How to Fix Male (In)Fertility

Sperm counts are declining, and that’s not a good thing. Seminal epidemiological meta-analysis studies over the last five years have painted a concerning picture: sperm counts have dropped by half in the West since the 1970’s. According to the CDC, among married women aged 15 to 49 years with no prior births, about 1 in 5 (19%) are unable to get pregnant after one year of trying (infertility). Beyond that, about 1 in 4 (26%) women in this group have difficulty getting pregnant or carrying a pregnancy to term (impaired fecundity). There is evidence to suggest that the decreased birthrate can be attributed to a variety of socioeconomic variables, but there is no arguing that [clinically speaking] we are having more difficulty getting pregnant than ever before.

Infertility has historically been a topic that almost exclusively puts the cause, blame, and onus on women (which should be no surprise). However, of all infertility cases, approximately 40-50% are due to “male factor” infertility. This is not just a problem for women.

To be certain, male fertility can be [and is] impacted by age, exposure to testosterone, exposure to radiation, frequent exposure of the testes to high temperatures, certain medication, and exposure to environmental toxins (which, unfortunately, we are all being exposed to these daily). But of the most prevalent and significant causes of infertility in men are associated with smoking, excessive alcohol use, and being overweight and obese. Interestingly, not only are these factors the most substantial in regard to prevalence and impact but they are also modifiable – meaning they can be actively changed (i.e., we have the power to change the landscape of fertility).

When addressing fertility in relation to women, the account if far more complex – we cannot only address hormone balances, ovulation, and an optimal menstrual cycle. We must also address the state of uterine health for implantation, micronutrient adequacy for fetal growth, and the ability to carry a baby successfully to full term. Men are a far more simple avatar, with sperm health and quality being the main account that must be prioritized.

If we are to consider sperm health and quality as the key metric of male fertility, we can distill the proactive and preventative approach to optimizing sperm down to a means of additions and avoidances. As noted earlier, exposure to several chemicals, radiation, heat, and the like can disrupt sperm production either directly or indirectly. And therefore, it is suggested to simply avoid endocrine disruptive chemicals (e.g., pesticides, parabens, BPA, sulfates, phthalates, etc.), tobacco, recreational drugs, and alcohol. If substance abuse is a concern for you, it is highly suggested that you work with a licensed professional to overcome your addiction for the sake of not only your fertility but the health of our future generations.

It should be no surprise that both the rate and prevalence of overweight and obesity has been steadily climbing for decades. The last 30-50 years have been characterized with an influx of more ultra-processed foods, higher reports of sedentary behavior and lifestyles, increased use of herbicides and additives, and an exponential rise in anxiety and depression. You may be asking yourself what came first, the chicken or the egg? But my own anecdotal [albeit scientific] input would suggest the two are not simply associated but rather related by a causal undertone. We are fat because of the foods we are eating and the foods we are avoiding (this is augmented with chronic sitting, unnecessary exposure to toxins, and over-stressed).

We could ameliorate a substantial number of male infertility cases by addressing obesity alone. Optimal nutrition practices can do a lot more than just aid weight loss. The right balance of functional foods can combat reactive oxygen species with antioxidants, influence hormonal balance, restore efficient metabolic health, [literally] nourish the growth of healthy sperm, facilitate gut health that regulates stress levels, and improve blood pressure metrics for optimal circulation and nutrient delivery.

Why is obesity a [physiological, metabolic, and biochemical] problem for male fertility? Obesity has been illustrated to impact the hypothalamic-pituitary-gonadal axis (a fancy term for the hormonal connection between the brain and the testes). This can lead to hypogonadism, which essentially means the sex hormones (i.e., testosterone) are not being produced in sufficient amounts and testosterone plays a significant role in the proper growth and development of sperm.

Obesity is characterized as excess amounts of adipose tissue (i.e., subcutaneous and visceral fat), which causes insulin resistance, leading to hyperinsulinemia (too much insulin in the blood), hyperglycemia (too much glucose in the blood), and oxidative stress (too many reactive oxygen species). This has a domino effect that inhibits the uptake of glucose by sperm cells. Sperm cells (spermatozoa) require ATP (i.e., energy) which is highly dependent on the presence of glucose inside the cell. So, too much fat means insulin resistance and low energy availability for sperm cells, resulting in reduced sperm motility.

Adipose tissue also secretes leptin, a hormone responsible for regulating appetite, hunger, and satiety cues to the brain and is directly related to how much fat is in the body. Unfortunately, leptin has a role in the chronic pro-inflammatory state in the testicular microenvironment and excurrent ductal system, thus increasing reactive oxygen species and inflammation that are responsible for a decrease in sperm quality.

Excess fat cells and tissue are also responsible for an increased activity of aromatase, the enzyme that converts testosterone to estradiol (estrogen). As you can imagine, more fat leads to higher turnover of testosterone to estradiol, resulting in low sperm production.

Obesity and excess body fat is also characterized by dyslipidemia, or the imbalance of lipids such as cholesterol, low-density lipoproteins, triglycerides, and high-density lipoproteins. This can have both up- and downstream impacts on sperm health, number, quality, and motility.

As you can see, carrying excess weight can impact a lot more than which loop of your belt you’re currently using. And though we can equate some variable degree of obesity to our genetics, diet is undeniably the largest contributor to being overweight. It is worth noting that the current landscape of diet and nutrition for men [particularly the Western diet] not only contributes to excess weight but is also highly lacking beneficial and essential nutrients needed for systemic and reproductive health.

So, what to do about it all? As a dietitian and nutrition expert, I would be remiss to say there is one specific diet that will ameliorate any and all infertility causes in men and confer guaranteed benefit. As the ever colloquially popular nutrition claim goes, there’s no one-size-fits-all approach to fixing infertility in men. However, there are nutrients we know to be beneficial for regulating male fertility and promoting better sperm health. We have also successfully identified food(s) that are associated with reduced sperm quality and its upstream effects.

Let’s talk fats, carbohydrates, protein, and micronutrients.

Not all [dietary] fats are equal. With monounsaturated, polyunsaturated, saturated, trans, omega-3, and omega-6 fats, it can be confusing which ones you should be including and which you should be avoiding. Here is the most simple breakdown of each:

• Monounsaturated Fats: Improve blood cholesterol levels, reduce inflammation, benefit heart and vascular health. Found in olive oil and other vegetable oils, avocados, nuts (e.g., almonds, hazelnuts, pecans), and seeds (e.g., pumpkin, sesame).
• Polyunsaturated Fats: Improve blood cholesterol levels, reduce inflammation, benefit heart and vascular health. Found in sunflower oil, soybean oil, flaxseed oil, walnuts, flax seeds, fish, and canola oil.
• Omega-3 Fatty Acids: A subset of polyunsaturated fats that are essential, meaning the body cannot make them (hence why they are such a popular supplement). Omega-3’s are potent anti-inflammatory fats that should be included in the diet. Found in fish and seeds (ground flaxseed, hemp, chia).
• Omega-6 Fatty Acids: A subset of polyunsaturated fats that are essential, meaning the body cannot make them. These fatty acids have pro-inflammatory properties and are necessary for regulating several processes. Found in walnuts, sunflower seeds, tofu, eggs, and almonds (to name a few).
• Saturated Fats: These fats contribute to cholesterol production, hormone production, and when in excess, fat deposition, elevated blood lipid levels, inflammation, and insulin resistance. These fats are beneficial to health in small quantities and should be eaten in moderation. Found in cheese, whole and reduced fat milk, butter, dairy, meat products (sausage, bacon, beef, poultry), and many [if not all] processed foods.
• Trans Fat: These fats are either manufactured when heating liquid vegetable oils in a process called hydrogenation OR found in beef fat and dairy fat (though in small amounts). These fats are highly inflammatory, raise low-density lipoprotein levels and reduce high-density lipoprotein levels, contribute to insulin resistance, and are overall harmful to health. These should be avoided completely. Found in products containing partially hydrogenated vegetable oils, margarine, shortening, processed foods, fatty cuts of beef and meat, and some dairy products.

What does science tell us about dietary fat intake and male fertility?

Monounsaturated fat intake is associated with improved sperm membrane composition, sperm metabolism and energy production, and reduced oxidative stress. That is to say these fats are highly beneficial for promoting high-functioning sperm. Some fat-soluble vitamins (vitamins A, C, E, and K) have antioxidant qualities – or simply put, reduce reactive oxygen species – so it’s no surprise that we see clinical benefits from supplementing with these fats.

As we noted earlier, the human body cannot manufacture omega-3 and omega-6 fatty acids (polyunsaturated fats) but rather need to acquire them from the diet. Considering both types are essential for health and have opposing mechanisms (omega-3 = anti-inflammatory; omega-6 = pro-inflammatory), the main concern or area of focus should be the ratio of the two. It would make sense that more omega-3’s would be beneficial to overall health, facilitating systemic anti-inflammation. Diets with an unbalanced omega-6/omega-3 polyunsaturated fatty acid ratio (a hallmark of a Western diet) negatively affects sperm quality. This essentially means we need both, but we should focus on more omega-3’s than omega-6’s.

Several studies indicate that high dietary intake of saturated fats is negatively correlated with total sperm count and concentration. As noted earlier, we need some saturated fats for proper lipid and hormone production and metabolism, but too much can be detrimental [especially to sperm health].

What about cholesterol, isn’t that fat as well?

Technically speaking, cholesterol is a fat, but it’s transported in the blood and body as a lipoprotein (which is part fat and part protein). Cholesterol has been vilified for generations as a bad thing, yet literally every cell of the body has and needs cholesterol. Cholesterol provides cells with the structure they need to exist (i.e., no cholesterol means no cells). Cholesterol is also the building block for sex hormones, including testosterone and estrogen. It is interesting to note that cholesterol levels in the sperm membrane contribute to its fluidity, which will dictate its motility, and ultimately, its ability to fertilize an egg. Cholesterol sounds great, so where’s the poop? Too much cholesterol (hypercholesterolemia) can cause cholesterol to accumulate and induce cellular stress in the Leydig cells (where testosterone is made in the testes). This can result in a decrease in testosterone production, interfering with sperm production.

Here's the takeaway on dietary fat, cholesterol, and male fertility: eat more mono- and polyunsaturated fats (with a preference for omega-3 containing fats), moderate your intake of saturated fats with less processed foods and animal products, and cut out trans fats, ultra-processed foods, and added sugar junk.

One of my favorite quotes growing up was from the talented Mike Meyers in his third installment of the Austin Powers saga Goldmember. In addition to several roles in the film, he plays a henchman (whom I will not name) and states “…you know, carbs are the enemy” when discussing his failed attempts at dieting following a sumo wrestling inspired altercation in the locker room. In the world of media and news, carbohydrates are our best friends one week and the key culprit for bad health the next. Unfortunately, misinterpreted science and news paints this picture that nutritional scientists don’t really know what they’re talking about. Yet, the real science has never changed. And it states [clearly] that carbohydrates are not only beneficial for health, but essential.

Carbohydrates are simply just a classification for different types of sugars (glucose, fructose, lactose, galactose, maltose, glycogen, starch, etc.). We naturally find carbohydrates in whole grains, fruits, vegetables, seeds, nuts, and the like. We also ADD simple sugars, processed sugars, and synthetic “sugars” to our foods and ultra-processed “foods” – and that is where the problem is found. When carbohydrates are consumed in their natural and complex state, they have significant health benefits, which includes serving as an energy substrate for the brain and the gut. The real concern [in terms of male fertility] is the established link between sugar intake and lower sperm motility that can be almost entirely influenced by insulin resistance. “In sperm cells glucose is the main substrate for glycolysis, where it is metabolized to pyruvate and/or lactate to obtain cellular energy in the form of ATP.” The bottom line: sperm need glucose to function properly; too much simple sugar intake causes insulin resistance; and glucose can’t get into the sperm cell to mature and function optimally.

Though there are few, if any, studies that investigate the precise role in preserving male reproductive potential, there is one promising candidate for why carbohydrates benefit male fertility. Prebiotic fiber – which is the preferred energy substrate for healthy gut microbiota – is a carbohydrate. Our gut flora (an immense, complex, collection of beneficial bacteria, parasites, fungi, viruses, etc.) plays an undisputed intricate role in regulating and managing hormone production and balance, inflammation, insulin resistance, nutrient absorption, blood pressure, immunity, and stress. Without a healthy gut we cannot be [wholly] healthy.

Here's the takeaway on carbohydrates and male fertility: embrace and eat carbohydrates in their natural form (from whole grains, vegetables, fruits, seeds, and nuts) and eliminate processed foods that will inevitably cause varying levels of insulin resistance and metabolic dysfunction. Carbohydrates literally fuel sperm cells.

Is there anything more masculine than a high-protein diet, flooded with grilled T-bone steaks and organ meats? It’s been all the rage recently, with some extreme social media influencers touting the benefits of carnivorous diets, that only include meat, organs, and the occasional piece of fruit. As an expert in nutrition, I would advise against such idiocy. The only real benefit you are seeing in those practicing this style of eating is the food and food stuff they are otherwise eliminating from their diet (i.e., processed foods with added sugars and fats). This type of eating will inevitably contribute to dyslipidemia and high cholesterol levels, which news flash, will also increase insulin resistance, high blood pressure, poor gut health, and disrupted hormone production.

But protein is a necessary component of good health and optimal male fertility. Studies indicate that a low-protein diet can be a risk factor for male infertility, related to a reduction in reproductive organ function. Plant-based proteins are low in sulfur-containing amino acids like cysteine and methionine. Interestingly enough, higher levels of cysteine, methionine, and phenylalanine (amino acids) in sperm are associated with reduced sperm motility. Though not exactly equivalent, studies in monkeys show that subjects fed a plant-based diet had better sperm counts, motility, and less abnormalities than subjects fed an animal-based diet. These studies have not been replicated in humans (to my knowledge) but the findings are suggestive of a compelling reason for men to reevaluate where their protein is coming from [if they are focused on fertility].

Here's the key takeaway on protein and male fertility: prioritize your protein intake (you need at least 0.8 grams/kg bodyweight/day); when possible, get your protein from plant sources rather than animal sources (and no, we’re not talking about meat-substitutes or synthetic meats).

Okay, that’s a lot to unpack already. We know that obesity and excessive weight is a contributor to male infertility. We understand that disturbed metabolic health can impact how sperm are produced and regulated. And it’s clear that testosterone levels need to be managed (both directly and indirectly) with nutrition. What else is there? We keep coming back to this reactive oxygen species concept or “oxidative stress”. This is a problem that systematically damages testosterone levels, reproductive organs, and male fertility. How do we address that more directly with nutrition?

Reactive oxygen species (ROS) are closely related to mitochondrial health. To simplify things, think of your mitochondria (and you have many, 100’s, in every cell) as the engines of your cells. As they become over-stressed, they inevitably leach out harmful byproducts. These byproducts cause oxidative damage to cellular components and processes. We can combat this with an oil change and a tune-up – in nutritional science, we refer to these as antioxidants (i.e., they scoop up these reactive oxygen species and render them inert). The main antioxidant vitamins that help regulate these free radicals are vitamins A, E, C, and K. But there are several other nutrients, referred to as phytonutrients or polyphenols, that can help as well. Polyphenols and flavonoids (found in plant products) like quercetin, resveratrol, naringenin, lycopene, and xanthophyll can potentially act as powerful antioxidants and modulators of oxidative stress.

Does your head hurt yet? Science and studies are still evaluating the degree of impact these many polyphenols have on general health, not to mention male fertility. Though the picture has yet to be fully painted, there are promising functional nutrition applications for these compounds. How do you, in the most simplest and effective way, reap the benefits of such a health- and fertility-promoting nutrition approach? Eat more produce (fruits and vegetables) and increase the variety of choices.

Let’s wrap this up before the ice melts. There are some components of fertility that may not be entirely in control. But it’s clear (thanks to promising real science) that you can significantly position yourself for better success with a few simple [and effective] dietary changes. We have addressed several components of how your diet can impact weight, testosterone levels, oxidative stress, and sperm quality. But an additional, and perhaps most significant topic that is worth addressing is our future. These lifestyle and diet modifications will do more than help you and your partner start a family. These healthy practices will also influence the genetic health of your sperm, laying a more promising foundation for optimal fetal health, and ultimately, adult health. With infertility rates and prevalence on the climb, it’s clear that our population and society is struggling with their health. No public initiative, policy change, or overhaul of the food industry will have much impact if our kids are already predisposed to metabolic dysfunction that we are actively programming with our damaging health practices.

My final note is addressed to all of the men reading this. As your fellow man, I recognize the XY programmed discomfort of asking for help. An additional layer of discomfort, and perhaps vulnerability, may be introduced if you are struggling with your fertility. Let me tell you this: there’s nothing more “manly” than doing what you need to improve the health of your family. If you are struggling with fertility or your health in general, please seek the guidance you need. I am always here to help! Cheers to a thriving future for you, your family, and our world. Be well!

By Alek Dinesen, MS, RDN, CSCS, PN1
Fertility, Prenatal, & Postpartum Dietitian