What Is The Role Of Vitamin A In Sperm Production (Episode 594)

Full Transcript: Episode 594

Lisa Hendrickson-Jack:

This is the Fertility Friday podcast, episode number 594.

Today I’m sharing a brand new episode in our FAM research series, and I’m going to be tackling the role of vitamin A in sperm production. I think this topic is really important and really interesting because the research is astounding, yet it’s not something that I hear a lot of people talking about — the importance of vitamin A, especially as it relates to sperm production and fertility in general. So while we’ll be focusing today on male reproduction, particularly sperm production and testosterone and the role of vitamin A in that process, know that vitamin A plays an equally significant role in female reproduction. And there’s a lot of research through animal studies that sheds light on why this nutrient is so important. So today we’ll be going through a paper. It’s called The Role of Retinoic Acid in Spermatogenesis and Its Application in Male Reproduction.

So this study is a narrative review. It’s not a clinical trial. It pulls together findings from animal models, cell studies, human data, and it really maps out the role of retinoic acid, which is the active form of vitamin A, in spermatogenesis. So while this study goes into a lot of detail, it’s really high level. If you were to pull it and try to read it, there’s a lot of terms, let’s just say, because it goes into a lot of really specific detail. What we’ll be doing today is just kind of getting a feel for how essential this nutrient is in this process, how it works, and we’ll also be talking about the role of nutrition and the potential for vitamin A to really support and improve sperm production in men.

So a little bit of background information. I’ve spoken about vitamin A and written about it in both The Fifth Vital Sign as well as Real Food for Fertility. We shared some research and some studies, and it’s so interesting because there are animal studies out there that show that essentially vitamin A is kind of like an on or off switch for sperm production as well as testosterone production in men. So there are animal studies where if they provide the animals with a vitamin A deficient diet, the male animals will potentially stop making testosterone or stop making sperm altogether. So it’s really significant and astounding that a nutrient that plays such a crucial role — to the point that we could literally say that it could be the on and off switch for sperm production — it’s astounding that we don’t talk about it more.

And to go into that further, there are also a variety of studies that are looking at retinoic acid and the different enzymes that activate it, and looking at depriving the male body of vitamin A in one shape or form as a contraceptive method. So they know that it has such a significant implication in sperm production that they’ve looked at creative ways to potentially shut that down as an actual contraceptive method for men. So I feel like that gives a really interesting introduction into this topic and also shows us why it’s so important and fascinating.

So basically this paper breaks it down. It gives us a really good overview of the role of vitamin A in this process of spermatogenesis. And so I’ll walk you through basically what they’re saying in layman’s terms so that you can kind of get the picture. So one of the key things to note about vitamin A is that we do have to get it through food. And when we talk about vitamin A, we hear that term a lot. And sometimes when we say vitamin A, you’ll think of carrots, you’ll think of beta-carotene. But what we’re talking about is retinol — the preformed vitamin A that is only found in animal foods. So just keep that in mind when we’re talking through it. The beta-carotene that we associate with carrots and other vegetables is not what we’re talking about. And while we do get some vitamin A from eggs and from butter, the most significant source truly is when we’re eating liver in particular.

So with that said, vitamin A, as I’ve already mentioned, it comes from food. It’s not something our body can make. So in order for our body to be able to utilize it, break it down and use it, especially in this process of spermatogenesis, we actually do need to eat it. And as I mentioned, the richest food sources are liver and potentially cod liver oil, as well as some of the fatty animal foods.

So once we eat the foods that contain vitamin A, our liver acts like essentially a storage warehouse. That is where the vitamin A is stored, and once our body needs it, then it’s transported from our liver. So in order for men to make sperm, once the liver is transporting the vitamin A to the testicles, the retinol in its original form has to be converted into retinoic acid. And this process involves special enzymes that actually break it down and make it into its usable form. So retinoic acid — the usable form — is essentially the on switch that actually makes sperm production possible. As retinoic acid moves into the nucleus, which is the command center of the cell, that is what is signaling to start to make sperm. And without retinoic acid, the sperm cells are not able to proceed and differentiate and go through this process.

Interestingly, with retinoic acid, it doesn’t just flow constantly. It comes in little bursts and waves, and these pulses keep sperm production on a schedule. And this is one of the reasons why men are always making new sperm every single day. This is something I’ve talked about a lot — the myth that women are the ones that are fertile every day. It turns out that we’re not. We have a fertile window that’s about six days long, which is what the research tells us. We ovulate on one day per cycle, and then our cervical fluid keeps the sperm alive for up to five days. So we have this fertile window of about six days per cycle, whereas men from puberty forward, they’re making sperm every day. And it’s the retinoic acid and these pulses that make that possible and make it so that men are always having this supply of sperm.

Not only is retinoic acid important, but just the right amount is important too. So if there’s too little, sperm production can shut down. If there’s too much, the sperm can be damaged. And so there’s this ideal amount that our body kind of regulates to ensure that these enzymes are able to break down the retinol into the usable form, the retinoic acid, and that this level is maintained in order to maintain optimal sperm production.

So this paper goes into a whole lot of detail. Like I said, I’m explaining it in a very basic way, but there’s a lot of different aspects. It’s a very intricate, complicated, incredible process. And retinoic acid is playing this crucial role. It’s helping immature sperm to develop and grow. It plays a role in splitting their DNA through the process of meiosis to lead to them finally being able to be released as a mature sperm. And without this process, without retinoic acid, without the enzymes, without this conversion, and without the raw material — without the retinol in the first place — this process stalls at every stage.

So what this paper does is it really breaks down, step by step, all the different processes that are happening based on pulling together all the different research that has been done in this area, to help us understand how crucial retinoic acid — so retinol, vitamin A — is in the process of sperm production. And as I mentioned at the top of the episode, in animal studies and in human studies, when there is a profound vitamin A deficiency, it can even affect the size of the testes. It’s affecting testosterone production. It’s affecting sperm production. So it can even result in a smaller volume in the testicles — some level of shrinkage — and can lead to the complete cessation of sperm production. So it can completely cause it to stop.

And then the strange thing about these studies — if they give animals a vitamin A deficient diet, sperm production stops, testosterone production stops, and the testicle volume reduces. But then if they give the vitamin A back, all of a sudden the sperm production starts to happen again. So this is the reason why I thought this study would be a really interesting one to talk about and to kind of center the discussion, because a lot of the information that you’ll see about male fertility is focused on a variety of different nutrients and there’s tons of studies on tons of nutrients. And I certainly don’t only talk about vitamin A. I talk about a lot of different nutrients for sperm production. We talk about different dietary strategies and go through what the research has to say. So there’s certainly not just one thing that we should be looking at, but I think that we should be able to talk about the nutrient that is essentially the on and off switch for sperm production.

And then what are the implications if you are trying to conceive and your partner has a diet that is devoid of vitamin A rich foods — if liver isn’t a part of your regular diet and maybe you don’t really eat a lot of eggs or maybe you don’t really consume a lot of foods that would contain it. And as I mentioned, when we’re eating eggs and butter and different animal foods, we’re not getting as concentrated of an amount. So if we’re not consuming liver or cod liver oil on a regular basis, what are the implications of that?

And interestingly, in the study, they’re not recommending people go and eat liver. They’re experimenting with the potential for supplementation, retinoic acid supplementation as a solution. And they’re talking about some of the challenges because if they provide too high of a dose of the retinoic acid, it can have negative effects. So they’re looking at trying to find the right amounts.

But one of the things that we can do if we want to have a better understanding of whether consuming more liver could have an impact is to look at some of the research. And in Real Food for Fertility, I shared a study in our sperm chapter — the improving sperm quality chapter, which is chapter nine. And it’s a section entitled “Poor Dietary Habits” that kind of goes through some of the research. And I found this study, and I’ve talked about it a few different times because I remember going through and reading the abstract, and essentially the abstract was giving the impression that the Mediterranean diet is just the way to go. But then when I actually read through the data, I found this really significant stat. So I’ll just read a little excerpt here for you.

Conversely, consumption of organ meats, fish, shellfish, and fruits and vegetables is associated with an overall increase in sperm parameters. One study found that on average, men who consumed organ meat, including liver, had a 53% higher total sperm count, a 41% higher sperm concentration, and 8% higher progressive sperm motility compared to non-consumers.

So when I was reading that study, that was a really significant finding — 53% higher total sperm count, 41% higher sperm concentration. The men that are eating liver in particular and other organ meats have a lot more sperm available. And I think that those findings are significant enough that they could have titled the paper that. But interestingly, that result didn’t even make it to the abstract. So if you were to dig through and find that study and find the abstract, you wouldn’t even see that result on it. So that in and of itself is interesting. I mean, if something can increase sperm count by 53%, I feel like we should be talking about it.

So as they conclude their research and their description, the kind of step-by-step process of how retinol is turned into retinoic acid, the different enzymes that are involved in this very complicated but incredible process by which men make sperm — they have a final section called The Application of Retinoic Acid in Male Reproduction. And they go through some common fertility issues in men that studies have kind of shown this association with retinoic acid.

So the researchers mentioned two specific conditions. So one is cryptorchidism — and basically that is a congenital condition where one or both testes failed to descend into the scrotum at birth. This is a significant issue because in order for sperm production to be optimal, the testes hang outside in the scrotum for a reason: they need to be a minimum of one to two or more degrees cooler than the rest of the body. And what the researchers point out is that in this condition, when they’re researching and comparing subjects who have it versus those who don’t, they do find that there’s a significantly lower concentration of retinoic acid. And the researchers share some animal studies that show when retinoic acid is introduced into the situation, these animals are then going on to start producing sperm even when previously this condition was preventing that from happening.

And given the essential role of retinoic acid in sperm production and testosterone production — and when we also look at animal studies done in female animals — when retinoic acid is deficient or totally devoid in female animals, what you see is what they call fetal reabsorption. Sometimes the pregnancies cannot go forward; they can’t go to term. So when you have a female rat or mouse and they give them a totally retinoic acid deficient diet, even if they’re able to conceive, the pregnancies don’t go to term. And if they’re deficient but not profoundly deficient, then you see a variety of different developmental issues — mice born without eyes or born without ears or things like that. So retinoic acid, vitamin A, retinol — it plays a really significant role in reproduction.

So there’s an interesting connection between varicocele and retinoic acid. The researchers shared some studies that showed that the administration of retinoic acid decreased the oxidative stress. One of the key factors — when Lily and I wrote Real Food for Fertility and we’re talking about sperm and egg quality — one of the biggest factors is this concept of oxidative stress and how it can have a negative impact on quality and even on DNA integrity. And so a lot of the approaches — supplementation, dietary approaches — to supporting egg and sperm quality are directly related to reducing oxidative stress. That’s why we talk about a lot of antioxidants in this specific area of fertility and supporting egg and sperm quality. And so the researchers are saying that in the studies they looked at, treatment with retinoic acid reduced the oxidative stress and protected sperm from this damage, and therefore has implications to improve fertility in men with varicocele.

And the third piece of this puzzle that they talked about was low sperm count and poor sperm quality. They’re saying that some infertile men have been found to have low levels of an enzyme that is needed to make retinoic acid. And so they shared a small study where they gave these men oral retinoids — a supplement of retinol — and they found that it increased sperm count and morphology. And so again, like the study that I shared with men who just ate organ meat compared to the men who didn’t — just looking at the population data and summarizing it, they were seeing that men who were consuming liver regularly did have an increased sperm count. So it’s not necessarily surprising that when they had men with low sperm counts and gave them retinoic acid, knowing the depth of the research on the role of retinoic acid in sperm production, that it did improve it.

So what does this mean for us? I feel like the results speak for themselves. The reason why I wanted to talk about this is because it’s so interesting to me that people don’t necessarily talk about this. The research is very, very clear. And retinol has been found to have such a profound effect that we could literally call it the on and off switch for sperm production and testosterone production.

So the takeaway from my perspective is that it’s a good idea to consider adding in liver and organ meats into your diet — for both men and women. Today we focus primarily on men, but if you’re trying to conceive, if you’re planning to conceive in the near future, there is a kind of increasing number of men who have been found to have low testosterone. And one thing to consider is that given that liver contains vitamin A, and vitamin A has been found to essentially be an on and off switch for sperm production and testosterone production, it would make a lot of sense to consider incorporating it and seeing what happens.

And this is something where when you look at the research and they talk about supplementation, it’s not always so straightforward. They talk about how sometimes too much could be a problem and things like that. But when we’re consuming these nutrients in food and they’re coming from these natural sources, our bodies know how to deal with them. And we do have research to show that it can make a good difference.

So the takeaways from today’s episode are that retinol — vitamin A from animal foods, not beta-carotene — has been shown to have a really crucial role in sperm production, to the point that if we’re not getting vitamin A, men are not able to produce sperm without it. It plays such a central role in this process that without it, sperm are not going to be produced. And when it’s deficient, it does impair sperm production. Research has linked vitamin A to certain conditions that we talked about, and in a lot of those studies they’re showing that adding in a supplement of retinoic acid has improved the sperm production and the output.

So this is really just the tip of the iceberg. If you were to have a read through the sperm chapter of Real Food for Fertility, we certainly don’t spend all those chapters and over 250 citations talking about only one nutrient. So I think for couples who are struggling to conceive, while it’s not always male fertility at the core of the issue, we do find that 30% of cases of infertility are related to male factor. Specifically, male factor infertility is the cause for 30% of all infertility cases. And in 50% of infertility cases, male factor is a contributing factor. So up to 50% of the time, for couples that are struggling with fertility issues, the men are involved.

One of the things that I talk about a lot in the chapter — and I’ve talked about on the podcast, we share it with our practitioners and our practitioner program — is that I have yet to work with a female client whose partner has had a sperm test who was really provided with a detailed breakdown of what it means, and whose practitioner really explained to them what the WHO guidelines say and how that might compare to optimal. Because ultimately the bar for sperm is very low. In 2010, the World Health Organization set the lower limit for sperm parameters, and it was based on a really interesting study. They looked at over 2,000 couples. They looked at which couples successfully conceived within one year of trying, and then they measured the sperm parameters of all of those men. And out of that, in the study itself, they plotted on a graph — and I share this information in Real Food for Fertility — and they looked at the lower fifth centile. That means that 95% of the men would have better sperm parameters than the lower fifth percentile. And that is what the WHO criteria is based on. So in no way, shape, or form does that criteria tell us what’s optimal. It just provides us with a very low bar below which there’s probably an issue that needs to be looked at.

So when all these women are being told that their partner’s sperm is totally fine, it’s all great — there’s usually more to the story. And this represents a really great opportunity for couples who are trying to conceive. It doesn’t mean it’s always just going to be the perfect solution, but it’s certainly something that is not being looked at enough. And it’s one of the very few areas of fertility where you can get really specific information. Your partner ejaculates into a cup and they count the sperm and you get these very definitive numbers. And if you start out and the numbers aren’t so great, within four to six months of following a nutritional protocol and incorporating evidence-based nutrition that has been shown to improve sperm parameters, it can really change those numbers.

It’s not overnight. Obviously it takes a minimum of three months or so — 74 days according to the research — for a sperm to go through the entire process of spermatogenesis from start to finish. So you don’t see the results in the actual output for at least three to four months. I would say four to six months — give yourself a decent timeframe of consistent application of the changes that you’re making before you’re starting to really expect big results. But there’s a lot of potential there.

And this is certainly a missed opportunity for many couples because it’s not something that is always talked about. And because the parameters of what is considered normal for a sperm test are so low, many couples are just under the false impression that it’s totally fine. So definitely a lot to think about.

So I am going to leave this here. And if you found today’s episode to be helpful, if you can think of somebody who really needs this information today, then I certainly encourage you to share it. You’ll find the episode at fertilityfriday.com/594. And when you jump over to the show notes page, that’s where you’ll also find the research that we talked about. And this series, the FAM Research Series, has been going on for quite some time. In this series I’m going through interesting papers, interesting research, and just talking it through. And it’s really a treasure trove of information for those of you who, like me, are curious about these topics and curious about what the research has to say about it. And one of the things that I know is that many of our practitioners absolutely love the series, and it often sparks conversations within our programs just because we’re going through all of this different information in such depth.

So I hope that you enjoyed today’s episode. I hope you have a wonderful week, weekend, whenever you’re tuning in to the show. And of course, as always, until next time, be well and happy charting.