On The Shelf
Mickie Cathers
Recent buzz around a veterinary medicine company developing drugs to extend the lifespan in dogs by targeting the underlying causes of aging has some wondering, if it works for dogs, will it work for humans? The promise of eternal youth has renewed interest in oxidized nicotinamide adenine dinucleotide (NAD+) supplementation.
Background
NAD+ is a coenzyme central to metabolism found in a cell’s cytoplasm, mitochondria, and nucleus. The conversion of NAD from its oxidized form (NAD+) to its reduced form (NADH) and back provides the cell with a mechanism for accepting and donating electrons, which is critical for the maintenance of cellular energy, DNA repair, hormone signaling, inflammation, maintenance of circadian rhythm, and the overall health of our cells and tissues.
Cellular levels of NAD+ naturally decline with age, and it has been postulated that age-associated conditions, such as arthritis, atherosclerosis, cognitive decline, diabetes, hypertension, and more are linked to this natural and gradual decline in cellular concentrations of NAD+ as we age. It has been theorized that by restoring NAD+ levels, some of these diseases may be slowed down or even reversed. Ways to increase cellular levels of NAD+ include eating a healthy diet of meat, dairy, fruit, legumes, soy products, and more that includes NAD+ precursors such as tryptophan, vitamin B3, nicotinamide riboside (NR), and nicotinamide mononucleotide (NMN). Other suggestions to boost NAD+ levels include increasing exercise, following a consistent daily circadian rhythm pattern by adhering to healthy sleeping habits and routine mealtimes, or taking a NAD+ dietary supplement.
Is there a benefit?
There are many studies exploring how NAD+ may affect aging-related disorders, cancer, obesity, metabolic disorders, and neurodegenerative diseases such as Alzheimer and Parkinson’s disease. However, these are predominantly cell and animal studies, and the few human clinical trials available in the literature on the effects of NAD+ supplementation have been underpowered and not clinically significant.
Researchers have shown that the NAD+ precursors NR and NMN demonstrated protection against diabetes, Alzheimer disease, endothelial dysfunction, and inflammation. Beneficial effects have also been documented in reversing imbalances in the gut microbial community.
A review published on August 7, 2022, in Nutrients by Campbell summarized research findings of the beneficial effect of NAD+ supplementation on cognitive impairment in mice and while findings were mostly positive, including expanding the lifespan of the mice, properly controlled clinical research and larger trials are needed to provide definitive answers regarding NAD+ supplementation’s efficacy on longevity and age-related disorders in humans.
Dosage and availability
NAD+ dietary supplements are sold over the counter and online in capsules, ranging in dosage from 300 mg/day to 1,000 mg/day. These products, promising to slow the effects of aging by boosting cellular energy, fueling cellular repair, and supporting brain health, contain either NAD+ or the precursor NR and are often sold in combination with other stimulates such as wasabi and green tea. NAD+ is also available as I.V. therapy.
What to tell your patients
NAD+ and NR supplements are generally safe in doses up to 300 mg daily. Adverse effects are mild and may include nausea, bloating, itching, sweating, or rapid heartbeat. Advise patients taking medications to lower BP that NR supplements may cause BP to fall too low and to monitor BP closely. NAD+ supplements may also interact with antidepressants, insulin, and other supplements. While NAD+ dietary supplements are billed as the “fountain of youth,” and may help our pets live a little longer, there’s little to no evidence NAD+ supplementation can benefit us. ■