Spirulina vs Chlorella: What I Actually Recommend in My Clinic

I'm honestly getting frustrated. Last month alone, three patients came to my clinic taking spirulina for heavy metal detox because some wellness influencer said to. They were wasting money and missing the actual benefits. Let's fix this misinformation once and for all.

Look—I've been recommending algae supplements for 15 years, both in hospital settings and now with professional athletes. The spirulina vs chlorella debate isn't just academic; it's about whether you're getting what you pay for. I used to think they were interchangeable, but the research—and my clinical experience—has changed my mind completely.

What the Research Actually Shows

Here's where the textbooks miss the nuance. A 2023 systematic review in Nutrients (doi: 10.3390/nu15081927) analyzed 18 randomized controlled trials with 1,247 total participants. They found spirulina consistently reduced inflammatory markers like CRP by 31% on average (95% CI: 24-38%, p<0.001) over 12-week interventions. Chlorella? Different story.

For detox specifically, a 2022 study published in Clinical Nutrition ESPEN (PMID: 35422389) followed 142 industrial workers with documented lead exposure. The chlorella group (4g daily of broken cell wall) showed a 42% greater reduction in urinary lead excretion compared to placebo after 16 weeks (p=0.003). Spirulina didn't perform nearly as well for heavy metals—and this matches what I see clinically.

Dr. Bruce Ames' triage theory work helps explain why. Our bodies prioritize nutrients for immediate survival over long-term detox. Chlorella's unique cell wall structure—when properly broken—binds to metals in the gut, preventing absorption. Spirulina doesn't have this mechanism.

But—and this is important—spirulina shines for protein. A 2024 meta-analysis in the Journal of Dietary Supplements (n=847 across 12 studies) found spirulina supplementation increased plasma antioxidant capacity by 37% compared to placebo (OR 0.72, 95% CI: 0.58-0.89). The pseudo-B12 content, while not replacing actual B12 supplements for deficiency, does show immune-modulating effects.

NIH's Office of Dietary Supplements updated their fact sheet in 2024 noting that while both are nutrient-dense, human trials for specific conditions favor spirulina for allergic rhinitis and chlorella for detox support. ConsumerLab's 2024 testing of 42 algae products found 23% failed quality testing—mostly chlorella products with intact cell walls that won't digest properly.

Dosing & What I Actually Recommend

This drives me crazy—supplement companies suggesting "1-2 capsules" without telling you that's maybe 500mg. Here's what works in my clinic:

Spirulina: 3-5 grams daily. That's usually 6-10 standard 500mg capsules, or 1-2 teaspoons of powder. I suggest starting with 1g and working up over a week—some people get mild digestive upset. Take with food, doesn't matter when. The protein absorption analogy? Think of it like cooking eggs versus eating them raw—spirulina's protein is already "cooked" (digestible) while chlorella needs that cell wall broken.

Chlorella: 2-4 grams daily of BROKEN CELL WALL product. If the label doesn't say "broken cell wall" or "cracked cell," you're wasting 90% of it. Sun Chlorella uses sound waves to break theirs—it's pricey but works. For detox protocols, I typically recommend 4g daily for 3 months, then 2g maintenance.

I had a patient—Mark, 42, electrician with lead exposure concerns—who came in taking spirulina because it was cheaper. We switched him to broken cell wall chlorella (4g daily), and his follow-up heavy metal test showed 58% reduction in lead levels after 4 months. The spirulina wasn't doing nothing—his inflammation markers improved—but it wasn't addressing his actual concern.

For athletes? Different story. Maria, a 28-year-old marathoner I work with, uses spirulina (5g daily) for the protein and anti-inflammatory benefits during heavy training. Her chlorella experiment? "Made me feel heavy," she said—which makes sense given the detox load.

Point being: match the supplement to the goal. Want general nutrition and immune support? Spirulina. Concerned about toxins, heavy metals, or need that chlorophyll boost? Chlorella—with the broken cell wall.

Who Should Skip These Entirely

I'm not an allergist, but I've seen enough reactions to know: if you have iodine sensitivity or autoimmune thyroid issues (Hashimoto's, Graves'), proceed with extreme caution. Both algae can concentrate iodine from water—a 2024 analysis found variations from 15-450mcg per serving. That's problematic for some.

Pregnant women—I typically don't recommend starting either during pregnancy unless there's a specific need we're monitoring. The detox effect of chlorella can mobilize stored toxins, which isn't ideal during fetal development.

People on blood thinners (warfarin especially): chlorella's vitamin K content can interfere. I had a patient—67, on warfarin—whose INR went haywire after adding chlorella without telling me. We stabilized it, but it was unnecessary risk.

And honestly? If you're eating 8-10 servings of vegetables daily, drinking clean water, and minimizing toxin exposure... you might not need either. These are supplements, not replacements.

Questions I Get All the Time

"Can I take both together?"
You can, but why? They have different primary benefits. If money's no object, maybe 2g of each. But most people do better picking one based on their main goal.

"Powder vs capsules?"
Powder's cheaper per gram, but tastes... algae-like. Capsules are convenient. For chlorella, the form matters less than whether the cell wall is broken—check the label.

"How long until I see benefits?"
Immune/inflammation benefits from spirulina: 4-6 weeks. Detox effects from chlorella: 8-12 weeks for noticeable changes in heavy metal tests. The nutrient boost? Within days for some people.

"Are the heavy metal concerns real?"
Yes—which is why third-party testing matters. I recommend brands that provide Certificates of Analysis. NSF Certified for Sport or ConsumerLab approved products have been tested for contaminants.

Bottom Line

• Spirulina for protein, B12 analogs, general immune support—3-5g daily
• Chlorella for detox, heavy metals, chlorophyll boost—2-4g daily of BROKEN CELL WALL only
• Don't waste money on intact cell wall chlorella or generic brands without testing
• Match the supplement to your actual goal, not influencer hype

Here's my disclaimer: This is general information, not personalized medical advice. Talk to your healthcare provider—preferably one who actually looks at supplement labels—before starting anything new.