Vitamin D and Uterine Fibroid Growth: What the Research Shows (Episode 504)

Full Transcript: Episode 504

Lisa Hendrickson-Jack:

Today I’m sharing a brand new episode in the FAMM Research Series. In light of last week’s episode where I shared an interesting study that looked at the impact of vitamin D on AMH levels, I thought it would be a perfect time to share my FAMM Research Series episode where we looked at the impact of vitamin D on fibroid growth. Again, vitamin D is one nutrient in a sea of nutrients that can be beneficial for fertility, but I do think that it’s interesting to highlight, at least in these cases, how vitamin D can affect these conditions. So without further ado, let’s go ahead and jump into this week’s FAMM Research Series episode about the impact of vitamin D on fibroids.

As I mentioned, the topic of today’s episode is vitamin D and fibroids. And as I mentioned, in case you missed the first episode in the FAMM Research Series, this is a new series that I’m starting this year where I will be going through some interesting research. Whenever I’m looking through different research papers, I’m putting a few aside and I’ll be going through some of the findings and what it means in terms of whether it’s fertility awareness charting or hormone health, and that will be essentially the format of the FAMM Research Series episodes.

So today we will be going through a study and the title of the study is “Effect of Oral Consumption of Vitamin D on Uterine Fibroids: A Randomized Clinical Trial.” So for those of you that are wanting to do further reading and research, if you go to the show notes page for today’s episode at fertilityfriday.com/504, you’ll find the link to the abstract so that you can have a look at the study that we’re looking at today.

So before I get into the study itself, I wanted to just do a quick review about uterine fibroids. And so you can always also go back to listen to last week’s episode, but I just wanted to give us a nice little starting point here. So uterine fibroids, also known as myomas or leiomyomas, are benign tumors of the smooth muscle cells found in the uterus. And what we know about fibroids is that estrogens and also progestogens proliferate tumor growth. So what we know is that left unchecked, fibroids tend to grow. If they’re going to grow at any point in your life, it’s going to be during your reproductive years, and they do tend to regress somewhat after menopause.

So a couple of interesting facts — or important facts — to know about fibroids. Fibroids are the most common benign tumors in women, and they’re the leading cause of hysterectomies in the United States. They’re extremely common, and so the prevalence of fibroids is anywhere from 20 to 40% among women who are of reproductive age. Fibroids are more common in African-American women, so Black women have a higher rate of fibroids. In a few different research studies, rates of fibroids in Black women by age 35 were as high as 60%, increasing to over 80% by age 50. In contrast, white women showed a rate of about 40% by age 35 and almost 70% by age 50. So it’s clear to see that fibroids are extremely common in all women, but it is of note that they do tend to show up at a higher rate in Black women specifically.

And so fibroids can be asymptomatic, where you can have them and not necessarily know you have them. But there are a number of different complaints that are associated with fibroids — a number of different symptoms. And so a lot of those symptoms we went over in last week’s episode with Dr. Hammond, but some of the most common issues and symptoms that are associated with fibroids include abnormal uterine bleeding, heavy and prolonged period bleeding. So heavy bleeding is a significant symptom of fibroids, and women with fibroids are much more likely to experience heavy bleeding depending on where they’re located. And depending on where they’re located, they may also be associated with pain. And of course, with regards to fertility, that depends again on where they’re located, how large they are, and a lot of different things.

So I just wanted to start the podcast today by going over a few basic details about fibroids. I know personally, I have experienced fibroids — I have uterine fibroids myself. Fortunately, in my case, they have never really grown at an accelerated rate or anything like that, so they’ve kind of remained fairly stable over the years. And just on an anecdotal level, I attribute that to a number of different things, whether it’s a combination of reducing xenoestrogen exposure and doing my best to support healthy cycles so that I’m not necessarily exposing myself to excess estrogen. I know in my 20s I had longer cycles, and so that was a bit more of an imbalance in terms of estrogen relative to progesterone. So that’s more on an anecdotal level — just to kind of put it out there that it really varies, the experience of women with fibroids. So some women may find, like myself, that they’re fairly small and they stay that way, and depending on where they’re located, they don’t cause problems with fertility or pregnancy, although they may contribute to heavier bleeding. I know that’s something I did experience more so in my early and mid-20s. And for other women, they may grow more rapidly and they may be in a location where they’re causing different problems, and they may require surgery. So one woman’s experience of fibroids is not necessarily the same as another.

So to get a little bit into the study itself — just to kind of go over what they did and what some of the results were. So again, the name of the study: “Effect of Oral Consumption of Vitamin D on Uterine Fibroids.” So in the study, they were specifically administering vitamin D and then paying attention to see what happened. This was a well-designed study, so it’s a placebo-controlled trial. What that means is that there were two groups — there was the study group where they were administering the vitamin D, and then there was a control group where they were administering something that was not vitamin D. So they’re essentially administering a placebo, but doing it in a way that you wouldn’t know — everyone’s taking something, so you wouldn’t know if you’re taking the actual vitamin D or not.

In these types of studies, it really does give us the best-case scenario where we can have two groups side by side to see if the topic of concern — the vitamin, the nutrient of concern here — is actually doing anything. And so it’s interesting when you kind of spend a lot of time looking at research studies, because it’s important to recognize that there’s no perfect research study necessarily. There are always things that could have been done differently, or they could have looked at different markers, or they could have administered it in a different way. It’s always helpful to remember that these studies just kind of add to our overall general information about a variety of different topics.

And so basically, when they were choosing the study participants, they chose women, obviously, with fibroids — that was part of the study that they were looking at. But they also specifically chose women that were more likely to have lower vitamin D levels. So they specifically chose women who had not been taking vitamin D supplements within, I believe it was a six-month window before the study began, and they also tested vitamin D levels. So they were looking for women whose vitamin D levels were below a certain level — essentially just looking at women who could have stood to actually increase or improve their vitamin D levels in a general sense. And the way that they did it is they administered a one-time dose of 50,000 IUs of vitamin D per week for the duration of the study. So it was a 12-week study period — about three months. And during that time, they gave these women 50,000 IUs of vitamin D per week.

Although that might sound like a really high amount, vitamin D is a fat-soluble vitamin, and different vitamins can be administered in different ways. There are some vitamins where you couldn’t do something like that — giving them a weekly dose. There are potentially a lot of different reasons why they chose to do it that way. I would imagine convenience would be one, and it would be a way to keep it quite consistent. Because if you’re monitoring all these people and trying to make sure that they’re taking a certain amount every day, it’s probably easier to administer once a week if you’re able to do it that way. And again, because vitamin D is fat-soluble, I would imagine they did it for practical reasons as well — to keep everything consistent, because it’s easier to monitor someone taking something once a week than to monitor them taking it every single day.

So anyways, that’s just my two cents on why they probably did it that way. But that gives you a sense of what was happening. There’s a group of women, they have fibroids, they’re measuring the fibroids going into the study — getting a good assessment of where they’re starting from. They’re choosing women specifically who could do with a bit more vitamin D, who are not currently taking any supplementation, and who are potentially a little bit lower in their levels. And then they’re administering the vitamin D over a 12-week period to see if it has any effect on their fibroids.

And the results of the study were that — interestingly — the vitamin D didn’t necessarily reduce the size of anyone’s fibroids in any significant way. So it wasn’t one of those studies where they took vitamin D and it shrunk fibroids and they went away or anything that dramatic. But what was interesting is that in the control group — the group that’s not getting the vitamin D — the fibroids actually grew. So without the vitamin D, the people that were getting the placebo, their fibroids grew. And in the group that was getting the vitamin D, the fibroids didn’t grow. And there was a very marginal but not statistically significant reduction in the size of fibroids in some of the women, but the fibroids generally speaking did not shrink. The main finding was that they didn’t grow. And so that’s really interesting because it shows this link — potentially — between fibroid growth and vitamin D.

So going into looking at what do we do with this information — what does the study tell us? The study, I would say, tells us that there is a correlation between vitamin D levels and fibroid growth. If you look at the research regarding fibroids and vitamin D, there’s quite a bit of it. You’ll find that there is this connection, this correlation, and women with fibroids tend to be more likely to have lower vitamin D levels compared to women that don’t have fibroids. So there are lots of different ways that these potential connections have been studied. But it is really interesting to just note that that is one of the things that this study is suggesting.

If anyone took statistics in university and can remember some of those classes — correlation does not equal causation. So we’re not saying that lack of vitamin D is causing the fibroids. We’re not really saying what is causing them, and I haven’t really seen in the research literature a very clear explanation. I don’t think that we fully know exactly what causes fibroids. I think we know what contributes to them and what contributes to their growth, and there are a lot of different factors that play a role. But I don’t think we ultimately know what causes it. So by no means am I saying that low vitamin D causes fibroids — but what we do know is that there is this correlation between vitamin D levels and fibroid growth. And generally speaking, women who have fibroids tend to have lower vitamin D levels. And in this particular study, it’s showing that vitamin D has the potential to somehow control or affect the growth.

So if you’re deficient in vitamin D, there’s this potential — based on what we saw in the study — that low vitamin D can be associated with higher rates of growth or faster growth or something like that, and higher levels of vitamin D could be associated with slowing the growth. And the question that kind of comes out of that is: is it possible that vitamin D could have an effect of shrinking fibroids? And when would that happen? Would it be a certain size? Would it have a different effect on certain types versus others? So there are of course a lot of different future questions that future research studies could potentially look at.

Again, just to point out — it’s really interesting that the study didn’t show a decrease in the size of fibroids. If you look at the full text of the study, you can see that there was, again, a marginal — not significant — decrease, but some of the women did experience a small decrease in the size of fibroids. So generally speaking, the overall result was that the vitamin D seemed to stabilize and prevent additional growth, at least over the course of the study period, in the women who were taking the vitamin D.

And so it does leave that possibility open — maybe vitamin D could shrink the size of fibroids in some cases. And there are animal studies that have shown those types of results, where certain animal studies have shown that administering a certain level of vitamin D is associated with shrinking fibroids in the animals. And another thing to keep in mind is that this study period has a limited time — there was a three-month period where they’re doing this research — so there’s all kinds of questions that come out of it.

So when I look at studies like this and reflect on them, there are a couple of things that come to mind. One is that there’s so much discussion about vitamin D in the field of fertility. If I reflect on vitamin D in the work that I’ve done with my clients and practitioners — related to the menstrual cycle, related to egg and sperm quality, related to fertility in general, related to hormone production — there are so many different connections with vitamin D and overall fertility. And put simply, the bottom line is that optimal fertility and optimal hormone health is associated with optimal vitamin D levels.

So if you are fortunate to live in a sunny climate and you do tend to go outside frequently and you are getting enough vitamin D, that’s great. But the majority of us — even if we live in warmer climates or if it’s the summertime — don’t necessarily go outside for 20 to 30 minutes every day. And so most of us need to supplement with vitamin D. It is something to consider in a general sense, and a lot of women who are not supplementing with it, especially if they’re not also in a climate where they’re getting a lot of sunshine, are deficient to some degree if they don’t have any way of supplementing.

So just to give you a sense of the role that vitamin D plays in fertility in different ways — there’s so much research on the connection between vitamin D levels and egg quality, follicular development. And that lends itself also to when we’re talking about egg quality and follicular development in the menstrual cycle — having optimal vitamin D levels is associated with stronger follicular development and stronger hormone production, optimal hormone production.

And there’s a lot of research showing this connection where, if women have low vitamin D, that’s associated — women who have ovulatory disturbances like in the case of PCOS, for example, where PCOS is characterized by long, irregular cycles because it’s taking these women a lot longer to have a successful ovulation — women with PCOS who are having these long irregular cycles are more likely to have low vitamin D levels. And that’s one of the kind of standard things: if you’re working with a practitioner who specializes in PCOS and you’re showing those kinds of symptoms, they’ll want to check your vitamin D levels. And the majority of women that have these PCOS symptoms and long, irregular cycles do find that they are lower in vitamin D.

And so we already have that connection between vitamin D and optimal follicular development, and conversations related to egg quality and having that follicle develop in an efficient manner, producing sufficient estrogen, as we work towards ovulation in the menstrual cycle. Vitamin D plays a crucial role in that process. Vitamin D deficiency is associated with hormonal imbalances, and there are even studies that show a link — a potential link — between vitamin D and period pain. So there’s a whole lot of really interesting research about the role that vitamin D plays.

But if we take it back to fibroids, what this research tells us is that women who are deficient could have a higher rate of fibroids. And so this is something — especially as a Black woman living in a cold place, I live in Canada, I’m in the Toronto area. And Toronto is, I think, one of the sunniest and warmest places in Canada — we’re one of the southernmost places. But even so, we get a lot of winter. We get a lot of months where there’s not really a whole lot of direct sunshine. And even if there is sunshine, we’re all bundled up, so it’s not like it’s getting in and doing anything for us.

So as a Black woman growing up in a cold climate, knowing also that there’s a higher rate of fibroids in Black women — and it’s quite a consistent specific statistic — it makes me wonder. Because for anyone who doesn’t know, dark-skinned individuals — not only do we all need vitamin D, but if you’re a dark-skinned individual like myself, if I was outside in a bathing suit on a hot summer day and I was laying beside one of my fairer friends — a light-skin, dark-skin scenario here — it would take me anywhere from two to three times as long in the same sunlight to make the same amount of vitamin D. And so as Black people, as dark-skinned people, we actually need more sun to make the same amount of vitamin D as our fair-skinned counterparts. So that’s just something to ponder — just information in case this is something that you didn’t know — but we need more sun just to make the same amount of vitamin D. So living in a colder climate, having less sunshine, it puts us at a greater risk of having that vitamin D deficiency.

And given the potential link there — the correlation between vitamin D levels and the size and growth of fibroids — it makes you wonder if that’s one of the reasons why we have a higher prevalence of fibroids in Black women. That’s a question that I don’t necessarily have the answer to, but it’s certainly something that I’ve wondered, and I’ll just put it out there for you to ponder also.

I think also, you know, studies like this show us that there’s so much more to a lot of these topics than we know. Looking at this very specific factor — this podcast episode is kind of looking at this research study and ruminating on it — there are so many other factors that we could look at. I’ll link a few previous podcast episodes. There was an episode that I recorded maybe a year or two ago about the potential connection between xenoestrogen chemicals and the development of endometriosis — but potentially fibroids as well — and even how being exposed to various chemicals in utero at the time of development matters. So if you’re pregnant with a baby girl and you’re exposed to xenoestrogenic, hormone-disrupting chemicals while the uterus and endometrium are developing in that baby, that in some cases may predispose that child to a higher risk of endometriosis, depending on when the child was exposed to those chemicals and at what stage of development.

And so that’s really interesting to think about — the different factors that also contribute to this problem of fibroids. Whether it’s exposure to different chemicals, estrogens — we know that there’s this hormonal aspect to fibroids where estrogen is feeding them, and they tend to grow during those reproductive years, and the growth tends to settle off and potentially regress during the menopausal years. So it’s really interesting then to consider not only the role that vitamin D is playing, but the potential other factors that we’re not even talking about today.

I think that when we look at research like this, it shows us that there’s still so much more for us to learn. We can see that there’s this correlation, but there’s so much more research that would have to be done to optimize that — to determine if there is a level of vitamin D that could potentially reduce the size of certain fibroids, or if it could reduce the size of smaller ones but not larger ones, or to what extent, or how long we would have to administer it for that to happen, or if we kept vitamin D levels optimal whether it would stabilize them. There are so many questions that we don’t necessarily have the answer to. But at the end of the day, I still think it’s always important to look at these different topics to learn as much as we can. We have to start somewhere.

And there is a really interesting statistic when it comes to research: on average, it takes anywhere from about 20 years for the latest cutting-edge research to make its way into everyday medical practice in terms of your interactions with your doctor. And so it is really interesting then to think about the discrepancy between what’s coming out in the latest research and the way that fibroids are dealt with in practice.

So I am going to stop this episode here. I think that this has been a really interesting discussion about this particular study and the potential role of vitamin D in the context of fibroid growth. I think the takeaway — if you listened to this episode today because you have fibroids, you’re concerned about fibroids — the basic takeaway is that if you have fibroids, it’s a good idea to either have your vitamin D levels checked, or if you’re not supplementing with vitamin D but you don’t necessarily live in a sunny area or you don’t get a lot of natural sun, to make a point of starting to do that. The best way to optimize your vitamin D levels is to have them tested, and then if they’re low, to supplement, and then have it retested to see how you’re responding.

There are other co-nutrients that help to support our ability to process vitamin D, including magnesium and vitamin A. Eat your liver. And also consider doing some Epsom salt baths, or find other ways to get magnesium in if you’re also taking vitamin D, to ensure that you’re really processing and optimizing the absorption and utilization of it. But the bottom line is that if you do have fibroids and you have concerns, this is one of the ways that you can at least support your body, even if there’s that potential that it could help to slow the growth of said fibroids.

So with that said, I hope you have a wonderful week — or weekend, whenever you’re tuning into the show. And of course, as always, until next time, be well and happy charting.