Vitamin D supplementation is best when paired with vitamin K2 to support gut and immune function. They work together to provide even more benefits than taking vitamin D alone! 

Reading Time: 12 minutes

Vitamin D is not new to the scene, but are you familiar with the importance of taking vitamin D with K2 for maximum benefits? Vitamin D is among the most well-known and familiar supplements people search for. 

However, vitamin D supplementation is best when paired with vitamin K2 to support gut and immune function. Vitamin D and K2 work together to provide even more benefits than taking vitamin D alone! 

WHY VITAMIN D IS IMPORTANT FOR OVERALL HEALTH 

Vitamin D is a fat-soluble vitamin that acts as a hormone. Vitamin D regulates the expression of genes anywhere from 200 to over 2,000 by binding to vitamin D receptors within the nucleus. For this reason, it is often crucial in supporting leaky gut and reversing autoimmunity.

Vitamin D plays a role in many bodily functions, including:

• Gut function and integrity 
• Hormonal balance
• Heart health 
• Mood regulation
• Calcium and phosphorus homeostasis
• Bone health
• Gene expression
• Healthy immune function
• Cell growth and differentiation
• Blood sugar regulation 
• Blood pressure regulation
• Muscle health

WHAT IS VITAMIN K2 AND WHY IS IT IMPORTANT?

Vitamin K is a fat-soluble vitamin that exists in three forms: phylloquinone (K1), menaquinone (K2), and menadione (K3). It is best known and referred to as the “koagulation vitamin,” or vitamin K for short.

Despite flying under the radar, vitamin K2 is essential for overall health, especially immunity, bone health, and cardiovascular function.

Vitamin K plays a vital role in: 

• Blood clotting
• Bone health 
• Prevents tissue calcification (Vitamin K helps prevent calcium from getting deposited in soft tissues, like the arteries)
• Regulation of cell growth
• Blood sugar regulation
• Hormone production

In addition, K2 can be helpful for:

• Regulating and distributing calcium
• Strengthening bones and teeth
• Reducing inflammation
• Protecting gut integrity
• Improving skin elasticity 

There are three primary forms of vitamin K to discuss regarding improving the absorption of vitamin K. 

1. Vitamin K1 (phylloquinone)

Vitamin K1 is a natural form of the vitamin found in plants. It makes up the majority (>90%) of dietary vitamin K intake in humans. 

While vitamin K1 is the primary form of vitamin K in our bodies, it appears that vitamin K is most effective at improving bone health and preventing arterial calcification after it has been converted to vitamin K2.

Vitamin K1 stays in the liver, where it is used to make blood clotting factors.

2. Vitamin K2 (menaquinone)

Some vitamin K1 is converted to K2 (MK-4) in tissues throughout the body, but it is primarily synthesized by bacteria in fermented foods and the intestines.

Vitamin K2 is incorporated into LDL and released into the bloodstream, where it can be transported to bone, blood vessels, and other tissues that require it.

3. Vitamin K3 

Vitamin K3 is generally not consumed but can be formed from vitamin K1 after absorption and is eventually converted to MK-4 in the liver.

WHY VITAMIN D DEFICIENCY IS SO COMMON 

Unfortunately, despite its various functions within the body, vitamin D deficiency is extremely common in adults. If your body cannot absorb enough of it, consuming adequate amounts of vitamin D may not be enough for some.  

A trusted functional practitioner can help you address the root cause of a vitamin D deficiency through symptom analysis and functional testing. 

Common reasons for vitamin D deficiency include: 

• Taking certain medications, like laxatives, cholesterol-lowering drugs, and steroids
• Being obesity
• Having darker skin pigmentation 
• Aging 
• Having nutrient deficiencies 
• Having autoimmunity, like Celiac or Crohn’s disease
• Having liver or kidney disease
• Exclusively breastfed infants
• Having high stress
• Eating a diet high in sugar and processed foods
• Having poor gut health

Why is the absorption of vitamin D so tricky?

While many factors play a role in vitamin D absorption, such as stress, diet, and medication use, poor gut health and intestinal permeability or “leaky gut” are the number one contributors I see due to malabsorption. 

Vitamin D is fat-soluble and absorbed in the small intestine via chylomicrons. Once in the bloodstream, vitamin D is stored in fat cells or taken to the liver to be converted to 25-OHD.

After conversion in the liver, 25-OH then heads to the kidneys, where it is converted to the active form 1,25-OHD (this conversion can also occur in smaller amounts in the placenta and specific immune cells).

When our gut lining is compromised due to GI conditions, vitamins, and minerals are less likely to get into our cells and distribute to the places in our body that require these nutrients.

Low Fat Soluble Vitamins

Vitamin D absorption largely depends on the gut’s ability to absorb dietary fat. Fat malabsorption is common in those with Leaky Gut or autoimmune diseases. This means the body is unable to process and utilize dietary fats. 

In the case of leaky gut or autoimmunity, there are many reasons for fat malabsorption: damage to the intestinal lining, imbalanced gut microbiome, poor production of digestive enzymes, and bile acid dysfunction. 

When gut or immune dysfunction is present, the goal is to understand and address the root cause immediately to prevent further nutrient deficiencies. Healing the root cause can often reverse nutrient deficiencies, such as vitamin D deficiency.

VITAMIN K DEFICIENCY AND CAUSES

An additional consequence of fat malabsorption is a vitamin K2 deficiency. Vitamins D and K2 have a synergistic relationship, so K2 is essential in helping cells absorb vitamin D into the body. When vitamin K2 levels are low, this can worsen a vitamin D deficiency. 

Common causes of low vitamin K: 

• Diet: Inadequate intake of vitamin K food sources. 
• Malabsorption conditions: Celiac disease, Crohn’s disease. Ulcerative colitis, etc. 
• Imbalanced gut flora: Broad-spectrum antibiotics kill vitamin K-producing bacteria. 
• Interactions with medications: Statins, blood thinners, anticonvulsants, etc. 

Vitamin K deficiency (evidenced by excessive bleeding) is rare, except in newborns.

Newborns are at greater risk of vitamin K deficiency bleeding (VKDB) because vitamin K stores are very low at birth, concentrations of vitamin K are low in human milk, and newborn GI tracts haven’t yet been colonized with vitamin K-producing gut bacteria. 

In addition, long-term vitamin K stores are associated with inflammation. 

SYMPTOMS OF VITAMIN D AND VITAMIN K DEFICIENCY 

Signs of a vitamin D deficiency are not always obvious. They can range from mild to severe and may even be confused for other illnesses or dysfunctions. 

Common symptoms of a vitamin D deficiency include:

• Fatigue or lack of energy
• Poor immune function or frequent illness
• Depression and/or anxiety
• Bone pain
• Muscle weakness
• Delayed wound healing
• Hair loss
• Inflammation 

Symptoms of vitamin K deficiency are more obvious than vitamin D deficiency. The main symptoms include excessive bleeding or bruising and or heavy periods.

WHAT ARE OPTIMAL LEVELS OF VITAMIN D?

Identifying a vitamin D deficiency is the first step. How do you know if your vitamin D levels are optimal? Working with a trusted practitioner is the best way to determine your vitamin D levels, as they can utilize functional testing. 

You can quickly and accurately see how vitamin D is in your blood through functional testing. This can help determine if supplementation is necessary and an appropriate dosage. As with all supplementation, we highly recommend testing, not guessing. 

Since the functional renege is smaller and more precise, it is often more effective at addressing potential vitamin D deficiencies. My clients have many health breakthroughs, including improved energy, weight loss, digestion, mood, and mental clarity when vitamin D levels are in the optimal range of functional medicine. We also see a significant improvement in inflammation levels, quickly improving gut health. 

It’s important to note that functional medicine and conventional medicine use different ranges when considering a possible vitamin D deficiency. A “normal range” for conventional medicine is considered to be 30-50 ng/mL. However, the “normal range” in functional medicine is 60-80 ng/mL. 

You can download the free lab panel checklist below to learn about the routine labs I recommend regularly doing for optimal health. 

THE SYNERGISTIC EFFECT OF VITAMIN D WITH K2

While vitamin D alone can significantly impact your health, when combined with vitamin K2, its effects are even more impressive.

Vitamin D and vitamin K2 work synergistically. This means they are more effective when they work together than alone. Of special importance is the way these two vitamins affect calcium metabolism. While vitamin D supports the body in absorbing calcium from the gut into the bloodstream, studies show that vitamin K2 ensures calcium gets where it needs to go (i.e., bones and teeth). 

Without vitamin K2, calcium can be distributed to other areas of the body, like arteries and soft tissues. This is why vitamin K2 can prevent or reduce the side effects of vitamin D.  

Since vitamin D and vitamin K2 work synergistically, they are most effective when taken together (via food or supplementation). In fact, most whole foods sources that are naturally high in vitamin D also contain sufficient amounts of vitamin K2.

HOW VITAMIN D WITH K2 AFFECT GUT AND IMMUNE HEALTH  

When it comes to the health of our gut and immune system, vitamin D and K2 work together to protect these systems.

Vitamin D strengthens the gut lining, reduces inflammation, and supports microbial balance. 

It is also known for increasing the protection of AMPs (antimicrobial peptides), which fight off pathogens and strengthen the immune system. Vitamin K2 works along with vitamin D by supporting immune cells and reducing inflammation. By protecting and strengthening the gut, these powerhouse nutrients provide additional immune system support because most of the immune system is housed in the gut. 

More so, studies show that vitamin D has an immunomodulating effect that can help reverse autoimmunity. 

TOP SOURCES OF VITAMIN D & VITAMIN K2

Since vitamin D is so critical for overall health, from immunity to bone health, it’s essential to make sure you’re getting enough vitamin D through food. Top sources of vitamin D and K2 include:

Food Sources of Vitamin D 

Many whole foods are naturally high in vitamin D, including:

• Mushrooms (1110 IU per raw cup)
• Wild-caught canned Sockeye salmon (730 IU per 3 oz)
• Wild-caught canned pink salmon (493 IU per 3 oz)
• Wild Atlantic salmon (375 IU per raw 3 oz)
• Wild Pink Salmon (370 IU per raw 3 oz)
• Smoked salmon (582 IU per 3 oz)
• Sardines 
• Mackerel (720 IU per raw 3 oz)
• High-quality raw dairy (90 to 150 IU per cup, varies by brand)
• Whole eggs 
• Cod liver oil (450 IU per teaspoon)

Vitamin K1 is abundant in green vegetables. This is because vitamin k1 is involved as an electron acceptor in photosynthesis, so leafy green vegetables that contain lots of chlorophyll also contain lots of vitamin k1.

Foods high in vitamin K1: 

• Spinach (889 mcg per cooked cup)
• Collard greens (836 mcg per cooked cup)
• Beet greens (697 mcg per cooked cup)
• Dandelion greens: (579 mcg per cooked cup)
• Swiss chard (573 mcg per cooked cup)
• Turnip greens (529 mcg per cooked cup)
• Kale (494 mcg per cooked cup)
• Brussels sprouts (218 mcg per cooked cup)
• Cabbage (163 mcg per cooked cup) 
• Broccoli (156 mcg per cooked cup)
• Asparagus (91 mcg per cooked cup)
• Watercress: 85 mcg per raw cup
• Lettuce (63 mcg per raw cup) 
• Green beans (60 mcg per cooked cup)
• Edamame: 41 mcg per cooked cup

In contrast, vitamin K2 is produced by microbes and animals, so it is mostly found in fermented foods and some animal products.

Vitamin K2 food sources:

• Fermented foods: sauerkraut, kimchi, kefir, natto, miso, yogurt (highest amount–will vary)
• Natto: (998 mcg per 100 grams)
• Hard cheeses (51 mcg per 100 grams)
• Soft cheeses (40 mcg per 100 grams)
• Egg yolk (31 mcg per 100 grams
• Butter: (15 mcg per 100 grams)
• Chicken liver: (14 mcg per 100 grams)

Bonus Food Tip

I recommend increasing your healthy fat intake to boost the absorption of fat-soluble vitamins (A, D, E, and K). Include 1-2 servings of healthy fats at every meal, such as fatty fish, dark meat chicken, ghee, pasture-raised butter, beef tallow, duck fat, olive oil, avocados, coconut oil, and more. 

Sunlight Exposure 

Natural sunlight exposure on the skin encourages the body to create more vitamin D, which is why it’s so important to prioritize time in the sun daily (even during the Winter months)

When it comes to getting vitamin D from the sun, I recommend 30 minutes of morning exposure to support energy levels. Exposing your eyes to sunlight first thing in the morning can help regulate your circadian rhythm and ensure quality sleep! In addition to the morning sun, make it a goal to eat lunch outside to soak up some extra sun rays and take a few deep breaths. 

SUPPLEMENTING VITAMIN D WITH K2

Vitamin D and K supplementation is a helpful way to improve nutrient levels if absorption is compromised or if these nutrients aren’t consumed daily. 

Supplementing with vitamin D:

There are many vitamin D supplement options (which we will explain later), including whole food supplements, like cod liver oil and desiccated beef liver. 

Recommendations vary, but generally, 5,000 to 10,000 IU per day of vitamin D3 is recommended to replete a deficiency in adults (retest in 4 to 6 months). 

An analysis of repletion methods found that a total dose of 600,000 IU (administered over 60 days or so) is most effective at raising vitamin D levels above 30 ng/mL). Once repleted, a maintenance dose of at least 2,000 IU per day is recommended. 

It is essential to understand that vitamin D supplements are available in the form of vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Vitamin D3 is the more biologically active form and is most commonly used for repletion. It has been shown to raise vitamin D levels more effectively than D2. 

Supplementing with vitamin K: 

The adequate intake is calculated based on reported vitamin K1 (phylloquinone) intakes in healthy adults living in North America without classic signs of vitamin K deficiency (bleeding).

Adequate intakes (AI) for vitamin K (111):

• Birth to 6 months: 2 mcg/day
• 7-12 months: 2.5 mcg/day
• 1-3 years old: 30 mcg/day
• 4-8 years old: 55 mcg/day
• 9-13 years old: 60 mcg/day
• 14-18 years old: 75 mcg/day
• Males 19+ years old: 120 mcg/day
• Females 19+ years old: 90 mcg/day
• Note: Requirements do not increase during pregnancy or breastfeeding. 

There is no official recommendation for how much vitamin K2 is required to fully support bone, metabolism, and heart health.

Studies on bone health in postmenopausal women have used supplements containing anywhere from 180 mcg to 45 mg of vitamin K2, mainly in the form of MK-4. A 1,000 mcg dose of MK-7 is better absorbed than the same dose of vitamin K1 and has a much longer half-life. 

Clearly, vitamin D and K are superstar nutrients, and our well-being depends on receiving and producing adequate amounts! Remember that food alone is typically insufficient to meet daily needs. Adequate sun exposure and/or a supplement are usually needed to improve vitamin D levels. 

Other Cofactors to keep in mind: 

While vitamin K is the primary nutrient that enhances vitamin D absorption, other vital nutrients are required for vitamin D activation in the body. 

Magnesium is a required cofactor for the activation of vitamin D in the liver and kidneys. Boron may help reduce the breakdown of vitamin D, keeping levels adequate. 

WHICH VITAMIN D WITH K2 SUPPLEMENT IS BEST?

As with all supplementation, quality matters! Always look for supplements that are third-party tested to ensure their quality, efficacy, and safety. 

You can shop my online pharmacy through Fullscript, which contains my most trusted vitamin D and vitamin K2 supplements, such as Designs for Health Vitamin D Supreme. I recommend looking for supplements that contain 2,000+ IUs of vitamin D. 

There are also whole food supplements to consider. Most cod liver oil and desiccated beef liver supplements provide adequate vitamin D and K2.

Important Note: Your vitamin D supplementation should always be based on your current vitamin D levels. 

POTENTIAL SIDE EFFECTS & RISKS OF VITAMIN D + K2

When supplementing with vitamin D, it’s important to be aware of these possible rare side effects:

• Hypercalcemia (too much calcium in urine and blood)
• Kidney issues
• Atherosclerosis
• Stomach upset
• Constipation 
• Depression
• Mental confusion 
• Excessive urination
• Excessive thirst
• Heart arrhythmias 

There is no evidence of toxicity with vitamin K1 or K2, so no upper limit has been established.

When supplementing with vitamin D and K2, the K2 helps reduce the risk of many side effects of vitamin D toxicity. Although rare, it is possible to experience vitamin D toxicity when consuming extremely high amounts of vitamin D for long periods of time. 

For this reason, always check your current vitamin D levels and consult with your healthcare professional before trying new supplements. 

WRAPPING IT ALL UP

Studies show that vitamin D and vitamin K2 are very beneficial to our immune and gut health when paired together and have a synergistic effect. Taking vitamin D and K2 together will enhance the absorption of these fat-soluble vitamins. 

Getting enough vitamin D and K daily is essential to improve gut health and autoimmunity and support overall health and wellness. The good news is that it is possible to have healthy vitamin D levels with strategic dietary, lifestyle, and supplement modifications! 

This is why I recommend asking your healthcare practitioner and checking your vitamin D levels if you struggle with an autoimmune condition or gut health issues.  Remember: test, don’t guess! 

If you are ready to personalize a protocol or address the root cause of any nutrient deficiencies and gut imbalances, check out my Microbiome Makeover program. This one-on-one program includes the most advanced functional medicine lab testing and a proven 3 phase system to address GI issues head-on and heal the leaky gut and reverse autoimmunity. Learn more here! 

READ THE LATEST BLOG POSTS:

• Vitamin D with K2: Why this Combo is Essential For Gut Health
• Best 5 Herbs To Boost Immune System
• How to Reset Your Digestion the Right Way
• What is The Best Probiotic for Bloating and Better Gut Health?
• Gut Healing Chicken Soup Recipe