NAD vs NAD+: What's the Difference and Why It Matters for Aging Well

NAD and NAD+ are the same thing, just at different moments in your cells' day. NAD+ is the form that's actually working. It's the one your body uses to make energy, repair daily damage, and keep skin and brain feeling sharp. By midlife, it drops a lot: roughly half of what you had in your 20s by the time you hit 60². The good news is the science on how to support it is finally clear.

If the labels confuse you, you're not alone. NAD, NAD+, NADH, NR, NMN. They all sound the same and they're sold like different things. Let's untangle it so you can buy what actually works for you.

NAD vs NAD+ vs NADH: what they actually are

Think of NAD as a tiny rechargeable battery inside every cell. The "+" version is the charged one. It's ready to power the work your cells need to do, like turning food into energy, fixing little bits of damage, and keeping skin and brain feeling like yours. After it does the job, it becomes NADH, the "drained" version. Then it gets recharged back to NAD+ and the cycle starts again. This happens thousands of times every minute, in every cell.

So when a supplement label says "NAD" or "NAD+," they pretty much mean the same thing. The "+" is the form scientists track when they study aging, because that's the version that actually fades. You don't need to memorize the chemistry. You just need to know that "raising NAD+" is the goal.

NADH isn't something you supplement on its own. Your body makes it automatically as part of normal energy production. Adding more NADH doesn't really help. What matters is keeping NAD+ topped up.

Why NAD+ drops as you age

Two things tip the balance starting in your 40s. First, your body slows down making new NAD+. The building blocks come from food (B vitamins, fish, turkey, leafy greens), but the machinery that turns them into NAD+ gets sluggish in your muscle, liver, and even body fat².

Second, your cells use NAD+ up faster than ever. Daily damage from stress, sun, and low-grade inflammation needs more repair work, and the repair crew runs on NAD+. There's also an enzyme called CD38 that breaks NAD+ down, and it gets more active with age and inflammation².

The result: you're making less, and burning through it faster. Researchers describe this as one of the central things that goes wrong with cellular aging. When NAD+ falls, energy production slows, the "cleanup crew" slows, and the body's natural repair signals get quieter²⁵.

How to actually raise NAD+

Two building blocks have real human trial data behind them: NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide). Both get absorbed, both get converted into NAD+ inside your cells. The difference is mostly where in the conversion line they jump in: NR takes one more step, NMN is one step closer to NAD+ already.

The strongest evidence for NR comes from a 2018 trial of 140 healthy adults in their 50s, 60s, and 70s. Daily NR for 6 weeks raised whole-blood NAD+ by about 60%, with no serious side effects (PMID: 29599478)¹. It's still the biggest, longest human trial we have.

For NMN, the most relevant trial for women in midlife came out in 2021 in Science. Twenty-five postmenopausal prediabetic women (mean age 55) took 250 mg of NMN daily for 10 weeks. Their muscle responded better to insulin and showed signs of doing more cellular maintenance (PMID: 33888596)⁴. According to Happy Aging's review of the research, this is the trial that most directly speaks to the women-over-40 question, because it's actually run in women in our population.

A 2018 review pulled together everything we know across animal and early human studies. The pattern: when you raise NAD+, you tend to see better mitochondrial function (your cells' energy engines), better muscle, and fewer "old" cells hanging around making trouble³. Bigger long-term human trials are still in progress, but the early signals are consistent.

What's on the label	What it actually is	Does your body absorb it?	Human trial evidence	Best for
NAD+	The active, switched-on form	Not well. Broken down in your stomach unless it's in a special "liposomal" delivery (a tiny fat bubble that protects it).	Limited for plain tablets; better for liposomal	Liposomal forms only
NR (nicotinamide riboside)	A building block. Your cells turn it into NAD+.	Yes	Strongest, biggest trial (140 people, PMID: 29599478)	Broad NAD+ support, very well-tolerated
NMN (nicotinamide mononucleotide)	A building block one step closer to NAD+ than NR	Yes	Growing. The Yoshino 2021 women's trial is the standout (PMID: 33888596).	Muscle, energy, women in midlife
NMNH (reduced NMN)	A newer form of NMN that may absorb a little better	Looks good in early studies	Mostly animal data so far; small early human studies	Faster NAD+ boost (still emerging)
NADH	The "drained" form of NAD+	Not the right thing to take for longevity	Some research on fatigue, not on aging	Skip. It's not what's missing.

What the evidence does NOT support

Plain oral NAD+ tablets, the ones that just say "NAD+" on the bottle without a special delivery, don't really get into your cells in any meaningful way. NAD+ is a big, fragile molecule, and your stomach breaks it down before it can do anything useful. Liposomal NAD+ (wrapped in a tiny fat bubble) is different. The wrapper protects it through digestion. But most budget NAD+ products skip the wrapper entirely. Read labels closely.

NADH supplements aren't really worth it for aging. NADH is what's left over after NAD+ does its job. Adding more "leftovers" doesn't help your cells make more energy or do more repair work. The trials on NADH have mostly looked at fatigue, not at aging itself, and even there the effects are small.

Mega-doses aren't automatically better. The Martens trial used a generous dose (1,000 mg of NR) and got good results, but doubling that doesn't double the benefit. Animal studies with absurdly high doses don't translate to humans. Happy Aging's position: NR or NMN works best as part of the bigger picture. Strength training, enough protein, and good sleep all help your body make more NAD+ on its own, so the supplement has more to work with.

The Happy Aging recommendation

This is for women in perimenopause and beyond who want to actually do something about NAD+ decline. If you're pregnant, nursing, on immunosuppressants, or have a history of hormone-sensitive cancer, talk to your doctor first. The cancer research on NAD+ is still evolving.

Happy Aging's protocol for supporting NAD+:

1. Pick a supplement that includes more than one building block. NR and NMN (or NMNH) come into the system at slightly different points, so a formula that pairs them is more thorough than either alone.
2. Make sure it has trans-resveratrol. Resveratrol works with NAD+ to switch on the cellular "repair crew" (a group of proteins called sirtuins). They work better together than apart.
3. Take it in the morning, with food. Your body makes more NAD+ earlier in the day naturally, so morning matches the rhythm. A bit of healthy fat in your meal helps the supplement absorb.
4. Don't skip the basics. Strength training two or three times a week and adequate protein both help your body make more NAD+ on its own.
5. Give it 8 to 12 weeks. Your blood NAD+ rises in the first 2 to 4 weeks, but you usually feel the energy and sleep changes by 2 to 3 months.

Frequently Asked Questions

Is NAD the same as NAD+?

Pretty much, yes. NAD is the name of the molecule. NAD+ is the form your cells actually use. When researchers or supplement labels say "NAD," they almost always mean NAD+. That's the version that's switched on and doing the work.

Can I take NAD+ directly as a pill?

Plain NAD+ pills don't work very well. Your stomach breaks the molecule down before your cells get any. Liposomal NAD+ (wrapped in tiny fat bubbles) is better because the wrapper protects it through digestion. But for most people, taking NR or NMN, the building blocks your body converts into NAD+, has more human trial evidence behind it.

How long until I notice anything?

Your blood NAD+ goes up within 2 to 4 weeks, but the things you actually feel (better energy, steadier sleep, sharper mornings) usually show up over 8 to 12 weeks. Trying it for just a week or two and quitting is the most common reason people give up before it kicks in.

When should I take it?

Morning, with a meal that has some fat. Your body makes NAD+ on its own rhythm (more in the morning, less at night), so taking it then matches the natural pattern. The fat helps the absorption.

Is it safe to take every day?

For most people, yes. NR at 1,000 mg daily was well-tolerated in the 140-person trial¹. NMN at 250 mg daily was also fine in the women's trial⁴. The most common side effects are mild: mild nausea, flushing, or a bit of GI discomfort in the first couple of weeks. Check with your doctor first if you have a history of hormone-sensitive cancer, since NAD+ research in cancer is still evolving.

What about NADH? Should I take that too?

No. NADH is just the spent form of NAD+ after your cells use it. Adding NADH supplements doesn't raise NAD+ levels in any meaningful way. Skip it and focus on the building blocks (NR, NMN) instead.

For the full landscape on how NAD+ decline shapes longevity for women over 40, see Happy Aging's NAD+ Women's Longevity guide.