Do most people get enough K2? The shocking truth about deficiency

October 29, 2025 •

4 min read

A study on healthy adults revealed that a staggering 97% of them were deficient or insufficient in vitamin K2. This startling statistic raises a critical and often overlooked question: Do most people get enough K2, or is this vital fat-soluble nutrient missing from modern diets?

Quick Summary

The modern Western diet is a poor source of vitamin K2, leading to widespread inadequacy that impacts bone and cardiovascular health. Learn the crucial differences between K1 and K2 and how to optimize your intake.

Key Points

Widespread Deficiency: Despite adequate intake of Vitamin K1, the majority of the Western population is deficient or insufficient in Vitamin K2 due to modern dietary habits.
Distinct Functions: Vitamin K1 is primarily for blood clotting, while K2's main role is to regulate calcium, directing it to bones and preventing it from hardening arteries.
Bone and Heart Health: Adequate K2 intake is vital for strong bones and preventing arterial calcification, which reduces the risk of heart disease.
Food Sources Differ: K1 is found in leafy greens, while K2 comes from fermented foods like natto and certain animal products, especially from grass-fed animals.
Supplementation is Often Necessary: Because most Western diets lack significant K2, especially the long-lasting MK-7 form, supplementation is often the most reliable way to ensure adequate intake.
Not all K2 is the same: MK-4 is found in some animal products, while the more bioavailable MK-7 is prominent in fermented foods, especially natto.

What is Vitamin K2?

Vitamin K refers to a group of fat-soluble vitamins essential for various physiological processes. While many people are familiar with Vitamin K1 (phylloquinone), which is abundant in green leafy vegetables and primarily functions in blood clotting, Vitamin K2 (menaquinone) serves a distinct and equally important role. There are several subtypes of K2, with MK-4 and MK-7 being the most well-studied. K2's primary function is to activate specific proteins that regulate where calcium goes in the body. This prevents calcium from depositing in soft tissues like arteries and directs it toward hard tissues, such as bones and teeth.

MK-4 vs. MK-7: Two Key Players

Both MK-4 and MK-7 are important forms of Vitamin K2, but they differ in their sources and how the body uses them.

MK-4: Found mainly in animal products like organ meats, egg yolks, and high-fat dairy from grass-fed animals. The body can also convert K1 into MK-4, but this process is often inefficient.
MK-7: Primarily found in fermented foods, with natto (fermented soybeans) being the most concentrated source. MK-7 has a longer half-life, meaning it stays in the body's circulation for longer than K1 or MK-4, making it highly effective for tissues outside the liver.

The Modern Diet and Widespread K2 Deficiency

The modern Western diet has shifted away from traditional K2-rich foods like grass-fed organ meats and fermented products. This dietary change is the leading cause of widespread K2 deficiency or insufficiency, which is surprisingly common despite K1 intake often being adequate. The reliance on lean, muscle-based animal products and a decrease in traditional fermented foods means that a majority of the population is missing out on crucial K2 sources.

The Crucial Roles of K2 in the Body

The health benefits of adequate Vitamin K2 intake are significant, particularly concerning bone and heart health.

Bone Health

Vitamin K2 activates osteocalcin, a protein that binds calcium to the bone matrix, promoting proper bone mineralization and density. Several studies have linked higher K2 intake to improved bone mineral density and a reduced risk of fractures, especially in postmenopausal women. In Japan, where natto is a traditional food, K2 is sometimes used as a therapy for osteoporosis. For optimal bone health, K2 works synergistically with vitamin D3, which aids in calcium absorption.

Heart Health

One of K2's most compelling functions is protecting cardiovascular health. It activates matrix Gla protein (MGP), which helps prevent calcium from accumulating in arterial walls. This mechanism helps reduce arterial calcification and stiffening, both significant risk factors for heart disease. Observational studies have shown that high K2 intake, but not K1, is associated with a lower risk of coronary heart disease.

Vitamin K1 vs. K2: A Critical Comparison

Understanding the differences between the two main forms of Vitamin K is essential for optimizing your health.


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinone)
Primary Source	Leafy green vegetables (e.g., spinach, kale, broccoli)	Fermented foods (natto, cheese), organ meats, eggs, grass-fed dairy
Absorption Rate	Generally poorly absorbed from plant sources	Better absorbed, especially from fatty foods
Circulation Time	Short half-life, quickly filtered by the liver	Long half-life (especially MK-7), circulates for days
Primary Function	Blood clotting	Directs calcium to bones/teeth, prevents arterial calcification
Deficiency Prevalence	Rare in healthy adults	Widespread in Western populations

How to Increase Your Vitamin K2 Intake

Given the low prevalence of K2 in the average Western diet, increasing your intake requires a conscious effort. Here are some strategies:

Eat Natto: This fermented Japanese dish is the richest source of MK-7 by far. However, it has a strong flavor and texture that many find unappealing.
Consume Grass-Fed Animal Products: Choose eggs and dairy from grass-fed animals and include organ meats like liver in your diet to increase your MK-4 intake.
Include Specific Cheeses: Hard and soft aged cheeses like Gouda, Brie, and Jarlsberg are reliable sources of longer-chain K2 variants.
Consider Supplementation: For those who cannot get enough K2 from diet alone, high-quality supplements containing MK-7 are a practical option. Taking K2 alongside Vitamin D3 is also recommended, as they work together synergistically. You should always consult a doctor before starting any new supplement, especially if on blood thinners.

Conclusion: A Necessary Nutrient for Modern Health

While overall vitamin K deficiency (primarily K1) is rare in the adult population, widespread insufficiency in vitamin K2 is a significant, hidden health issue in modern Western societies. The decline in traditional dietary sources means that most people are not getting enough K2 to support optimal bone and heart health. By consciously incorporating K2-rich foods into your diet or considering supplementation, you can help protect your long-term cardiovascular and skeletal health. Research highlights the distinct roles of K1 and K2, underscoring why focusing on both is key for comprehensive well-being. Evidence for the use of vitamin K2 continues to grow, emphasizing its importance beyond simple blood clotting.

Frequently Asked Questions

The single richest source of Vitamin K2 (specifically MK-7) is natto, a fermented Japanese soybean product. Other good sources include hard and soft cheeses, grass-fed butter, egg yolks, and organ meats like liver.

It is very challenging to get enough K2 from a vegetarian or vegan diet alone, as most rich sources are animal-based or derived from specific fermented foods like natto. The body's conversion of K1 to K2 is typically inefficient.

Vitamin K1 helps with blood clotting, while K2 directs calcium to the bones and keeps it out of arteries and soft tissues. They come from different food sources and K2 has a longer circulation time in the body.

While severe deficiency is rare and marked by bleeding issues, a subclinical K2 deficiency can lead to long-term health problems like reduced bone mineral density and increased arterial calcification, which can take years to show symptoms.

Given the widespread insufficiency in modern diets, supplementation is a practical way to ensure adequate intake, especially for bone and heart health. However, you should consult a healthcare provider, particularly if you are taking blood thinners.

Excessive intake of K2 from food or supplements is unlikely to cause serious side effects. The main concern is for individuals on anticoagulant medications like warfarin, where high and inconsistent vitamin K intake can interfere with treatment.

Vitamin D promotes the absorption of calcium, while Vitamin K2 helps ensure that this calcium is properly utilized in the body, primarily by directing it to the bones instead of depositing in the arteries.