This article is for informational purposes only and should not be considered medical advice. Always consult a healthcare professional or a registered dietitian before making significant changes to your diet or starting any supplementation.

Introduction

Vitamin K1, also known as phylloquinone, is a fat‐soluble vitamin crucial for human health. It gained attention due to its pivotal role in blood clotting, but research over the last few decades has revealed additional benefits that extend to bone metabolism and vascular health. Despite its importance, vitamin K1 often receives less public awareness compared to vitamins like C or D. This article will guide you through the science of vitamin K1, its functions, food sources, health benefits, and practical tips for ensuring you get enough every day.

Role in the Body

Specific Functions

Vitamin K1 acts as a coenzyme for the enzyme γ‐glutamyl carboxylase, which catalyzes the conversion of specific glutamic acid residues in proteins to γ‐carboxyglutamic acid (Gla). This modification allows these proteins to bind calcium ions, a requirement for their biological activity.

Key proteins that depend on vitamin K1 include:

• Prothrombin (Factor II), which is essential for converting fibrinogen to fibrin in the clotting cascade

• Factors VII, IX, and X, which sequentially activate clot formation

• Matrix Gla protein (MGP), which prevents calcium deposition in soft tissues such as blood vessel walls

• Osteocalcin, a bone‐building protein that binds calcium during bone mineralization

Effects of Deficiency

Insufficient vitamin K1 impairs the activation of clotting factors, leading to a tendency for excessive bleeding and bruising. In newborns, the risk is so high that most health systems administer a single injection of vitamin K1 shortly after birth to prevent hemorrhagic disease of the newborn.

Clinical manifestations of deficiency may include:

• Prolonged bleeding, visible as nosebleeds, gum bleeding, or heavy menstrual flow in women

• Easy bruising, with discolorations appearing with minimal trauma

• Osteopenia or osteoporosis over time, due to reduced osteocalcin activity resulting in weaker bones

• Calcification of arteries, owing to inactive MGP, which can contribute to cardiovascular disease risk

According to a study published in the Journal of Thrombosis and Haemostasis (2015), subclinical vitamin K deficiency may be more prevalent than previously believed, particularly among older adults and individuals on long‐term antibiotic therapy.

Dietary Sources

Best Food Sources

• Kale (raw, 1 cup): ~547 µg of vitamin K1

• Spinach (raw, 1 cup): ~145 µg of vitamin K1

• Collard greens (cooked, ½ cup): ~530 µg of vitamin K1

• Broccoli (cooked, ½ cup): ~110 µg of vitamin K1

• Brussels sprouts (cooked, ½ cup): ~109 µg of vitamin K1

• Parsley (fresh, ¼ cup): ~164 µg of vitamin K1

• Swiss chard (cooked, ½ cup): ~289 µg of vitamin K1

• Lettuce (green leaf, raw, 1 cup): ~62 µg of vitamin K1

Supplementation

While a balanced diet can typically meet vitamin K1 needs, supplementation may be necessary in the following scenarios:

• Individuals with malabsorption disorders such as celiac disease, Crohn’s disease, or cystic fibrosis, which hinder fat‐soluble vitamin absorption.

• People taking long‐term antibiotics, as these can reduce vitamin K–producing gut bacteria.

• Newborn infants, who receive a single prophylactic dose to prevent hemorrhagic disease of the newborn.

• Patients on anticoagulant therapy (e.g., warfarin), where careful monitoring and controlled dosing of vitamin K1 is used to manage therapeutic ranges.

When choosing a supplement, look for phylloquinone (vitamin K1) standardized to at least 100 µg per serving, and consult a healthcare provider before starting any new regimen.

Health Benefits

Beyond coagulation, research has identified several health benefits associated with adequate vitamin K1 intake:

1. Bone Health: Vitamin K1 carboxylates osteocalcin, enabling it to bind calcium to the bone matrix. In a randomized controlled trial published in Osteoporosis International (2013), postmenopausal women receiving vitamin K1 supplements showed improvements in bone mineral density and reduced markers of bone turnover compared to placebo.

2. Cardiovascular Protection: Matrix Gla protein (MGP) requires vitamin K1 for activation. A healthy MGP prevents vascular calcification. An observational study in the European Journal of Nutrition (2018) found that high dietary vitamin K1 intake was associated with a 21% lower risk of coronary heart disease over 10 years.

Daily Requirements

Recommended Dietary Allowances (RDAs) for vitamin K are expressed in micrograms (µg) of phylloquinone per day. Guidelines vary slightly by region, but generally are as follows:

• Infants 0–6 months: 2 µg/day

• Infants 7–12 months: 2.5 µg/day

• Children 1–3 years: 30 µg/day

• Children 4–8 years: 55 µg/day

• Children 9–13 years: 60 µg/day

• Teens 14–18 years: 75 µg/day

• Adult men (≥19 years): 120 µg/day

• Adult women (≥19 years): 90 µg/day

• Pregnant or lactating women: 90 µg/day

Note: These values are based on adequate intake levels set by the Institute of Medicine. Individual needs may vary depending on health status, medications, and lifestyle factors.

Tips for Incorporation

• Add a handful of spinach or kale to your morning smoothie for a quick vitamin K1 boost

• Steam or sauté leafy greens as a side dish with garlic and olive oil to enhance absorption of fat‐soluble vitamins

• Mix shredded cabbage or Brussels sprouts into salads and slaws to increase daily intake

• Use fresh herbs like parsley and basil to garnish soups, stews, and omelets

• Blend broccoli or Swiss chard into cream soups for hidden nutrients your family will love

• Incorporate green leafy vegetables into casseroles, stir‐fries, and pasta dishes for added color and nutrients

• Pair vitamin K1–rich foods with healthy fats (e.g., avocado, nuts, olive oil) to improve absorption

• Try freezing chopped greens into ice cube trays, then add to sauces, stews, or smoothies when fresh produce is low

Conclusion and Call to Action

Vitamin K1 is a vital nutrient that supports blood clotting, bone health, and cardiovascular function. By incorporating a variety of leafy greens and other high‐K1 foods into your diet, you can help prevent deficiency‐related complications. Whether you’re blending a green smoothie, tossing a salad, or experimenting with new recipes, small daily choices add up to big health rewards over time.

“Ensuring adequate vitamin K intake is an often‐overlooked strategy for maintaining strong bones and a healthy heart.” – Dr. Julia Thompson, Registered Dietitian

Make vitamin K1 a priority today by planning meals around nutrient‐dense greens, educating yourself on food sources, and consulting a healthcare professional if supplementation is needed. Your future self will thank you for the proactive approach to lifelong wellness.