We further conducted stratified analyses to observe changes

We further conducted stratified analyses to observe changes in enzyme levels across the periods by subgroups. Fig. 1 shows the changes in GPx levels by subgroups of age, sex, and smoking status. In all participants, GPx levels decreased when air pollution levels declined but increased after the Olympics when air pollution levels rose. However, the responses after the Olympics differed among subgroups. The magnitude of increase among males, older participants, and smokers was smaller compared to females, younger participants, and nonsmokers. The changes in the former groups were not statistically significant (Fig. 1). Among males, GPx levels decreased from 951.35U/L before the Olympics to 847.79U/L during the Olympics, and the change was statistically significant (P<0.0001). However, after the Olympics GPx levels slightly increased to 868.25U/L (95% CI: 834.16, 902.33), but the change did not reach statistical significance (Table A.1). Similar patterns were seen among smokers and older participants (Tables A.2, A.3). Among all the participants, the trend of TAS activity was different from GPx. TAS levels decreased during the Olympics and continued to decline when air pollution levels rose after the Olympics (Fig. 2). Among younger participants, non-smokers, and females, TAS levels increased after the Olympics. However, among males, older participants, and smokers, TAS levels continued to decrease after the Olympics. The changes in TAS levels after the Olympics did not reach statistical significance among younger participants and nonsmokers (Fig. 2). A significant interaction was observed between air pollution and sex, pinteraction<0.0001. Male TAS levels slightly decreased during the Olympics, from 1.17mmol/L to 1.09mmol/L, and kept decreasing when air pollution levels went up after the Olympics (0.91mmol/L). However, TAS levels in females decreased during the Olympics from 0.90mmol/L to 0.83mmol/L, and then increased after the Olympics (0.91mmol/L), pinteraction<0.0001 (Table A.1). A similar pattern for TAS was seen among smokers and nonsmokers (Table A.3).
Discussion
Conclusions
Source of funding This work was supported in part by the National Institute of Environmental Health Sciences grant awarded to Dr. Lina Mu (Grant number: R01ES018846, R21ES026429) and in part by Department of Epidemiology and Environmental Health, UB School of Public Health and Health Professions.
Introduction Over the last decade, there is increasing awareness that diet markedly affects health and well being of individuals. Association between nutrition and health outcomes has become a MK-571 sodium salt hydrate of concern and understanding this association is important as nutrition related chronic diseases such as obesity, diabetes, cardiovascular diseases and some forms of cancer are major contributions to the global burden of diseases (Dangour, Mace, & Shankar, 2017). Rapid changes in diets and lifestyles due to industrialization, urbanization and economic development are having a significant impact on nutritional status and overall health of population worldwide (Kumar, Kumari, Devi, Choudhary, & Sangeetha, 2017). That food has a direct and substantial impact on health has been known since centuries as indicated in a quote of Hippocrates which aptly says “let food be thy medicine and medicine be thy food” and this concept has been followed since long in many cultures like Chinese, Indian and Greek. In recent years, there has been an upsurge, particularly in the western world, for finding ways to prevent diseases rather than curing them. In this context, antioxidant rich foods have generated a lot of interest and attention as it plays an important role in disease prevention. Antioxidants are substances or compounds which inhibit the oxidation of other molecules in our body and prevent the formation of free radicals by scavenging them. Most of the health benefits of antioxidants arise from their anti-inflammatory properties within the body. The important role of antioxidants is to promote cardiovascular health, to inhibit the growth of cancerous tumors, to slow the aging process in the brain and nervous system, and to lessen the risk and severity of neurodegenerative diseases including Alzheimer's disease and Parkinson's disease (Sanguigni, Manco, Sorge, Gnessi, & Francomano, 2017). Antioxidants are also of immense importance in industries dealing with petrochemicals, food, cosmetics and medicine where they are used for stabilization of polymeric products (Pisochi & Negulescu, 2011). In the food and pharmaceutical industries, antioxidants are used to prevent deterioration, rancidity and discoloration caused by oxidation during processing and storage (Schillaci, Nepravishta, & Bellomaria, 2013). There are several known natural compounds with antioxidant properties that can be extracted from plants, which are mainly phenols, polyphenols, vitamin C, vitamin E, beta-carotene, flavonoids, amino acids and amines that are known to have the potential to reduce disease risk. However, due to lack of natural antioxidants, nowadays most food and pharmaceutical products contain synthetic antioxidants that cause concerns about their adverse effect on health. Hence, more emphasis is given to the use of natural antioxidants (Schillaci et al., 2013).