Testosterone is the main hormone which regulates sperm production but it does not necessarily follow that high testosterone levels means high sperm production. Those gym bunnies who supplement their diets with testosterone either by injection or other means, are often  hairy, sweaty and strong but the chances are, they wouldn't make it into the olympic sperm squad. In fact, very high levels of testosterone can stop sperm production. Sperm production is complex and relies on the normal function of the testicles, other glands and a delicate transport system. Conditions need to be optimal for men to produce plenty of high quality, healthy sperm.

And it is not all about the numbers. Count is important but the way the sperm swim and the integrity of the DNA they are transporting, also matter. 

Here are some pointers to getting yourself  good sperm:

1. Keep cool; especially your testicles. They hang outside the body because sperm is best produced at a core temperature of about two degrees below body temperature. Anything that heats up your testicles – such as hot baths, tight underwear and working in a hot environment, can lower your sperm count. Therefore, try to keep your testicles cool..

2. Don't smoke. Don't ever smoke, and if you do, give up because nicotine will harm you and your sperm.  By quitting smoking, you can reduce the amount of “free radicals” (oxidative stress) your sperm is exposed to. This prevents potential DNA damage and can improve the quality of your sperm, in turn, making them more likely to be successful in fertilisation.

3. Eat well. Avoid junk food. Give yourself a treat now and again but if you eat rubbish, don't naturally expect to have great sperm. It just doesn’t work like that. 

Research has shown that men’s diets are affecting their fertility. By ensuring you’re eating lots of fruit and vegetables, and a range of nutritious foods, you can help create and maintain healthy sperm. Many nutrients such as Vitamin B9 (folate), Zinc, Omega 3 and Vitamin D are key to keeping your sperm in tip top condition. These are all readily available in a balanced diet.

4. Try not to be overweight. Overweight, and underweight people for that matter, can be less fertile than those of a normal weight. To calculate your Body Mass Index (BMI), divide your weight in kilograms by your height in meters squared and the result should ideally be between 18.5 and 24.9, according to the World Health Organisation..

5. Be active. Besides being beneficial to your health overall, regular exercise can boost testosterone levels and improve fertility. Studies show that men who exercise regularly have higher testosterone levels and better semen quality than inactive men. 

6. Keep it natural. Health supplements are of little benefit, especially if you eat and live well. It’s sometimes hard to believe what some health foods claim to provide you with. A good healthy diet should be all you need and if you want to give your sperm an extra boost, you could take some  zinc or vitamin E supplements. There is no need to go for the reassuringly expensive “Superman Supplements” – it’s all marketing and there is little evidence to support their use. In fact, some can have nasty side effects.. Long term steroid use can interrupt the hormones responsible for sperm production being released naturally and sperm production can cease; sometimes irreversibly.

7. Have a healthy sex life; the tubes in and around your testicles need clearing out every few days. Sitting in the testicles for longer than this is not good for the sperm.

8. Check your medication. If you have to take medication and you are trying for a baby, be sure to ask your doctor about its effect on sperm production and for an alternative treatment, if necessary.

9. Think about your medical history. If you suffered from undescended testicles as a child, or any other below the belt operations, or if you have suffered from a serious illness, this may have harmed your testicular health.

As it takes about 10 weeks to make sperm, a recent period of illness or high temperature can affect the manufacturing of your sperm. If this is detected by a semen analysis, you may be asked to repeat it in a few months to allow for recovery and to make new sperm.   

10.  Alcohol. Alcohol can be detrimental to sperm production so be careful what you drink. Too much alcohol can  impact your fertility and also the health of the baby. Occasional drinking will most likely not cause harm but a significant reduction in intake is well worthwhile if you drink regularly and excessively.

11.  Oxidative Stress.  All of our cells (including sperm) use the oxygen we breath to produce energy, but this causes highly reactive molecules, known as free radicals or reactive oxygen species, to be produced which can cause damage to cells and tissues. High levels of oxidative stress can cause changes in the sperm cell membranes, affecting their shape (morphology) and motility, as well as causing damage to their DNA. Taking in enough antioxidants, such as vitamin C, in fresh fruit and veg, may help counteract some of these harmful effects.

Remember that sperm counts can vary significantly over time which is why repeating the test can be a good idea if parameters are outside normal limits.

Don’t forget, sperm are amazing cells. We estimate that to swim from the testicle to the egg is about the equivalent of a man swimming from Liverpool to New York at 600 miles per hour! They are remarkable, so look after them - they may just change your life.