Vitamin K

Vitamin family · Food, labels and topical research

One letter, several related molecules.

Vitamin K helps activate proteins involved in blood clotting and bone metabolism. [3]

A leafy-food discussion and a topical vitamin K study follow different routes. The family name is useful, but K1, K2 and a vitamin K oxide preparation do not identify the same material.

FAMILY MAP · NOT A MOLECULAR STRUCTURE

Meet the family

The shared core is only part of the identity.

Vitamin K compounds are fat-soluble molecules built around a related naphthoquinone core. Differences in the attached side chain help distinguish the forms. [1]

K1

Phylloquinone, also called phytonadione or phytomenadione, has a phytyl side chain. These names identify the K1 molecule, not every member of the vitamin family. [2]

K2

Menaquinones are a series of related forms. MK-4 and MK-7 are examples; the number describes side-chain length, not a product's strength or quality. [3]

MK-7

Menaquinone-7 has seven repeating isoprene units in its side chain. It is one specific K2 form, not another name for the whole K2 group. [4]

Inside the body

A helper for protein chemistry.

Vitamin K helps modify clotting and bone-related proteins. Leafy foods mainly supply K1; some animal and fermented foods supply menaquinones. [3]

At the table

Read the food, portion and form together.

NIH's reference table lists 145 micrograms of K1 in one cup of raw spinach and 850 micrograms of MK-7 in three ounces of natto. These are different foods, portions and forms, not a head-to-head ranking of their health effects. [3]

Food

Which preparation and portion supplied the amount?

Form

Was the measurement K1 or a particular menaquinone?

Outcome

Was a nutritional role or a topical effect being investigated?

The cookbook's Peach & Burrata Summer Salad offers a familiar leafy-food connection through arugula. Its recipe has not been nutritionally analyzed here, so the spinach reference should not be used as the salad's vitamin K value.

Original topical research

Bruising studies give a more specific picture.

A 2002 randomized, double-blind study enrolled 22 people receiving pulsed-dye laser treatment. Each person used vitamin K cream on one side of the face and its vehicle on the other. In the 11-person pretreatment group, vitamin K did not significantly prevent bruising. In the 11-person post-treatment group, the vitamin K side had lower bruising-severity scores. [6]

A 2009 randomized split-face study of 20 people tested a vitamin K oxide gel after pulsed-dye laser treatment. The active side showed a trend toward faster fading, but the differences from vehicle did not reach statistical significance during the roughly nine-day study. [7]

Why bruising research cannot be generalized to every dark circle

These small studies involved procedure-induced bruising and specific topical preparations. They do not establish a benefit for everyday dark circles, dietary supplementation or every product marketed under the vitamin K name. The oxide-gel result should not be described as a proven benefit simply because the trend favored it.

Across the cosmetic label

“Oxide” changes the ingredient name.

Phytonadione Epoxide has its own cosmetic ingredient entry. “Oxide” is part of its identity, not a decorative extra word. [8]

For label literacy, keep three questions separate: Which chemical form is named? What preparation was studied? What result was actually measured? A nutrient amount on a food label is not a cosmetic use percentage, and an ingredient-database function is not evidence that a finished eye cream removes bruising.

A practical note

Consistency matters with warfarin.

With warfarin or similar medicines, keep vitamin K intake consistent and discuss changes with a clinician. Do not independently eliminate leafy foods. [3]

At a glance

Reference box

Family: Vitamin K · Fat-soluble vitamers with related quinone chemistry.
K1 names: Phylloquinone · Phytonadione · Phytomenadione.
K2 names: Menaquinones, including distinct MK-4 and MK-7 forms.
Cosmetic distinction: Phytonadione Epoxide is not simply another name for dietary K1 or K2.
Evidence lens: Nutritional function, food composition and topical clinical outcomes answer different questions.

Sources to follow

Revised October 25, 2026. Sources below distinguish chemical identity, food composition and the particular preparations or populations studied. Research methods and interpretation remain alongside the findings.

ChEBI: Vitamin K family. Chemical classification.
ChEBI: Phylloquinone. K1 structure and synonyms.
NIH Office of Dietary Supplements: Vitamin K. Nutritional roles, food forms and medication interaction.
ChEBI: Menaquinone-7. Specific side-chain identity.
Shah and colleagues, 2002. Randomized topical vitamin K study after laser treatment.
Cohen and Bhatia, 2009. Randomized vitamin K oxide gel study.
COSMILE Europe: Phytonadione Epoxide. Ingredient name and listed cosmetic function.