A recent study published in Nutrition investigated whether muscle-building supplements are associated with deoxyribonucleic acid (DNA) damage in individuals practicing resistance training.
Resistance training enhances muscle strength, endurance, and power and is popular among individuals involved in recreational sports. The proportion of recreational athletes using nutritional supplements for performance and body composition enhancements has increased. Muscle-building supplements are classified into three types based on the evidence of their safety and efficacy.
These are supplements with strong (SESEAS), limited/mixed (LMESE), or little/no (LNESES) evidence to support safety and efficacy. Few studies have evaluated the associations between sports supplements and genotoxicity. DNA damage is a promising approach among the markers of genotoxicity to assess health risks.
About the study
In the present study, researchers explored the potential associations between using supplements for muscle building and DNA damage in individuals on resistance training. This cross-sectional study was conducted among resistance training practitioners aged 18-60 across 14 gyms in Santa Cruz do Sul, Brazil.
Individuals were excluded if they lacked adequate data or declined to provide biological samples. A self-reporting questionnaire was completed by participants that captured data on sociodemographics, training habits, and lifestyle. Body fat percentage and body mass index were determined.
Oral mucosal and blood samples were obtained. Supplements were stratified into one of the three evidence categories. DNA damage was assessed using comet and buccal micronucleus cytome (BMCyt) assays. Lymphocytes were isolated from whole-blood samples; two slides of cells (per participant) were prepared and analyzed under a microscope.
DNA damage was classified based on tail size and intensity. Feulgen was used to stain the prepared slides. Cells were examined for nuclear buds (a biomarker of elimination of amplified or unresolved DNA) and micronuclei (a biomarker of chromosomal missegregation or breakage). Participants were stratified into supplement users and non-users.
Pearson’s chi-squared test and analysis of variance (ANOVA) were used to compare categorical and continuous variables, respectively, among groups. Analysis of covariance (ANCOVA) was performed after adjusting for sex, age, smoking or alcohol status, body fat percentage, exercise type, duration, and frequency.
The study included 307 individuals, mostly males (52%), with an average age of 37.9. Of these, 150 did not use supplements. SESEAS supplements were used more often than other supplement types. Males and individuals under 40 had more frequent usage of supplements. There were significant differences in the type, duration, and frequency of exercises among groups.
Most individuals practiced several exercises; users of LNESES or LMESE supplements practiced more than an hour five to seven times a week. Likewise, SESEAS supplement users exercised for one hour up to seven times per week. Non-users had a significantly higher percentage of body fat than supplement users.
Comet assay revealed significantly elevated DNA damage index and frequency in supplement users than non-users. There were no significant differences in the nuclear bud and micronucleus frequencies in elevated groups. SESEAS supplement users had significantly increased DNA damage index and frequency than LMESE or LNESES supplement users.
To summarize, resistance training practitioners using muscle-building supplements had elevated DNA damage index and frequency in the comet assay. SESEAS supplement users presented significantly higher index and frequency of DNA damage. Nevertheless, micronucleus and nuclear bud frequencies were not significantly different between groups.
The findings suggest a relation between supplements and genotoxic effects and emphasize using supplements cautiously and only to complement the diet. Participants mainly used whey protein and creatine supplements, classified as SESEAS supplements. Prior studies reveal the antioxidant properties of creatine and whey protein supplements.
No significant changes between users and non-users were observed in nuclear buds or micronuclei. This implied that although DNA lesions occurred, they were repaired, preventing chromosomal damage. The significant DNA damage among users identified in the comet assay was not observed in the BMCyt assay indicating damage repair possibly due to the presence of DNA repair agents and antioxidant cofactors in creatine and whey protein supplements.
Therefore, these types of supplements might not cause chromosomal instability. Furthermore, regular exercise can result in low oxidative stress, leading to increased DNA damage repair. Overall, the findings suggest that muscle-building supplements are safe and not associated with permanent DNA damage.