Nicotinamide adenine dinucleotide, commonly known as NAD+, is a molecule present in every living cell, involved in countless biological processes. It plays a significant part in converting the food we eat into energy. NAD+ also assists in repairing DNA, maintaining the health of our cells, and regulating various metabolic pathways. This molecule is involved in over 500 enzymatic reactions.
The levels of NAD+ naturally decrease as we grow older, and various environmental stressors can also contribute to this decline. For instance, by age 40, NAD+ levels can drop by approximately 50%, and by age 60, this reduction may reach 80%. This age-related decrease in NAD+ is associated with a decline in cellular efficiency.
Dietary Precursors for NAD+ Synthesis
The human body does not directly absorb NAD+ from food, but rather synthesizes it from precursor molecules found in our diet. The two primary dietary precursors are Niacin (Vitamin B3) and the amino acid Tryptophan.
Niacin can be found in several common foods, including:
Turkey, chicken, salmon, and tuna
Mushrooms, avocados, and legumes like beans and lentils
Whole grains such as brown rice, and fortified cereals
Peanuts and sunflower seeds
Tryptophan is an amino acid the body converts into niacin, which then becomes NAD+. Foods rich in tryptophan include:
Turkey, chicken, salmon, and eggs
Dairy products such as milk and cheese
Nuts, seeds, and oats
Once these precursors are consumed, the body primarily utilizes a process called the salvage pathway to recycle and create new NAD+. This pathway efficiently converts nicotinamide, a byproduct of NAD+ consumption, back into NAD+. While a de novo pathway also exists, converting tryptophan into NAD+, it primarily occurs in the liver.
Physical Activity and Cellular Stress Response
Engaging in regular physical activity stimulates the body’s natural mechanisms to produce more NAD+. Exercise introduces a temporary, beneficial stress on cells, a concept known as hormesis, which signals them to adapt and become more resilient. This increased demand for energy encourages cells to enhance their NAD+ production to meet metabolic needs.
Specific types of exercise are particularly effective in influencing NAD+ levels. High-Intensity Interval Training (HIIT), characterized by short bursts of intense activity followed by brief recovery periods, creates a rapid energy deficit within muscle cells. This intense demand can lead to an increase in NAD+ and its precursor, nicotinamide mononucleotide (NMN).
Endurance or aerobic exercises, such as running or swimming, also play a role in supporting NAD+ levels. These activities can elevate the activity of an enzyme called NAMPT, which is involved in the synthesis of NAD+. Consistent physical activity, including both aerobic and resistance training, can help maintain or even increase NAD+ levels.
Caloric Restriction and Fasting Protocols
Caloric restriction or specific fasting protocols can influence NAD+ levels by activating particular cellular pathways. When the body enters a fasted state, or when calorie intake is reduced, it triggers survival-related processes that optimize energy use.
These survival pathways rely on a family of enzymes known as sirtuins, which are directly dependent on NAD+ for their activity. Sirtuins are involved in regulating various aspects of cellular health, including metabolism, DNA repair, and stress responses. The increased demand for sirtuin activity during periods of caloric restriction or fasting can signal the body to boost its NAD+ production to fuel these enzymes.
Practical methods to achieve this state include time-restricted eating, where food consumption is limited to a specific window each day, such as the 16:8 method (16 hours of fasting, 8 hours of eating). Intermittent fasting protocols, like the 5:2 method (normal eating for five days and restricted calorie intake for two non-consecutive days), also promote similar metabolic changes. These approaches encourage the body to tap into stored energy and activate cellular repair mechanisms.
Minimizing Factors That Deplete NAD+
Protecting existing NAD+ levels is as important as increasing their production. Certain lifestyle factors and environmental stressors can accelerate the consumption and depletion of the body’s NAD+ stores, making it harder for cells to maintain optimal function.
Chronic inflammation is a significant consumer of NAD+. When the body experiences prolonged inflammatory responses, the immune system becomes highly active, which is an energy-intensive process. This increased activity can activate enzymes like CD38 and poly(ADP-ribose) polymerases (PARPs), which extensively consume NAD+, leading to a decline in its cellular concentration.
Excessive exposure to the sun’s ultraviolet (UV) rays also depletes NAD+. UV radiation can cause DNA damage in skin cells, and the body’s repair mechanisms, particularly enzymes like PARP, require substantial amounts of NAD+ to fix this damage. A high demand for DNA repair can rapidly use up available NAD+.
High alcohol consumption is another factor that can significantly reduce NAD+ levels. The liver, responsible for metabolizing alcohol, utilizes NAD+ in this detoxification process, converting it into a reduced form called NADH. This conversion diminishes the pool of available NAD+, impacting the function of NAD+-dependent enzymes like sirtuins.