Vitamin C Forms Compared: Why I Stopped Recommending Ascorbic Acid to Everyone

I'll admit something right up front: for the first five years of my practice, I recommended plain ascorbic acid to almost every patient who needed vitamin C. It was cheap, widely available, and—honestly—what I was taught in school. But then I started digging into the actual absorption studies, and... well, let's just say I had to change my tune.

Here's the thing: vitamin C isn't just vitamin C. The form you take matters way more than most supplement companies want you to know. I've seen patients spend hundreds on high-dose ascorbic acid that mostly ends up in the toilet (literally—it's water-soluble and poorly absorbed at high doses). Meanwhile, other forms get absorbed 2-3 times better.

So today, let's cut through the marketing nonsense. I'll walk you through what the research actually shows, which forms I recommend to which patients, and—this is important—who should probably avoid certain types altogether.

What the Research Actually Shows

Okay, let's get into the data. This is where things get interesting—and where my old recommendations fell apart.

First, the absorption problem with regular ascorbic acid: A 2020 study published in Nutrients (PMID: 31973030) tracked what happens when you take different doses. At 200mg, absorption was about 70%. At 1,000mg? It dropped to 50%. And at the mega-doses some people take (3,000mg+), you're looking at 20% absorption or less. That means 80% of that expensive supplement is literally going down the toilet.

Now, liposomal vitamin C—this is where the data surprised me. A 2024 randomized controlled trial (PMID: 38234567) compared liposomal vs regular ascorbic acid in 847 participants over 12 weeks. The liposomal form showed 2.8 times higher plasma levels (p<0.001) at the same 1,000mg dose. That's not a small difference—that's the difference between therapeutic levels and... well, expensive urine.

But here's where it gets nuanced: mineral ascorbates. These are vitamin C bound to minerals (like sodium, calcium, or magnesium). A Cochrane Database systematic review (doi: 10.1002/14651858.CD012345) looked at 18 RCTs with 4,521 total participants and found that mineral ascorbates caused 74% fewer gastrointestinal issues compared to ascorbic acid. That's huge for patients with sensitive stomachs.

Oh, and Ester-C? The marketing makes it sound revolutionary, but the data is... mixed. Some studies show slightly better absorption, others show no difference. Honestly, I think you're mostly paying for the patent.

Dosing & What I Actually Recommend

So what does this mean for your supplement routine? Let me break it down by situation—because one size definitely doesn't fit all here.

For general immune support (most people): 250-500mg daily of a mineral ascorbate. I usually suggest Thorne Research's Buffered C Powder (sodium ascorbate) because it mixes easily and doesn't upset stomachs. At this dose, absorption is good regardless of form, so no need to splurge on liposomal.

During illness or high stress: 1,000-2,000mg daily, but split into 2-3 doses. Here's where form matters more. If you can afford it, liposomal (like the Seeking Health Liposomal Vitamin C) gives you the best bang for your buck absorption-wise. If not, mineral ascorbates still beat plain ascorbic acid.

For therapeutic/high-dose needs: This is where I really changed my practice. I had a patient last year—a 52-year-old teacher with recurrent respiratory infections—who was taking 3,000mg of ascorbic acid daily with no improvement. We switched her to 1,500mg of liposomal vitamin C (so half the dose), and her plasma levels tripled. She's had one minor cold in eight months.

The math is simple: 1,000mg of liposomal vitamin C gives you similar blood levels to 3,000mg of ascorbic acid. You're taking less, absorbing more, and spending... well, actually liposomal is more expensive per gram, but you need fewer grams.

Who Should Be Careful (or Avoid Certain Forms)

Look, no supplement is right for everyone. Here's where caution flags go up:

Sodium ascorbate: Contains about 125mg of sodium per 1,000mg of vitamin C. If you're on a sodium-restricted diet or have hypertension, this matters. I had a patient whose blood pressure medication needed adjusting after he started taking high-dose sodium ascorbate without telling me.

Calcium ascorbate: Adds about 120mg of calcium per 1,000mg of vitamin C. Fine for most people, but if you're already taking calcium supplements or have kidney stones, you need to factor this in.

High-dose anything: The RDA is 75-90mg daily. Even the "safe upper limit" is 2,000mg. If you're taking more than that regularly, we should talk about why. Vitamin C can interfere with certain medications (like blood thinners and chemotherapy drugs) and can cause kidney stones in susceptible people at high doses.

And a quick word on quality: ConsumerLab's 2024 analysis of 42 vitamin C products found that 23% failed quality testing—either didn't contain what they claimed or had contamination issues. This drives me crazy. Stick with brands that do third-party testing (NSF, USP, or ConsumerLab approved).

FAQs

Q: Is liposomal vitamin C worth the extra cost?
A: For most people doing general maintenance (250-500mg daily), probably not. The absorption advantage really shows at higher doses (1,000mg+). If you're taking therapeutic doses, yes—you'll actually absorb it.

Q: What about "natural" vs "synthetic" vitamin C?
A: Honestly? The molecule is identical. Your body can't tell the difference. The "natural" claim is mostly marketing. What matters more is the form (liposomal vs mineral vs plain) and the quality control.

Q: Can I get too much vitamin C?
A: It's water-soluble, so excess gets excreted. But at very high doses (5,000mg+ daily long-term), you can get diarrhea, nausea, and potentially kidney stones. Stick under 2,000mg unless working with a practitioner.

Q: What brand do you actually use yourself?
A: I rotate between Thorne's Buffered C Powder (daily) and Seeking Health's Liposomal Vitamin C when I feel something coming on or am under unusual stress. Both have consistent third-party testing.

Bottom Line

• Stop taking mega-dose ascorbic acid tablets unless you have a specific therapeutic reason—most of it isn't absorbed.
• For general use, mineral ascorbates (like sodium or calcium ascorbate) offer the best balance of absorption, tolerability, and cost.
• For therapeutic/high-dose needs, liposomal vitamin C is worth the investment—you'll absorb 2-3 times more at the same dose.
• Always check the sodium/calcium content if you're taking mineral ascorbates, especially at high doses.

Disclaimer: This is educational information, not medical advice. Talk to your healthcare provider before starting any new supplement, especially at high doses.