Energy homeostasis is a biological process by which our cells balance energy production and expenditure. By energy, we are referring to “cellular energy”, rather than the energy that comes to mind when you think of coffee or energy drinks. Maintenance of energy homeostasis is critical for survival and proper functioning of our cells.
Most of the cell’s energy (~95%) is produced by mitochondria. Mitochondria convert chemical energy from the food we eat into an energy form that the cell can use—ATP (adenosine triphosphate)—which is why they are often referred to as “the powerhouse of the cell.” ATP is the energy currency, powering most of the non-spontaneous reactions (which require energy) in our cells. ATP cannot be stored, so it has to be constantly replenished, which is why the integrity of the mitochondria is so crucial to energy homeostasis. Processes involved in maintaining energy homeostasis are dynamic, constantly responding to the changing environment. Unfortunately as we age this balance becomes dysregulated.
Energy expenditure varies throughout the body, with certain organs needing more energy than others : The brain uses the most energy at 19%, the liver uses 18%, and the kidneys use 10%.
The role of sirtuins and NAD+
In 1999, Elysium co-founder, chief scientist, and renowned aging researcher, professor Leonard Guarente, Ph.D., identified sirtuins as playing an essential role in the lifespan of yeast cells.
Since Guarente’s discovery, sirtuins have emerged as key regulators of the nutrient-sensitive metabolic regulatory circuit, with SIRT3 (which along with SIRT4 and SIRT5 are primarily located in the mitochondria) specifically playing a crucial role in energy homeostasis and regulating basal ATP levels. The major function of mitochondrial SIRT3 in mitochondria is maintaining basal ATP levels through regulation of the electron transport chain (ETC). SIRT3 plays a critical role in producing ATP through the generation of acetyl-CoA, and also converts acetyl-CoA into ketone bodies, an alternate fuel source to carbohydrates produced by our bodies during fasting, ketogenic diets, and exercise.
Sirtuins rely on NAD+ (nicotinamide adenine dinucleotide), a universal coenzyme found in every cell in your body to function. NAD+ plays a key role in cellular respiration (process by which ATP is produced) by accepting and donating electrons. NAD+ also serves as a coenzyme, or helper molecule, for hundreds of critical enzymes in the cell (such as sirtuins)—from those involved in metabolism to DNA repair. Preclinical studies have shown that increasing NAD+ levels results in increased cellular ATP. However, NAD+ cannot be directly supplemented, so efficient NAD+ precursors such as NR (a form of vitamin B3) or NMN are needed to support healthy ATP levels and energy homeostasis. NMN is one of the most efficient NAD+ precursors, requiring the least number of reaction steps and energy to convert to NAD+.
Human clinical studies have demonstrated that dietary supplementation with NMN—as in our supplement Signal—is a safe and effective way of increasing NAD+ levels. Signal is designed to support cellular energy homeostasis by providing an NAD+ precursor and by combining this with a SIRT3 Metabolic Activation Complex to promote mitochondrial health. Learn more about the science behind Signal here.