Research to Reader: fertility science
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Research to Reader: fertility science
Micronutrients, such as vitamins and minerals, are compounds found in trace amounts that are essential for normal growth and development. Before conception, conception, implantation, the formation of the placenta and embryo growth can all be affected by nutritional intake and in particular, micronutrient imbalances.
Micronutrient deficiencies are associated with higher reproductive risks such as infertility and negative effects during pregnancy. Ensure you eat a wide variety of fresh food in your diet and if you are vegetarian pay extra attention to sources for the micronutrients below.
Iron is needed to carry oxygen in the blood and for energy production. A low iron intake can result in iron deficiency anaemia, with symptoms such as tiredness, loss of appetite and decreased ability to exercise. Worldwide, iron deficiency is the most common nutrient deficit.
There are two forms of iron in the diet: haem iron found in animal foods such as red meats, seafood, poultry and offal, and non-haem iron found in plant foods including legumes, dark green leafy vegetables, nuts, wholegrain breads and cereals. Non-haem iron is less well absorbed by the body than haem iron.
You can improve your absorption of non-haem iron by eating it with a food rich in Vitamin C eg. citrus fruits and juices, berries, dark green and orange vegetables (particularly broccoli, capsicum and brussels sprouts). Natural substances in tea can decrease absorption of non-haem iron, so it is best to drink tea between meals.
Zinc is required by the body for growth and repair of body cells, playing an important role in ovulation and the menstrual cycle. Zinc is a vital part of many enzyme reactions and assists in wound healing and maintenance of your immune system. Similarly to iron, the best sources of zinc are animal foods, and this is also the most well absorbed form.
Meat is the richest source of zinc, however eggs, milk and milk products include some zinc. Plant based sources of zinc include breads and cereals, legumes, nuts and seeds. Phytates are natural substances in wholegrains and soya beans which can reduce zinc absorption from these foods. Hence it is important to include a range of zinc containing foods, and not rely on one particular food to help meet your requirements.
Meat substitutes are made from vegetable protein, often described as textured vegetable protein (TVP) or nutmeat. Whilst they are not essential, they are a useful source of high quality protein and also contain some iron and zinc. If you are vegetarian have a read of our 'Controverisal Soy....' resource.
Vitamin B12 is vital for blood cell formation and functioning of the nervous system. The best sources of vitamin B12 are animal foods such as meat, fish, poultry, eggs, milk and milk products. Some plant foods also contain vitamin B12, however this form of the vitamin is not useful to the body.
Some non-dairy milks, such as So Good®, contain added vitamin B12 in a form that the body can use. A strict vegan must include foods with added vitamin B12, or take a vitamin B12 supplement. A vitamin B12 deficiency may take years to show up and can have very serious effects, particularly for babies of vitamin B12 deficient mothers who are breast fed for a long period of time. While a supplement may be required during the pre-conception period, a vegan mother is strongly recommended to take a B12 supplement during pregnancy and breastfeeding. It is incredibly difficult to obtain sufficient B12 from plant foods.
Calcium is vital for healthy bones and teeth. It also plays a role in blood clotting and nerve and muscle function. Those who exclude milk and dairy foods also need to carefully plan their diet to ensure adequate calcium as milk and milk products are the best sources of calcium.
Non-dairy milks fortified with calcium are an acceptable substitute. Always check that the products you choose though are fortified. Small amounts of calcium are present in plant foods such as broccoli, hummus, dried fruit and nuts such as almonds, brazil nuts, dried figs. These foods alone will not provide adequate calcium in the diet. To obtain 300mg of calcium (roughly the amount in 1 glass of milk) you would need to eat 12 cups of cooked broccoli or 5 cups of cooked spinach! If avoiding dairy or non-dairy fortified milk a calcium supplement may be necessary.
Extra folate is recommended for any woman trying to conceive. Leafy green vegetables are a fantastic source of folate and many products such as cereal and bread are also fortified with folate. Supplementing with ~400mcg however is still recommended during the pre-conception period and into pregnancy.
When you head to the shops next why not buy some new fruits and vegetables to add a variety of micronutrients to your diet. Grab something you have always wanted to try and learn how to include it in your cooking. Variety is the spice of life as they say.....
Soy contains isoflavones which are phytoestrogens with potential hormonal activity due to their similar chemical structure to estrogen (17-β-estradiol) and compounds that modulate estrogen receptors. This biological activity of soy derivatives has raised the question of whether dietary soy intake influences fertility. The answer is not a definitive yes or no but below is a summary of key evidence investigating soy intake and chance of conception.
In cows and sheep there is clear evidence that grazing on pastures high in phytoestrogens (which are found in soy) impairs ovarian function, reduces conception and increases embryo loss  and may lead to permanent infertility . Given this realisation in livestock it became a focus of research in humans to determine if there was an association between dietary soy intake and fertility, in both men and women.
Intakes in Women
The intake of soy products is most often higher in vegetarian diets where soy is included in the diet as a source of protein. The intake of vegetarian meat replacers, soy milk, and tofu/other soybean products all increases levels of isoflavones. On average, European intake of isoflavones is <1mg per day while women living in China and Japan consume 5–27mg per day. a recent British study reported intakes of ~10mg/day in vegetarian women, compared to an intake of 0.23 mg per day in non-vegetarians , but vegetarian intakes of isoflavones have been reported as high as 150mg a day.
A recent study carried out in North American Adventist women suggests a relationship between isoflavone intake and the chance of having a child . In women with high isoflavone intakes (≥40 mg/day) the lifetime probability of have a live birth was reduced by 3% compared to women with lower intakes (<10 mg/day). Women with higher isoflavone intakes also had a 13% risk of never being pregnant.
Bisphenol A, which you have heard of as BPA, is a chemical found in plastics that has detrimental effects on reproduction, in animals and humans. Data in rats and mice show that certain dietary factors can reduce the harmful effects of BPA and one of these is isoflavones . Does the same hold true in humans?
One study has investigated if soy intake modifies the association between BPA and fertility in women undergoing IVF . In women that did not consume soy products BPA concentrations were related to the chance of a live birth. Women with high BPA concentrations had a 17% live birth rate compared to a much higher birth rate of 54% in women with low BPA levels. In women that did eat soy products (and therefore had a higher intake of isoflavones), there was no relationship between BPA levels and birth rate, suggesting that soy was somehow protective against the adverse effects of BPA on fertility. In women that did eat soy and had low levels of BPA, fertilization rates were similar to women that did not eat soy (72% v 74% in non-soy consumers). A take home message from this study would be to avoid BPA!
Intakes in Men
A comprehensive study that looked at semen quality, morphology and DNA fragmentation has shown that isoflavone concentrations were associated with a lower percentage of normal sperm and increased abnormalities in other sperm health markers . In very overweight men however this association was not as strong, and this is most likely attributable to the fact that being overweight reduces fertility in men by ~50%, regardless of how much soy you eat!
Interestingly another study has shown that Male partner's intake of soy foods was unrelated to fertilization rates, the number of poor quality embryos, accelerated or slow embryo cleavage rate, and implantation, clinical pregnancy and live birth . Isoflavone intake was ~24mg per day in the highest intake group which is much higher than typical western intakes of around 1mg per day but still lower than intakes in Asia which are ~40mg per day.
Studies in healthy males that have added high amounts of soy to diets claim no impact upon sperm  however these intervention studies are often short (~8 weeks). Sperm takes around 3 months to go through the entire production process (from initial growth to being ready for ejaculation) so these studies should be viewed with caution as longer term impacts (> 3 months) need to be investigated.
Take Home Message
Low intakes (~10mg per day) of isoflavones do not appear to have a negative impact upon fertility but there is a chance that higher intakes for prolonged periods may not be conducive to conceiving.
If you are vegetarian your intake of isoflavones is likely to be higher than someone that includes meat in their diet so it is a good idea to do an audit of how much soy you consume. You could look for alternatives in some instances, such as replacing soy flour with high protein wheat flour, or soy beans with lima beans or chickpeas which have a much lower isoflavone content.
1. Adams NR. Detection of the effects of phytoestrogens on sheep and cattle. J Anim Sci. 1995;73: 1509-1515.
2. Tang BY and Adams NR. Oestrogen receptors and metabolic activity in the genital tract after ovariectomy of ewes with permanent infertility caused by exposure to phytooestrogens. J Endocrinol. 1981;89: 365-370.
3. Travis RC, Allen NE, Appleby PN, Spencer EA, Roddam AW and Key TJ. A prospective study of vegetarianism and isoflavone intake in relation to breast cancer risk in British women. Int J Cancer. 2008;122: 705-710.
4. Jacobsen BK, Jaceldo-Siegl K, Knutsen SF, Fan J, Oda K and Fraser GE. Soy isoflavone intake and the likelihood of ever becoming a mother: the Adventist Health Study-2. Int J Womens Health. 2014;6: 377-384.
5. Muhlhauser A, Susiarjo M, Rubio C, Griswold J, Gorence G, Hassold T, et al. Bisphenol A effects on the growing mouse oocyte are influenced by diet. Biol Reprod. 2009;80: 1066-1071.
6. Chavarro JE, Minguez-Alarcon L, Chiu YH, Gaskins AJ, Souter I, Williams PL, et al. Soy Intake Modifies the Relation Between Urinary Bisphenol A Concentrations and Pregnancy Outcomes Among Women Undergoing Assisted Reproduction. J Clin Endocrinol Metab. 2016;101: 1082-1090.
7. Mumford SL, Kim S, Chen Z, Boyd Barr D and Buck Louis GM. Urinary Phytoestrogens Are Associated with Subtle Indicators of Semen Quality among Male Partners of Couples Desiring Pregnancy. J Nutr. 2015;145: 2535-2541.
8. Minguez-Alarcon L, Afeiche MC, Chiu YH, Vanegas JC, Williams PL, Tanrikut C, et al. Male soy food intake was not associated with in vitro fertilization outcomes among couples attending a fertility center. Andrology. 2015;3: 702-708.
9. Beaton LK, McVeigh BL, Dillingham BL, Lampe JW and Duncan AM. Soy protein isolates of varying isoflavone content do not adversely affect semen quality in healthy young men. Fertility and sterility. 2010;94: 1717-1722.
Getting the right amount of protein in your diet plays an important role in maintaining your muscle mass, providing essential amino acids for cell growth and repair and can influence the outcome of assisted reproductive treatments. Protein intakes of at least 25% have been associated with improved IVF success  so here are a few ways to boost your protein intake:
Add a handful of nuts to your salad. Walnuts are a great choice as they contain lots of omega-3 essential fatty acids that have been associated with improved IVF outcomes .
Add hummus to a sandwich or choose hummus as a dipping sauce accompaniment to some celery or carrots. Chickpeas that form the base of hummus are 20% protein.
Having a slice of cheese for a snack, rather than something sweet and sugary, will not only up your protein intake but has been shown to make you feel fuller and eat almost 10% less calories during the day.
A few slices of lean meat or fish on a cracker with some avocado will fill the protein void and with the good fats in the avocado this should stave off any afternoon cravings.
Homemade meatballs made with lean pork or lamb mince packed with grated zucchini, carrot, onion and mushroom (and a pinch of salt and pepper) are a great go to for a high protein snack. Mix the mince and veges and simmer in some tomato passata for an hour or three. Melt in the mouth amazing! Portion them into containers in the freezer and reheat for a protein snack.
1. Russell JB, Abboud C, Williams A, Gibbs M, Pritchard S and Chalfant D. Does changing a patient's dietary consumption of proteins and carbohydrates impact blastocyst development and clinical pregnancy rates from one cycle to the next? Fertility and sterility. 2012;98: S47.
2. Moran LJ, Tsagareli V, Noakes M and Norman R. Altered Preconception Fatty Acid Intake Is Associated with Improved Pregnancy Rates in Overweight and Obese Women Undertaking in Vitro Fertilisation. Nutrients. 2016;8.
Choosing foods which are high in fibre and contain protein will help to keep you feeling full for longer. Finding healthier substitutes for your current snacks may take some planning but is worth the effort!
Sometimes we are unaware of just how much energy we are taking on board in the food and drinks we consume. Using your Food App to monitor your energy intake is a great step to being more aware of your food choices.
Did you Know That....
What’s the secret to improving the quality and quantity of your little swimmers (aka sperm)? Well, there is not really any secret – just eat a healthy, well balanced diet (and getting the right amount of exercise of course). It is an easy answer but not so easy to implement!
What we Know Improves Fertility Outcomes
A recent meta-anlaysis (a scientific way of looking at the outcomes of all studies in a particular area) of observational studies confirms that healthy diets rich in some nutrients such as omega-3 fatty acids, some antioxidants (vitamin E, vitamin C, β-carotene, selenium, zinc, cryptoxanthin and lycopene), other vitamins (vitamin D and folate) and is low in saturated fatty acids and trans-fatty acids are associated with improved semen quality . Conversely, diets rich in processed meat, soy foods, potatoes, coffee, alcohol, sugar-sweetened beverages and sweets have been detrimentally associated with the quality of semen in some studies. It is clear though that a high intake of alcohol, caffeine and red meat and processed meat by males has a negative influence on the chance of pregnancy or fertilization rates in their partners [1, 2].
Your diet influences not just your chance of conception but can leave a legacy influencing the health of your offspring.
Unfortunately no one ‘super food’ is going to rescue your sperm from a high fat diet or a diet high in processed foods. Making healthy choices will give you the best chance of success.
What Could you Include in Your Diet?
Some of the best minerals and vitamins (as whole foods) to incorporate in your diet include:
Vitamin B12: eggs, milk and cheese are great sources of B12. If you are partial to seafood then shellfish such as clams, oysters, muscles and crab, and salmon are loaded with B12. Eating sufficient B12 will boost your sperm parameters .
Vitamin D: Getting some sun is the best way to soak up some Vitamin D but if live far from the equator you may need some additional sources, particularly during winter. One third of Australians are vitamin D deficient! If you are not getting sun then you can obtain some vitamin D (and your B12) from salmon. Fortified dairy and cereal products containing added vitamin D can also be a way to up your intake. You can get your vitamin D levels checked through your doctor with a blood test and if you are just at or below the normal range a vitamin D supplement would be recommended. Vitamin D deficiency impairs the development of sperm and fertility index so make sure you are getting enough !
Zinc and Selenium: Zinc and Selenium are significantly lower in poorer quality sperm  so boosting your diet with whole foods containing these minerals is beneficial. A handful of brazil nuts is a great source of selenium while lean beef delivers selenium and zinc. Fortified multigrain bread and low sugar cereals are also a good source of zinc.
Antioxidants: These powerful free radical quenching vitamins are best sourced by eating a diverse range of fruit and vegetables. A mixed berry smoothie, lots of leafy green vegetables (a great time saver is a supermarket readymade kale-slaw), capsicum, citrus fruit and raw onion are loaded with antioxidants. Make a super quick salad for lunch and a stirfry for dinner to boost your veggie intake for the day. At a minimum aim for 2.5 cups of veggies a day.
Snacks to Get you Through the Day
1.Salas-Huetos, A., M. Bullo, and J. Salas-Salvado, Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies. Hum Reprod Update, 2017. 23(4): p. 371-389.
2.Fu, L., et al., Vitamin D deficiency impairs testicular development and spermatogenesis in mice. Reprod Toxicol, 2017.
3.Najafipour, R., et al., Effect of B9 and B12 vitamin intake on semen parameters and fertility of men with MTHFR polymorphisms. Andrology, 2017. 5(4): p. 704-710.
4.Nenkova, G., L. Petrov, and A. Alexandrova, Role of Trace Elements for Oxidative Status and Quality of Human Sperm. Balkan Med J, 2017.
Controlling your body weight can have positive effects on your general wellbeing and importantly on your fertility, for both men and women.
People who are considered a healthy weight tend to report higher success with assisted reproductive treatments. While reaching a healthy weight may take some time, the good news is that eating well and getting physically active improves your fertility, even before you see changes in your body weight!
Why Do People Gain Weight?
Generally speaking, weight gain is usually the result of eating more than the body needs and not doing enough physical activity over a long period of time. If we constantly take in more energy than our body burns up, the excess energy is stored as fat. If you have Polycystic Ovary Syndrome your body is less sensitive to the hormone insulin, which influences testosterone levels and leads to weight gain so diet and exercise interventions that influence insulin will alter body composition.
Time to Start a New Diet?
There are an endless array of new diets and weight loss methods, all claiming to be the latest miracle cure. Unfortunately, it's not that simple. Most diets and weight loss products offer a quick fix, and are useless for permanent weight control. Some are even dangerous. There is no fast easy way to lose body fat. Fast weight loss which occurs with fad diets or programs is mainly a loss of water and lean muscle tissue. Once you go off the diet, the lost water soon returns. The lean tissue does not come back unless you exercise so your new body will weigh much the same as before but have less muscle and more fat than before.
So How Do I Lose Weight?
The only sure way to lose excess fat is by taking it slowly. Fat on the body doesn't appear overnight and it certainly doesn’t disappear quickly. To lose fat and keep it off, you need to change eating and exercise habits. Starving or skipping meals is not effective. Without food, your body will think it needs to conserve everything you do put into it, storing energy for later and burning up fewer calories. To lose weight, we do not follow a “diet”. By following a sensible, long term healthy eating and activity plan you can successfully lose weight and keep it off.
How Much Weight Should I Lose?
A weight loss of no more than ½ -1 kg per week is recommended. A loss of 1kg per month however is a good goal for many. Most people gain weight over a long period of time and it is unrealistic to expect it to disappear overnight. Slow, steady weight loss is more likely to be sustained, rather than losing a large amount in a short time and having it all come back again, generally with some more. Body weight can fluctuate substantially, depending on the time of day, temporary fluid
retention, menstruation or increasing muscle mass with exercise. You should not weigh yourself any more than once per week. Always use the same set of scales and weigh yourself at the same time of day.
Reducing Energy Intake
Our weight depends on the amount of energy we take in and the amount we burn up. "Energy" comes from the food we eat and is measured in kilojoules (kJ) or calories (cal). Carbohydrate, protein and fat provide energy in foods while water, vitamins, minerals and fibre provide no energy. Alcohol also provides energy.
The energy in the different macronutrients per gram are:
Carbohydrate 16 kJ or 4 calories
Protein 17 kJ or 4 calories
Fat 37 kJ or 9 calories
Alcohol 29 kJ or 7 calories
The three main macronutrients in our diet are carbohydrates, and proteins, and fats. These are essential because they provide us with energy to fuel our basic functions such as sleeping, eating, daily chores, exercise, growth and repair. Each food contains different proportions of macronutrients. For example, yogurt has a combination of all macronutrients, bok choy is a great source of fiber, or carbohydrate, but is virtually fat free and has only a small amount of protein. Meat and nuts are a great source of protein, contain little carbohydrate and fiber, and varying amounts of fats. Given the unique combination of macronutrients of different foods, eating a healthy, diverse range of foods is essential to our health and well being. In addition to macronutrients, it's important to consider the energy that it yields, or the energy that our macronutrients provide to our diet and to our eating plan. So currently, en vogue are low-carb or no carbohydrate diets. People are concerned that they gain weight on carbohydrates. And there's a real move away from including carbohydrates
In addition to getting the balance of our macronutrients right, it is important to consider the energy that our macronutrients provide to our diet and to our eating plan. Low carbohydrate or no carbohydrate diets have become very trendy but focusing on the type of carbohydrate you are eating is important. There is a difference in how the body responds to a handful of lollies compared to eating wholegrain bread. A low carbohydrate diet (<40% of your daily energy needs) has actually been associated with an increase risk of obesity!
The energy content of carbohydrate and protein is almost identical. Removing carbohydrate from the diet means an increase in protein and fat which often leads to a greater energy intake. Carbohydrates are a really important component of a balanced, healthy diet and importantly wholegrain intake has been associated with improved outcomes for fertility treatment. Getting the balance of carbohydrate in your diet right to enhance your fertility is important. Your nutrition plan macronutrient guide is tailored to guide you on the ideal percentage for your eating plan.
Body Mass Index or BMI can be used to provide a general indication of whether you are underweight, normal weight or overweight. Your height and weight are used to calculate your BMI. Determine your own BMI - click here for a link to an online BMI calculator.
Your body mass is made up of fat, lean mass which includes muscle, and bone. In most cases the component contributing to a high BMI comes from fat rather than muscle. A healthy BMI range for fertility is 20-25. Fertility studies have investigated BMI and outcomes for spontaneous conception and assisted reproductive treatments.
Studies have shown a raised BMI is associated with a high risk of reproductive complications in women such as menstrual dysfunction, lack of ovulation, infertility and lower conception rates. In males there is also a relationship between BMI and sperm quality, with increases in BMI (above 25+) associated with reduced sperm count, sperm concentration and semen volume.
Low levels of body fat, indicated by a low BMI (under 20) can also affect fertility and these can be addressed through the right exercise and energy balance.
The good news is that physical activity and diet can improve male factor fertility and the chance of conception in females. Women with a high BMI (30+) that undertake regular exercise and eat healthy before IVF and ICSI have a 3 fold higher chance of getting pregnant and having a baby than those who do not. A 300% increase- that is absolutely HUGE! This increase in chance of pregnancy is realised even without a significant reduction in body weight. That means that no matter what your BMI is - combined exercise and diet will improve your chances!
Your exercise program and nutrition guidance are tailored to your BMI (calculated from your height and body weight). If your BMI is 25 or greater our resource on improving body composition can be found here. If you have a BMI of less than 20 you will find relevant information here.
I underwent my fertility treatment a few years ago and often wondered why no one had yet created a great app to help keep track of the medications for stimulation cycles and frozen transfers, and for all of the appointments! Well- the good news is that I have recently found an app that does just this and more. I talked with the creator of Naula, Paula Campos, and she has been kind enough to share with The IVF Project members her story and information about the app.
This is Paula's Story
As anyone who has gone through any fertility treatments knows, it’s a complicated process, both emotionally and logistically. Simply coming to terms with needing medical help to get pregnant can be a major challenge. Add to that the incredibly complicated and precise nature of the treatment. And needles! It can be the most stressful time in a couple’s life.
After years of trying to conceive, I went through several rounds of infertility treatments. Not only I experience the stress and confusion first-hand, but I was shocked at how arcane the support was for such cutting-edge medical treatments.
Naula was created to help women going through Assisted Reproductive Technology (ART) treatments, manage medications and appointments. Keeping everything in one place was key. It includes the most common treatments IVF, IUI, Egg Freezing, Egg Donation, FET and Surrogacy. We compiled the best instructional videos and added step-by-step instructions with custom illustrations one tap away from your fingerprints. Users get reminders and alerts on their phone no matter where they are.
The ability to instantly add medications and appointments to an easy to use calendar, provide a bird’s eye view of the entire protocol and privately share with loved ones was very important. Having gone through IVF several times, we added a feature that allows users to duplicate a treatment which saves a lot of time. Most importantly, security and privacy was top priority, all of the data transfer and personal information is encrypted and protected.
Infertility is a heavy topic. Emotional support and empathy is not as available as anyone might expect. And, I think for most women and men not being in control is what makes this so hard. It gave me a new perspective about getting pregnant, making a baby, having a family, adopting and also none of the above.
My IVF treatments ended but my journey is not over yet. Creating Naula gave me a new beginning and I will get another chance to write how my story ends.
At the time of writing this the Naula app is free to download. While the app is only available on iOS at the moment there are plans for an android version so stay tuned!
For more information please check out the Naula website: https://www.naula.com/
Once we let you know that we have created your nutrition intake goals (total energy intake and macronutrients) you can start tracking your nutrition. The first step is to download the 'Calorie, Carb & Fat Counter' via Google Play or the App Store links below.
Now you have your Food Diary you can add a food by clicking on the plus sign in the top right.
It opens a screen with all kinds of food products. You can search in the search bar for your product. Once you have found your product, click the product and you can specify how much you have eaten of the product, in this case one banana of 152 grams. You can change the number and weight, and specify for which meal of the day that food applies.
You can see an overview of how many carbs, proteins and fats you eat per day. The food app also syncs with The IVF Project app, when you check your workouts, it will sync with the Food app. Here you also can see how many carbs, proteins or fats a product contains and compare your goals to what you have eaten that day. Click on one of the rounds, and you are getting a summary of your daily goal of protein, and the total amount of eaten that day.
A weekly overview can be found under the menu under 'Performance'. Here you can see the performance of the calories from 1 week, if you click on the 'weekly score' button, you can see how it is with the calories, carbs, protein and fats per week. The app gives you a score on how well you have followed the nutrition plan.
Take the time to read our eating for fertility resources. Any small change is a step in the right direction to improve your chance of success!
There are so many incredible benefits of exercise for those undergoing fertility treatments but it is possible to have too much of a good thing. If you participate in a number of hours of endurance exercise each week and you will be providing a sperm sample for analysis or fertilisation, then read on!
A Delicate Balance
When we are getting an athlete ready for competition it is a delicate balance to ensure they have quality training sessions yet have sufficient time to recover and repair, ensuring optimal adaptations and performance. If we overload an athlete their performance suffers and we see alterations in their biochemical, physiological and psychological profiles.
With increases in training stress we experience increases in oxidative stress. Oxidative stress is important in stimulating training adaptations but too much and it can have negative implications. Sperm is quite susceptible to oxidative stress and indeed research has shown that high levels of oxidative stress (indicated by the lipid peroxidation marker MDA) are associated with increases in DNA fragmentation (1) – not great for baby making.
How Many Hours a Week?
In endurance athletes training 4-5 days per week for ~2hrs (VO2max 62ml/kg/min) sperm parameters such as semen volume, motility, and number of spermatozoa were all lower when compared to recreational exercisers (VO2max 50ml/kg/min) undertaking ~4-5 hours per week at low to moderate intensities (1).
In high level triathletes (VO2max 70 ml/kg/min) with 5 years racing history and training approx. 416 km of swimming, 13,000 km of cycling and 2,600 km of running per year, semen parameters were at the lower end of the ‘normal’ reference range set by the World Health Organization (ranges used in laboratories to determine sperm quality) (2). DNA fragmentation was high (2), supporting similar studies that suggest that high volumes and intensities of endurance training may have negative effects on sperm quality (2, 3).
Put That Mountain Climb on Hold...
Sperm are very susceptible to damage as a result of exposure to oxidative stress. High volumes and intensities of exercise may overwhelm our antioxidant defences designed to counteract oxidative stress, with damaging effects on sperm. Oxidative stress levels also rise when we are exposed to environments where oxygen delivery may be compromised. If you undertake any altitude training or training in a simulated hypoxic environment it would be recommended that you avoid this, particularly in the weeks prior to sample collection.
Exposure to altitude in animals induces changes to reproductive hormones, and reversible fertility impairments in humans (4). In healthy, but older (~47years), mountain climbers a five day climb to Mount Kilamanjaro’s summit (900m to 5895m) led to a reduction in the forward motility of sperm (5). If you are not acclimatised to living at altitude then exposure to extreme altitudes is not conducive to reproduction.
Is Lycra Your Attire of Choice?
If you are partial to donning some lycra and hitting the asphalt it may be time to consider the type of activities you are participating in and whether swapping off on the front on the next bunch ride is going to give your little swimmers the best chance of making healthy embryos.
In trained cyclists undertaking 16 weeks of prescribed training (371 km/wk for 8 weeks then 659 km/wk for 8 weeks) following a four week off season, sperm parameters were negatively affected compared to before training (6). The cyclists had an average training history of just under six years with VO2max values of 64 ml/kg/min). While sperm motility recovered after 7 days of rest, the number of sperm were reduced and sperm abnormalities increased after 30 days of no exercise. In combination with another study that has shown cycling for more than five hours a week is associated with a 92% chance of low sperm concentration (7), it appears that intense and prolonged cycling negatively influences male fertility.
If your preferred mode of exercise is cycling then you may need to reduce the time spent on the bike and importantly limit the number of high intensity exercise sessions.
1. Tartibian B, Maleki BH. Correlation between seminal oxidative stress biomarkers and antioxidants with sperm DNA damage in elite athletes and recreationally active men. Clin J Sport Med. 2012; 22: 132-9.
2. Vaamonde D, Algar-Santacruz C, Abbasi A, Garcia-Manso JM. Sperm DNA fragmentation as a result of ultra-endurance exercise training in male athletes. Andrologia. 2017.
3. Hajizadeh B, Tartibian B, Eghbali M, Asri-Rezaei S. Comparison of seminal oxidants and antioxidants in subjects with different levels of physical fitness. Andrology. 2013; 1: 607-14.
4. Verratti V, Giulio CD. High-altitude hypoxia and reproduction: is there an environmental limit to the human male reproductive system? Sport Sciences for Health 2012; 7: 39-40.
5. Verratti V, Di Giulio C, D'Angeli A, Tafuri A, Francavilla S, Pelliccione F. Sperm forward motility is negatively affected by short-term exposure to altitude hypoxia. Andrologia. 2016; 48: 800-6.
6. Hajizadeh Maleki B, Tartibian B. Long-term Low-to-Intensive Cycling Training: Impact on Semen Parameters and Seminal Cytokines. Clin J Sport Med. 2015; 25: 535-40.
7. Wise LA, Cramer DW, Hornstein MD, Ashby RK, Missmer SA. Physical activity and semen quality among men attending an infertility clinic. Fertility and sterility. 2011; 95: 1025-30.