In the US, NMN alone suits people who want the same ingredient that published NMN human trials tested. An NMN + TMG formula adds betaine as a methyl donor. That choice rests on a methylation rationale, not on proof. No human trial has compared the two. So choose by label, dose and goal, not by promised results.
Why NMN Is Often Paired With TMG
The NMN + TMG pairing comes from biochemical reasoning. You should know what that reasoning says and what it does not say.
An enzyme called NNMT (nicotinamide N-methyltransferase) uses SAM (S-adenosylmethionine) as a methyl donor. It turns nicotinamide (NAM) into methylnicotinamide (MNA). This reaction also makes SAH, which is a precursor of homocysteine (Li 2024).
Betaine, also called trimethylglycine (TMG), has two main roles: osmolyte and methyl donor. As a methyl donor, it works in the methionine cycle, mainly in the liver and kidneys. Low methyl intake is linked to higher homocysteine and lower SAM (Craig 2004). Betaine gives methyl groups to homocysteine to form methionine (Zeisel 2003).
So the logic runs like this: NMN leads to NAM, methylating NAM uses methyl groups, and TMG supplies methyl groups. That is a mechanistic rationale. It is not a proven clinical benefit of the combination. No published human trial has tested NMN + TMG against NMN alone. Our explainer on why NMN and TMG are paired covers the pathway in more depth.
What the NMN Human Trials Actually Tested
Each NMN trial below gave NMN on its own. None of them added TMG. So the human evidence for NMN applies to NMN alone.
- Middle-aged adults: 80 healthy adults took placebo or 300, 600 or 900 mg NMN daily for 60 days. Blood NAD rose in all NMN groups and was highest at 600 and 900 mg. Six-minute walking distance improved compared with placebo. Insulin resistance (HOMA-IR) did not differ from placebo. Industry co-sponsored this trial (Yi 2023).
- Women with prediabetes: Postmenopausal women who were overweight or obese took 250 mg NMN daily for 10 weeks. Muscle insulin sensitivity and muscle insulin signaling increased after NMN but not after placebo (Yoshino 2021).
- Older men: Men took 250 mg NMN daily for 6 or 12 weeks. Blood NAD+ rose. Gait speed and left grip improved nominally, but the authors said these results "should be validated in larger studies." Body composition did not change (Igarashi 2022).
- Runners: In 48 trained runners, 600 and 1,200 mg NMN daily for 6 weeks raised oxygen uptake and power at ventilatory thresholds more than control. VO2max and peak power did not change (Liao 2021).
The safety data also come from NMN alone. Single doses of 100 to 500 mg caused no significant clinical symptoms in 10 healthy men (Irie 2020). A dose of 1,250 mg daily for up to 4 weeks caused no severe adverse events in 31 adults. The NMN supplier funded that study (Fukamizu 2022). In an open-label study, 11 men took two 125 mg capsules daily for 8 weeks and tolerated them well (Yamaguchi 2024).
These trials are small, and some had industry ties. For dose ranges, read how much NMN per day. For tolerability, read NMN side effects.
What Betaine (TMG) Does in Human Studies
Betaine is already part of a normal diet. Foods with the most betaine include wheat bran (1,339 mg per 100 g), wheat germ (1,241 mg) and spinach (645 mg) (Zeisel 2003). Usual dietary intake is about 0.5 to 2 g per day (Olthof 2003).
Human trials of betaine supplements used doses measured in grams:
- In healthy adults, 1.5, 3 and 6 g daily for 6 weeks lowered fasting homocysteine by 12%, 15% and 20% compared with placebo (Olthof 2003).
- A meta-analysis of 5 trials that used 4 g or more daily found that homocysteine fell by 1.23 µmol/L (McRae 2013).
- At the same high doses, a meta-analysis of 6 trials found that total cholesterol rose by 0.34 mmol/L. LDL, HDL and triglycerides did not change significantly (Zawieja 2021).
- A larger 2022 meta-analysis found higher total cholesterol (+14.12 mg/dL) and LDL (+10.26 mg/dL), and lower homocysteine (-1.30 µmol/L). Triglycerides, HDL, fasting glucose, CRP, liver enzymes and blood pressure did not change (Ashtary-Larky 2022).
Now compare these doses with the 250 mg of TMG in one AgeAura serving. That amount is far below the 1.5 to 6 g tested for homocysteine. It is also far below the 4 g or more linked to cholesterol changes. It is even below usual dietary intake. Do not expect 250 mg to lower homocysteine. Do not assume the cholesterol finding applies at 250 mg either. No trial tested 250 mg.
NMN Alone vs NMN + TMG: A Side-by-Side View
| Factor | NMN alone | NMN + TMG formula |
|---|---|---|
| What it contains | NMN only | NMN plus betaine (TMG), sometimes with other ingredients |
| Evidence base | Same ingredient as the NMN trials above | No published trial of the combination |
| Methyl-donor rationale | No methyl donor added; diet supplies betaine | Adds a methyl donor because of the NNMT/SAM pathway; rationale, not proof |
| Label checks | NMN mg per serving, servings per container | NMN mg, TMG mg, each added ingredient, allergens |
| Who it may suit | People who want to stay close to trial conditions | People who want a methyl donor in the same capsule and accept the limited evidence |
On outcome evidence, neither column wins. NMN alone is closer to what the trials tested. The combination adds a reasonable idea that nobody has tested as a pair.
AgeAura Pure NMN + TMG NAD+ Complex is an example of the second type. Use the label checks below on any formula you are considering.
How to Compare NMN Labels and Prices in the US
Compare labels serving by serving, not bottle by bottle. Use AgeAura as a worked example:
- Serving size. The label says 2 capsules daily. Check how many servings each container holds.
- NMN per serving. Each serving gives 500 mg NMN. The trials above tested 250 to 1,250 mg daily.
- TMG per serving. Each serving gives 250 mg betaine anhydrous. This is the low amount discussed above.
- Other ingredients. Each serving also gives 100 mg trans-resveratrol, 150 mg quercetin, 50 mg apigenin, 1 mg spermidine and 400 mcg DFE folate as L-methylfolate. Each extra ingredient is one more item to review with your doctor.
- Allergens. The label lists wheat as an allergen, because the spermidine comes from wheat germ extract. The label also says the product is free from gluten, soy, dairy, fish and shellfish.
- Price and terms. The one-time price of AgeAura Pure NMN + TMG NAD+ Complex is $69.95. Subscription options are 15% off every 4 weeks or 14% off every 12 or 24 weeks. A 90-day money-back guarantee applies. The product page lists non-GMO vegan capsules, made in a USA cGMP-certified partner facility, without artificial fillers or preservatives.
Shopping for something other than NMN? Browse the Wellness Nest best sellers.
Dietary supplements are not FDA-approved to treat, cure or prevent disease. The product page says this: if you are pregnant, nursing, under 18, taking medication or managing a medical condition, talk to your doctor before use. It is not a medicine and does not replace medical care.
Which Option May Fit Your Goal
- You want to stay close to the research. NMN alone matches the ingredient that the human trials tested.
- You want NMN and a methyl donor in one daily capsule. An NMN + TMG formula such as AgeAura Pure NMN + TMG NAD+ Complex fits this preference. Accept that the pairing is a rationale and that 250 mg TMG is a small amount.
- You track homocysteine or cholesterol. Betaine changed these markers only at gram-level doses. Talk with your doctor before you start.
- You avoid wheat. Check every label for wheat-derived ingredients.
Neither option guarantees a result. Wellness Nest suggests that you choose the label you understand best. For other options, see the Wellness Nest best sellers.
Frequently Asked Questions
Do I need TMG if I take NMN?
No study shows that you need it. The pairing rests on a rationale: NNMT uses SAM to methylate nicotinamide (Li 2024), and betaine is a methyl donor (Craig 2004). No published human trial has tested NMN + TMG against NMN alone.
Did the NMN studies use TMG?
No. The NMN trials reviewed here gave NMN alone, at 250 to 1,250 mg daily. Their results apply to NMN, not to a combination formula.
Will 250 mg of TMG lower homocysteine?
Nobody has shown that it does. The trials that lowered homocysteine used 1.5 to 6 g daily (Olthof 2003). The 250 mg amount is below even usual dietary intake.
Is NMN legal in US dietary supplements?
Yes. On September 29, 2025, FDA answered a Natural Products Association citizen petition and confirmed that NMN is lawful in dietary supplements (NPA). FDA found that NMN was sold as a supplement in the US as early as 2017.
Can I get betaine from food?
Yes. Wheat bran, wheat germ and spinach are among the richest sources, at 1,339, 1,241 and 645 mg per 100 g (Zeisel 2003). A usual diet supplies about 0.5 to 2 g per day.
About the Author
Dr. Marcus Hale — Dr. Marcus Hale is the resident health researcher behind Wellness Nest's editorial team, translating peer-reviewed sports-nutrition and longevity research into practical daily guidance for US readers.
