If you’ve been keeping up with aging and science news, you’ve probably already heard of a critical molecule known as nicotinamide adenine dinucleotide (NAD). You may even already know that NAD is critical to human survival, and decreases as we get older and undergo metabolic stresses. There are a few different ways of increasing NAD, and although the science here is important, it can easily turn into an eye-glazing-over experience for most people who don’t study cells for a living.

Here's a quick breakdown of the key differences between nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR):

1. NR is a vitamin. NMN is not.

NMN is not a form of vitamin B3, and there are no clinical trials to prove it increases NAD in humans. NMN is also not the type of molecule that would ever be considered as a vitamin as it contains a phosphate, which affects its ability to enter cells.

2. NR can enter the cell. NMN cannot.

NR is the largest part of NAD that can enter the cell. This is why NMN supplements turn into NR first before they are able to make NAD.

3. NMN makes NAD in 3 steps. NR requires only 2.

In its supplement form, NMN must become NR first before entering the cell. Then once inside the cell, it converts back into NMN to make NAD. This is a 3-step and rather inefficient process.

NR can directly access the cell, so it only requires two steps to begin creating NAD.

4. NR has 4 published human studies. NMN has 0.

NMN’s only published trials are in mice and rats.* NR has at least 4 published human studies and all of them confirm NR is a safe and effective way of increasing NAD in people.

5. NR is taken orally. NMN is mostly studied by injection.

Despite NMN being sold as a pill to people, NMN is frequently studied through injections in rodents. In NR trials, it’s most commonly added to food or water. Plus, in all of NR’s published human studies it was administered in capsule form, which represents the recommended way of taking NR as a vitamin.*

6. NR increases NAD by up to 60% in humans. NMN may not.

In this 2018 study, 1000mg/day of NR increased NAD levels by 60% on average in older adults. There is no published data to show how NMN affects human NAD levels.*

7. NR has at least 4 published trials confirming it’s safe for humans. NMN has 0.

There are no data available stating whether or not NMN is safe for human consumption.* Careful analysis of all the information available on NR confirms it is safe and well-tolerated.

8. NR has 3 FDA safety notifications. NMN has 0.

The only commercially available form of NR, NIAGEN®, has twice been successfully reviewed under FDA's new dietary ingredient (“NDI”) notification program and has also been successfully notified to the FDA as generally recognized as safe (“GRAS”). NMN has no safety notifications from the United States FDA.*

There aren’t any human studies comparing NR to NMN (because NMN doesn’t have any clinical trials), but we do have them in animal models. And there the evidence is clear: NR is a more efficient way of increasing NAD. That’s because NR and NMN are structurally different in one very important way: NR can get directly into the cell, and NMN can’t. [1–4]

NAD is getting a lot publicity lately for its potential impacts on human health. Recent publications include TIME, Fast Company, The Atlantic, AARP The Magazine, and more. If you think NAD is as important as some leading biochemists and nutritionists believe it is, it’s worth making sure you’re investing in the most effective way to increase NAD. After all, isn’t that why all of us keep up with the news surrounding aging and science? We care about things like that.