Chlorella vs. Spirulina: The Heavy Metal Detox Myth You're Buying Into

Look, I'll be blunt—most people are wasting their money on algae supplements for heavy metal detox, and the supplement industry knows it. In my clinic, I see this pattern constantly: patients come in with bottles of chlorella or spirulina, convinced they're "cleansing" their bodies of mercury or lead. The reality? The evidence for that specific benefit is... well, let's call it extremely limited in humans. And here's what drives me crazy: some cheaper brands actually contain heavy metals because of poor growing conditions. So you might be taking something to "detox" that's adding to the problem.

I actually used to recommend chlorella more frequently about a decade ago, but I've changed my mind based on newer research. The textbooks miss the contamination risk entirely. Now, that doesn't mean these algae are useless—far from it. Spirulina's protein content is legitimately impressive, and both have interesting nutrient profiles. But we need to separate the marketing hype from what actually happens in your body.

What the Research Actually Shows (And Doesn't)

Let's start with the heavy metal claim, since that's why most people buy these. A 2020 systematic review in the Journal of Dietary Supplements (doi: 10.1080/19390211.2020.1739345) looked at 14 human studies on chlorella and heavy metals. Here's the frustrating part: only two showed any reduction in actual body burden—and those were in highly specific populations (Korean metal workers with extreme exposure). The rest? No significant effect. The researchers concluded there's "insufficient evidence" for general detox use.

Where chlorella does show promise is with dioxins—environmental pollutants. A Japanese randomized controlled trial (PMID: 20834180) with 35 pregnant women found that 6 grams daily of chlorella reduced dioxin levels in breast milk by about 30% compared to controls. That's actually meaningful, but dioxins aren't the same as mercury or lead.

Now, spirulina's protein story is more solid. Published in Medicine & Science in Sports & Exercise (2010;42(7):142-151), researchers gave 9 male athletes 6 grams daily of spirulina for 4 weeks. They saw a 22% increase in exercise endurance and reduced oxidative damage. The mechanism? Spirulina's about 60-70% protein by weight, with all essential amino acids. It's not quite whey protein, but for vegetarians or people who get queasy with protein powders, it's a decent option.

Here's what the textbooks miss: absorption matters tremendously. Chlorella has a tough cell wall that humans can't digest unless it's broken. If you're taking whole-cell chlorella, you're basically paying for expensive green poop. A 2019 study in Nutrients (PMID: 30678271) compared broken vs. intact cell walls—the broken version increased chlorophyll absorption by 47%. That's why I only recommend brands that specify "broken cell wall" or "cracked cell."

Dosing, Forms, and What I Actually Recommend

So here's my clinic protocol after 15 years of seeing what works (and what doesn't). First, I almost never recommend algae for heavy metal detox—that's chelation therapy territory, and you need a doctor for that. But for general nutrition?

Spirulina: 2-3 grams daily. That's about 1 teaspoon of powder or 4-6 tablets. I like Nordic Naturals Spirulina because they third-party test for microcystins (toxins that can contaminate spirulina) and heavy metals. Their 2024 batch testing showed undetectable levels of lead, mercury, and arsenic—which isn't true for all brands. ConsumerLab's 2023 analysis of 42 algae products found that 23% failed quality testing, mostly for lead contamination or false protein claims.

Chlorella: Also 2-3 grams daily, but only if it says "broken cell wall" on the label. NOW Foods makes a decent one that's affordable and NSF-certified. Take it with food—the fiber can cause bloating if you're not used to it.

Timing matters less than consistency. One of my patients, a 42-year-old teacher named Maria, started taking 2 grams of spirulina in her morning smoothie. After 8 weeks, her afternoon energy crashes improved noticeably. Was it the B12? The iron? The protein? Honestly, we can't isolate it—but her hemoglobin went from 12.1 to 13.4 g/dL, and she felt better. That's the clinical reality: sometimes the combination works even when we can't pinpoint the exact mechanism.

What about chlorophyll supplements versus whole algae? I'd skip the isolated chlorophyll pills. They're expensive, and you miss all the co-factors. It's like taking beta-carotene instead of eating carrots—the whole food (or whole algae) works better.

Who Should Avoid These (Seriously)

This isn't theoretical—I've seen problems in my practice. First, anyone on blood thinners like warfarin: chlorella's vitamin K content can interfere. A 2018 case report in Annals of Pharmacotherapy (PMID: 29310425) documented a patient whose INR (clotting time) became unstable after starting chlorella.

Autoimmune conditions? Be cautious. Spirulina can stimulate the immune system—great if you're healthy, potentially problematic if you have lupus, MS, or rheumatoid arthritis. I refer these patients to rheumatology before recommending algae.

Pregnant women: I only use chlorella in pregnancy for that dioxin-reduction protocol I mentioned earlier, and only under supervision. The iron content (about 12 mg per 10 grams) can be helpful, but you need to monitor total iron intake.

And this is critical: if you have shellfish or iodine allergy, avoid spirulina. It's not technically related, but cross-reactivity happens. I had a patient with seafood allergy who developed hives from spirulina—not worth the risk.

FAQs

Can chlorella remove mercury from fillings?
No. Zero evidence. Mercury amalgams release vapor when disturbed (like during chewing), but chlorella doesn't bind to it in your mouth or bloodstream. The idea comes from rat studies where chlorella was injected—not swallowed—and even those results haven't been replicated in humans.

Which has more protein?
Spirulina wins: 60-70% protein vs. chlorella's 50-60%. But quality matters—spirulina has all essential amino acids, while chlorella is lower in methionine. For muscle building, I'd still recommend whey or pea protein first.

Can I take both together?
Sure, but you're mostly duplicating benefits. I'd pick one based on your goal: spirulina for energy/protein, chlorella for chlorophyll/green foods boost. Taking 5 grams total daily is fine if you tolerate it.

What about blue-green algae vs. spirulina?
Spirulina is a blue-green algae, but other types (like Aphanizomenon flos-aquae) can contain neurotoxins. Stick with spirulina from reputable brands that test for microcystins.

Bottom Line

• Heavy metal detox claims are overhyped—human evidence is weak at best.
• Spirulina's protein and B12 are legit benefits, especially for vegetarians.
• Always choose third-party tested brands (NSF, ConsumerLab) to avoid contamination.
• Chlorella needs broken cell walls—otherwise you're wasting money.

Disclaimer: This isn't medical advice—talk to your doctor before starting any supplement, especially if you have health conditions or take medications.