In a small pilot study consume who consumed a natural dietary supplement called nicotinomide riboside (NR) daily showed signs of mimicking caloric restriction, which in mice has been linked to health benefits.

Caloric restriction is a starvation diet. When lower level organisms such as fruit flies, roundworms, rodents are raised on such a diet from birth, slashing of caloric intake by about a third has health benefits and, in some cases, extended lifespan. No humans have done that, it would be a human rights violation to wean a baby on a starvation diet, and claims about benefits in adults who took it up have too many confounders to be anything more than anecdotes. 

In a small pilot study, 12 lean and healthy men and women ages 55 to 79 from the Boulder area were given a placebo for six weeks, then took a 500 mg twice-daily dose of nicotinamide riboside chloride (NIAGEN). Another 12 took nicotinamide riboside for the first six weeks, followed by placebo. The researchers took blood samples and other physiological measurements at the end of each treatment period. They found that the supplement slightly improved blood pressure and arterial health, particularly in those with mild hypertension but what they wanted to find was that 1,000 mg daily of nicotinamide riboside boosted levels of another compound called nicotinamide adenine dinucleotide (NAD+) by 60 percent. NAD+ is required for activation of enzymes called sirtuins, which is hypothesized to be involved in the beneficial effects of calorie restriction. It's involved in a host of metabolic actions throughout the body, and tends to decline with age.

Some suggest that as an evolutionary survival mechanism, the body conserves NAD+ when subjected to calorie restriction and that led to the idea of supplementing with so-called "NAD+-precursors" like nicotinamide riboside  to promote healthier aging.

The pilot study also found that in 13 participants with elevated blood pressure or stage 1 hypertension (120-139/80-89 mmHg), systolic blood pressure was about 10 points lower after supplementation. A drop of that magnitude could translate to a 25 percent reduction in heart attack risk but this is a pilot study in healthy people, so it should only be considered a viable technique if a company is willing to enter it into clinical trials. Otherwise, it will remain just another supplement for people who want to believe.