Get to Know Your Vitamin Series: Vitamin K2

Vitamin K2

Vitamin K2, also known as menaquinone, is a fat-soluble vitamin essential for regulating calcium in the body. While its better-known counterpart, Vitamin K1, is primarily used by the liver for blood clotting, Vitamin K2 acts in extrahepatic tissues to support bone and cardiovascular health.

As we age, the body’s ability to manage calcium efficiently declines, making Vitamin K2 especially important for seniors focused on long-term bone, heart, and cognitive health.

Primary Functions

Vitamin K2 acts as a “traffic controller” for calcium, ensuring it reaches the right places while staying out of the wrong ones:

• Blood Clotting: Like all K vitamins, it is essential for the production of proteins required for normal blood coagulation.
• Bone Health: It activates a protein called osteocalcin, which binds calcium to the bone mineral matrix, strengthening the skeleton and reducing fracture risk.
• Heart Health: It activates Matrix Gla Protein (MGP), which prevents calcium from depositing in artery walls and soft tissues. This helps prevent arterial calcification, a major risk factor for heart disease.

Together, these functions highlight why Vitamin K2 plays a unique role in healthy aging beyond basic clotting needs.

Mental Health Benefits

Research indicates that Vitamin K2 plays a critical role in brain health beyond its traditional association with bone and heart health. It is the primary form of Vitamin K found in the brain, specifically as MK-4, where it supports neuronal survival and cognitive function. 

1. Benefits for Cognitive Health and Dementia

Vitamin K2 is strongly linked to preserving mental sharpness and reducing the risk of neurodegenerative decline.

• Memory and Attention: Higher levels of Vitamin K2 are associated with better verbal memory, processing speed, and global cognitive performance in older adults.
• Dementia Prevention: Research suggests that high brain concentrations of MK-4 are linked to a reduction in the risk of dementia and mild cognitive impairment (MCI).
• Alzheimer’s Disease: K2 may slow Alzheimer’s progression by reducing neuroinflammation and inhibiting the formation of amyloid-beta plaques.

2. Benefits for Mental Health

Recent findings have expanded the potential of K2 to include mood regulation and the mitigation of psychiatric symptoms.

• Depression and Anxiety: Observational studies (including NHANES data) show an inverse relationship between Vitamin K intake and depression scores, particularly in older women. Preclinical models have demonstrated that K2 supplementation can normalize blood glucose and reduce anxiety and depression behaviors.
• Mood Regulation: K2 is thought to assist in the synthesis of essential neurotransmitters like dopamine and serotonin, which are critical for mood stability.
• Suicide Risk: Preliminary research from 2024–2025 has observed an association between low Vitamin K levels and increased suicide attempts in patients with clinical depression, suggesting it may be a potential biological risk factor.

3. Benefits for Other Brain Conditions

• Parkinson’s Disease: K2 has shown promise in restoring mitochondrial function and increasing ATP production in Parkinson’s models, which helps protect the neurons responsible for motor control.
• Multiple Sclerosis (MS): Emergent evidence suggests K2 may aid in myelin repair and reduce neuroinflammation, potentially slowing the progression of MS.

4. How It Works (Mechanisms)

The benefits of Vitamin K2 for the brain are driven by several unique biological pathways:

• The Heart-Brain Connection: K2 reduces arterial stiffness and vascular calcification, ensuring optimal blood flow and nutrient delivery to brain tissue.
• Sphingolipid Metabolism: K2 regulates enzymes involved in the synthesis of sphingolipids, a class of fats essential for the growth and survival of brain cells.
• Anti-Inflammatory Effects: It calms overactive immune cells in the brain (microglia) and reduces oxidative stress.
• Epigenetic Modulation: Recent 2025 research highlights K2’s ability to “turn off” certain genes associated with neurodegeneration through DNA methylation.

Note on Research Status: While 2026 data shows significant promise, many human studies remain observational. Large-scale randomized controlled trials (RCTs) are currently underway to confirm these benefits and determine optimal dosages for mental health.

This is for informational purposes only. For medical advice or diagnosis, consult a professional. 

Key Forms (Subtypes of K2)

Not all forms of Vitamin K2 behave the same way in the body, and understanding these differences can help explain why some forms are discussed more often in senior health research.

Vitamin K2 is a group of compounds called menaquinones, labeled MK-4 through MK-13 based on the length of their side chains. Let’s concentrate on MK-4 and MK-7 for now. The primary difference between Vitamin K2 forms MK-4 (menaquinone-4) and MK-7 (menaquinone-7) lies in their chemical structure (side-chain length), which directly affects how long they stay in your body and their required dosages.

1. Absorption and Half-Life

• MK-7 (Long-Chain): Has a much longer half-life of approximately 72 hours. Because it stays in the bloodstream for days, it can accumulate to stable levels, allowing for simple once-daily dosing.
• MK-4 (Short-Chain): Has a very short half-life of about 1–2 hours. It is rapidly cleared from the blood, often requiring multiple high-milligram doses throughout the day to maintain therapeutic levels.

2. Sources and Origins

• MK-7: Derived mainly from fermented foods like natto (Japanese fermented soybeans), sauerkraut, and certain cheeses. It is synthesized by bacteria.
• MK-4: Found predominantly in animal products such as liver, eggs, grass-fed butter, and meat. It is the only form of Vitamin K2 that mammals can produce internally by converting Vitamin K1.

3. Dosing and Bioavailability

• MK-7: Highly bioavailable even at low doses. Standard nutritional doses typically range from 90 to 200 micrograms (mcg) daily.
• MK-4: Less efficient as a supplement at nutritional doses; research indicates it often requires milligram (mg) doses—thousands of times higher than MK-7—to be effective for bone health.

4. How the Body Uses Them

• Heart and Bone Health (MK-7 Focus): Due to how long it stays active in the body, MK-7 is highly effective at reaching and activating proteins in the bones (osteocalcin) and arteries (Matrix Gla Protein).
• Tissue Specificity (MK-4 Focus): MK-4 is the form that naturally accumulates in specific tissues, including the brain, pancreas, and reproductive organs. However, current research as of 2026 suggests that the body can convert MK-7 into MK-4 within these tissues as needed. 

Is a Typical Diet Enough for Seniors

For many seniors, the challenge isn’t awareness — it’s access. Research indicates that typical Western diets do not supply enough Vitamin K2 for the specific health needs of seniors. While most adults consume enough Vitamin K to support basic blood clotting, they fall significantly short of the levels required for bone density, cardiovascular health, and cognitive preservation.

1. The “Shortfall” in Seniors

Current data shows a widespread deficiency in the elderly population:

• Widespread Insufficiency: An estimated 97% of Western adults are considered insufficient or deficient in Vitamin K2 when measured by its ability to activate vital health proteins.
• Gender and Age Gaps: Approximately 60% of men and 40% of women over age 51 do not meet even the basic “adequate intake” levels for total Vitamin K.
• Older Men: Among men over age 70, roughly two-thirds fail to reach recommended dietary targets.

2. Clotting vs. Optimal Aging

The primary reason for this shortage is that official dietary recommendations (roughly 90–120 mcg of total Vitamin K) are designed only to prevent bleeding. 

• The Liver Gap: The body prioritizes the liver to ensure blood clotting. In a typical diet, there is rarely enough K2 left over to support “extra-hepatic” tissues like the bones, arteries, and brain.
• The 2026 Consensus: Many researchers now recommend that seniors consume 100 to 200 mcg of Vitamin K2 daily—levels nearly impossible to reach through a standard diet without specific fermented foods or supplements. 

3. Why Typical Diets Fail

Vitamin K2 is largely absent from modern eating habits because it is found in very specific, often avoided, sources:

• Missing Foods: The richest source of K2 (specifically MK-7) is natto (fermented soybeans), which is not a staple in Western diets.
• Processing Issues: Modern industrial farming has reduced K2 levels in animal products; for example, grass-fed butter and meat contain significantly more K2 than grain-fed versions.
• Inefficient Conversion: While the body can convert Vitamin K1 (from leafy greens) into K2, this process is highly inefficient in humans and becomes even less effective with age. 

4. Consequences for Seniors

Low Vitamin K2 status in older adults is directly linked to several “aging” conditions:

• Frailty: Lower K2 levels are a strong predictor of increased frailty, reduced grip strength, and slower walking speeds in seniors.
• Vascular Stiffness: Insufficient K2 allows calcium to build up in the arteries rather than the bones, increasing the risk of heart disease and stroke.
• Cognitive Decline: 2025–2026 studies suggest that K2 deficiency is a key determinant of arterial health in the brain, contributing to the onset of dementia and memory loss.

Why It Matters

A deficiency can lead to calcium in arteries and weaker bones, highlighting K2’s vital role in overall cardiovascular and skeletal wellness. 

Intake Recommendations

Information provided here is for general knowledge and should not be taken as medical advice. Consult with a healthcare provider before making any decisions about your health or treatment.

These are the current recommendations regarding Vitamin K intake for basic health, as well as levels suggested by research for seniors aiming for long-term bone and heart support.

1. Official Adequate Intake (AI)

The National Academies of Sciences, Engineering, and Medicine (NASEM) provides an Adequate Intake (AI) for total Vitamin K (K1 and K2 combined). These levels are primarily intended to support healthy blood clotting.

• Men (19+ years): 120 mcg/day
• Women (19+ years): 90 mcg/day

Currently, there is no separate official Recommended Dietary Allowance (RDA) established specifically for Vitamin K2 as of 2026.

Also, there is no official Tolerable Upper Intake Level (UL) established for natural Vitamin K2 by major health organizations like the National Institutes of Health (NIH) or the European Food Safety Authority (EFSA). This is because research hasn’t identified a toxic dose for natural forms of the vitamin (K1 or K2) in healthy individuals.

2. Research-Backed Considerations for Seniors

Because the official AI focuses on the liver’s clotting needs, many experts and 2026 clinical guidelines suggest considering levels specifically for Vitamin K2 to support health in areas beyond the liver, such as bones and arteries. Research has explored different levels of Vitamin K2, particularly the MK-7 form, for potential benefits related to general heart and bone health. Some studies investigating advanced bone support, particularly in clinical settings for osteoporosis, have used significant levels of the MK-4 form under medical supervision.

In other words, the amount of Vitamin K needed to prevent bleeding is not necessarily the amount associated with long-term bone and cardiovascular support in older adults.

Are Supplements Recommended

For seniors, supplements are often highly recommended by nutrition experts and medical researchers to ensure adequate Vitamin K2 intake, primarily because typical diets are insufficient for optimal bone and cardiovascular health. While official US and Canadian guidelines do not have a specific RDA for K2, the clinical evidence supporting its use for age-related conditions is substantial.

Rationale for Supplementation

• Dietary Gaps: Foods rich in Vitamin K2, particularly the MK-7 form, such as natto, are not typically consumed in large quantities in Western diets.
• Optimal Health vs. Clotting: The established Adequate Intake (AI) for total Vitamin K, which is between 90-120 mcg/day, is primarily sufficient for blood clotting in the liver. This leaves limited amounts for other tissues like bones and arteries where Vitamin K2 is important for activating specific proteins.
• Age-Related Decline: The body’s efficiency in converting Vitamin K1 (found in leafy greens) to Vitamin K2 may decrease with age, potentially increasing the need for direct K2 intake.
• Research Findings: Studies have indicated that supplementation with Vitamin K2 (MK-7) may help reduce age-related decline in bone density and improve arterial elasticity in postmenopausal women.
• Synergy with D3: Vitamin K2 is often discussed in conjunction with Vitamin D3. Vitamin D3 supports calcium absorption, while Vitamin K2 is understood to play a role in calcium utilization in the body, directing it to bones and teeth.

For many older adults, supplementation is discussed not as a replacement for diet, but as a way to address age-related nutritional gaps.

Important Considerations

• Fat-Soluble: For optimal absorption, Vitamin K2 is best taken with a meal containing some fat.
• Warfarin/Anticoagulants: Seniors taking blood thinners like Warfarin must consult a doctor before making changes to Vitamin K intake, as it can significantly interfere with the medication’s effectiveness.

Conclusion

Vitamin K2 may be less familiar than some nutrients, but its role in healthy aging is essential. By helping direct calcium to the bones and away from the arteries, it supports the systems seniors rely on most for strength, mobility, and long-term heart health.

Vitamin K2 is also an important partner to Vitamin D3. Together, they support how the body absorbs and uses calcium—one reason these two nutrients are so often paired in discussions about bone and cardiovascular wellness later in life.

Because many diets don’t provide enough Vitamin K2, some seniors choose to include K2 and D3 together as part of a well-rounded wellness routine. Our K2 + D3 supplement was created with this complementary relationship in mind, focusing on education first and thoughtful formulation.

Thank you for continuing the Get to Know Your Vitamins series with us. We invite you to share your thoughts with us on Facebook and Instagram as we keep exploring nutrients that support healthy aging.