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Chlorophyll for Body Odor: The Trial Nobody Quotes

Liquid chlorophyll is one of the most-recommended internal deodorants on the internet. There is a randomised, placebo-controlled trial of it for odour — in exactly the people this site writes for — and it failed. Everything chlorophyllin has been shown to do, it does in the gut.

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Of all the things people swallow hoping to smell better, liquid chlorophyll has the most confident following and the least examined evidence. The threads have moved past whether it works and on to delivery: pills or liquid, which brand, how many drops, copper or copper-free. That is a strange place for the discussion to be, because the underlying question has been tested — with a placebo, in older adults whose odour was rated by other people — and almost nobody cites the result.

The green in the bottle is not chlorophyll

Chlorophyll is the pigment plants use to catch light, and it is built around a magnesium atom. It is also fat-soluble and unstable, which makes it a poor thing to put in a bottle of water, so the supplement industry almost universally sells something else: chlorophyllin, a semi-synthetic, water-soluble derivative.

The clearest description of it is in the US regulation that lists it as a colour additive. Sodium copper chlorophyllin is “a green to black powder prepared from chlorophyll by saponification and replacement of magnesium by copper” (21 CFR 73.125). The parallel listing for drug colouring adds that “the source of the chlorophyll is dehydrated alfalfa” (21 CFR 73.1125).

That settles a question readers keep asking and nobody answers. In one r/bodyodor thread, somebody taking a chlorophyll capsule wanted to know whether it was safe for them, mentioning that it was

The copper is not a stray contaminant to be screened out; it is how chlorophyllin is made. A genuinely copper-free preparation is a different material from the one in every study below, and nobody has tested it for anything described here. If you avoid copper for a medical reason, note that the food-colour specification sets total copper at 4 to 6 per cent by weight, with free copper capped at 200 parts per million.

There is a randomised trial, and it is from 1983

In 1980, two clinicians reported in the Journal of the American Geriatrics Society on giving chlorophyllin tablets to 62 geriatric nursing home patients, and found it “helpful in controlling body and fecal odors”, with no ill effects (Young & Beregi, 1980). There was no control group and no blinding, and the authors were candid about what that meant: in the same abstract they record that the tablets “served at times as a useful and morale-building placebo”.

Three years later somebody did the controlled version. Twenty incontinent geriatric patients, all catheterised, each took chlorophyllin 100 mg a day for two weeks and an identical placebo for two weeks, in a randomised, double-blind crossover, with odour intensity rated ten times on each arm. The numbers went the way enthusiasts would hope: chlorophyllin was associated with a 21 per cent decrease in mean urinary odour intensity, while placebo increased it by about 9 per cent. It still was not enough. The effect “was not significantly greater than that of placebo”, and the authors concluded that chlorophyllin 100 mg a day for two weeks “may not be effective in incontinent geriatric patients with mild to moderate urinary odor” (Nahata, Slencsak & Kamp, 1983).

Two things deserve saying plainly rather than being used selectively. The first is a fair caveat against our framing: that dose was low. The studies with positive results used 100 mg three times a day, or 180 mg a day; this one used 100 mg a day for a fortnight, and nobody has repeated it higher. A negative result at one dose is not a negative result at every dose.

The second cuts the other way and is the more useful. The placebo arm did not sit still — rated odour rose 9 per cent on sugar pills, in patients whose smell was being assessed by other people ten separate times. If ratings wander that much under placebo, two weeks of noticing your own armpits is a very poor instrument, and that is most of what the internet is running on.

What chlorophyllin has actually been shown to do in people

It would be unfair to leave the impression that chlorophyllin is inert. It is not, and the evidence is better than for most things sold alongside it. In Qidong, China, where liver cancer risk is raised partly by aflatoxin-contaminated food, 180 healthy adults were randomly assigned to 100 mg of chlorophyllin or placebo three times a day for four months, double-blind. Urinary aflatoxin-N7-guanine, a biomarker of the aflatoxin dose reaching DNA, fell by 55 per cent against placebo (P = 0.036), with no adverse events reported (Egner et al., 2001). The mechanism the authors describe is “blocking carcinogen bioavailability”: chlorophyllin forms a tight complex with a bulky, flat, aromatic molecule in the gut, so less of it crosses into the body.

That is a real pharmacological effect, in people, with a control arm. The shape of it is what matters: a binder, acting in the digestive tract, on a large planar molecule, reducing how much is absorbed.

Why a gut mechanism cannot reach nonenal

Now put the stale, greasy, slightly cardboard smell most readers of this site are chasing next to that mechanism. It is attributed to 2-nonenal, and the paper that identified it says where it comes from: it is generated when omega-7 unsaturated fatty acids are “oxidatively decomposed” using lipid peroxides as the initiator, and across ages 26 to 75 it was “detected only in older subjects (40 y or older)” (Haze et al., 2001). The reaction runs in the oil film on the outside of your skin. There is no bacterium in it and, more to the point here, no digestive step at all. Nothing is absorbed, metabolised and excreted; sebum reaches the surface and the air does the rest.

A gut binder has nothing to bind — and 2-nonenal is the wrong shape for it anyway: a small, strongly fat-preferring molecule of molecular weight 140 (PubChem CID 5283335), not a bulky flat ring system. Unsurprisingly, nobody has looked. A title-and-abstract search pairing any chlorophyll word with 2-nonenal returns six records: four plant biology, one on herbs and spices slowing lipid oxidation in heated beef, and one on 4-hydroxy-2-nonenal in a freshwater alga — a different compound, and the standing false friend of this subject. Not one involves human skin or smell.

If the smell you are shifting comes off collars and pillowcases, it is a washing problem rather than a swallowing one, which is why our comparison of the best persimmon soap options exists. What a bar can and cannot do is set out in does persimmon soap work.

The one smell with a measured result is a diagnosed condition

There is a genuine exception, and it is the only place in this literature where chlorophyllin and a human odour meet with numbers attached. Trimethylaminuria, sometimes called fish odour syndrome, is a metabolic disorder in which the enzyme FMO3 fails to convert dietary-derived trimethylamine into its odourless N-oxide, so the amine leaves in breath, sweat and urine (Yamazaki & Shimizu, 2007). Here there is a digestive step: gut bacteria make trimethylamine out of what you eat.

In seven Japanese patients with reduced conversion capacity, copper chlorophyllin at 180 mg a day for three weeks reduced free urinary trimethylamine and brought the N-oxide back into the normal range, with effects lasting several weeks — longer than the activated charcoal tested alongside it (Yamazaki et al., 2004). Seven people, no placebo arm, one molecule in a condition defined by that molecule.

And then the detail that keeps this honest: an NHS trust leaflet on dietary management of trimethylaminuria, issued in February 2026, does not mention copper chlorophyllin anywhere, nor charcoal. Its advice is a low-choline, low-trimethylamine diet, with vitamin D and a dietitian-agreed multivitamin the only supplements named. Even where chlorophyllin has a measured odour result, the guidance a patient is handed has not adopted it.

Liquid, capsules, gummies: nobody has compared them

The most common question in these threads is one of the few that can be answered quickly: nobody has compared the forms, for odour or anything else. What is worth noticing is that all three studies with measured results used a stated milligram dose in a solid form — 100 mg three times daily, 180 mg daily, 100 mg daily. Drops and teaspoons are not a dose until somebody converts them, and the conversion is often not on the label in comparable terms. If you want an amount that has been studied, the only products you can match are the ones that tell you their milligrams.

The threads converge on the same conclusion from the other direction. In one discussion comparing two brands, two commenters reported no effect from either, and a third landed on what the evidence also says:

That is the useful frame. Gut-origin odour has a plausible route for a binder; oxidised skin oil does not, and neither does the sharp, sour underarm kind made by skin bacteria out of sweat. For that one, the options with any human measurement behind them are topical — see hypochlorous acid and glycolic acid.

What chlorophyllin is, legally, and what follows from that

One last piece of context explains why the evidence base looks the way it does. The two places chlorophyllin appears by name in US federal regulation are both colour listings: one permits it in citrus-based dry beverage mixes at up to 0.2 per cent, the other for colouring drug toothpaste at up to 0.1 per cent. Its regulatory identity is a green dye with two narrow permitted uses. Sold as a supplement, it sits in a category where, as the NIH Office of Dietary Supplements puts it, FDA “does not determine whether dietary supplements are effective before they are marketed”, and where supplements “can also interact with some medicines in ways that might cause problems”. None of that makes chlorophyllin dangerous. It does mean no regulator has ever asked anybody to prove the deodorant claim — which is why there is one small negative trial from 1983 and then forty years of anecdote.

What we sell, and what it does not do either

We should be explicit about where we are standing. The Soap Digest is owned by the same company that makes TanniBar, the persimmon tannin bar ranked first in our own comparison, and this article argues against a category that competes with it. Judge the argument accordingly.

Then judge this, which cuts the other way. A persimmon tannin bar has no published human trial behind it either: a search pairing persimmon with soap still returns zero results, re-run today. Our bar is a rinse-off true soap acting on the oil film on the skin surface while it is in contact with it. It does nothing for odour arising from the gut, nothing for a metabolic condition, and nothing between showers. On the question this article is about, we have no evidence in our own favour — only the observation that the competing product has one controlled trial and it is negative, which is a weaker argument for us than it sounds.

Our pick · our product

TanniBar Persimmon Tannin Bar

If you want to test the washing route instead, the sensible version is the cheapest bar you can find, used for two to three weeks, before anybody spends money on a bundle.

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If you are going to try it anyway

Plenty of readers will, and that is reasonable with a cheap, widely sold supplement. A few points make the attempt more informative.

1. Clear it with a pharmacist or doctor first, particularly on blood thinners or immunosuppressants, and particularly if you avoid copper.
2. Pick a product that states milligrams, so you are taking a dose somebody has at least studied.
3. Expect green or very dark stools. That is the dye, not a result.
4. Change one thing at a time. These experiments usually produce nothing usable because a new soap, a new deodorant and a new supplement all started the same week.
5. Get a second nose. The 1983 trial had other people rating the smell ten times for a reason, and self-assessment is unreliable — the whole subject of can you smell your own body odor.
6. Give it a fair window, then stop. If three or four weeks at a stated dose changes nothing, the record suggests that is the expected outcome, not a dosing error.

The bottom line

Chlorophyll supplements are not a scam and chlorophyllin is not inert. It has a respectable randomised trial behind it, and that trial was about aflatoxin. What it has for odour is one uncontrolled 1980 report whose own authors called it partly a morale-building placebo, one small randomised trial in 1983 that did not beat placebo, a measured effect on one specific amine in seven people with a diagnosed disorder, and nothing at all on the oxidised skin oil behind the smell most people are trying to fix.

If your smell is stale, greasy and comes off fabric, the mechanism points outward rather than inward, and a wash is the logical place to start — which is what our persimmon soap comparison is for. If it is sharp and localised, look at topicals. And if it is fishy, ammoniacal or newly changed, that is a doctor’s appointment, not a bottle of green drops.

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