There’s a very good reason why my book begins with male fertility – or rather all the reasons that male fertility rates are dropping…rapidly.
Male fertility is declining sharply, with sperm counts dropping over 50% in the last 50 years.
Environmental toxins, lifestyle factors and diet all impact your fertility so making the right choices is crucial to ensuring optimal fertility.
The Sperm Count Nosedive
Let’s start with some cold, hard facts. Research indicates that sperm production has taken a significant nosedive since the 1900s, putting male fertility and overall health at risk. A meta-analysis conducted by Carlsen et al. in 1992 reported a worldwide decline in sperm counts from 1938 to 1990, based on the semen analyses of nearly 15,000 men from 23 countries.1
More recent studies have reinforced this alarming trend, with a review suggesting that global sperm counts have plummeted by more than 50% over the past 50 years.2 Another study found a staggering 51.6% reduction in average sperm count worldwide between 1973 and 2018, with the decline becoming even steeper after 2000.3
The Testosterone Tumble and Sperm Stress
Now, you might be wondering, “What’s causing this sperm apocalypse?” While there are certainly several complicated factors, there are a few culprits taking centre stage: declining testosterone levels and poor sperm quality.
Environmental toxins, lack of exercise and movement, and life stresses are of course playing major roles here, but so are dietary fats. Enter PUFAs, Polyunsaturated Fatty Acids, which have infiltrated modern diets, replacing the good old saturated fats and animal fats that our ancestors thrived on.
Modern Diets are Inflammatory
Over the past 120 or so years our diets have changed from locally grown, natural produce to ultra-processed, genetically engineered highly sprayed (chemicals and toxins) fast ‘foods’.
Let’s look at just one major change in our diets – the change in oils and fats we consume and their effect on male fertility.
PUFAs have multiple double bonds in their chemical structure, which makes them more susceptible to oxidative stress because free radicals can easily react with their double bonds. And this oxidation can lead to the formation of harmful by-products such as lipid peroxides.5
Well, oxidative stress in sperm is a major factor in male infertility.6,7 Think of it as rust accumulating on your car — over time, it weakens the structure and impairs function. The same thing is happening to your sperm, and the results aren’t pretty. Miscarriages are a complex issue and can result from a variety of factors involving both partners. But research is now demonstrating that male factors are playing a significant role in miscarriages.
High levels of sperm DNA fragmentation (the breaking or damage of the DNA strands within sperm cells resulting from oxidation) have been shown to double the likelihood of a miscarriage occurring.8
Let that sink in for a moment — DNA fragmentation in sperm from oxidation can be a causal factor in miscarriages. In fact, research by Examen has observed high sperm DNA damage in over 85% of men whose partners had recurrent miscarriages.9
Dietary fats aren’t just energy molecules. They serve as structural components and signalling molecules in your body. The types of fat a man eats can regulate different signalling pathways throughout the body, including those crucial for reproductive health.
The fats you eat also get deposited in your reproductive tissues, influencing reproductive function and fertility. Changes in the fatty acid composition of phospholipids in the sperm membrane, seminal plasma, and semen can significantly impact sperm function and male fertility.10,11,12
One study found that men suffering from varicocele (a condition where veins within the scrotum are inflamed which negatively impacts fertility) had significantly higher levels of omega-6 PUFAs compared to healthy men.13
The Arachidonic Acid Assault
One of the biggest dietary shifts have been an increase in Linoleic Acid (LA). LA is an Omega 6 PUFA that is high in vegetable/seed oils, various nuts and seeds, and conventional pork and chicken.
Some of the LA we consume is used for energy or as structural components in our bodies. And some is converted into a compound called Arachidonic Acid (AA) through a series of chemical reactions.
One study demonstrated that AA plays a significant role in suppressing male fertility.14 Sperm have a progesterone ‘receptor’ on their tail, and the activation of this receptor by progesterone allows sperm to make the final push into the egg for fertilization. However, AA interferes with this process.
This may be why many men benefit from progesterone supplementation while simultaneously reducing PUFA consumption.15
But AA’s assault on male fertility doesn’t stop there. Another study found that AA causes decreased function or even death of Sertoli cells (crucial cells in the testicles) and reduced sperm production.16 AA caused negative metabolic actions, including reduced expression of electron transport complexes, increased glycolysis, and reduced oxygen consumption, all of which led to lower mitochondrial function – all essential for energy production.
Remember, sperm require sufficient energy production to function properly, and PUFAs hinder this energy production.
Now, you might think adding some “healthy” seeds to your diet could help. Unfortunately, the main PUFA in pumpkin seeds is LA. In 100 grams of pumpkin seeds, the LA content typically ranges from about 20 to 30 grams (which is the same LA content of 100 grams of canola oil).
One study found that the addition of pumpkin seeds to the diet caused infertility and androgen deficiency.17 Thankfully, these effects were reversed when pumpkin seed consumption was stopped. The authors even concluded that a fluted pumpkin seed-supplemented diet (DFPS) may be an “effective and readily reversible agent that meets the required criteria of a male contraceptive.”
On top of the PUFA content, many seeds contain phytoestrogens (flax seeds are some of the highest sources), which are plant-derived compounds that can mimic or modulate the effects of estrogen in the body. These plant-based compounds, on top of the many and varied sources of other environmental oestrogens (including hops in beer) can lower testosterone levels,18,19 adding insult to injury for your already struggling sperm.
Now, it is fine to consume nuts and seeds on occasion — but we don’t need to go overboard here as that will drastically increase our PUFA consumption. (and potentially negatively impact fertility) Perhaps the most alarming finding comes from a study that investigated how a high-fat and high-PUFA diets in early life impacts fertility later in life. [NB: a pertinent fact to note if you are or are considering a vegan diet]
Excessive fat intake promoted an overaccumulation of proinflammatory Omega-6 polyunsaturated fatty acids in the testis, which is strongly correlated with negative effects upon sperm quality. Although diet reversion with weight loss during adulthood prevents the progression of metabolic syndrome, testicular content in fatty acids is irreversibly affected. Therefore, the adoption of high-fat diets during early life correlates with irreversible changes in testicular lipid content and metabolism, which are related to permanent damage to sperm quality later in life.”20
In other words, the amount of and types of dietary fat we consume in childhood can impact our fertility later in life.
So, what’s a man to do in the face of this fertility fiasco? The good news is that there are simple lifestyle and dietary changes you can make to improve the quality of your sperm DNA and boost your overall reproductive health.
1. Maintain a healthy weight — Holding on to excess body fat is not going to be helpful in improving fertility, as obesity is also linked to infertility. Losing body fat has been shown to improve testosterone in overweight male subjects.23 So, eating a calorie amount appropriate for your needs, cooking most of your meals from home, hitting a consistent daily step count, and regular exercise are vital lifestyle habits.
2. Manage stress and develop healthy sleep habits, as high levels of cortisol can negatively impact testosterone production.
3. Improve metabolic rate with carbs — Dietary fats are of course an important part of a healthy dietary strategy. However, you don’t need to go crazy overboard on your fat consumption to experience the benefits.
Plus, the research shows that to maximize fertility, having a good metabolic rate and being a good carb burner (meaning the mitochondria machinery is good at turning carbs into energy) is very helpful! Yep, your gonads need glucose to produce testosterone.
“Energy status is essential for normal reproductive function, since the reproductive axis has the capacity to respond to metabolic cues.”24 In fact, “reduced availability of glucose may be responsible for decreased testosterone synthesis or hypoandrogenism in the testis of mice during aging.”25 Another study further supports this, stating, “This study thus further supports the earlier finding that Leydig cells cannot produce testosterone in the absence of glucose.”26
This may explain why low-carb, high protein diets can lower testosterone levels in men.27 Proper structure and function requires adequate energy production.
4. PUFA consumption — Yes, there may be supplements that may improve your fertility and testosterone levels. However, what you eat every single day plays a huge role in determining your overall health status.
So, to improve fertility, it is beneficial to reduce your PUFA consumption by cutting back on vegetable oils, processed foods, conventional chicken/pork, and excessive nut and seed consumption. Opt for healthier sources like tallow, organic butter, dairy fat, organic-free range naturally low PUFA eggs, dark chocolate and coconut oil.
The fats found in these sources may have the greatest testosterone boosting effect, because saturated fatty acids (SFAs) are positively associated with testosterone.28,29,30,31
Gentlemen, it’s time to face the facts: what you eat matters, not just for your overall health, but for future generations. A diet rich in PUFAs is like kryptonite for your fertility. The types of fat we consume have a profound impact on our reproductive health, and it’s time we start paying attention.
But don’t despair — by adjusting your diet and lifestyle, you can take charge of your reproductive health and give your future children the best possible start in life.
It’s time to get your ducks in a row, gentlemen. Your future children are counting on you. Remember, when it comes to fertility, you truly are what you eat.
You can read more about how to improve your fertility in my book, Conversations with my Daughter: How to Have a Healthy Baby available on Amazon.
Sources and references:
Ashley Armstrong and Nourish Cooperative
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