Background: Excessive intakes of vitamin A have been shown to have adverse skeletal effects in animals. High vitamin A intake may lead to an increase

The COVID-19 pandemic changed various lifestyle habits worldwide due to the prevention measures implemented in each country, these changes may affect or benefit people’s health. We aimed to systematically review changes in diet, physical activity (PA), alcohol consumption, and tobacco use habits during the COVID-19 pandemic in adults. Two databases: PubMed and ScienceDirect, were used for this systematic review. The research was limited to open-access, peer-reviewed original articles published in English, French, or Spanish from January 2020 to December 2022 and investigated diet, PA, alcohol consumption, and tobacco use habits before and during the COVID-19 pandemic in adults. Excluded studies were review studies, intervention studies with a sample size of fewer than 30 participants, and poor-quality articles. This review followed PRISMA 2020 guidelines (PROSPERO: CRD42023406524), whereas to assess the quality of the studies, we used the quality assessment tools developed by the BSA Medical Sociology Group for cross-sectional studies and the QATSO for the longitudinal studies. Thirty-two studies were included. Some studies reported changes to promote healthy lifestyles; 13 out of 15 articles reported an increase in healthy diet consumption habits, 5 out of 7 studies reported a decrease in alcohol consumption, and 2 out of 3 studies reported a decrease in tobacco use. On the other hand, the other studies reported changes to promote unhealthy lifestyles: 9 out of 15, and 2 out of 7 studies reported an increase in unhealthy diet and alcohol consumption habits respectively, 25 out of 25 reported a decrease in physical activity, and 13 out of 13 reported an increase in sedentary behavior. During the COVID-19 pandemic, there have been changes to promote a healthy and unhealthy lifestyle; the latter can affect people’s health. Therefore, effective responses are needed to mitigate the consequences.

Telomere length (TL) is a predictive biomarker of premature aging. Telomere shortening has been linked to age-related diseases and noncommunicable diseases (NCD), and may reflect the effects of behavioral, psychosocial and environmental factors on health status. Telomere attrition can be affected by lifestyle factors such as diet and physical activity. The search of studies included in this review was conducted on PubMed Central database. A majority of studies are cross-sectional, as there is a clear lack of prospective studies to evaluate the individual effect of dietary components, dietary patterns, and physical activity on TL in the long term. The current literature suggests that high adherence to Mediterranean diet (MD), with consumption of antioxidants, fiber and vegetables, as well as seeds and walnuts, is associated with longer TL. The dietary components of a healthy diet, such as carotenoids, vitamins A, C, D, E, polyphenols, fiber, and omega-3 fatty acids could help maintain TL. In contrast, a high consumption of sugary beverages, processed meat, and proinflammatory diets is associated with telomere shortening. In a majority of studies TL is positively associated with moderate physical activity. The predominant mechanisms through which a healthy diet and moderate physical exercise could mitigate telomere attrition include decreasing oxidative stress and inflammation. We shall not discuss the associations of possible risk or protective factors in terms of causality since the majority of studies are cross-sectional and randomized controlled trials are limited; accordingly, some results are inconclusive. For future research, we suggest evaluating the individual effects of dietary components, dietary patterns and physical activity, considering repeated measurements and exercise intensity, on TL. It is also advisable to include biomarkers of oxidative stress and inflammation proteins, and to measure telomerase activity.