Aches and pains. A growing waistline. Diminishing eyesight, hearing loss, memory lapses. These are the woes of growing older for some people, once considered inevitable. But recent, exciting discoveries in the fast-growing field of longevity science have some doctors and researchers pronouncing that these “symptoms” of aging may one day be treatable with pharmaceuticals, gene therapies or other yet-to-be-discovered medical technologies.
Many people haven’t been content to wait, though. Dozens of commercial producers are selling hundreds of so-called longevity supplements right now, and sales data suggest an awful lot of people are trying them. But do they work? Are they even safe?
To find out, we scoured the latest research and interviewed two top scientists in the field. What we learned suggests that you may want to hold off on ordering a supply, or at least do your research very carefully.
There is a solid handful of compounds that look very promising in the scientific quest to slow the aging process. One of the most exciting is nicotinamide adenine dinucleotide, or NAD, which has been shown to extend both the lifespans and youthful function of yeast and animals in clinical trials. Human trials are ongoing, with only a handful published to date.
NAD (also often written as NAD+) is a substance found in every cell in your body, which controls all kinds of metabolic processes, including the regulation of sirtuins, the so-called “longevity genes.” As you age, your NAD+ levels decline, and scientists think it is perhaps this decline that leads to all sorts of other age-related declines.
The working theory, then, is that if we can boost our NAD+ levels as we age, we can slow our decline tremendously. Lab studies on yeast and rodents lend strong support to that theory. The most recent studies have primarily involved the administration of either nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN), which is then converted into NAD in the body.
To learn more about NAD, Next Avenue talked to Dr. Shin-Ichiro Imai, professor of developmental biology at the Washington University School of Medicine in St. Louis. Along with Leonard Guarente, Imai discovered the link between NAD and sirtuin control in 1999. He’s been studying the molecule ever since.
“There have been 10 human clinical trials using NR, most at very high dose, with no safety issues,” Imai said. Most of those trials, however, lasted for a duration of weeks or months at most.
Is it safe to take NAD-boosting supplements continuously, for years?
“NMN and NR have already been available in Japan and the U.S. since 2015, and some people have been taking it since then,” Imai noted. “Anecdotally, I haven’t heard of any side effects from the taking of these supplements.”
Some trials, however, have recorded mild side effects including headaches, nausea, diarrhea and skin flushing.
More troubling, however, is the conclusion of a 2019 study that showed a possible link between elevated levels of NAD and tumor growth in isolated cells and animals. Rugang Zhang, deputy director at the nonprofit Wistar Institute Cancer Center in Philadelphia, was the lead researcher on that study. The study, published in the UK journal Nature Cell Biology, did not find that NAD causes cancer, rather that elevated levels appeared to accelerate oncogenesis (tumor formation) already in motion.
“We don’t want to oversell the results of our study,” Zhang said. “Lots of studies in the literature have clearly demonstrated that as normal cells age, there is lower NAD. So, supplementing NAD could be beneficial. It’s possible that NAD boosters could help people live longer and healthier. We’re not saying that if people take NAD boosters they will get cancer. This was a very early study on mouse models, and more study is needed.”
He suggests a course of action grounded in a deep preponderance of evidence: “At the end of the day, we just need more knowledge, through more research. We need the scientific community to come to a consensus. The risk to potential benefit remains to be seen.”