HSOS #17: You’re Not Just Tired: A Vitamin D Chat for Midlife Women

Vitamin D takes center stage in this conversation about mood, sleep, joint pain, immunity, and bone health for women over 40. Kim breaks down what the 25-Hydroxyvitamin D lab actually measures, how to interpret deficiency versus optimal ranges, and why midlife bodies struggle more with production and absorption. She also walks through symptoms of low Vitamin D, food and sun sources, who needs more support, and how to use a Vitamin D3 plus K2 supplement wisely and safely.

Let’s talk.

Welcome to Her Season of Strength—where women over 40 reclaim their bodies, their energy, and their voices, without apologies. I'm Kim Duffy—registered dietitian, personal trainer, mom, and your biggest hype woman when it comes to aging like you mean it.

This show isn’t about chasing skinny or counting wrinkles. It’s about building real strength—physical, emotional, and hormonal. Each week, I’ll share straight-talking nutrition tips, sustainable fitness strategies, and conversations that help you feel powerful in your skin once again.

Menopause is not an ending, it is only the beginning. This is your season of strength.

Episode Topics Covered

• Depressed mood, poor sleep, joint aches, more frequent colds, and how they can be related to Vitamin D deficiency in peri and post menopause
• Life update: visiting Alabama, soaking up more sun than in Minnesota, and the chaos of current air travel
• Why baseline Vitamin D labs matter, what 25-Hydroxyvitamin D measures, and deficiency, insufficient, and optimal ranges
• How aging and hormonal shifts decrease Vitamin D production and absorption, even if you “go outside all the time”
• The many roles of Vitamin D: hormone-like actions on bones, muscles, mood, immunity, inflammation, and blood sugar balance
• Symptoms of deficiency: heavy fatigue, muscle aches and weakness, joint stiffness, seasonal depression, frequent illness, sleep issues, and bone tenderness
• Food and sun sources of Vitamin D: fatty fish, egg yolks, fortified foods, UV-exposed mushrooms, and why diet and winter sunlight usually aren’t enough
• Current research on Vitamin D’s impact on immune health, depression, bone density, muscle strength, metabolic health, and autoimmune risk
• Who needs higher Vitamin D support: women over 40, those in northern states, darker skin tones, indoor workers, autoimmune conditions, digestive issues, and seasonal depression
• Practical supplementation tips: choosing Vitamin D3, pairing it with Vitamin K2, typical summer and winter dosing, working with your provider on higher doses, taking it with fat, rechecking labs, and focusing on consistency

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Transcript

[00:00:00] Hi there, and welcome to her season of Strength, where women over 40 reclaim their bodies, their energy, and their voices, without apologies. I'm Kim Duffy, registered dietician, personal trainer, mom, and your biggest hype woman. When it comes to aging like you mean it, this show isn't about chasing skinny or counting wrinkles.

[00:00:20] It's about building real strength, physical, emotional, and hormonal. Each week, I'll share straight talking, nutrition tips, sustainable fitness strategies. And conversations that help you feel powerful in your skin. Once again, menopause isn't an ending. It's only the beginning. This is your season of strength.

[00:00:39] Welcome back to her season of strength. I'm so happy you're here, and thank you for just taking a couple minutes to listen in today. So today I wanna talk about a vitamin, actually, that is the most common one that I recommend to my clients. So if you are noticing [00:01:00] more of a depressed mood. Poor sleep, increased joint aches and stiffness.

[00:01:05] Maybe you're picking up colds and sicknesses much easier than you used to. Might not only be related to hormonal changes during peri and post menopause, it actually could be related to a vitamin D deficiency. Yes, you're right. We're talking about vitamin D today, and it's vitamin D is one of those nutrients that everyone thinks they're getting enough of because hey, I go outside sometimes.

[00:01:29] And sometimes I feel the sun. Sometimes it's warm, but midlife has some jokes and one of them is that our bodies don't make vitamin D nearly as well as they used to. And because that little powerhouse acts more like a hormone in our body than a vitamin, low levels can show up in so many ways from mood to muscles to immunity.

[00:01:51] So I wanna talk about what your levels actually mean. What's normal versus. Optimal and why this nutrient deserves a little more [00:02:00] airtime in your life. So first of all, I'll just tell you a little life update. I just got back on Sunday from my visit down to Alabama, so I got a little more sun than I normally would living up here in Minnesota in.

[00:02:15] Cold. And it, yes, the temperature is starting to drop and we don't get a ton of sunshine up here. So this is such a perfect topic as the weather is changing and we are needing higher levels of vitamin D supplementation. But I had an amazing time visiting my and babysitting, and boy, you just cannot beat it.

[00:02:38] And, then I got to spend a little time in the airport, which, oh my goodness, if you have to fly somewhere right now, it is a little bit of a scary time. You do not know how, how long your flight might be delayed or even if that flight was canceled. So I sure hope this gets better because it is not fun trying to fly places, but I'm [00:03:00] fortunate that I got home safely on Sunday night and.

[00:03:04] Jumped right back into work on Monday. So let's talk a little about vitamin D. First of all, why the heck does it matter? Why? How do lab values actually help you? So the lab that we get checked, and I always recommend my clients to have understand what their baseline vitamin D levels are because you know what, some people are gonna be just be naturally more deficient than others.

[00:03:29] And so it's always important to know a baseline. Vitamin D level, because that's gonna tell you like, do you need to supplement? And what levels do you need to be supplementing at? Because this is the only way to truly for us to know what our vitamin D stores look like in our body. It's a blood test.

[00:03:48] It's called 25 Hydroxy vitamin D. Okay. That's what the actual blood test is called. It's a blood test most providers can order, and it gives just real actionable data [00:04:00] instead of guessing, oh, I'm sure my vitamin D is just fine. So what this test is measuring, it's measuring the circulating form of vitamin D, which is essential for bone health, for mood, for muscle function, for immune support, and for hormonal.

[00:04:15] Support and balance, right? It's that best snapshot of your true vitamin D status. So what ranges are we looking for? Deficiency range is gonna be less than 20 nanograms per milliliter, and frequently when we're in that deficient range, it's strongly linked with bone loss, with higher fracture risk, with mood issues, with weakened immune system fatigue and metabolic issues, so this could be a very easy.

[00:04:44] Fix. To some of those issues or, and I'm not saying you're gonna take one little, vitamin D supplement and everything is gonna just be wonderful, right? It is just a natural it's a vitamin. It's just, it's going to be a very easy [00:05:00] way to see benefit. Okay, so an insufficient range is 20 to 29 nanograms per milliliter.

[00:05:08] And in that range you might not be feeling sick, but you're not thriving, right? Many women over 40 live here, in this little 20 to 29 range, and they might feel just a little bit off, but they don't, really understand why optimal range is. Usually between 30 to 50 nanograms per milliliter, ideally between 40 and 60.

[00:05:30] And this is where inflammation is better regulated. Our bones are staying stronger, our mood feels more stable, and our hormones are gonna function more smoothly. I want you to understand that as we age, we can confer less vitamin D through our skin. So you might be like, oh, I go outside all the time.

[00:05:48] We can't actually absorb that and use it in the same way we did when we were younger. Not to mention as we get older, we spend a little more time indoors and our hormones, we know they're shifting [00:06:00] right? As we hit perimenopause and. And post menopause. And that is gonna also influence our absorption of that, that lovely vitamin.

[00:06:08] And it's also gonna affect metabolism so once you know your number, the next question is, what exactly is vitamin D doing in your body that makes it. So important, right? So it technically works as a hormone. It interacts with receptors in almost every single tissue, which influences hundreds of biological processes.

[00:06:28] So it's way more than just bones, right? It helps us to regulate calcium and keep our bones strong. So without vitamin D, only about 10 to 15% of our dietary calcium is absorbed. So with vitamin D we see more like 30 to 40% is absorbed, right? So if you are someone who has osteoporosis or osteopenia and you're taking all this vi this calcium, but not without adequate vitamin D, it might be be spending this money on this supplement [00:07:00] and you're just basically excreting it.

[00:07:02] We're not getting the benefit as much of the benefit of it. Vitamin D also supports our muscle strength and our physical performance. So you know, we can find that lower levels are linked to weaker grip strength, slower walking speed, poor recovery, and higher fall risk. Isn't that interesting? And all of these things we will see with age.

[00:07:23] As well. Vitamin DII can, during the winter months, it is a powerful immune system regulator. It's important all year round, in the winter months when we're starting to see more colds and flu and COVID and all the above, we wanna make sure our immune systems are strong and Vitamin D can help those immune cells to respond more appropriately.

[00:07:43] Like boosting when needed, calming when overreacting. It's, which is really important for autoimmune type tendencies. Vitamin D also helps to regulate infl inflammation and we understand, chronic inflammation. It's a major driver of midlife symptoms, right? Not [00:08:00] to mention chronic disease.

[00:08:01] Vitamin D helps to keep that in check. Vitamin D also helps to support mood and emotional wellbeing. Okay, so we have vitamin D receptors in the brain, which is tied to mood and memory. Low levels, we're gonna, it's gonna correlate more with seasonal depression, irritability, brain fog, and low motivation.

[00:08:21] All of these things we can find that we struggle more with once we hit post menopause and even through perimenopause. Then lastly, vitamin D helps with blood sugar balance. It improves our insulin sensitivity and it can reduce our risk of metabolic syndrome in midlife women. And what metabolic syndrome is gonna be more of that inclination to have higher blood sugar levels, higher hemoglobin A1C.

[00:08:47] We can see higher lipid levels like cholesterol and LDL. Those things that can tend to increase our risk of chronic disease as, as well as cardiovascular disease. And because [00:09:00] vitamin D does so much, it's not surprising that when it drops too low, your body starts sending you little signals. But you know what, we're not always realizing what, why we're getting those signals or what's causing it.

[00:09:13] So here's some symptoms of Vitamin D deficiency. One of 'em is heavy fatigue. The kind that makes, movement and motivation feel 10 times harder. Okay, next. Muscle aches, weakness, or slower recovery. It's essential for muscle contraction and repair. And if you're putting that time in with exercise and strength training, like I'm always talking about, we wanna make sure that we're doing everything we can to give our body what it needs to repair those muscles after we are breaking 'em down in that strength training.

[00:09:44] 'cause that's how we build that strength. That's how we build, muscle, which is gonna build metabolism as well. Okay. Next symptom is joint stiffness or pain. Low levels can actually contribute to inflammation, which we talked about in our connective [00:10:00] tissues. Next is a low mood or signs of seasonal depression.

[00:10:05] So if you find that like during the winter months it starts getting colder, that you find that, you know your mood decreases. You might need to evaluate, how much vitamin D are you taking? And I want to make sure to say that with vitamin D supplementation and we're, I'm gonna talk about that here as we go on.

[00:10:24] It's not about the more, the better. Okay. Because it is a fat soluble vitamin. Meaning that it our body doesn't get rid of excess as easy as it would a water soluble vitamin like vitamin B or all I should say, all the vitamin B's, right? But. You do have to take a significant amount in order for it to be toxic levels, but it's definitely something you wanna talk to your doctor about.

[00:10:49] But we'll talk about supplementation and kind of amounts here in just a little bit. If you find that you're getting frequent colds or you're recovering slowly from illness, that might be a sign that your immune system's [00:11:00] struggling, and we might need a little more vitamin D if you're finding that you're struggling with sleep.

[00:11:05] Vitamin D plays in a role in melatonin production, which regulates our sleep cycles. And then lastly, bone tenderness. And this is gonna be in more severe cases, more of vitamin D deficiencies. But prolonged deficiency can actually soften our bones. Another word for that is osteomalacia.

[00:11:24] So if you're nodding along thinking, oh shoot, this sounds like me. Let's talk about where vitamin D actually comes from. And spoiler, your fridge is not going to save you. Okay. Food sources of vitamin D are gonna be in Lowe's, fatty fish like salmon, sardines, mackerel, the highest natural source. Three to four ounces of these fish can give you about 300 to 600 I of vitamin D.

[00:11:52] Okay. And egg yolks. We're gonna get about 40 to 50 IUs per yolk. It's not huge, but it's helpful. [00:12:00] Then in fortified foods, so like milk alternatives, yogurt, cereals, and orange juice often have vitamin D added in after the fact. So it's fortified with it. Another areas are UV or ultraviolet exposed mushrooms, the plant-based option, for vitamin D, but the ev, the amount of vitamin D can vary widely in that.

[00:12:22] So food alone frequently is not enough. Most people get less than 300 IUs daily from food, which is far below the, two to 4,000 IUs that many women need. Okay. Now let's talk a little bit about sun exposure. 'cause we know, oh, we can get some vitamin D from the sunlight, right? The sunlight is the main natural source.

[00:12:45] The skin makes vitamin D when it's exposed to ultraviolet rays, right? But the problem is winter. Between, October to March, especially living up here, I'm in, in Minnesota, right? So in these northern [00:13:00] states and even the Midwest, we cannot produce during those winter months meaningful vitamin D from sunlight, right?

[00:13:08] So think you know, Minnesota, Wisconsin, Michigan, new England, Canada, your skin is basically on airplane mode for making vitamin D during those winter months. Next darker skin tones actually require more sun exposure. 'cause melanin naturally blocks UVB reducing your vitamin D synthesis. And then if you have an indoor lifestyle or you have office jobs where you're, inside all day long, even in sunny states, many women don't get meaningful sun exposure, when they're in these kind of jobs.

[00:13:43] And most of us are right. Sunscreen blocks up to 90% of vitamin D production, so it's great for the skin so important for, preventing skin type cancers, but it can complicate our absorption of vitamin D. And then women over 40, we're [00:14:00] naturally at higher risk regardless because we are less able to make it in the skin from sunlight exposure.

[00:14:07] Because those hormonal shifts put us at a disadvantage. So if food isn't enough and the sun only helps half the year, what does the research say about the impact of vitamin D on our health? So let's talk about some key areas, vitamin D and immune function. Research shows that vitamin D deficiency increases our susceptibility to infections.

[00:14:28] So supplementation can reduce the risk of respiratory infections, especially in people who are deficient. In the next area of research, vitamin D and depression, many studies link low vitamin D levels with higher rates of depression, especially in women and especially women during winter months. So supplementation and deficient individuals shows modest improvements in mood.

[00:14:52] Next, vitamin D and bone density women with higher vitamin D levels have better bone mineral density and fewer fractures. [00:15:00] Deficiency can accelerate our bone loss after menopause. Vitamin D and muscle strength trials show low levels of vitamin D contribute to muscle weakness, falls, and reduced power output, especially in women over 40, vitamin D and metabolic health research suggests it plays a role in insulin sensitivity, weight management, and decreasing inflammation.

[00:15:27] Vitamin D and autoimmune disease. Lower levels are associated with higher rates of autoimmune condition like Hashimoto's thyroiditis or hypothyroid multiple sclerosis and rheumatoid arthritis. The takeaway from research is just the more we study vitamin D, the more we see that it acts like a ho, a global health regulator.

[00:15:49] It's not just a bone vitamin. So now that we let you know the science nerd moment have its time, let's talk about who actually needs more Vitamin D than the average person. [00:16:00] So women over 40, yes, us. US ladies. We have lower natural synthesis and hormonal shifts. Increase our need. People living in northern states just because the sun angle is simply too low for half of the year.

[00:16:16] Individuals with darker skin, they have naturally lower synthesis due to a higher melanin. People who work indoors, office work, indoor lighting, does nothing for vitamin D. Women with autoimmune conditions, they often have lower baseline levels and higher needs. People with digested digestive or absorption issues.

[00:16:39] So if you have celiac or Crohn's disease, ulcerative colitis, inflammatory bowel disease, or if you've had a gastric bypass, all these things are gonna decrease your absorption of vitamin D. So you are probably gonna need higher levels of supplementation. And then anyone who struggles with fatigue or seasonal depression, low levels are extremely common in this group.[00:17:00] 

[00:17:01] So now let's move on and chat a little bit about supplementation, what to take and why. Vitamin D three is the perfor preferred form because it raises blood levels more effectively than vitamin D two. Typical daily MA maintenance. I usually recommend 2000 I use in the summertime and 4,000 I use in the wintertime, but.

[00:17:23] I always recommend you have your levels checked because you might need higher levels of supplementation. You might need up to, 50,000 IUs a week. So that's definitely something I would never recommend. Me personally, I would never recommend to a client to take higher than that 4,000 use in the winter time because I feel that's something that we want, you would want to be working with your doctor if you're taking higher levels and having those labs rechecked.

[00:17:52] Just to make sure that you aren't getting too high of levels of vitamin D. Okay. Higher dosing, it's, [00:18:00] it would be more for people who have levels less than 20 nanograms per milliliter. Okay. And, like I said, done under provider supervision. And now I want to talk about a supplement that it is super important for.

[00:18:16] Menopausal women to add with vitamin D three and that is vitamin K two. Okay. It actually helps us to shuttle calcium into the bones where it belongs. It's gonna prevent calcium buildup in those arteries. It's gonna improve bone density and overall absorption. Okay. Vitamin D three plus K two is a powerhouse combo.

[00:18:40] It helps, give us stronger bone sport. It helps with better absorption, more balanced calcium metabolism, and really safer long-term supplementation. Okay, so you know, if you're looking for a vitamin D three supplement, look for one that has K two. My favorite is [00:19:00] I have a liquid vitamin D three plus K two supplement.

[00:19:03] That I can just take 14 drops a week to get 2000 I use, right? Super easy. And the big thing with vitamin D three that I tell all my clients is make sure when you take it. Take it with a bit of a fatty snack or meal that's gonna help to help you to absorb it even better because it's a fat soluble vitamin, so it needs a little bit of fat with it.

[00:19:29] Then, especially if you are supplementing more than that 4,000 IUs in the wintertime, you're gonna wanna recheck those labs every three to six months. But if you're doing, that standard range of two to 4,000 IUs, maybe have it checked once a year until you're more stable and that it's normalized because consistency matters more than the dose.

[00:19:47] So vitamin D builds up slowly. So daily or weekly intake is gonna beat those sporadic high doses. Taking 5,000 here and there because [00:20:00] vitamin D, it affects nearly every system in our body. Mood, bones, immunity, muscle strength, inflammation, sleep, metabolism. And most women over 40 are not getting enough.

[00:20:10] First of all, know your lab value. Support yourself with sun and food, and supplement with D three plus K two can really be, life changing. So that is your vitamin D deep dive. If you've learned something new today, please share this episode with another woman who needs it. Ratings and reviews help this show grow and reach more women stepping into their season of strength.

[00:20:34] So I appreciate. I appreciate you jumping in and giving me five stars. That would be fantastic. Because this is all about progress over perfection. We're in this for the long haul, and this is your season of strength. Have a fantastic day.