Can low vitamin K cause anxiety? Unpacking the nutritional connection

October 12, 2025 •

5 min read

Animal studies have shown a connection between low vitamin K levels and an increase in anxiety-like behaviors, suggesting a potential relationship. This emerging research raises an important question: can low vitamin K cause anxiety in humans? While direct causal evidence in humans is still limited, the nutrient's role in brain function and metabolic health provides potential avenues for this link.

Quick Summary

Limited research, particularly animal studies, suggests a connection between low vitamin K levels and anxiety-like behaviors. Potential mechanisms involve the vitamin's impact on oxidative stress and metabolic functions linked to brain health.

Key Points

Emerging Evidence: Preclinical (animal) studies show low vitamin K is linked to anxiety-like behavior, while human studies find associations between lower intake and depressive symptoms.
Brain Functions: Vitamin K, particularly K2, is vital for brain health through its antioxidant and anti-inflammatory roles, protecting against damage and supporting neuronal function.
Important Mechanisms: Proposed mechanisms connecting vitamin K and mood include reducing oxidative stress, regulating sphingolipid metabolism, and activating mood-influencing proteins like osteocalcin.
K1 vs. K2: Vitamin K1 is from plants, mainly for blood clotting. Vitamin K2 is from fermented and animal foods, and is the key form found in the brain, suggesting a more specific role in neural health.
Symptoms vs. Cause: While deficiency is most known for causing bleeding problems, the anxiety link is still under investigation; maintaining optimal levels supports overall neurological wellness.
More Research Needed: Conclusive evidence for a direct causal link between low vitamin K and anxiety in humans is lacking, and further clinical trials are necessary.
Consult a Doctor: It is essential to consult a healthcare provider before taking vitamin K supplements, especially if on blood-thinning medication.

The potential link between vitamin K and anxiety

Emerging research, primarily from animal studies, suggests a link between vitamin K levels and mental health conditions like anxiety and depression. While vitamin K is best known for its critical role in blood clotting and bone health, its influence on brain function and neurological processes is gaining attention. Specifically, the vitamin K2 subtype, menaquinone-4 (MK-4), is the predominant form found in the mammalian brain, where it is involved in various neuroprotective functions.

For example, a 2016 study on rats with metabolic syndrome found that supplementation with vitamin K2 normalized blood glucose levels and significantly reduced symptoms of anxiety and depression. Another animal study in 2022 showed that vitamin K2 treatment could reverse age-related declines in brain function, social anxiety, and depressive-like behaviors in rats. While these animal findings are promising, they cannot be directly translated to humans, and more research is needed to understand if similar effects occur in people.

Proposed mechanisms linking vitamin K to brain health

Researchers have identified several potential biological pathways through which vitamin K may influence mental health and anxiety:

Antioxidant and anti-inflammatory properties: The brain is highly susceptible to oxidative stress and inflammation, which are known to contribute to mood disorders. Vitamin K, particularly MK-4, has demonstrated potent antioxidant effects, helping to protect brain cells from damage caused by harmful free radicals and reducing inflammatory responses.
Regulation of sphingolipid metabolism: Vitamin K is a critical cofactor in the synthesis and metabolism of sphingolipids, which are vital components of brain cell membranes and are crucial for neuronal signaling and nerve cell health. Disruptions in sphingolipid metabolism have been implicated in various psychiatric disorders.
Activation of vitamin K-dependent proteins (VKDPs): The vitamin is essential for activating VKDPs, such as Growth Arrest-Specific 6 (Gas6) and osteocalcin. Gas6 is involved in cell signaling in neurons and glial cells, offering anti-apoptotic (anti-cell death) and neuroprotective benefits. Meanwhile, osteocalcin, a bone-derived hormone, can cross the blood-brain barrier and has been shown to influence mood and cognition. Mice with osteocalcin deficiency exhibit increased anxiety- and depression-like behaviors.
Blood glucose regulation: As shown in the rat study, vitamin K2 treatment normalized blood glucose and reduced anxiety symptoms, suggesting a metabolic link. High blood sugar is associated with an increased risk of anxiety and cognitive impairment.

K1 vs. K2: different forms, different roles

Vitamin K exists in several forms, most notably K1 (phylloquinone) and K2 (menaquinones). Understanding the differences is important when considering their impact on neurological health.

Vitamin K1 (Phylloquinone): Found primarily in leafy green vegetables like spinach and kale. It is mainly involved in liver functions, particularly blood clotting.
Vitamin K2 (Menaquinones): Found in fermented foods like natto, and certain animal products like meat, eggs, and cheese. The body can also convert K1 into K2. The MK-4 subtype of K2 is particularly relevant for brain health, as it is the form most prevalent in brain tissue.

This distinction is important because K2, especially MK-4, appears to have more specific neuroprotective effects than K1. Supplementation or dietary focus on K2 might be more beneficial for brain-related health, but more research is needed to confirm this.

Symptoms of vitamin K deficiency

While severe vitamin K deficiency is rare in healthy adults, certain risk factors, like fat malabsorption disorders or long-term antibiotic use, can increase vulnerability. The most well-known symptom is excessive bleeding, but subtle neurological effects may also be present.

Common physical signs of deficiency include:

Easy bruising
Nosebleeds or bleeding gums
Excessive bleeding from wounds or injections
Blood in urine or stool
Heavy menstrual bleeding

Animal studies also point to potential behavioral changes like hypoactivity and a lack of exploratory behavior in deficient subjects.

Clinical evidence vs. preclinical evidence: a comparison


Feature	Clinical Evidence (Human Studies)	Preclinical Evidence (Animal Studies)
Research Scope	Primarily correlational studies linking overall vitamin K intake with mood disorders like depression. Limited data specifically on anxiety.	Experimental studies on rodents investigating causal relationships between deficiency/supplementation and anxiety-like behaviors.
Study Findings	Observational data suggests an inverse relationship between higher vitamin K intake and lower depressive symptoms. One small RCT showed K2 improved depression scores in women with PCOS.	Consistently shows K2 supplementation reduces anxiety-like and depressive-like behaviors in rats.
Causation	Cannot establish direct causation due to study designs. The association may reflect a generally healthier diet.	Can establish a causal link under controlled lab conditions, showing a direct effect on behavior.
Mechanistic Insights	Limited direct evidence in humans, but plausible mechanisms are proposed based on animal findings and broader neurobiology.	Provides robust evidence for mechanisms like reduced oxidative stress, reduced neuroinflammation, and altered sphingolipid metabolism in the brain.
Limitations	Potential for confounding factors and lack of isoform-specific analysis (K1 vs K2). Limited number of human trials focused on mental health.	Results are not directly generalizable to humans due to species differences. Findings require verification in human clinical trials.

Conclusion: the full picture

While the question "can low vitamin K cause anxiety?" does not have a definitive yes or no answer for humans yet, the evidence is compelling enough to warrant further investigation. Preclinical research provides strong support for vitamin K's role in mitigating anxiety-like behaviors, likely through its anti-inflammatory, antioxidant, and signaling functions in the brain. These findings underscore the broader importance of nutrition for mental wellness.

Maintaining adequate vitamin K status through a balanced diet rich in leafy greens and other sources is a sensible health strategy that can support overall brain health. Given the potential link to conditions like anxiety and depression, ensuring you get enough of this often-overlooked nutrient is a proactive step. For those concerned about vitamin K deficiency, or those taking blood-thinning medication, it is essential to consult a healthcare provider before considering supplementation. The full therapeutic potential of vitamin K in mental health is still being uncovered, and future human trials will be key to solidifying our understanding.

High-vitamin K food sources

To ensure adequate intake, consider including a variety of foods rich in both K1 and K2 in your diet:

K1-Rich Foods:
- Kale
- Spinach
- Broccoli
- Brussels sprouts
- Collard greens
K2-Rich Foods:
- Natto (fermented soybeans)
- Eggs
- Certain cheeses
- Chicken
- Grass-fed dairy products

Potential risks and considerations

One important point of clarification is the distinction between dietary vitamin K2 and the synthetic drug known as "K2" or "spice." The synthetic drug is entirely unrelated to the vitamin and has severe adverse effects, including extreme anxiety, paranoia, and seizures. Natural, dietary vitamin K has a very low potential for toxicity and is not associated with such side effects.

If you take blood-thinning medications like warfarin, maintaining a consistent daily intake of vitamin K is crucial to avoid interfering with the drug's effectiveness. Always speak with your doctor or a registered dietitian before making significant changes to your vitamin K intake or starting a supplement.

Additional resources

National Institutes of Health, Office of Dietary Supplements: Provides comprehensive fact sheets on vitamin K, including its functions, recommended intakes, and food sources.(https://ods.od.nih.gov/factsheets/VitaminK-Consumer/)

Frequently Asked Questions

There is currently no definitive evidence in humans showing that low vitamin K directly causes anxiety. However, animal studies have shown a link between low vitamin K2 and anxiety-like behaviors, suggesting a potential connection through its role in brain health.

Vitamin K is involved in protecting the brain from oxidative stress and inflammation, regulating important lipids (sphingolipids) for neuronal signaling, and activating key proteins like osteocalcin that influence mood and cognition.

Emerging evidence suggests vitamin K2, specifically the MK-4 subtype, is more relevant for brain health. It is the dominant form of vitamin K found in the brain and has shown potential neuroprotective and mood-regulating effects in animal studies.

The most common signs include easy bruising, excessive bleeding from cuts, nosebleeds, and bleeding gums. Deficiency can also lead to weakened bones.

Good sources of vitamin K1 include leafy green vegetables like kale, spinach, and broccoli. Rich sources of vitamin K2 include fermented foods like natto, as well as eggs, cheese, and chicken.

While some animal studies suggest supplementation can reduce anxiety-like behaviors, there is not enough evidence from human clinical trials to recommend vitamin K supplements specifically for treating anxiety. It is best to focus on a healthy, balanced diet rich in vitamin K.

Vitamin K supplements are generally considered safe for most people and have a low risk of toxicity, especially when sourced from dietary forms. However, you should always consult a doctor before starting any new supplement, particularly if you are taking blood-thinning medication.