Dear Dr. Roach: I was diagnosed with advanced osteoporosis years ago. I started taking vitamin K2 because I read that it helps move calcium from the blood into the bones. Fast forward to last year, my doctor had me do a scan to check for arterial plaque because my total cholesterol went over 300 mmol/L. I had declined her recommendation to take prescription medications for it. My calcium score from the scan came back at 0%.

My question is, could the vitamin K2 be responsible for my clear arteries, and if so, why don’t doctors recommend K2 first rather than jumping to statin scripts?

— D.D.

Answer: Vitamin K2 is widely used in Japan, but no study in the United States has found benefit. So, I don’t recommend K2.

Vitamin K2 is necessary for the production of a protein called osteocalcin that binds to hydroxyapatite, which is the mineral component of bone. Our intestinal bacteria make vitamin K2 in our gut and uses vitamin K1, which is found in dark leafy greens, as a precursor. I suspect vitamin K2 may be useful for bone health in people whose microbiome do not make K2 well or people whose diets are low in K1.

This doesn’t apply to most North Americans. K2 may have other roles in calcium metabolism that aren’t as well-understood. In particular, K2 may have an activating effect of matrix Gla protein. This may reduce the deposition of calcium into the artery walls, which is what is measured during a calcium score test. So, there is a reasonable theory as to why K2 might reduce the risk of calcification of the blood vessels, which is highly (but not perfectly) associated with blockages in the arteries to the heart.

The data on statin drugs, by contrast, are well-established, with many studies showing that statin drugs reduce the risk of heart attack and death. We have abundant data that shows how much risk can be reduced with a statin. We don’t know yet if K2 can lead to better outcomes.

Some people and physicians may choose to take or recommend K2 in advance of strong data, but I am a very conservative physician who waits for good data before making a recommendation, even though it is probably safe.

Dear Dr. Roach: My neighborhood has many free-ranging peacocks and has had them for many years. Of course, there are many dogs and cats, and a few years ago, we had a plague of rats. The rats seem to have lessened now with all the cats.

What is our risk for bird flu? How should we take care not to contract it for ourselves and our pets?

— D.F.

Answer: Unfortunately, peafowl (peacocks and peahens) can be infected with avian flu. Just a few days before writing, a backyard flock of ducks, chickens and peafowl needed to be euthanized by officials in Connecticut to keep the highly infectious illness from spreading.

If possible, keep the peacocks away from any wild migrating birds (especially waterfowl) who might spread the influenza to your flock of peafowl. Stay away from any bird that seems to be ill. Transmission to humans is unlikely but possible.

Many states, including yours, have a state bird hotline to call if you see sick or dead birds.

Contact Dr. Roach at ToYourGoodHealth@med.cornell.edu.