Short-term time-restricted feeding is safe and feasible in non-obese healthy midlife and older adults.

Chronic calorie restriction (CR) improves cardiovascular function and several other physiological markers of healthspan. However, CR is impractical in non-obese older humans due to potential loss of lean mass and bone density, poor adherence, and risk of malnutrition. Time-restricted feeding (TRF), which limits the daily feeding period without requiring a reduction in calorie intake, may be a promising alternative healthspan-extending strategy for midlife and older adults; however, there is limited evidence for its feasibility and efficacy in humans. We conducted a randomized, controlled pilot study to assess the safety, tolerability, and overall feasibility of short-term TRF (eating <8 h day-1 for 6 weeks) without weight loss in healthy non-obese midlife and older adults, while gaining initial insight into potential efficacy for improving cardiovascular function and other indicators of healthspan. TRF was safe and well-tolerated, associated with excellent adherence and reduced hunger, and did not influence lean mass, bone density, or nutrient intake. Cardiovascular function was not enhanced by short-term TRF in this healthy cohort, but functional (endurance) capacity and glucose tolerance were modestly improved. These results provide a foundation for conducting larger clinical studies of TRF in midlife and older adults, including trials with a longer treatment duration.

Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults.

Nicotinamide adenine dinucleotide (NAD+) has emerged as a critical co-substrate for enzymes involved in the beneficial effects of regular calorie restriction on healthspan. As such, the use of NAD+ precursors to augment NAD+ bioavailability has been proposed as a strategy for improving cardiovascular and other physiological functions with aging in humans. Here we provide the evidence in a 2 × 6-week randomized, double-blind, placebo-controlled, crossover clinical trial that chronic supplementation with the NAD+ precursor vitamin, nicotinamide riboside (NR), is well tolerated and effectively stimulates NAD+ metabolism in healthy middle-aged and older adults. Our results also provide initial insight into the effects of chronic NR supplementation on physiological function in humans, and suggest that, in particular, future clinical trials should further assess the potential benefits of NR for reducing blood pressure and arterial stiffness in this group.