Dear Doctors: Does taking calcium help keep your bones strong or not? I am going through perimenopause now, and osteoporosis is on my mind. A friend says that just a calcium supplement isn't enough, you need to think about vitamin K. I haven't even heard of that. Can you please explain?

Dear Reader: Perimenopause refers to the physical changes that take place as a woman nears the end of her reproductive years. A shift in hormone production by the ovaries triggers these changes. Most notably, estrogen begins to fluctuate and gradually decline. As blood levels of estrogen and other reproductive hormones rise and fall, a range of symptoms occur. These include irregular periods, hot flashes, sleep disruption and mood changes. Because estrogen helps maintain bone density, perimenopause can also set the stage for osteoporosis. This is when the cycle of bone remodeling falls out of balance. Bone tissue is broken down more rapidly than it can be rebuilt. This results in porous, brittle and fragile bones that can be easily injured.

That brings us to the concept of supplemental calcium. The idea is that, because dietary calcium provides the raw material for bone remodeling, adding the mineral to the diet should help offset the bone loss. But as with many of our bodily processes, the reality is more complex. Calcium does not act alone. Its efficacy in bone remodeling is tied to vitamin D, zinc, magnesium, phosphate and vitamin K -- more specifically, vitamin K2.

Vitamin D boosts the absorption of calcium and phosphate from the intestine. It keeps blood levels of these minerals within the range needed to build bone. Zinc, magnesium and vitamin D each play a role in promoting bone formation. They support the balance between bone growth and resorption. Phosphorus contributes to bone mineralization. Vitamin K2 makes sure that calcium in the blood gets to the matrix of the bone, not the soft tissues of the circulatory system. It does this by activating a protein that binds calcium to the bone matrix.

As one reader wrote to us on this topic, "... taking calcium alone without zinc, magnesium and vitamin K2 is like trying to make a cake when the only ingredient you put in the bowl is flour." That means thinking about multiple dimensions when eating for skeletal health. It is possible to get each of these important building blocks in dietary supplements. However, we always urge patients to seek out real food sources.

You can find vitamin K2 in animal-based and fermented foods, including cheese, butter, egg yolks and liver. The traditional Japanese dish known as natto, made from fermented soybeans, is also a rich source of vitamin K2. Vitamin K2 is also produced in the gut microbiome. Good sources of zinc and phosphorus include red meat, poultry, seafood and shellfish, eggs and milk. You'll find vitamin D in fatty fish like salmon, eggs, liver and dairy products. And for magnesium, look to the plant-based world with leafy greens, avocados, bananas, nuts, seeds and legumes. Bottom line: Strong bones aren’t built by calcium alone.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Kansas City, MO 64106; 816-581-7500

Dear Doctors: My question is about the holidays, and it's two parts. The to-do list just seems to get longer each year, and I'm already feeling stressed-out. Also, I just turned 44 and I don't recover from the eating and drinking like I used to. Do you have any realistic ideas other than “just say no”?

Dear Reader: The holidays can be too much of a good thing for many of us. Health surveys find that in the weeks between Thanksgiving and the start of the new year, people sleep less, eat and drink much more, and as the season plays out, feel increasingly bad about all of it. Add in the increasing pressure to put together the perfect holiday -- think of it as the Instagram effect -- and a time of year when we seek warmth and community can feel more like an endurance test.

Rather than completely opting out of the holidays, try a gentle edit. Choose a few moments that bring genuine pleasure -- maybe a twilight walk, trying a new cookie recipe or watching a Hallmark movie with your phone turned off. Schedule these in, one or two per week, just as you would any social obligation. Small pauses can be an antidote to the relentless pace of the season and restore your sense of enjoyment. They can also give you a second wind to face your holiday obligations and the breathing room to enjoy them.

Eating and drinking are a big part of this time of year, and it's important to have a plan. Last week, we looked at food strategies. Now let’s focus on drinking. In a season of open bars and “just one more” rounds, be strategic. Create a template for how you will navigate the alcohol at any gathering. The buzzy enjoyment of a cocktail or glass of wine comes with a physical price. It disrupts sleep, your immune system takes a hit, your liver works overtime and blood sugar takes big swings. This can leave you feeling tired and irritable and, as research has shown, even more vulnerable to junk food cravings the next day.

Set a drinking limit before each event, including the option to not drink at all. When you do plan to indulge, have something in your stomach first. Start with at least a snack before the event. Then double down by making the protein and high-fiber foods your first stop. They will help stabilize blood sugar, keep you feeling full and slow the effects of alcohol. You can also start with something nonalcoholic to quench thirst. When you do switch to adult beverages, track not just how many, but also portion size. If you’re having more than one drink, you can alternate with something nonalcoholic.

Pacing yourself with food, drink and your commitments is practicing preventive medicine in real time. You're setting the stage for better sleep, steadier mood and the energy to enjoy the things you love about this season.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers! Welcome to a bonus letters column. This time, we're focusing on two questions, one important and one just plain interesting, so let's dive in.

-- A reader from San Diego is worried about the upcoming cold and flu season. He echoes the concerns of many people making a post-pandemic return to the office. “During the two years we were working from home, I never got sick once,” he wrote. “We were back for just a month when a co-worker came in with the flu and spread it to a bunch of us. Can you please talk about why you should stay home when you're sick?”

Just a moment of contact with the flu virus can lead to a full-blown infection. The droplets released in a cough or sneeze from an infected person can hang in the air for a surprisingly long time. Large droplets may last a minute or two, while smaller ones -- still carrying the virus -- can stay suspended for hours. You can either breathe these in, or they may settle on commonly touched surfaces such as desks, keyboards, doorknobs or coffeepots. This is especially true in poorly ventilated indoor spaces.

A case of the flu strains the heart and lungs, worsens asthma and, for older adults or immunocompromised people, can escalate to pneumonia. Even healthy young adults can develop inflammation and lingering fatigue. All of this makes the first rule of flu etiquette simple: Stay home. When you do return to your routine, take steps to prevent spreading any lingering virus particles -- wear a mask, wash your hands often, dispose of used tissues carefully and hold off on hugs or kisses.

-- We also heard from a reader in New Hampshire asking about the phenomenon known as brain freeze. “My 5-year-old son took a big bite of his Popsicle, grabbed his head and burst out crying,” she wrote. “His first brain freeze. If the cold food is in your mouth, why does it make your forehead ache?”

Brain freeze, also known as an ice cream headache, is a fascinating phenomenon. Swift and surprisingly painful, it's triggered when something very cold rapidly chills the roof of your mouth. Ice cream is the classic culprit, but Popsicles, slushies, smoothies, frozen fruit or even a gulp of cold soda can bring the pain.

The reason lies in simple physics. The sudden chill causes blood vessels in the palate to constrict and then quickly dilate. This effect activates pain receptors that communicate through the trigeminal nerve, the conduit for facial pain. When the “ouch!” message reaches the brain, it’s misread as coming from the forehead or behind the eyes. Even though the source is in the palate, the brain tells a story about forehead pain. Happily, brain freeze is short-lived. You can speed relief by warming the roof of your mouth with your tongue, or just approach that chilly treat with a bit more caution.

Thank you to everyone who took the time to write. We love hearing from you. We will be back soon with more of your thoughts and questions in our regular monthly letters column.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)