On Nutrition: Why vitamin K is important for bone health

Vitamin K1 is found in leafy greens such as broccoli and spinach; vitamin K2 is found in cheese, egg yolk and meats.

  • Wednesday, June 9, 2021 1:30am
  • Life

By Barbara Quinn / Special to The Herald

Reader Kari B. from Lincoln, Nebraska, writes:

“Would you be able to review vitamin K2 sometime in your nutrition column? I was researching bone health online and came upon an article that discusses how important this vitamin is in bone health. It states that vitamin K2 is part of the bone health package that includes magnesium, calcium, weight-bearing exercise, minimizing inflammation in the body, and having a healthy gut (microbiome).

It appears that some docs might take the easy way out and only tell their patients to take calcium supplements, possibly along with vitamin D.

If you could shed some light on this? It could be very helpful to know how much Vitamin K2 to ingest each day. Thank you for any consideration!”

Happy to comment on this interesting topic! Vitamin K is the term given to a family of compounds that are similar but somewhat different. Thus, vitamin K1 (phylloquinone) and several types of vitamin K2 (menaquinones) are collectively called “vitamin K.” You might also read about MK-4, MK-7 or MK-9, which are various forms of vitamin K2. And that’s all the chemistry we need for now.

Vitamin K has historically been known as the “coagulation vitamin” because of its important role in helping our blood to clot. In fact, a classic symptom of a vitamin K deficiency is abnormal bleeding.

More recently, vitamin K has been studied for its role in bone health. Both vitamin K1 and K2 are involved in processes that help build bone strength, but it appears that vitamin K2 is the most protective in this particular job. A deficiency of the K2 form of vitamin K has been linked to osteoporosis (fragile bones) as well as calcium deposits in the arteries (commonly called hardening of the arteries).

The current recommendation for an adequate intake vitamin K for people 19 years of age and older is 90 micrograms for women and 120 micrograms for men. This includes both forms, K1 and K2.

Because of its emerging role in bone and heart health, some researchers now believe vitamin K needs its own recommended daily requirement. And whether or not to take a supplement of K2 is not yet clear.

In 2020, a randomized controlled study (the best kind) tested various doses of Vitamin K2 on 311 older men and postmenopausal women. After one year, they found that the most effective dose to reduce bone loss in the femoral neck (hip) for postmenopausal women was 90 micrograms a day, with or without additional calcium or vitamin D3. Interestingly, no change in bone health was found in the men of this study.

For now, the best recommendation is to include food sources of vitamin K1 and K2 in our diets. And those sources differ.

Vitamin K1 is more abundant in leafy greens such as broccoli and spinach. Vitamin K2 is found in fermented foods (especially natto, fermented soybeans), cheese, egg yolk and meats (especially liver).

Why animal foods? Experts say animals have a unique ability to synthesize vitamin K2 from the vitamin K1 they obtain from grass.

Thanks for writing!

Barbara Quinn-Intermill is a registered dietitian, certified diabetes educator and the author of “Quinn-Essential Nutrition.”Email her at barbara@quinnessentialnutrition.com.

Talk to us

More in Life

The Port of Everett is adjusting its summer outdoor movie series, Sail-In Cinema, to meet public health guidelines this year. It'll be a drive-in theater. (Port of Everett)
Outdoor movies on the waterfront: Drive in or lawn seating

A six-movie lineup by the Port of Everett features action, cartoons and rom-com.

Willem Wolters, 9, is half way through reading "Space Case" by Stuart Gibbs. Wolters was given the title of the nation's highest point earner in the Accelerated Reader program on Thursday, June 17, 2021 in Bothell, Washington. Willem is a fourth grader at Cedar Wood Elementary School in Bothell. The new national record is 2,145 points. That is over 14 million words read and 377 books. (Andy Bronson / The Herald)
This Bothell boy read 380 books to set a new national record

Willem Wolters, 9, smashed the record for Accelerated Reader points, but mostly he just loves to read.

pizza with cheese. vector illustration on white background
You voted: The best pizza in Snohomish County

Even during a pandemic, people still have their favorites

Photo courtesy Laura Thompson 

Madison Thompson and her dog Stella.
Whidbey teen, golden retriever make top 8 in NY kennel show

Madison Thompson was one of the youngest competitors in her division of 80 kids.

Chris Stack and Samantha Soule film a scene of their movie, "Midday Black, Midnight Blue," on the Coupeville wharf June 14. (Photo by Karina Andrew/Whidbey News-Times)
Indie film crew: Whidbey residents are ‘generous and welcoming’

The movie makers are shooting scenes for a full-length feature at various sites around the island.

A blacked-out diamond pentagon grille and four-element LED headlights signal assertiveness in the 2022 Acura MDX. (Manufacturer photo)
Acura presents an all-new MDX luxury SUV for 2022

Bold exterior styling, better handling, a more versatile interior, and technology upgrades dominate.

When in came to wearing babies, this mom had strong skills — over a decade ago. (Jennifer Bardsley)
All strapped in: Help, I’m trapped in the baby backpack!

A newer model of the Ergobaby backback was a challenge for this aunt, even though one from 2005 was a snap.

After a tough year, don’t get your hopes up for summer vacation

If you leave your expecations at home, you’re more likely to enjoy your family trip. Here are some tips.

The heretic Giordano Bruno stands on the spot where he was burned.
Rick Steves: A perfect cafe and a romantic breeze in Rome

Perhaps the best way to describe this quintessential Roman moment is “bella.”

Most Read