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Male Gym-Goers Unaware of Fertility Risks From Lifestyle and Protein

A person creating a protein drink in the gym.
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January – it’s that time of year when new gym memberships soar as people pursue New Year’s resolutions to be fitter and healthier. But how many avid exercisers are considering the impact that their gym lifestyle could have on their fertility?

A new study published in Reproductive Biomedicine Online suggests not enough.

Researchers led by Dr. Meurig Gallagher, assistant professor at the Centre for Reproductive Health at the University of Birmingham, surveyed 153 gym-going students between February and March last year. The survey was designed to probe young adults’ level of understanding about the potential impact of exercising and protein supplementation on male reproductive health (MRH).

“Infertility is a problem of increasing concern, affecting one in six people worldwide according to the World Health Organization. Globally, there is limited understanding of the fact that men contribute to half of these cases of infertility,” Gallagher said. “Being healthy and having a healthy lifestyle is a good thing – but there has been a huge surge in the availability of protein supplements with little understanding of what they do to the body.”

The scoop on protein powders

Consuming enough protein is essential for healthy functioning of the human body, where protein is broken down into amino acids.

Protein powder is a supplemental form of protein that can be derived from a variety of animal or plant-based sources. While most people can obtain their recommended dietary allowance of protein (0.8 g/kg) through their diet, an increasing number of people are choosing to add supplements. The global protein supplements market was worth $24.34 billion in 2022 and is estimated to reach $51.81 billion by 2030.

Science is yet to produce concrete answers on how protein supplements affect MRH. A small human pilot study by Ketheeswaran et al. found that abstinence from protein supplementation significantly increased sperm concentration. Chavarro et al. identified an inverse association between soy food intake and sperm concentration in 99 male partners of subfertile couples. “However, studies in rodents have shown conflicting results,” said Gallagher. “The fact that the existing scientific evidence is not settled led us to wonder how much – if at all – the users of protein supplementation considered any impacts that it could be having on their fertility.”

Few men consider how their gym routine impacts reproductive health

The survey asked respondents general questions about their lifestyles and assessed their awareness of MRH. If participants reported using protein supplementation, they were asked why. The researchers also included two focus groups in their study, recruiting participants who may or may not have completed the survey to preserve anonymity.

“It was important for us to understand not just the key facts and figures about protein supplement usage, but also the ‘why’,” Gallagher explained. “Focus groups provide a great way to understand more about people’s perceptions and feelings, which can provide deeper insight into how people react and relate to a topic.”

Over half of the male participants declared thinking about their fertility before, but only 14% had considered the effects that gym routines or the use of supplements might have on it, despite 79% of male respondents using supplements. Gallagher and colleagues found a significant difference in levels of awareness about the effects of high-intensity exercise on MRH across males and females.

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When male participants were asked whether they would change their behavior if they knew it could have long-term effects on their fertility, 76% agreed or strongly agreed. Only 41% would change their behavior if they knew that their gym routine had a short-term impact on fertility.

“Men do care about their fertility when presented with potential negative consequences, but crucially they don’t think about their fertility unprompted,” Gallagher said. “This highlights that we need better and wider education into MRH across society.”

More data on the effects of protein supplementation on reproductive health is required

Of all the factors investigated through the survey, awareness of the potential impacts of protein supplementation was the lowest. “In some senses, I think it was quite an unsurprising finding – the fact that the science itself is full of unknowns suggests that we shouldn’t expect the wider public to have a good grasp of the issues,” Gallagher said.

“I think the prevalence of marketing aimed at the ‘health’ market, and, particularly for men to appear ‘strong’ and ‘virile’, has the potential to give a false sense of security that what people are doing is getting fitter, which must be good for you. It highlights the complexity of health, and how we should be careful consuming things which may have side effects,” he added.

Improving awareness of how a gym routine might impact fertility

The self-report nature of questionnaire-based studies is a limitation that must be considered here, in addition to the fact that the researchers investigated a small number of students in a single geographical location.

Students also self-selected for this project, meaning they could have a higher baselines awareness of the effects of exercise on MRH than the general population. It might also suggest that the lack of awareness surrounding MRH highlighted in this study could be wider than the research suggests.

The research demonstrates the need for a better understanding of the impact of protein supplementation on long-term MRH and educational awareness campaigns for young gym enthusiasts. “There are a small number of groups looking into the effects of supplementation on MRH, including those of Dr. Stine Gry Kristensen and Dr. Peter Humaidan in Denmark,” Gallagher said.

“I am not aware of any specific gym-going awareness campaigns, particularly yet as the science is not fully settled, however the global Male Reproductive Health Initiative (MRHI) is working to raise the profile of MRH more generally. As MRHI points out, this is an area of research that is significantly underfunded, and much more is needed given the scope of the problem,” he concluded.

Dr. Meurig Gallagher was speaking to Molly Campbell, Senior Science Writer for Technology Networks.