GLP-1 + B12 vs GLP-1 + NAD+: What Compounders Are Adding and Why
Adding ingredients to compounded GLP-1 medications serves both a legal and clinical purpose. Here's an honest look at what each additive actually does — and which ones have evidence behind them.
If you've shopped for compounded semaglutide or tirzepatide recently, you've noticed that most products aren't just the active GLP-1 ingredient alone. They come with additions: vitamin B12, L-carnitine, NAD+, glycine, or other compounds. Some providers call these "enhanced formulations." Others are more straightforward about it.
The reality is that these additives serve two functions — one regulatory, one potentially clinical. Understanding both helps you make a better-informed choice.
The Regulatory Function: Why Additives Exist
After the FDA removed semaglutide and tirzepatide from the drug shortage list, compounding pharmacies needed a legal basis to continue producing these medications. The most widely used pathway is creating a formulation with a "clinically significant difference" from the commercial product — meaning it's not an "essentially a copy."
Adding an ingredient like B12, NAD+, or L-carnitine to a semaglutide injection creates a formulation that doesn't exist commercially. This is the regulatory logic. The clinical question is separate: does the additive actually improve outcomes for the patient?
Additive-by-Additive Breakdown
Vitamin B12 (Cyanocobalamin / Methylcobalamin)
Strong RationaleWhat it does: B12 is essential for energy metabolism, nerve function, and red blood cell production. GLP-1 medications slow gastric emptying and reduce food intake, which can contribute to lower B12 absorption over time — particularly in patients already at risk for deficiency.
Clinical evidence: B12 deficiency is a documented concern in patients on long-term metformin (a common co-prescription with GLP-1s) and in patients with reduced dietary intake. Studies have shown that 10–30% of metformin users develop B12 deficiency. Adding B12 to a GLP-1 injection is a plausible preventive measure, though no randomized trial has specifically tested the combination.
Bottom line: The most well-supported additive. B12 is safe, inexpensive, and addresses a real nutritional risk in the GLP-1 patient population. Most providers offer methylcobalamin (the bioactive form) rather than cyanocobalamin.
NAD+ (Nicotinamide Adenine Dinucleotide)
Emerging — Limited Direct EvidenceWhat it does: NAD+ is a coenzyme involved in cellular energy metabolism, DNA repair, and sirtuin activation. Proponents argue it supports mitochondrial function, may slow aging, and helps maintain energy levels during caloric restriction.
Clinical evidence: NAD+ research is active but most studies are preclinical (animal models) or in early-stage human trials for conditions unrelated to weight loss. There are no published trials specifically examining NAD+ combined with GLP-1 agonists. The longevity and anti-aging claims around NAD+ remain largely theoretical in clinical settings.
Bottom line: An intriguing addition that aligns with consumer interest in longevity and cellular health, but the evidence base is thinner than B12. Patients paying a premium for NAD+ formulations should understand that the clinical benefit specifically alongside GLP-1 therapy is not established.
L-Carnitine
Moderate RationaleWhat it does: L-carnitine transports fatty acids into mitochondria for energy production. It's widely used in fitness supplements and is sometimes marketed as a fat-burning aid.
Clinical evidence: A meta-analysis published in Obesity Reviews found that L-carnitine supplementation produced a modest additional weight loss of approximately 1.3 kg compared to placebo in overweight/obese adults. The effect is real but small. No published data exists specifically on L-carnitine combined with GLP-1 medications.
Bottom line: A defensible addition with some evidence for modest weight loss benefits. Lower priority than B12 in terms of clinical rationale, but not without basis.
Glycine
Limited EvidenceWhat it does: Glycine is an amino acid involved in protein synthesis, collagen production, and neurotransmitter function. Some compounders include it for potential benefits in skin elasticity (relevant given "Ozempic face" concerns) and sleep quality.
Clinical evidence: Glycine has shown benefits for sleep quality in small studies and plays a role in collagen synthesis. However, the amounts typically included in compounded GLP-1 formulations are small relative to therapeutic doses used in glycine research (typically 3–5g orally, vs. milligram quantities in injections). The clinical impact at injection doses is likely minimal.
Bottom line: A reasonable ingredient on paper, but the therapeutic dose in most compounded GLP-1 formulations is probably too low to deliver meaningful benefits.
What to Ask Your Provider
When evaluating compounded GLP-1 formulations with additives, ask these questions:
What specific additive is in my formulation, and at what dose? The answer should include the ingredient name, concentration, and amount per injection. Vague answers ("we add vitamins") are a yellow flag.
Is the additive the basis for your "clinically significant difference" claim? Understanding the regulatory logic helps you assess whether the provider has thought through their legal compliance.
What's the additional cost for the enhanced formulation? Some providers charge a premium for B12 or NAD+ additions. B12 is inexpensive to add; NAD+ costs more. Know what you're paying for.
Providers With Transparent Formulations
Care Bare Rx
Compounded semaglutide · From $199/mo · Clear formulation disclosure
MEDVi
Injectable + oral options · Includes clinical support · Compounded GLP-1
Oak Weight Loss
Compounded GLP-1 programs · Clinical support included · Transparent pricing
The Practical Takeaway
B12 is the most clinically justified additive in compounded GLP-1 formulations — it addresses a real nutritional risk in this patient population and adds minimal cost. NAD+ and L-carnitine have theoretical benefits but lack direct evidence in combination with GLP-1 therapy. Glycine is unlikely to deliver meaningful effects at the doses used in injection formulations.
Regardless of additive, the GLP-1 medication itself is doing the heavy lifting. Choose your provider based on pharmacy quality, regulatory compliance, and transparent practices — then view the additives as a secondary consideration.
Compare Provider Formulations
See which providers offer which additives — and at what cost.
Compare Providers →Sources
- Aroda VR et al. — Long-term metformin use and vitamin B12 deficiency. J Clin Endocrinol Metab, 2016
- Talenezhad N et al. — Effects of L-carnitine supplementation on weight loss. Obesity Reviews, 2020
- Yoshino J et al. — NAD+ intermediates: biology and therapeutic potential. Cell Metabolism, 2018
- Bannai M et al. — Effect of glycine on sleep quality. Sleep and Biological Rhythms, 2012
- FDA — Compounding and the FDA: Clinically significant difference guidance
- FDA — Warning letter to MEDVi, February 2026