According to the findings published in the journal Physiologia, social media was a primary channel of information, with a notably small proportion trusting healthcare professionals to advise about protein supplements.
Participants reported various side effects from protein supplementation, and many believed the products undergo regulatory processes similar to those for medications.
“Despite the perceived benefits, reliance on non-expert sources and unregulated products raises concerns about consumer awareness and safety, while educational initiatives to promote evidence-based supplementation practices are deemed crucial,” wrote researchers at Democritus University of Thrace and other universities in Greece.
Valuable insights
While many studies on protein supplements have been conducted among sports professionals and elite athletes, the researchers note insufficient and conflicting evidence regarding influencing factors for supplement use among non-professional fitness enthusiasts.
Fitness trends and increased interest in body image, healthy lifestyles and well-being have driven a rise in protein supplement consumption among the general population.
However, the researchers of the study note that excessive protein intake has been associated with adverse effects, such as kidney damage, gastrointestinal symptoms and nutrient imbalance. And protein supplements often contain minerals like iron and zinc, which can be toxic at high levels or cause an imbalance in other minerals.
With a vast selection of protein supplements available, featuring different types of protein and additional micronutrients, consumers may find it challenging to determine what suits their individual needs. They often rely on general information available on the internet and from influencers.
The current study “emphasizes the need for targeted educational initiatives to improve awareness of safe PS [protein supplement] practices among non-professional athletes and fitness practitioners,” the researchers noted, adding that regulatory bodies should consider “strengthening supplement oversight to ensure product quality and accurate labeling.”
Study details
The cross-sectional study employed a questionnaire to collect information about protein supplement use, exercise habits and demographic factors.
They recruited 1,100 respondents from gyms, athletic organizations, amusement parks and playing fields.
There were 327 protein supplement users, of whom 62% were male, 42% were between the ages of 25 and 34, and 58% had a normal body mass index (BMI). Consumption was higher among participants who were not employed in sports-related fields and non-smokers.
Engaging in more than two types of physical activity and following high-intensity fitness exercise sessions more than doubled the odds of consuming protein supplements, and half of those who engaged in more than two activities reported that protein supplements are beneficial for health.
Protein powder was the most popular supplement, with 64% of supplement users opting for this, primarily post workout. The primary reasons reported for taking protein supplements were to increase muscle mass (35%) and enhance recovery (18%).
However, there were some adverse effects reported: sleep disturbances (16%), aggression (14%), nausea (12%), changes in hematology tests (12%), high blood pressure (12%), aches (11%), dizziness (9%) and allergic reactions (8%).
The participants reported that their primary sources of information about protein supplement use were the internet and social media (40%) and coaches (43.2%), particularly among fitness enthusiasts.
“Notably, only a small proportion of PS [protein supplement] users expressed trust in healthcare professionals (HCPs) as a source of PS-related information,” the researchers wrote, adding that “many participants believed PS undergo regulatory processes similar to medications, reflecting misconceptions about supplement safety.”
“Importantly, this research contributes to public health discussions by identifying areas where educational and regulatory interventions can promote safer and more informed PS practices,” they concluded.
The researchers acknowledged some study limitations and called for further research.
Source: Physiologia 2025, 5(2), 18. doi: 10.3390/physiologia5020018. “Trends in Protein Supplement Use Among Non-Professional Athletes: Insights from a Survey in Greece”. Authors: P. Athanasopoulou et al.
