The indispensable importance of NAD+ in cognition has been discovered by medical scientists, and they have discovered that NMN or NR, the precursor of NAD+, can effectively increase NAD+ levels in the body. However, based on current knowledge, we cannot store NAD+ stably at room temperature, nor can we directly increase NAD+ levels in the body by taking it orally.
In order to effectively increase NAD+, we need to take NMN or NR instead of taking NAD+ directly. However, there are many products on the market that are labeled NAD+ and can be taken directly. Instead of listening to the marketing techniques, it is better to take a closer look at what the US FDA says.
In 2017, the US FDA's Drug Ingredients Advisory Committee made the following conclusions on whether Nicotinamide adenine dinucleotide (NAD+) should be included in effective oral drug ingredients:
Against (Against)
The reason why the FDA rejected NAD+ as an effective oral drug ingredient is that NAD+ decomposes above minus 20 degrees Celsius (-20°C). In addition, NAD+ will also decompose under conditions such as slight alkalinity, sunlight or moisture, and will eventually decompose into substances such as nicotinamide riboside, nicotinic acid and nicotinamide, collectively called niacin. In other words, NAD+ is not stable in healthy supplement capsules at room temperature. From the moment it leaves minus 20 degrees Celsius, it is no longer NAD+, but becomes substances such as niacin.
The potential problem this brings is that there is an upper limit to the body's ability to absorb niacin. The recommended dietary allowance for adults is no more than 15 mg of niacin. (As shown below) 
NAD+ is decomposed into nicotine amine nucleotides. If the human body consumes more than 1,000 mg per day, it may cause adverse gastrointestinal reactions. If the human body consumes more than 3,000 mg, it may cause liver poisoning.
The US FDA recommends a daily intake of 15 mg of nicotinic acid, which is equivalent to 5 mg of NAD+.
Clinical studies have shown that ingesting high doses of vitamin B3 can cause symptoms such as redness, heat, burning and itching on human skin, which is called niacin flush. Professor David Sinclair of Harvard University has publicly stated that high doses of nicotinamide will inhibit the longevity genes sirtuins and PARP, hindering the repair of genetic damage.
If taking NAD+ directly is feasible, why do many scholars, including Professor Imai Shinichiro and Professor David Sinclair, mention NMN instead of NAD+ in their studies and books? Please be careful not to fall into the trap of traders and harm the health of you and your family.
In addition, NAD+ is not included in valid pharmacopoeias in places such as the United Kingdom, Europe and Japan. Based on the above considerations, the U.S. FDA refuses to include NAD+ as an active pharmaceutical ingredient under Regulation 503A of the Federal Food, Drug, and Cosmetic Act.
If you are planning to take NAD+, or are already taking foods that claim NAD+ as a direct supplement, be sure to understand its ingredients and content. If your body has any discomfort, you should stop taking it immediately and ask a professional doctor for assistance.
Therefore, the conclusion is that the human body cannot directly absorb NAD+, but must absorb NMN. If you want to know more about Chuanyu NMN, you are welcome to talk to our Tuanye Health Consulting Team.
Reference:
Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act
COMPOUNDERS UNDER SECTION 503A OF THE FD&C ACT: QUALITY STANDARDS AND FDA FINDINGS, Pharmacy Compounding Advisory Committee Meeting May 8, 2017
Niacin - Fact Sheet for Health Professionals, National Institutes of Health, US Department of Health & Human Services
