Dr Nady Briady. lecturer at Centre for Healthy Brain Ageing at the University of New South Wales, explained the importance of NAD+ while presenting at the Healthy Ageing Summit APAC 2019, organised by NutraIngredients-Asia and FoodNavigator-Asia.
NAD+, which is naturally occurring in the body, is consumed when the poly (ADP-ribose) polymerase (PARP) protein is activated for DNA repair and during the maintenance of the immune system.
A low NAD+ level, due to hyper-activation of PARP and inflammation, however, is link to the onset of age-related illnesses and cognitive problems such as the Alzheimer’s disease.
“Hyper-activation of PARP during pathology can lead to NAD and ATP depletion, and cell death via energy restriction.
“A significant decrease in intracellular NAD+ has been reported in the brain and other organs as a result of DNA strand breaks and PARP activation following exposure to hydrogen peroxide, nitric oxide, HIV infection, or during inflammation,” Briady explained.
Other factors that affect NAD+ include a long term high fat diet.
“In a recently accepted article, my group demonstrated that chronic high fat diet is associated with increased levels of oxidative stress, neuro-inflammation, impaired NAD+ metabolism, and cognitive decline in the brain,” he said.
They found that increasing NAD+ levels in the central nervous system could improve brain function in mice exposed to a high fat diet.
“Interventions aimed at increasing NAD+ levels in the central nervous system may improve brain function and reduce underlying degenerative processes that may lead to progressive neuronal loss and the development and progression of neurological disorders.”
Nicotinamide riboside the solution?
To increase NAD+ levels, Briady pointed out that the supplementation of nicotinamide riboside (NR) – a form of vitamin B3, was the most effective way.
Besides NR which is present in milk, other NAD+ precursors are also available in the natural diet, they include amino acid tryptophan found in salmon, poultry, and nuts.
NAD+ precursors are also found in two other forms of vitamin B3 – nicotinic acid (NA) and nicotinamide (NAM).
On the other hand, the provision of these vitamins to NAD+ production is affected by a number of factors, such as the gut microbiome.
Braidy pointed out that studies have shown that NR consumption could increase the intracellular NADome in a 52 year-old male subject who ingested 1,000 mg of NR daily for a week.
Another mouse study showed that increasing NAD+ via the supplementation of NR significantly normalised neuroinflammation, synaptic transmission, phosphorylated Tau, and DNA damage in an Alzheimer’s disease mouse model study.
Alternative methods
Lifestyle choices and habits could also influence NAD+ levels in the body.
Some of the habits include a low protein ketogenic diet, intermittent fasting, and regular exercise to boost caloric restriction.
For example, a study has shown that when rats were exposed to a ketogenic diet, there is a significant increase in NAD+ levels.
“Based on diverse published literature and these initial data, we suggest that increased NAD during ketolytic metabolism may be a primary mechanism behind the beneficial effects of this metabolic therapy in a variety of brain disorders and in promoting health and longevity,” Braidy explained.