Determinantes dietéticos de la fragilidad y la multimorbilidad en adultos mayores

Abstract

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Medicina Preventiva y Salud Pública y Microbiología. Fecha de Lectura: 05-09-2024Esta tesis tiene embargado el acceso al texto completo hasta el 05-03-2026The world population is aging at an upward pace. By 2050, the number of individuals over the age of 65 will exceed the number of children under the age of 5, adolescents, and young adults. Aging is associated with the accumulation of molecular damages and reduced physiological reserve that led to functional declines. The loss of function can be considered a proxy for the aging process, and it is reflected in the development of geriatric syndromes. Frailty and multimorbidity are two complex phenomena with major implications for older adults. They are highly prevalent in older age and are associated with the onset of adverse health-related outcomes, impaired quality of life, disability, and mortality. Moreover, they impose a significant burden on healthcare systems. Identifying lifestyle behaviors, such as adequate nutrition, that could help in the prevention and management of these conditions has become a priority in the field of healthy aging research. A substantial body of literature has shown that adherence to healthy dietary patterns, such as the Mediterranean diet, diet quality, and consumption of fruits and vegetables, are associated with a reduced risk of impaired physical function and frailty. The current focus of research is the identification of key nutrients. In Study I, we investigated the association of habitual zinc intake through diet with impaired lower-extremity function and frailty among adults aged 60 years and older from the Seniors-ENRICA 1 cohort. Zinc is a trace element with anti-inflammatory and proantioxidant mediation activity. We found that higher habitual intake of zinc was associated with lower risk of ILEF and frailty. In Study II, we investigated the associations of dietary leucine intake with ILEF and frailty in the same cohort. Leucine is a branched-chain amino acid that plays a central role in muscle protein synthesis pathways. We found that higher leucine intake was associated with reduced risk of ILEF and frailty. Higher consumption of important sources of leucine such as unprocessed beef, oily and white fish, and bread were also associated with the outcomes. These studies identify potential key nutrients in the prevention of frailty and the maintenance of physical function into old age. The investigation of the relationship between dietary factors and multimorbidity is a relatively recent field of research with many knowledge gaps. In Study III, we aimed to assess the prospective association between adherence to a micronutrient-based diet quality index and incidence of complex multimorbidity. Higher micronutrient adequacy was associated with lower risk of multimorbidity in 1461 community-dwelling older adults from the Seniors-ENRICA 2 cohort. In Study IV, we examined the prospective association between quality of plant-based diets and incidence of complex multimorbidity in a representative sample of middle-aged and older adults from the U.S, comprising the Health and Retirement Study. We found that adherence to a healthful plant-based diet was associated with lower risk of multimorbidity, while higher adherence to an unhealthful plant-based diet was not associated with multimorbidity. In Study V, we examined diet quality in association with the number of chronic conditions and the rate of multimorbidity development in the Seniors-ENRICA 2 cohort. Higher adherence to the AHEI- 2010 was cross-sectionally and longitudinally associated with lower number of chronic health conditions, and with a lower rate of multimorbidity development. Findings in these studies suggest that improving nutritional adequacy of diet, high-quality plant-based diets and the overall diet quality may help prevent the development of complex multimorbidity. Lastly, the Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) has updated the Spanish dietary guidelines by incorporating the latest evidence of the impact of diet on health as well as the sustainability dimension. Given the relevance of this report in the national context, we propose, in Study VI, the Sustainable Dietary Recommendations for the Spanish population Index (S-DRSI) to estimate adherence to these guidelines in a populationbased study of community-dwelling adults from Spain; and secondly, we examined the association between the S-DRSI and all-cause mortality in this population. We found that adherence to the guidelines was relatively poor, and that the S-DRSI reflected optimal intake of key nutrients and was associated with lower risk of all-cause mortalityThis doctoral thesis has been funded by the grants FIS 20/1040, 19/319, 22/1111, 23/272 (Instituto de Salud Carlos III, State Secretary of R+D+I and European Regional Development Fund/ European Social Fund), and co-funded by a European Regional Development Fund, “A way of shaping Europe”. Veronica Vega Cabello was supported by the “Training of university professors - FPU” grant (FPU19/06572) and “Supplementary mobility grant for FPU” (EST23/00086) from the Spanish Ministry for Universitie