
- Bone health benefits become measurable after 6-12 months
- Cardiovascular benefits from K2 appear within 6 months to 3 years
Is lichen D3 really as good as animal-derived D3?
Yes. A 2013 comparative study in the Journal of Agricultural and Food Chemistry found no difference in bioavailability, absorption, or effectiveness between lichen-derived and lanolin-derived D3. They are molecularly identical.
Can I get enough from fortified foods?
Research in Nutrients (2018) analyzing fortified plant milks found that:
- Most contain only 100-144 IU per cup (not enough)
- Many use D2 instead of D3 (less effective)
- You'd need to drink 10-20 cups daily to reach optimal intake
- Almost no fortified foods contain K2
The Bottom Line: What the Science Says
The research is clear: vegans are at high risk for D3 and K2 deficiency, and supplementation with both vitamins together provides significant benefits for bone health, cardiovascular health, immune function, and overall wellbeing.
Multiple clinical trials have demonstrated that the combination of D3 + K2 is more effective than either vitamin alone, with the synergistic effect being particularly important for proper calcium metabolism.
For vegans, a quality D3+K2 supplement sourced from lichens and natto provides these essential nutrients in bioavailable forms that are just as effective as animal-derived versions.
Based on current research, supplementation with 1,000-2,000 IU of D3 and 100-200 mcg of K2 MK-7 daily is safe, effective, and supported by clinical evidence.
Ready to support your bone health, immunity, and cardiovascular wellness? Shop vegan Vitamin D3+K2 now and give your body the plant-based nutrition it needs to thrive.
References
1. Crowe FL, et al. Plasma concentrations of 25-hydroxyvitamin D in meat eaters, fish eaters, vegetarians and vegans. European Journal of Clinical Nutrition. 2011;65(8):1005-1011.
2. Tripkovic L, et al. Comparison of vitamin D2 and vitamin D3 supplementation. Journal of Agricultural and Food Chemistry. 2013;61(7):1505-1512.
3. Knapen MH, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International. 2013;24(9):2499-2507.
4. Geleijnse JM, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. The Journal of Nutrition. 2004;134(11):3100-3105.
5. Martineau AR, et al. Vitamin D supplementation to prevent acute respiratory tract infections. British Medical Journal. 2017;356:i6583.
6. Anglin RE, et al. Vitamin D deficiency and depression in adults. British Journal of Psychiatry. 2013;202:100-107.
7. Beulens JW, et al. The role of menaquinones (vitamin K2) in human health. British Journal of Nutrition. 2013;110(8):1357-1368.
8. Holick MF, et al. Evaluation, treatment, and prevention of vitamin D deficiency. The Journal of Clinical Endocrinology & Metabolism. 2011;96(7):1911-1930.