Two vividly green powders, two very different promises. Your social feeds rave about “detox”, your local shop stacks tubs by the till, and a friend swears there’s a right answer. New research suggests the two algae don’t do the same job — and that matters if you actually want measurable results.

The smoothie bar on the corner smells like citrus and hope. A man in a paint-splattered hoodie weighs up two tubs — spirulina in one hand, chlorella in the other — as the barista leans in, whispering her choice like a secret. A woman behind us scrolls through before-and-after selfies, convinced the greener, the better.

I ask what “detox” means to them and get three different answers: less bloat, clearer skin, fewer headaches. The barista nods at the chlorella. The man shrugs toward spirulina. Someone mentions “heavy metals” in a way that makes the room go quiet.

Outside, traffic hums and the light turns that late‑afternoon London gold. A delivery driver raises an eyebrow at my green cup and grins. Which one actually works?

What the latest research really says

Scientists don’t love the word “detox”, yet they do test whether nutrients change how our bodies handle pollutants. Recent papers have sharpened the picture: spirulina and chlorella have different strengths. Spirulina (technically a cyanobacterium) seems to help the body tolerate and shift certain metals by bolstering antioxidant defences. Chlorella (a true green microalga with a tough, fibrous cell wall) looks more like a binder that can trap compounds in the gut.

Here’s where it gets interesting. A small clinical trial in Bangladesh reported that spirulina combined with zinc helped people exposed to arsenic feel better and improve lab markers, compared with a control group. A Japanese study with pregnant women found chlorella intake was linked to lower dioxin levels in breast milk and higher protective IgA antibodies. We’ve all had that moment when the wellness claims feel bigger than the evidence — yet these data points are real and measurable.

The logic tracks with biology. Spirulina is rich in phycocyanin and antioxidants that can dampen oxidative stress triggered by metals like arsenic or lead, supporting the liver’s normal machinery. Chlorella acts more like a binder in your gut. Its cell wall, chlorophyll, and fibres can latch onto certain compounds dumped into bile, escorting them out through the stool. That’s what “detox” means in a lab sense: more of the bad stuff leaves the body, and tissues show fewer signs of damage.

How to use them smartly and safely

Match tool to task. If your concern is environmental pollutants that recirculate via bile — think dioxins from certain foods — chlorella before meals makes practical sense. Look for cracked cell wall chlorella, start at 1–3 g daily for a week, then reassess. If your issue is exposure that stirs oxidative stress — like arsenic in well water or legacy lead — spirulina at 1–3 g daily, sometimes paired with zinc or selenium foods, is the “support the system” option.

Keep it boring and consistent. Take the algae with water, fold them into real meals, and track one simple marker you care about: digestion, energy, or a lab value if you’re working with a clinician. Quality matters: ask brands for recent certificates of analysis showing low heavy metals and no microcystin contamination. Space these supplements two hours away from prescription meds. Let’s be honest: nobody really does that every day.

Go gently if you’re new to green powders. Some people jump to high doses and end up with cramps, nausea, or headaches that make them swear off the whole idea. Spiral upwards slowly, and stop if your body votes no.

“In humans, ‘detox’ is mostly about supporting natural clearance and limiting reabsorption in the gut,” says a nutrition researcher I spoke to. “Algae can help at the margins when they’re the right tool for the specific job.”

Chlorella: 1–3 g with or just before meals; cracked cell wall; verify independent testing.
Spirulina: 1–3 g with meals; consider dietary zinc/selenium (e.g., seeds, fish) for synergy.
Hydration and fibre amplify results by keeping gut transit brisk.
If pregnant, breastfeeding, or on medication, talk to your GP first.
Neither algae is a magic eraser for years of exposure.

So which works best for detox?

It depends on the “what” and the “where”. For gut-level binding of compounds that hitch a ride with bile — dioxins are the classic example — chlorella has the better human signal. For exposures that punch up oxidative stress and deplete defences — arsenic is the headline case — spirulina looks more helpful, especially alongside minerals your cells use every day.

There isn’t a grand winner because toxins aren’t one thing and your biology isn’t identical to your neighbour’s. Mix in the basics — sleep, movement, fibre, less ultra‑processed food — and the algae become supporting actors, not the plot. Try one approach for four to six weeks, note how you feel, and, if you can, anchor the experiment with a lab or two. Share what actually changed.

Some readers will be drawn to the simplicity of a single scoop; others will layer algae with a gut‑first routine and call it a day. The new research nudges us toward specificity, not slogans. Your green powder earns its keep when it’s chosen for the mess you’re actually in.

Key points
Details
Interest for reader

Chlorella binds in the gut
Tough cell wall, chlorophyll and fibres trap certain compounds in bile and carry them out
Actionable if your concern is food‑borne pollutants like dioxins

Spirulina supports defences
Phycocyanin and antioxidants reduce oxidative stress from metals; synergy with zinc/selenium
Useful if you’re dealing with stress‑type exposures such as arsenic

Quality and pacing matter
Third‑party testing, start low, avoid stacking with meds; watch for GI side effects
Practical steps to avoid pitfalls and get real‑world results

FAQ :

Which is better for detox: spirulina or chlorella?Different tools, different jobs. Chlorella shows stronger evidence for binding certain pollutants in the gut, while spirulina shines for supporting the body’s antioxidant response to metals.
Can I take spirulina and chlorella together?Yes, many people do. Use modest doses and separate them from medications by two hours. Notice what each adds rather than doubling everything.
How long before I notice anything?Give it 4–6 weeks. Some feel digestive changes within days with chlorella; antioxidant benefits from spirulina tend to be quieter and slower.
Any risks or side effects?Possible nausea, cramps, or headaches if you start high. Rare allergies exist. Choose tested products to avoid contaminants, and speak to your GP if pregnant, breastfeeding, or managing a condition.
Will these remove mercury from dental fillings?No reliable human evidence shows spirulina or chlorella “pull” mercury from amalgams. Focus on reducing intake and supporting normal elimination, not on chelating at home.