The small, randomised placebo-controlled crossover trial demonstrated that six-week supplementation of nicotinamide riboside (NR) increased levels of a compound called Nicotinamide Adenine Dinucleotide (NAD+) by 60% in elderly adults. This compound is responsible for the activation of sirtuins enzymes, which are are widely considered to drive the beneficial effects of caloric restriction.
A one gram per day (g/d) dose of NR also appeared to lower systolic blood pressure (SBP) by around 10 points in people with elevated or stage-1 hypertension blood pressure categories (120-139 mmHg), said the team from the University of Colorado Boulder.
Furthermore, those in the supplement group also experienced a reduction in stiffening of the arteries.
"This was the first ever study to give this novel compound to humans over a period of time," said senior author Professor Doug Seals.
If replicated in larger studies, the effect could reduce heart attack risk by around 25%, he emphasised.
Supplementation also appeared to have no serious adverse effects, added the team
"We found that it is well tolerated and appears to activate some of the same key biological pathways that calorie restriction does," commented Seals.
Healthy ageing
Writing in Nature Communications, the team noted that the trial was conducted in adults aged 55-79 years - adding that the relatively elderly trial population was chosen because NAD+ production declines with age.
Boosting the availability of NAD+ using a precursor supplement might therefore help promote healthy ageing, as identified by previous research into caloric restriction, they suggested.
"The idea is that by supplementing older adults with NR, we are not only restoring something that is lost with ageing (NAD+), but we could potentially be ramping up the activity of enzymes responsible for helping protect our bodies from stress," explained first author Christopher Martens, now an assistant professor at the University of Delaware.
Compounds that mimic caloric restriction might eventually provide an additional means of lowering blood pressure - in conjunction with diet and lifestyle modifications, the team suggested.
Additionally, animal studies have shown that higher expression of certain sirtuin-related genes (activated by the presence of NAD+), can result in extended lifespan.
Future research
According to Seals and colleagues, further work is needed to confirm the findings of this pilot-sized trial.
"We are not able to make any definitive claims that this compound is safe or going to be effective for specific segments of the population," added Martens.
"What this paper provides us with is a really good stepping stone for future work."
The researchers are now looking to conduct a larger trial to explore the benefits of NR supplementation on blood pressure and arterial stiffness as the primary outcomes. Meanwhile the supplement’s effect on mild cognitive impairment will also be studied in a separate trial being launched by Martens, he confirmed.
Source: Nature Communications
Published online 29 March 2018, doi: 10.1038/s41467-018-03421-7
“Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults”
Authors: Christopher R. Martens, Douglas R. Seals et al