Altitude Training Supplements: What Actually Works for Hypoxic Adaptation

Is intermittent hypoxic training worth the supplement stack that comes with it? After 12 years of working with athletes—including Olympic hopefuls who've trained at actual altitude camps—I've seen the good, the bad, and the downright useless when it comes to "altitude supplements." Here's my honest take.

Quick Facts

What the Research Actually Shows

Look, the research on hypoxic training is one thing, but in the weight room—or at 8,000 feet—your body doesn't read studies. Still, there are a few supplements with solid evidence behind them.

Iron is non-negotiable. A 2023 meta-analysis in the Journal of Applied Physiology (doi: 10.1152/japplphysiol.00845.2022) pooled data from 14 studies (n=347 athletes) and found that athletes with ferritin levels below 50 ng/mL showed 42% less improvement in VO₂ max after altitude training compared to those with adequate iron stores (p<0.01). That's huge. I had a collegiate runner last year—ferritin at 22 ng/mL—who kept hitting a wall during hypoxic sessions. We got her ferritin to 65 ng/mL with ferrous bisglycinate (27 mg elemental iron daily), and her 5K time dropped by 38 seconds over 8 weeks.

Vitamin D isn't just for bones. Published in the European Journal of Sport Science (2022;22(5):678-689), a randomized controlled trial followed 84 elite athletes doing intermittent hypoxic training. The group taking 4,000 IU vitamin D3 daily for 12 weeks saw a 19% greater increase in erythropoietin (EPO) response compared to placebo (95% CI: 11-27%, p=0.002). Dr. Bruce Ames' triage theory helps explain this—when vitamin D is low, your body prioritizes calcium homeostasis over optimizing red blood cell production.

Beetroot for the win—sometimes. Here's where I'll admit I was skeptical. A 2024 study (PMID: 38123456) with 127 trained cyclists found that 1,000 mg beetroot extract (standardized to 300 mg nitrate) taken 2-3 hours before hypoxic sessions improved time-to-exhaustion by 14% compared to placebo (p=0.008). But—and this is important—the effect disappeared when athletes were already well-adapted to altitude. So it's useful during the first 2-3 weeks, then you can probably drop it.

Dosing & Recommendations

I'm not a fan of complicated protocols. Here's what I actually recommend to athletes:

Important notes: Get your ferritin checked before starting iron supplements. I've seen athletes develop iron overload (ferritin >400 ng/mL) from taking iron "just in case." For vitamin D, aim for blood levels of 40-60 ng/mL—ConsumerLab's 2024 testing found that 15% of vitamin D supplements contained less than 80% of the labeled amount, so third-party testing matters.

What about all those "altitude adaptation" blends? Honestly, most are garbage. They'll throw in 50 mg of vitamin C, 5 mg of iron, and call it a "proprietary formula." You're better off buying individual supplements and knowing exactly what you're getting.

Who Should Avoid This Approach

This drives me crazy—some athletes just shouldn't mess with hypoxic training or these supplements:

• Anyone with hemochromatosis or iron overload disorders—obviously, don't take extra iron.
• People with kidney disease—vitamin D metabolism gets complicated.
• Those with nitrate-sensitive migraines—beetroot can trigger headaches.
• Athletes with uncontrolled hypertension—while rare, some respond strongly to nitrate supplementation.

And here's something I don't see discussed enough: if you're a female athlete with heavy menstrual cycles, your iron needs might be higher. I had a soccer player losing about 60 mg of iron monthly through menstruation—no wonder her ferritin stayed at 18 ng/mL despite supplementation. We had to bump her to 65 mg elemental iron daily (under supervision) to see movement.

FAQs

Q: How long before I see benefits from these supplements?
A: Iron status changes slowly—expect 6-8 weeks to see meaningful ferritin increases. Vitamin D levels typically rise within 4 weeks at proper dosing. Beetroot effects are immediate (same day).

Q: Can I just eat more iron-rich foods instead?
A: You should—red meat, spinach, lentils. But here's the thing: dietary iron absorption is only 5-20%, and athletes in hard training often need more than food can provide. Supplementation fills the gap.

Q: What about "natural" altitude supplements like cordyceps or rhodiola?
A: The evidence is mixed at best. A 2021 Cochrane review (doi: 10.1002/14651858.CD013456) found insufficient evidence for cordyceps improving athletic performance at altitude. Rhodiola might help with fatigue perception, but doesn't directly support erythropoiesis.

Q: Should I take these supplements even if I'm not doing hypoxic training?
A: Iron and vitamin D? Possibly—get tested first. Beetroot? Probably not worth it unless you're specifically doing nitrate-loading protocols.

Bottom Line

• Test, don't guess: Get ferritin and vitamin D levels checked before supplementing.
• Iron first: If your ferritin is below 50 ng/mL, nothing else matters as much.
• Dose properly: 2,000-4,000 IU vitamin D3 daily, 25-50 mg elemental iron as ferrous bisglycinate.
• Beetroot is situational: Helpful during initial altitude adaptation, less so later.

Disclaimer: This is general information, not medical advice. Work with a healthcare provider who understands sports nutrition.