The science behind superstar sperm

With a 50%-freaking-decrease in sperm count globally over the last 40 years, sperm health has never been a bigger issue in the realm of fertility. 

I chat about what affects sperm quality and quantity, talk about male infertility testing including what kind of information a typical sperm test provides you with (spoiler: not enough!), and what are the biggest culprits that could be slowing down your road to parenthood. 

If you're a man wanting to have a baby, this episode is compulsory listening ;)

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Oh Goodness! Nutrition is an evidence-based dietitian practice. However, given the general nature of the content presented on this podcast, it can not replace individualised medical advice. Get yo'self a professional (psst, lik...

Chapters

• 0:00 Sperm Health and Fertility Impact
• 15:54 Size and Lifestyle Factors Affecting Sperm

Transcript

[00:00:00] Since it takes two to tango, learn more about sperm and what makes them great. Or not so great. Women often carry the burden of childbearing and yet 50% of a successful pregnancy relies on what the man offers. Sperm are more sensitive and more prone to damage than eggs making sperm health essential for anyone planning a family. 

[00:00:23] By the end of today's episode, you'll know how to test for sperm health, what those tests mean. And to what extent lifestyle can affect sperm quality. Welcome to the I'm thinking of having a baby podcast. I'm Hannah Eriksen, owner of Oh Goodness! Nutrition, a team of fertility dieticians, passionate about helping couples conceive really healthy babies. Bring on your dream fam. 

[00:00:51] In recent decades, there has been a significant and worrying decrease of around 50 to 60% in the number of [00:01:00] sperm in men's semen, regardless of whether they have fertility issues or not. Wow. This decline is a global problem, and it's so concerning that the world health organization now considers infertility a major worldwide public health issue. 

[00:01:18] When it comes to couples struggling to conceive, male related problems, either on their own or along with female ones, account for half of all cases. When you look at just male related infertility it's responsible for about 20 to 30%, we think of all infertility cases. 

[00:01:37] So what can cause male infertility? There's a whole bunch of factors that can play a role. It can be something a man is born with or something that happens over time. Like infections, genetic factors, hormonal problems. Or issues with the tubes that carry the sperm. Surprisingly around 30% of all male fertility problems fall into a category [00:02:00] called idiopathic, which means we don't know what actually causes it. 

[00:02:04] Lifestyle also has a big part to play in male infertility. Things like being overweight or dealing with chronic stress, heavily drinking, smoking, using drugs, exposure to certain chemicals, having inflammation in the body and even certain genetic factors can all contribute to unexplained male fertility issues. 

[00:02:25] Here's your biology lesson on the making of sperm. Sperm can take somewhere from 46 to 72 days to reach full maturity. Keep this in mind for any changes that you want to make to diet or lifestyle for tip-top sperm, because you probably won't notice an improvement in sperm, quality or function for close to three months. 

[00:02:47] Measuring sperm health typically involves measuring their total sperm count. The ejaculate volume, sperm, concentration, and pH of the sample. And I'll elaborate on a couple of these. [00:03:00] Total sperm count is important for obvious reasons. The more sperm present, the higher, the odds of conceiving. And like I often say: you only need one. 

[00:03:09] Here's an interesting fact. Only a quarter of the sperm that are initially produced end up in the ejaculate. Once there only 50% of these are in top form. The other half are malformed. Of all the sperm made, therefore only 12% have reproductive potential. Of course, when you're looking at how many millions are made on a regular basis, this redundancy starts to make a bit more sense. It's impossible to have perfectly formed sperm in such numbers and time. 

[00:03:42] Normal sperm count is more than 15 million sperm per mL. So even if you're on the lower end of normal, that's still 1.8 million healthy sperm per mL. Again, you only need one. But having a higher sperm count will of course boosts the odds considerably. [00:04:00] 

[00:04:00] Ejaculate volume is important because it is the fluid that the sperm swim in. It's like food to them and nourishes them and helps them swim through the vagina, and up to the fallopian tubes, a lot more smoothly. 

[00:04:13] In some sperm tests you'll also get vitality, morphology and motility looked at. As well as leukocyte count -leukocyte is a type of white blood cell. 

[00:04:23] Motility describes the ability of the sperm to swim in a straight line. If sperm can't do that, it's not going to fulfill its potential and it will be unable to penetrate the eggs' outer layer required for fertilization. Sperm come in all shapes and sizes too; the more abnormal a sperms morphology, or shape, the more hindered it will be. 

[00:04:46] If you are going to do a sperm analysis test, from your GP, you need to do two different tests at two different times. Because this will be the most accurate way to get a full picture. And timing is [00:05:00] everything. Sperm degrade the longer they are outside the body. And this is just a temperature thing. So if you're going to provide a sample, make sure that there's a shorter time as possible between taking the sample and giving it to the lab technicians who are going to analyze it. 

[00:05:16] It's important to know that when we analyze semen in this way, it tells us about sperm quantity. And some levels of quality, but not necessarily how well the sperm can do their job. In most cases, it doesn't actually give us a strong prediction of whether someone can easily have a baby naturally. I see this all the time, a couple is struggling to conceive, the man have had their sperm done in like, yeah, everything's normal. But it's not enough information to, to rule the guy out as part of the issue. 

[00:05:44] Other measures of sperm functional quality can be done. They're just not done routinely and they're not available through your GP. These measures of sperm quality are novel. They're quite new. .And so they're really available through some specialized means. One of the tests is [00:06:00] looking for levels of reactive oxygen species .Woah. That's a mouthful. Elevated levels of ROS can potentially cause male infertility by harming various aspects of sperm function. This includes damaging the outer layer of sperm. Reducing their ability to swim effectively, interfering with important reactions necessary for fertilization, and impacting the quality of sperm DNA. 

[00:06:24] Sperm DNA fragmentation is another test that can be done for couples that have had three or more miscarriages or several unsuccessful IVF attempts. This test usually costs and is available through fertility specialists. But high levels of DNA fragmentation usually suggests there are high levels of these ROS species; that is, inflammation. And or large numbers of activated white blood cells.

[00:06:50] With more and more infertility and with 50% of that being attributable to sperm health. Their role in fertility and getting pregnant can not be [00:07:00] understated. So what's the relationship then between nutrition and sperm health?

[00:07:03] Animal studies looking at obese mice have shown that having larger daddy mice slow the embryo's development before implantation. Slows down the implantation itself and slows overall development of the embryo. In vitro studies, so that's in a lab, of human sperm exposed to ROS, which mimics the levels of ROS found in the obese mice. It also slowed implantation and embryo growth. So in the lab and in animals, we know that high levels of ROS, as a result of weight can slow down the chance of someone having a baby. Now it can be tricky, obviously to do these studies in humans for ethical or mechanistic reason. So that's why we've got animal studies and in vitro studies. 

[00:07:49] But looking at people there's been a recent study conducted that shed light on the significant impact of male health on fertility outcomes. They did a case [00:08:00] control investigation, looking at 50 male partners of women who had experienced recurrent miscarriage.

[00:08:06] The findings were eye-opening revealing that these men had double the levels of sperm, DNA fragmentation, and notably elevated levels of ROS in their semen. When this group of men was compared to a control group and the control group consisted of healthy males with no known fertility issues, the differences became even more apparent. 

[00:08:28] These men from the recurrent miscarriage group were more likely to have a higher BMI, diminished sperm quality parameters and abnormal hormones. 

[00:08:41] And a separate study involving 651 couples undergoing IVF treatment. Research has uncovered a compelling association between the males BMI and fertility outcomes. Couples where a male partner, where a BMI over 28 experience lower [00:09:00] fertilization rates, reduced rates of high quality embryos and a decreased likelihood of achieving a clinical pregnancy compared to couples where a male, had a normal BMI. What's even more intriguing is that semen analysis in this study revealed that males with a higher BMI exhibited increased rates of DNA fragmentation, and higher levels of sperm ROS. 

[00:09:24] While many studies delve into the relationship between weight and its impact on sperm quality and reproductive outcomes. Not all studies arrive at the same conclusions. One study showed no significant associations between BMI and crucial fertility indicators like embryo quality, clinical pregnancy rate, or live birth rates in couples undergoing IVF. Interestingly recent research has brought a new perspective. It suggests that obesity when considered in isolation without other comorbidities and [00:10:00] characterized as metabolically healthy may not significantly impact semen quality. 

[00:10:06] However, when obesity is coupled with impaired glucose tolerance or liver function, categorizing it as metabolically unhealthy, it does become a strong predictor for reduced sperm count. And I find this so interesting because weight loss is like my bread and butter. I'm helping people lose weight all of the time. But here it's saying, look, just losing weight might not be the kicker here. If you want to be really efficient at it, focusing on metabolic factors or reasons that means livers or blood pressure or sugar levels are wonky. If you can address that partly through weight loss, but partly through other factors, you're more likely to affect the sperm health. 

[00:10:46] So this particular study, looking at the metabolic health was relatively small and it didn't delve into other aspects of metabolic fitness, like blood pressure, cholesterol, and triglycerides. Okay. Enhancing an individual's metabolic health might carry more weight in [00:11:00] improving reproductive outcomes in men than simply focusing on weight loss alone. 

[00:11:04] Previous studies have looked at how changing your diet and exercise habits can impact your sperm quality when you're trying to lose weight. So, if we're looking now specifically at just weight loss, they found that when men lost a significant amount of weight and for them, that was between 17 and 25% of their body weight, 

[00:11:21] through a combination of diet and exercise, the results were their sperm count, semen volume, and testosterone levels improved compared to before. When male partners lost weight on their own. So the lady didn't lose any weight, it increased the chances of successful pregnancy through in vitro fertilization.

[00:11:41] Another benefit to being a healthy weight before conceiving, is there some really interesting research in genetics and epigenetics. Which is all about how genes are turned on and off. It shows that a father's obesity can affect the health and traits of their children. 

[00:11:59] Some [00:12:00] specific changes were noticed in the genetic material within sperm, from obese men. These changes might very well influence genes that are related to behavior and food preferences in their children. Potentially making their kids more prone to obesity. This emphasizes the importance of offering advice to men about their weight before they become fathers and obviously doing that in a really supportive way. 

[00:12:24] So some other things around lifestyle choices, I've hopped on about weight a fair bit. And that's because we've got most of the research around it, but there are some other lifestyle factors that can also influence sperm quality. And some of these, you're not going to be surprised by it all. 

[00:12:38] Smoking for example, can harm sperm in many ways. A study involving over 5,800 men found that smoking was linked to lower sperm quality, especially in moderate and heavy smokers. It led to reduce sperm movement, more defects in sperm shape, lower sperm concentration, and a lower fertility index in heavy [00:13:00] smokers compared to mild or non-smokers. 

[00:13:03] Smoking can also lead to worse outcomes if you're going for IVF or similar. However, it's important to note that the definition of smoking varies between studies and we don't fully understand all the ways it affects male fertility. 

[00:13:18] Alcohol. We know that studies in mice have shown how much and for how long a person drinks alcohol can impact sperm quality, and the ability for that sperm to fertilize an egg. Research involving over 16,000 men from 15 studies found that alcohol intake was linked to lower semen volume and abnormal sperm shape, especially in daily drinkers compared to occasional drinkers. 

[00:13:44] And another study of Danish young men found that even modest alcohol consumption, which was more than five units per week could harm semen quality. Alcohol may also damage a type of cell called Leydig cells in the testes, which are really important for [00:14:00] testosterone production. So do a count of your drinking throughout the week. 

[00:14:04] A unit of alcohol is 330mL of beer, a hundred mLs of wine, which is piddly, and 30 mLs of spirits. So if it's over five, that would be considered moderate drinking. 

[00:14:17] Recreational drug use like cannabis, androgens and opioids can negatively affect sperm quality and male fertility. Because these substances cause high DNA fragmentation in sperm. 

[00:14:29] The effects of caffeine on testicular health is still uncertain. And laboratory cultured human Sertoli cells from the testicles high caffeine intake was found to reduce antioxidant capacity leading to oxidative damage. 

[00:14:44] A review of studies involving nearly 20,000 men suggested that caffeine consumption didn't seem to harm semen quality, but it was linked to increased sperm aneuploidy, which is an abnormal chromosome number and [00:15:00] DNA damage. So it might not seem to affect say the count or the shape of them, but it does affect the DNA. 

[00:15:07] Being physically active can also improve semen quality compared to a sedentary lifestyle. Obviously being active is part and parcel of being a healthy weight. So this means that regular exercise might help with reproductive health, especially in men with conditions like diabetes and obesity. However, very intense and strenuous exercise could potentially harm sperm. 

[00:15:29] Especially if it leads to low body weight, fatigue, and abnormal calorie intake. So if your man is a triathlete take note. Also the type of sport matters. Here we go. Cycling, for example, can be unique because prolonged or competitive cycling can reduce the total number of healthy moving sperm and increase the sperm DNA damage due to increased scrotal temperature. How about that? 

[00:15:55] So interesting. Look, I know I've gone into great detail today [00:16:00] about the effects of size and some lifestyle factors on sperm. I hope you got my key message, right? How to test sperm and take it with a grain of salt. It can mean that things are okay, but it can also mean that things aren't. And if you are experiencing recurrent miscarriages then that would be a high chance that there is something going on with the sperm. 

[00:16:21] And I'd strongly recommend that if you feel like your partner would benefit from seeing a dietician jump online give me a stalk ognutrition.co.nz. I have discovery calls right where you can discover if we're a good fit and we can have a chat about where to from here, and what nutrition can do to help you have your dream family. Till next time.