Abstract (eng)
The complex process of aging is a result of various biochemical mechanisms that accumulate throughout life and cause senescence of the body. The interacting hallmarks of aging include, amongst other things, the genomic instability with accompanying loss of gene function, telomere attrition with increasing age, epigenetic changes, deregulated nutrient sensing and most important to this work; the accumulation of RONS. The Free Radical Theory of Aging is based on the increased levels of free radicals and related prooxidants that can cause damage to cellular constituents, which, over the time, results in oxidative stress leading to structural and functional impairments of the body.
In view of the increasing life expectancy, it is especially important for older people to follow a healthy lifestyle to keep the pro- and antioxidant homeostasis in balance. A healthy diet and regular physical activity are two key elements that can maintain well-being, performance and independence of the older generation.
Nutritional choices should therefore focus on protein- and nutrient-rich products in the elderly; the DGE currently gives an estimated value of 1 g/kg/KG/d of protein for people 65 years and older. In addition, a coordinated resistance training program should be performed 2 to 3 times a week to maximize muscle adaptation.
Furthermore, resistance training may improve the adaptation of the antioxidant protection system and consequently mitigate the effects of oxidative stress in healthy elderly people. The aim of this master’s thesis was to investigate the effect of increased protein intake alone and in combination with resistance training on antioxidant capacity in elderly individuals. For this project, on the one hand, the FRAP assay was used to analyze the TAC of the subjects. This assay determines the antioxidant activity in terms of their iron-reducing capacity. On the other hand, the content of reduced GSH and oxidized GSSG was detected, and the ratio of both thiols was calculated to quantify the antioxidant potential.
The participants were randomly divided into three groups. There was a control group which diet and physical activity were not to change. The PL group had to focus on the D-A-CH reference values for recommended protein intake for 65 years and older, i.e., 1 g/kg/KG/d protein while the PH group had a notable increased intake of 1,6 g/kg/KG protein per day. Both intervention groups participated in an eight-week resistance training program twice per week after six weeks of dietary intervention. There were three measurement time points for medical, anthropometric, and functional surveys: T1 at baseline, T2 after eight weeks of
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protein intervention, and T3 after continuing protein intervention with additional eight weeks of strength training intervention.
The results showed that the increased protein intake in the PH group, significantly (p = 0.002) reduced FRAP concentration [μmol/l] in males and the total group (p = 0.001).
The additional strength training decreased the FRAP concentration [μmol/l] non significantly. The effects were observed for males as well as for both sexes. However, women generally have a lower total antioxidant capacity than men.
For GSH, GSSG, and the GSH/GSSG-quotient, no significant changes in antioxidant potential were observed by the dietary and exercise interventions in either sex. There was exclusively a negative correlation (r = -0.328; p = 0.008) of the GSH/GSSG-ratio, as only males showed a lower ratio of the antioxidant redox couple at increasing age.
In conclusion, excessive protein intake may imbalance the total antioxidant potential. However, this can be compensated by physical exercise, as seen by the FRAP values of the PH group.
Further studies are needed to better understand the effects of oxidative stress through pre- programmed RONS generation in older individuals as well as exercise-induced free radical production. The same can be said about the increased protein intake for people aged 65 and older.