Vitamin K2: The Overlooked Nutrient That Supports Heart and Bone Health

Many people know about vitamin D and calcium, but few pay attention to vitamin K2. Yet this nutrient plays a vital role in keeping calcium where it belongs - in your bones and teeth, not your arteries. If you care about heart health, strong bones, and healthy aging, it’s worth understanding what vitamin K2 does and how to get enough of it.

What Is Vitamin K2?

Vitamin K2 is one form of vitamin K, a fat-soluble vitamin involved in blood clotting and calcium metabolism. There are two main types:

• Vitamin K1 (phylloquinone) - found mostly in leafy greens like spinach and kale.
• Vitamin K2 (menaquinone) - found in animal products and fermented foods.

While both forms support normal blood clotting, K2 has unique effects on calcium use in the body. It activates proteins that help move calcium into bones and prevent it from building up in blood vessels.

How Vitamin K2 Works in the Body

Vitamin K2 supports two key proteins:

• Osteocalcin - helps bind calcium to bone tissue, improving density and strength.
• Matrix GLA protein (MGP) - helps prevent calcium from depositing in arteries and soft tissues.

Without enough vitamin K2, these proteins remain inactive. Calcium may then accumulate in arteries instead of strengthening bones. Over time, this can lead to both weaker bones and higher cardiovascular risk.

The Link Between Vitamin K2 and Heart Health

Several studies suggest that people who get more vitamin K2 from their diet have lower rates of arterial calcification and heart disease. According to research published by the National Institutes of Health, higher K2 intake is associated with reduced cardiovascular mortality.

Unlike K1, vitamin K2 seems to be more effective at reaching vascular tissues, where it activates MGP to keep arteries flexible. This makes it an essential nutrient for long-term heart and circulatory health.

Vitamin K2 and Bone Strength

Bone health depends on more than calcium and vitamin D. Without vitamin K2, your body can’t use calcium effectively. A study in the Journal of Nutrition found that people with higher K2 intake had stronger bones and fewer fractures.

In Japan, where fermented soybeans (natto) are a rich source of vitamin K2, rates of osteoporosis are lower compared to Western countries. Some research from the Office of Dietary Supplements suggests that K2 supplementation may help maintain bone density in older adults, especially women after menopause.

Different Forms of Vitamin K2: MK-4 and MK-7

Vitamin K2 includes several subtypes, known as menaquinones, labeled MK-4 through MK-13. The two most studied forms are MK-4 and MK-7.

• MK-4 - found in animal products such as egg yolks, butter, and liver. It has a short half-life, so you need regular intake to maintain levels.
• MK-7 - found in fermented foods like natto and some cheeses. It stays active in the body longer, so smaller doses are effective.

Most supplements use MK-7 because it’s more stable and requires less frequent dosing. However, both forms have benefits, and getting a mix from food sources can be ideal.

Best Food Sources of Vitamin K2

Vitamin K2 is less common in the diet than K1, which is abundant in vegetables. Common sources include:

• Natto (fermented soybeans) - the richest natural source of MK-7
• Hard and soft cheeses (especially aged varieties)
• Grass-fed butter and dairy products
• Egg yolks from pasture-raised hens
• Liver and other organ meats
• Fermented foods like sauerkraut or kimchi (small amounts)

Modern diets often lack these foods, especially if you avoid animal products or processed cheese. This may explain why vitamin K2 deficiency is more common than most people realize.

Should You Take a Vitamin K2 Supplement?

For many people, it’s hard to get enough K2 from food alone. If you rarely eat fermented foods or grass-fed animal products, supplementation can help. Most K2 supplements come in doses ranging from 50 to 200 micrograms daily, often combined with vitamin D3.

Vitamin D helps your body absorb calcium, while K2 ensures that calcium goes to the right places. This pairing supports both bone strength and cardiovascular health. Some research in the American Journal of Clinical Nutrition supports the synergistic effect of vitamins D and K2 on bone metabolism.

How to Choose a Quality K2 Supplement

When picking a supplement, look for these details:

• Form: MK-7 is more bioavailable and longer-lasting than MK-4.
• Source: Fermented natto-derived MK-7 tends to be the most studied and stable.
• Combination: K2+D3 blends can support better calcium balance.
• Certification: Choose brands that test for purity and potency through third-party labs.

Always consult a healthcare provider before starting supplements, especially if you take blood thinners like warfarin, since vitamin K affects clotting.

How Much Vitamin K2 Do You Need?

There’s no official daily recommended intake for vitamin K2 alone. Most guidelines combine K1 and K2 under “vitamin K,” with general targets of 90 micrograms daily for women and 120 micrograms for men. However, many experts believe these numbers are too low for optimal bone and heart health.

Some clinical studies have used 180 micrograms per day of MK-7 with good results and no known toxicity. Because it’s fat-soluble, it’s best taken with a meal that includes healthy fats for better absorption.

Vitamin K2 and Other Nutrients

Vitamin K2 doesn’t work in isolation. It interacts with several other nutrients:

• Vitamin D3 - promotes calcium absorption.
• Magnesium citrate - supports bone formation and helps activate vitamin D.
• Calcium - the mineral that K2 helps direct into bones.

Balancing these nutrients helps your body use calcium efficiently, reducing the risk of calcification and keeping bones strong.

Signs You Might Be Low on Vitamin K2

There’s no easy blood test for K2 status, but certain signs may suggest a deficiency:

• Frequent cavities or dental issues
• Early signs of arterial stiffness or calcification
• Low bone density or slow healing fractures
• A diet low in animal fats or fermented foods

If these apply to you, consider discussing K2 intake with your doctor or a registered dietitian. They can help you assess your diet and decide if supplementation makes sense.

Practical Tips to Boost Vitamin K2 Intake

1. Add a small serving of aged cheese or natto a few times per week.
2. Choose grass-fed dairy and pasture-raised eggs when possible.
3. Use fermented foods as condiments or side dishes to add variety.
4. If you take vitamin D, consider pairing it with a K2 supplement.

Some people find natto’s flavor challenging, so starting with small portions or choosing a supplement is often easier.

Potential Risks and Safety

Vitamin K2 is considered safe at normal doses. Because it’s fat-soluble, the body stores it, but toxicity is rare. The main caution applies to people on anticoagulant drugs, since vitamin K can affect medication function. Always check with your healthcare provider before changing your intake if you’re on such medication.

Otherwise, most healthy adults can take K2 safely as part of a balanced diet or supplement routine. Pregnant and breastfeeding women should consult their doctors before starting new supplements.

Research and Ongoing Studies

Scientists continue to explore vitamin K2’s broader roles beyond bone and heart health. Some emerging research suggests K2 may influence insulin sensitivity, inflammation, and even brain function. While results are early, they highlight how this nutrient affects many tissues throughout the body.

More long-term studies are underway to confirm optimal dosing, ideal forms, and interactions with other vitamins and minerals.

Final Thoughts

Vitamin K2 may not get the attention of vitamin D or calcium, but it’s a quiet cornerstone of good health. It helps guide calcium to your bones while protecting your arteries from buildup. Whether through diet or supplements, ensuring you get enough K2 supports strong bones, a healthy heart, and better aging overall.

If your diet lacks fermented foods or grass-fed animal products, consider adding a reliable K2 source. As research continues, one thing is clear: this small nutrient plays a big role in keeping your body balanced and resilient.