Conclusion
MNi
OXIDATIVE STRESS, CHROMOSOMAL INSTABILITY, LACK OF VITAMINS
Our analyses of chromosomal damage in PBMCs in a cohort of 100 community-dwelling older adults add important insights to the field of DNA stability, oxidative stress and mutagenesis. To our knowledge, we were the first who investigated the effect of different vitamin D regimens in older individuals during an ongoing strength training period of 10 weeks while receiving vitamin D supplementation at the recommended level of 800 IU per day vs. a single dose of 50.000 IU per month. Although we did not detect major effects of vitamin D supplementation on some parameters of chromosomal instability after the intervention, we observed some interesting tendencies of major chromosomal instability parameters. For instance, the number of NPBs was significantly reduced by 24% only in the vitamin D intervention group that received the recommended 800 IU daily. Moreover, the increase in MNi frequency, that might have been caused by the intensity of the strength training between T2 and T3, was the smallest in the VDD group. Interestingly, either the lack of vitamin D supplementation in the control group as well as vitamin D supplementation well above the recommended levels of 800 IU in the VDM group might have further increased chromosomal damage. Our results suggest that oxidative stress might have played a role in the detrimental progress on chromosomal stability parameters since the protective effect of GSH was reduced in all study groups at the end of the intervention, but the least reduction occurred also in the VDD group. Interestingly, the GSH:GSSG ratio increased only in the VDD group during the sports intervention. FRAP antioxidant capacity was reduced in all study groups, but the least reduction could be observed in the VDD and VDM groups at the end of the study. These results indicate that a supplementation with the recommended dose of 800 IU vitamin D per day might be more advantageous when it comes to chromosomal stability parameters such as MNi frequency and NPBs in older, formerly untrained participants undergoing demanding resistance exercise for 10 weeks. However, these effects might be more pronounced in old participants with even lower levels of vitamin D and should be considered in future studies.