Tracy M. Covey

Background/Objectives: Carotenoids are pigmented phytochemicals known for their antioxidant properties, known to protect against oxidative damage, especially in the context of intense exercise. The purpose of this paper was to observe and analyze the short-term effects of running a full marathon on skin and plasma carotenoid levels in endurance runners. Methods: This study recruited 24 healthy endurance runners (12 male, 12 female; mean age 37 years) registered for a 26.2-mile marathon. Skin carotenoid (SC) measures were taken via reflection spectroscopy, and plasma carotenoid concentrations (lycopene and β-carotene) were assessed via HPLC at three time points: pre-race, immediately post-race, and 48 h post-race. Changes across time were analyzed using repeated-measures ANOVA. Results: Skin carotenoid levels significantly changed over time, dropping from pre-race to post-race (p < 0.001), reflecting rapid utilization. At 48 h post-race, SC levels rebounded significantly, exceeding baseline measurements (p = 0.019). Plasma lycopene concentrations increased significantly from pre-race to post-race (p = 0.018) and remained elevated at 48 h. Plasma β-carotene concentrations showed no statistically significant change. Conclusions: The significant acute depletion of SC levels immediately following the marathon reflects the rapid utilization of these dermal antioxidants in response to the high oxidative stress generated by intense exercise. The elevation in plasma lycopene may reflect hemoconcentration resulting from intense activity and possible mobilization from tissue stores. The rapid rebound and overshoot in SC levels 48 h after the race are consistent with a recovery pattern of dermal carotenoid levels following acute depletion.

Photobiomodulation (PBM) therapy has numerous documented health benefits, but the physiological mechanisms are still being elucidated. In this work, a pilot study of salivary biomarkers was investigated to potentially understand physiologic oxidative stress changes associated with PBM therapy. Eighteen participants completed six PBM sessions and provided saliva samples prior to session one and after each of the six sessions. Salivary uric acid, acyl peptide enzyme hydrolase (APEH) activity, and total protein were measured. While salivary uric acid and total protein have been measured before, APEH is a novel salivary marker. When grouped into ‘heightened risk’ categories, 67% of participants with high starting uric acid had a reduction in salivary uric acid and 57% of participants with low starting APEH activity had an increase in salivary APEH activity over the six PBM sessions. While a larger and more comprehensive study is required to make conclusions, this pilot study suggests that PBM therapy has beneficial outcomes to selected oxidative stress markers, thereby providing a physiological mechanism that may accompany reported positive biological outcomes.

Type 2 diabetes mellitus (T2D) is a chronic metabolic disorder characterized by hyperglycemia and insulin resistance, which the CDC estimates currently afflicts one in ten U.S. adults and is projected to continue to rise sharply over the next 50 years. Acyl peptide enzyme hydrolase (APEH), an enzyme circulating in peripheral blood, has been implicated in rodent models of diabetes. To understand if APEH is affected in diabetes, the APEH activity was measured in the blood serum of patients with T2D compared to age-matched controls. Our results show that APEH activity is 22% lower (p = 0.0163) in T2D patients compared to matched controls. Importantly, there was no observable difference in APEH protein expression between cohorts, suggesting that APEH activity is regulated at the protein level. This work is important as it contributes to our knowledge of T2D and the role of APEH in human disease.