Human cells' ability to produce energy declines with age, prompting scientists to suspect that the steady loss of efficiency in the body's energy supply chain is a key driver of the aging process.
Now, scientists have shown that supplementing healthy mice with NMN—found in foods such as broccoli, avocado, cabbage, and cucumber—can compensate for this loss of energy production, reducing typical signs of aging such as gradual weight gain, loss of insulin sensitivity and declines in physical activity.
There are specific findings related to vision as well. "We demonstrated that tear production was increased after long-term NMN supplementation," said Rajendra S. Apte, MD, PhD, the Paul A. Cibis Distinguished Professor of Ophthalmology and Visual Sciences. "This may be relevant to dry eye syndrome, the prevalence of which increases significantly with aging. We also demonstrated some improvement in retinal function as measured by electrophysiology."
The study is based on the premise that NAD (another naturally occurring compound) levels decrease in multiple tissues as mice (and humans) age. But NAD was not effective when given directly to mice so the researchers at Washington University School of Medicine in St. Louis moved one step earlier in the NAD supply chain to NMN. Interestingly, younger mice did not benefit from NMN supplementation (likely due to the fact that the body naturally produces higher levels of NAD at younger ages), but as the mice aged, the supplementation significantly reduced signs of aging.
Dr. Apte notes that current research suggests that NAD+ biosynthesis is a critical process in cellular function and homeostasis in both animal models and humans. But, he notes that it will be necessary to perform well-designed clinical trials that test the safety and efficacy of high-grade NMN in humans before making the leap to using NMN (or perhaps its analogs) as pharmacotherapeutic agents.
When asked how the recent findings relate to the other research in which his lab is engaged, Dr. Apte explained, "My laboratory has a strong interest in understanding the programmatic changes that occur with aging and lead to immunosenescence [age-related deterioration of the immune system] and neurodegeneration. Understanding these molecular events will provide novel insights into eye diseases such as AMD, glaucoma and retinal degeneration."
Dr. Apte is a recipient of an RPB Physician-Scientist Award and the university's department of ophthalmology receives an unrestricted RPB grant.
To learn more about the NMN study, read the press release from Washington University in St. Louis or view the study in Cell Metabolism.
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