To examine the association of the quantity and the source of protein intake with mortality risk in Chinese older adults.
Prospective cohort study.
Community-dwelling Chinese adults aged >=65 (1,480 men, 1,540 women) in Hong Kong.
Food frequency questionnaire was used to capture baseline dietary intakes including protein, fiber, total grains, vegetables and fruit intakes. Primary outcome measures, identified from the death registry, were death from all causes, cancer and cardiovascular disease (CVD). Other demographic and lifestyle risk factors were also collected. Multivariate Cox proportion hazards regression was used to examine the association of protein intake with mortality risk.
During a median of 13.8 follow-up years, 963 all-cause deaths, 336 cancer deaths, and 205 CVD deaths were identified. Among men in the highest quintile of total protein intake, all-cause mortality and cancer mortality decreased by 29% [95% confidence interval (CI): 0.55-0.92, p-trend=0.017] and 38% [95% CI: 0.39-0.97, p-trend=0.041] respectively compared with men in the lowest quintile after adjustment for demographics, lifestyle factors and medical conditions. Men in the highest quintile of animal protein intake showed 20% reduced risk of all-cause mortality than men in the lowest quintile (p-trend=0.042). Women in the highest quintile of plant protein intake showed 39% decreased risk of all-cause mortality [95% CI: 0.44-0.85, p-trend=0.019] than those in the lowest quintile. In women, protein intake was not associated with cancer mortality. In both men and women, protein intake was not associated with CVD morality. Further adjustment for other dietary variables attenuated the significant associations.
Contrary to findings from Caucasian populations of all ages, among Chinese older adults, higher total protein intake was associated with lower all-cause and cancer mortality in Chinese older men. While higher animal protein intake was associated with reduced all-cause mortality in Chinese older men, higher plant protein intake was protective against all-cause mortality in Chinese women. The attenuated associations between protein intake and mortality risk after adjustment for other dietary variables also highlight the role of whole diet approach in mortality risk reduction among older adults.