Maggie McKay (Host): Welcome to Wellness in Reach: A Mount Carmel Podcast. I'm your host, Maggie McKay. Joining us today is physician, Dr. Mark Herbert, to discuss boosting immunity. Thank you so much for being here today.

Mark Herbert, MD: It is my pleasure.

Host: Let's start with how does reduced sun exposure in winter affect vitamin D levels and immune responsiveness? Because you hear so much about that whole thing about in winter people get depressed, et cetera.

Mark Herbert, MD: Well, your body can create its own vitamin D with sunshine, but the sunshine has to be relatively direct. The sun has to be 45 degrees above the horizon, which in Europe or in North America only occurs about six months out of the year. So, you don't get any vitamin D in the wintertime for six months. Your only vitamin D exposure would occur during the summer. And it only takes between seven and 30 minutes of exposure to the sun to adequately boost your vitamin D levels for the day.

Host: Wow. That's good to know. I didn't know it was such a little amount of time. Are there specific micronutrients like zinc, selenium, or vitamin C that have proven benefits for winter immunity?

Mark Herbert, MD: Well, many of the micronutrients you mentioned, vitamin D, vitamin C, and zinc especially have benefits for many of the different components of the immune system that can help prevent infection.

Host: And what about sometimes I've heard if you take too much zinc, it's not good for you. Is that true?

Mark Herbert, MD: Well, I think it's fair to say that if you take too much of any particular vitamin or micronutrient, it can cause ill effects. So, you need to be cautious and take just reasonable recommended daily allowance or a smaller increase that your physician or provider may recommend.

Host: And what role does regular physical activity play in maintaining immune resilience during cold weather? What type of exercise is most beneficial?

Mark Herbert, MD: Moderate aerobic exercise is the most beneficial to stimulate your immune system. Many of the cells that participate in the immune system will lie at rest if you are not active. And simply by being active and increasing the circulation in your body will move the immune cells throughout all parts of the body and help strengthen your immune system. There are also some hormones that your body produces with physical activity that will help stimulate the activity of these cells of the immune system.

Host: Is it better to work outside rather than indoors, or does it matter?

Mark Herbert, MD: Well, the type of activity, whether it's indoors or outdoors, it doesn't matter, but moderate activity has been shown to be helpful in strengthening the immune system. And by moderate, they usually mean about a hundred minutes of aerobic activity per week, so, say, 20 minutes each weekday. But if you have more exertion, if you exercise more than one hour a day, it can actually make the immune system worse.

Host: What?

Mark Herbert, MD: Yeah.

Host: How?

Mark Herbert, MD: The thing that happens sometimes is that if you exercise more than 60 minutes a day, it can break down some of the other nutrients and actually cause stress in the body.

Host: Wow. That is really good to know. Let's talk about sleep, Dr. Herbert. Can sleep quality significantly alter immune performance in winter? And what are the optimal sleep guidelines for immune support?

Mark Herbert, MD: So, having a good sleep pattern will definitely improve your immune system. It has many health benefits. Good sleep helps with blood pressure, coronary artery disease, neurologic conditions, and even stroke and dementia. So, the proper amount of sleep is generally described as six to seven hours a day or more. So if you're someone who habitually has four to five hours of sleep per night, that is not going to be healthy. So if you can achieve six to seven hours of sleep each evening, that will strengthen your immune system primarily by decreasing stress within your body. And it's interesting because the people who research these ideas say that napping to catch up actually does not help. So, It needs to be a scheduled routine, one phase period of sleep in order for it to help your immune system.

Host: I am learning so much today already. I love this conversation. What are the most common misconceptions patients have about "boosting" immunity, and how can primary care physicians address them?

Mark Herbert, MD: Well, I think that a common misconception is that there's a pill that you can take that's available over-the-counter or that your provider can prescribe that will cure all of these illnesses with the immune system. And the fact of the matter is that there's no one medicine, there's no one micronutrient, there's no combination pill that's going to fix this.

We've talked about several different important components of general health that all contribute. So, I think the most common misconception would be that there's a single thing that we can do that will help strengthen our immune system, when in fact we would need to alter several of the facets of our lifestyle in order to have the strongest immune system.

Host: And how can stress management interventions help maintain immune balance during the winter period?

Mark Herbert, MD: That's a great question about stress. Stress will initially strengthen your immune system. But then if you have prolonged stress, it actually weakens the immune system. One of the most important stress hormones is cortisol, and cortisol is a steroid hormone that has many different impacts on your body. And for a very short term stress, cortisol will assist the immune system in its work. But if there is prolonged stress, if there is daily stress, if you don't sleep well every night, if you are frequently exposed to noise or pollution, that type of everyday stress actually increases the cortisol production over a longer period of time and weakens the immune system. This has been shown really well in studies of animals, but it's not a great idea to stress humans consistently day after day, simply for the purpose of a health research study.

Host: Dr. Herbert, in the media, it seems like we're hearing a lot about this new version of a super flu, I guess you would call it, or an epidemic flu-wise. What can we do to stay healthy?

Mark Herbert, MD: Well, the influenza virus seems to change a little bit every year. And we try to predict what flu is coming because one of the most important things that we can do to help prevent flu is to take an influenza vaccine or a flu shot. This comes out every year and I always recommend that my patients have the flu shot every year. And one of the most important reasons is because the flu virus does change a little bit every year. And we are trying to anticipate what virus will be present. But sometimes the viruses are working faster than we are.

So this year, as the flu season is starting, it seems to be a strain that's a little different than it has been in the past. And whenever that happens, the flu episodes can be more severe or more frequent. So, we're seeing a big increase in the number of cases of flu. And in addition to the other things that we talk about with our nutrition and our sleep, it's important to have immunizations regularly, like the flu shot, and your primary care provider can advise you as to all the other vaccines that can be available and helpful for your particular situation.

Host: When is the latest, like month-wise, that you can get a flu shot for it to be effective? Because somebody just asked me the other day, "Is it too late to get a flu shot?" And I said, "I don't think so."

Mark Herbert, MD: The normal peak of flu season can occur anywhere between February and April. Most of the flu shots come out now in August or September. And so, most of the public health recommendations say start taking the flu shot as soon as it is available. And so, that's the general recommendation.

And the way the immune system works, a flu shot probably takes a couple of weeks before it's fully powerful and active. So, you could get it through January or February, or if the flu peak hasn't hit, March would even be reasonable. So, the flu shot can be used throughout several months of the year.

Host: And you touched a little bit about immunization and vaccines. How do you advise your patients when they ask you about that?

Mark Herbert, MD: Well, I advise my patients, and I see all kinds of patients from the very healthy to people who have difficulties with their immune system because of medical conditions. And I advise all of them as to the proper vaccines for their particular situation. I am a big proponent of receiving the flu shot and the COVID shot every year that they are available, and the other shots are more tailored to specific age groups or medical conditions.

Host: Well, thank you so much. This has been really enlightening and informative. And we appreciate your time.

Mark Herbert, MD: Yep. You're very welcome. It's been a pleasure.

Host: Again, that's Dr. Mark Herbert. Want to strengthen your immune system this season? Take charge of your health today. Schedule an appointment with a primary care provider at Mount Carmel Health System by visiting mountcarmelhealth.com/services/primarycare. I'm Maggie McKay. Thank you for listening to Wellness in Reach: A Mount Carmel Podcast.