Long-term calorie restriction in humans is not associated with indices of delayed immunologic aging: A descriptive study.

Delayed immunologic aging is purported to be a major mechanism through which calorie restriction (CR) exerts its anti-aging effects in non-human species. However, in non-obese humans, the effect of CR on the immune system has been understudied relative to its effects on the cardiometabolic system. To examine whether CR is associated with delayed immunologic aging in non-obese humans. We tested whether long-term CR practitioners (average 10.03 years of CR) evidenced decreased expression of T cell immunosenescence markers and longer immune cell telomeres compared to gender-, race/ethnicity-, age-, and education-matched "healthy" Body Mass Index (BMI) and "overweight"/"obese" BMI groups. Long-term human CR practitioners had lower BMI ( <  0.001) and fasting glucose ( <  0.001), as expected. They showed similar frequencies of pre-senescent cells (CD8CD28 T cells and CD57 and PD-1 expressing T cells) to the comparison groups. Even after adjusting for covariates, including cytomegalovirus status, we observed shorter peripheral blood mononuclear cell telomeres in the CR group ( = 0.012) and no difference in granulocyte telomeres between groups ( = 0.42). We observed no clear evidence that CR as it is currently practiced in humans delays immune aging related to telomere length or T cell immunosenescent markers.