Coffee, vitamin K and physical limitations among older adults

Resumen

GENERAL SUMMARY The aging population is a great challenge for modern societies, and therefore, ensuring healthy aging is essential to achieve a good quality of life in the elderly. Physical function impairment, frailty, disability and falls are major challenges facing the public health of the twenty-first century, as they compromise the quality of life of the elderly, increase the cost of the health system and increase the risk of adverse health outcomes. Lifestyles, such as diet and physical exercise, are modifiable factors that play an important role in the development of diseases, and therefore, knowing the dietary determinants that predispose to the public health problems mentioned above is important in order to design policies and strategies to prevent their development. This doctoral thesis aims to clarify the effect of habitual coffee consumption on the development of functional limitations, frailty and disability, as well as its effect on the risk of falls in elderly people, since coffee is the most consumed beverage in the world after water; therefore, any effect on health associated with this consumption have a high impact on the population. In addition, this thesis also analyzes the effect of vitamin K on frailty, measured with a plasma biomarker, which allows to take into account not only the intake, but also the biodisponibility of this vitamin. Therefore, this thesis covers two complementary approaches in Nutritional Epidemiology: the study of self-reported information on habitual diet and the study of biomarkers of nutients exposure. Summary to Article 1 Background: Habitual coffee consumption has been associated with lower risk of type 2 diabetes and cardiovascular disease. Since these diseases are main determinants of functional limitations, we assess the hypothesis that coffee consumption was associated with lower risk of physical function impairment, frailty and disability in older adults. We focused on women and those with obesity, hypertension or type 2 diabetes because they are at higher risk of functional limitations. Methods: Prospective study with 3,289 individuals ≥60 years from the Seniors-ENRICA cohort. In 2008-2010 coffee consumption was measured through a validated dietary history. Participants were followed-up until 2015 to ascertain incident impaired physical function, frailty and disability, assessed by both self-report and objective measures. Results: Compared with non-drinking coffee, consumption of ≥2 cups of coffee/d was associated with lower risk of impaired agility in women (hazard ratio [HR]: 0.71, 95% confidence interval [CI]: 0.51-0.97, P-trend: 0.04) and in those with obesity (HR: 0.60; 95% CI: 0.40-0.90, P-trend: 0.04). Intake of ≥2 cups of coffee/d was also linked to reduced risk of impaired mobility in women (HR: 0.66; 95% CI: 0.46-0.95, P-trend: 0.02) and among individuals with hypertension (HR: 0.70, 95% CI 0.48-1.00, P-trend: 0.05). Moreover, among subjects with diabetes, those who consumed ≥2 cups/d had lower risk of disability in activities of daily living (HR: 0.30, 95% CI: 0.11-0.76, P-trend: 0.01). Conclusions: In older people, habitual coffee consumption was not associated with increased risk of functional impairment, and it might even be beneficial in women and those with hypertension, obesity or diabetes. Summary to Article 2 Background: Habitual coffee consumption has been associated with lower risk of type 2 diabetes, cardiovascular disease and sarcopenia, which are strong risk factors of falls. In addition, caffeine intake stimulates attention, vigilance and reaction time. Therefore, a protective effect of coffee on the risk of falling can be hypothesized. Objective: To examine the association between habitual coffee consumption and the risk of ≥1 falls, injurious falls, and falls with fracture in older people. Design: Data were taken from 2,964 participants ≥60 years from the Seniors-ENRICA cohort and 8,999 participants ≥60 years from the UK Biobank cohort. In the Seniors-ENRICA study, habitual coffee consumption was assessed with a validated diet history in 2008-10, and falls were ascertained up to 2015. In the UK Biobank study, coffee was measured with 3 to 5 multiple-pass 24-h food records starting in 2006, and falls were assessed up to 2016. Results: A total of 793 individuals in Seniors-ENRICA and 199 in UK Biobank experienced ≥1 falls during follow-up. After multivariable adjustment for major lifestyle and dietary risk factors and compared with consumption of <1 cups/d of coffee, the pooled hazard ratio (HR) and 95% confidence interval of ≥1 falls was 0.75 (0.52, 1.07) for 1 cup/d of total coffee and 0.74 (0.62, 0.90) for ≥2 cups/d; p-trend: 0.001. Corresponding figures for caffeinated coffee were 0.67 (0.42, 1.07) and 0.70 (0.56, 0.87); p-trend< 0.001. Decaffeinated coffee was not associated with risk of falling in the analyzed cohorts. In Seniors-ENRICA, there was a tendency to lower risk of injurious falls among those consuming caffeinated coffee [0.83, (0.68, 1.00) for 1 cup/d, 0.83 (0.64, 1.09) for ≥2 cups/d, p-trend: 0.09]. No association was observed between caffeinated or decaffeinated coffee consumption and risk of falls with fracture. Conclusions: Habitual coffee consumption was associated with lower risk of falling in older adults in Spain and UK. Summary to Article 3 Purpose: No previous study has evaluated the relationship between vitamin K and frailty. Thus, we assessed the relationship between vitamin K status and frailty over 13 years in the Longitudinal Aging Study Amsterdam (LASA). Methods: Prospective cohort study with 644 community-dwelling adults ≥ 55 years from the LASA cohort. In 2002-2003, plasma desphospho-uncarboxylated matrix Gla protein (dp-ucMGP) was measured as marker of vitamin K status through a sandwich ELISA. Frailty was measured at baseline and in four follow-up examinations with the LASA Frailty Index (LASA-FI), which was used as both a continuous and a dichotomous measure (FI ≥ 0.25), as indicator of the degree of frailty and frailty risk, respectively. Statistical analyses were performed with multivariable generalized estimating equations using the lowest dp-ucMGP tertile, reflecting a high vitamin K status, as reference. Results: The mean (SD) age was 59.9 (2.9) years, and 54% were female. Compared with the lowest tertile, the medium and highest dp-ucMGP tertile were associated with a higher degree of frailty [1.40, 95% confidence interval (0.01-2.81) and 1.62, (0.18-3.06), respectively. P-trend: 0.03]. Additionally, the medium and highest dp-ucMGP tertile had a higher odds ratio of frailty [1.75, (1.11-2.77) and 1.63, (1.04-2.57), respectively]. The degree of frailty increased over time, but the differences by dp-ucMGP tertiles existed since baseline and remained stable during follow-up. Conclusions: Baseline plasma low vitamin K status was associated with a greater degree of frailty and frailty risk in this cohort of older adults, which highlights the importance of ensuring an optimal nutritional status of this vitamin in order to prevent frailty in later life.