Think testosterone and you typically think of the male sex drive. However, the hormone is actually found in both men and women and its purpose extends far beyond sex drive and fertility.
"Testosterone regulates sex drive, bone mass, fat distribution, muscle mass and strength and is also used in the production of red blood cells," says Dr Luke Powles, Associate Clinical Director at Bupa Health Clinics.
The bad news? Research has indicated that in men, levels of this vital hormone begin to steadily decline between the ages of 30 and 40.
“It’s the natural thing for a man or a woman – when we get unwell – to divert resources from reproduction into survival and so our sex hormone levels fall," explains Dr Richard Quinton, from the Society of Endocrinology and Senior Lecturer at Newcastle University Institute of Genetic Medicine. “The overwhelming elements of the fall in testosterone with age relates to the fact that as you get older, generally you are sicker and are more obese – and that’s a natural phenomenon."
In recent years, there has been a surge in supplements, treatments and therapies all promising to artificially increase testosterone levels, but here are some natural ways to boost them...
1. Get moving
For those looking to boost their testosterone levels, personal trainer Matt Roberts advises an exercise technique known as agonist-antagonist training, which he explains in the video below.
The technique consists of lifting exercises that engage both sides of the body, such as the chest and back. For ultimate effectiveness, he recommends doing 8-10 repetitions of exercises such as loaded squats and lateral lunges.
Exercise is also recommended by Professor Richard Sharpe, Principal Investigator at Edinburgh University's MRC Centre for Reproductive Health: “My view is that you are better to let your own body sort out your testosterone levels than resort to therapy," he says. "The way to do this is to eat a healthy balanced diet and do plenty of exercise so that you don’t pile on the weight as you age.”
Dr. Kesson Magid, a researcher in Endocrinology at Queen Mary University of London, agrees: "Muscle is one of the most responsive parts of the body to testosterone, and weight training has a very short-term effect of increased testosterone.
"Over time, with regular exercise it is likely that a man’s average daily testosterone will increase from whatever it was before he started exercising, but obsessing about the absolute levels of testosterone is not very useful.
"Since men differ in how sensitive they are to testosterone, what may be a big change for one will not appear to be very noticeable to another."
2. Eat well
A balanced diet is also key to maintaining healthy testosterone levels.
“We know that if you are a slim fit healthy man, your testosterone levels are very similar to younger men," says Dr Richard Quinton from the Society of Endocrinology. “So if you asked me, is there a natural way to boost testosterone levels – I’d say yes, stay healthy.”
This sentiment is shared by Bupa's Dr Luke Powles who recommends a diet rich in essential nutrients: "Eating foods with more whole grains or shellfish including zinc may help regulate testosterone levels. Potassium - which aids testosterone synthesis - can be found in bananas, beets and spinach."
However, registered nutritionist Rhiannon Lambert warns that a multitude of variants can influence hormone levels within the body. "Diet alone isn't the answer, exercise, genetics, sleep, stress and so many factors play a role.”
3. Get some sunshine
In 2010, Austrian researchers from the Medical University of Graz found that levels of testosterone in the body can be increased by vitamin D.
The team analysed 2,299 men and discovered that those with at least 30 nanograms of vitamin D per mililitre of blood had higher amounts of testosterone than those who had lower levels of vitamin D.
The study, published in the Clinical Endocrinology journal, also indicated that levels of testosterone peaked in August and were lower throughout the winter months.
However, experts have warned that it is still important to be sensible in the sun. Helen Callard, Cancer Research UK’s health information officer, says: “Some sun exposure raises people’s vitamin D levels, but too much damages the skin and raises the risk of skin cancer.
“Anyone worried about their own levels of testosterone or vitamin D should speak to their doctor for advice, rather than risk skin damage from being in the sun too long. And if you are outside when the sun is strong, you can protect your skin with a combination of shade, clothing and sunscreen with at least SPF15 and 4 or 5 stars.”
4. Should you take testosterone supplements?
Supplements, which can be purchased online for as little as £5, have in recent years gained substantial popularity and offer users a quick fix to supercharge their testosterone levels.
The research behind these supplements is still in its infancy. Last month for example, a new study published in the Lancet found that menopausal women who took testosterone supplements experienced increased sex drive, sexual satisfaction and sense of wellbeing. However, some experts have advised that taking supplements can disrupt the natural balance of hormones within the body.
"Testosterone works as part of a network of hormones, where higher levels of one hormone signals other hormones to go down," explains Dr Majid. "When men take extra testosterone, this throws the network off balance and eventually leads to less testosterone being made by the body than was being made before taking the supplement."
According to Dr Powles, the side effects of these supplements can also be considerable. "Taking supplements can lead to liver toxicity and while doctors can prescribe the supplement, it is usually avoided. Only older adults with severe clinical symptoms of low testosterone should be candidates for these supplements.
"Research has shown that testosterone supplements can cause more problems than they solve, including increased risk of heart problems. Side effects can include sleep apnea, acne flares, enlarged breasts and testicular shrinkage."
5. What about testosterone replacement therapy?
Dr Powles believes that testosterone replacement therapies should only be used if it is medically suitable. “In the UK, testosterone therapies are only recommended by medical professionals if a man has symptoms of testosterone deficiency. This is verified with a blood test which will show low testosterone levels."
“If the results show a low reading, you may be referred to an endocrinologist, who specialises in hormone problems.
"Following a consultation and if the specialist confirms the diagnosis, you may be offered testosterone replacement therapy to correct the deficiency and relieve symptoms”
Research is still ongoing to determine the risks, however a recent article published by Harvard Medical School highlighted that longer term therapy treatments have been linked to increased risk of cardiovascular issues such as heart disease and strokes.
Dr Powles says that the potential downsides are dependent on a range of factors and ought to be considered on a case by case basis. "Testosterone therapy has various risks, which should all be discussed with a medical professional before taking action. Potential side-effects are wide-ranging and can be dependent to a degree on the form of testosterone replacement therapy used."