Five Supplement Questions From Dr. Kim's Practice — and Honest Answers: Glutamine, curcumin, NAC, topical glutathione, and vitamin A | Integrative Medicine San Antonio Yoon Hang Kim MD
- John Kim
- 1 day ago
- 4 min read
by Yoon Hang Kim MD
Patients send me thoughtful supplement questions almost every week. Some are about products they already own, others about something they read online or heard from a friend. The five below come up often enough that I want to answer them publicly, in the same straightforward way I would during an office visit. My goal is not to promote or dismiss any brand, but to help you match the right formulation to the right goal — and to flag where the evidence is softer than the marketing suggests.
1. Is glutamine safe long-term, and does it actually raise glutathione?
Glutamine is generally well tolerated, and most people can take it for extended periods without obvious problems. That said, long-term universal benefit is not as well established as supplement marketing often implies. It has a reasonable place in certain gut-focused and recovery-focused protocols, but it is not a supplement everyone needs to be on indefinitely.
On the glutathione question specifically, I would not lean on oral glutamine as your primary strategy. At least one human study found that oral glutamine supplementation did not raise whole-blood glutathione, which matters because whole-blood glutathione is the pool most clinicians actually care about. If raising glutathione is the goal, there are more direct tools — NAC, glycine, liposomal glutathione, sulfur-rich foods, and addressing the upstream drivers of glutathione depletion — that deserve first consideration. Glutamine can still be part of the picture for other reasons, but I would not expect it, by itself, to do the heavy lifting on glutathione status.
2. Is the curcumin dose for the standard product or the liposomal one?
This question comes up constantly, and the answer is: the dose depends entirely on the exact formulation. Standard curcumin powders have notoriously poor absorption, which is why historical doses are often quite high. Enhanced-bioavailability forms — liposomal, phytosome (such as Meriva-type preparations), micellar, and nanoparticle curcumins — are engineered to deliver far more active curcuminoid per milligram, so they are usually dosed much lower than the older standardized 95% curcumin powders.
Practically, this means you cannot simply swap milligram for milligram between products. If your clinician recommended a specific dose, that dose was matched to a specific formulation, and switching brands without rechecking the label can leave you either under-dosed or unnecessarily over-dosed. Before changing products, confirm which formulation the dose was written for and re-match it to the new label.
3. Is Codeage Liposomal NAC a good choice, and is liposomal better than regular NAC?
Yes, I am familiar with Codeage Liposomal NAC, and it is a reasonable product. The broader question — whether liposomal NAC is categorically superior to standard NAC — does not have a clean yes answer. Liposomal delivery may help with absorption or gastrointestinal tolerability for some people, and those are legitimate reasons to pick it. But the evidence that every patient needs the liposomal version to get a clinical response is not there.
What I care about more than the word "liposomal" on the bottle is the rest of the ingredient list: the actual dose of NAC per serving, the presence or absence of unnecessary fillers, third-party testing, and whether the co-ingredients make sense for your situation. A clean standard NAC from a trustworthy manufacturer often works very well. Liposomal is a nice option to have, not a requirement.
4. Is topical glutathione cream available, and does it actually absorb?
Topical glutathione products do exist and are widely marketed. The harder question is whether they deliver enough glutathione through the skin to meaningfully raise systemic glutathione status. The data there are still early. Some formulations show local effects and modest systemic signals, but the evidence for strong, reliable whole-body absorption is not yet definitive.
My honest framing is that topical glutathione is promising rather than proven. It is not unreasonable to use it — especially for skin-focused goals — but I would not rely on a cream as your sole intervention if the clinical goal is to move systemic glutathione. Pair it with, or substitute in, better-studied approaches when the stakes matter.
5. If I need more vitamin A than AK Avail provides, what should I look at?
AK Avail is a perfectly good multi, but it is built for broad nutritional support rather than high-dose vitamin A delivery. If a patient genuinely needs more vitamin A — for example, because of known issues with beta-carotene conversion — the smarter move is usually a preformed vitamin A product, such as retinyl palmitate, rather than stacking more beta-carotene on top.
The reason is practical. Beta-carotene has to be converted into active retinol by the body, and a meaningful subset of people convert it poorly due to genetic variation and other factors. For those individuals, preformed retinyl palmitate bypasses the bottleneck and is generally far more effective per milligram. In that situation, a clean standalone retinyl palmitate formulation usually makes more sense than trying to force more conversion from carotenoids. Vitamin A is fat-soluble and has a real upper limit, so dosing should be individualized — but when more is needed, match the form to the physiology.
The common thread
Running through all five answers is a single theme: the right supplement decision almost always comes down to matching the specific formulation to the specific person and the specific goal. Brand names and buzzwords — liposomal, bioavailable, enhanced — do not substitute for understanding what your body actually needs and how well a given form can deliver it. If you are unsure whether what you are taking is doing what you hoped, that is a conversation worth having with your clinician rather than a decision to make alone in the supplement aisle.
Medical Disclaimer This article is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Supplement responses vary by individual based on genetics, absorption, concurrent medications, and underlying conditions. Do not start, stop, or change any supplement or medication without first consulting a qualified, licensed healthcare professional who knows your personal medical history. If you are a patient of Direct Integrative Care, please bring supplement questions to your scheduled visit or secure message. |
Comments