Ingredients 3 and 4 of 9
Kelp and Bladderwrack in Prostadine: Brown Seaweeds, Big Iodine Questions
Kelp and bladderwrack are lines three and four on the Prostadine info page. Both are brown seaweeds rich in iodine, and neither has a prostate trial. Memorial Sloan Kettering says bladderwrack's claimed benefits are not confirmed in clinical studies. Neither amount is printed on any image we have.
Written by the Prostadine label deskUpdated
What they are01
Two brown seaweeds that look alike and share a problem
Kelp is a name for large brown seaweeds, and bladderwrack (Fucus vesiculosus) is a brown seaweed with small air bladders that help it float. Both are harvested from cold coastal water and both are dense with iodine.
The Prostadine info page lists “Kelp Powder” third and “Bladderwrack Powder” fourth. Kelp gets the benefit lines “Keeps the system toxin-free” and “Supports a strong urine flow”. Bladderwrack gets “Strengthens prostate cells” and “Supports healthy libido levels”. We could not find a human study of either seaweed for urine flow, prostate cells or libido.
The info page's form is “powder”, which suggests dried and ground seaweed rather than a purified extract. Seaweed powder is a food-like material, and its iodine content depends on the species, the place and the season it was harvested.
| Name on the info page | Kelp Powder |
|---|---|
| What it is | Seaweed (large brown algae, laminarian kelps) |
| Place on the info page | 3 of 9 (not a verified weight order) |
| Amount in Prostadine | Not printed in any image we have |
| Amount used in research | Kelp supplements can hold several thousand times the 1,100 mcg upper limit |
| Strength of evidence | No human trial for urine flow found |
| Marketed or traditional use | Iodine source and food seaweed |
| Main caution | ATA advises against kelp or iodine supplements over 500 mcg of iodine a day. |
| Info-page benefit lines | “Keeps the system toxin-free” / “Supports a strong urine flow” |
| Name on the info page | Bladderwrack Powder |
|---|---|
| What it is | Fucus vesiculosus, brown seaweed |
| Place on the info page | 4 of 9 (not a verified weight order) |
| Amount in Prostadine | Not printed in any image we have |
| Amount used in research | No studied dose found |
| Strength of evidence | Claims of benefit not confirmed in clinical studies (MSKCC) |
| Marketed or traditional use | Seaweed sold for weight, skin and thyroid claims |
| Main caution | Iodine-rich; can carry arsenic, cadmium and mercury if harvested from polluted water. |
| Info-page benefit lines | “Strengthens prostate cells” / “Supports healthy libido levels” |
Iodine02
Why these two lines carry the most weight for safety
The NIH measured seaweeds ranging from 16 to 2,984 micrograms of iodine per gram (NIH ODS, Iodine). The adult upper limit is 1,100 micrograms a day (NIH ODS, Iodine). The American Thyroid Association warns that many kelp and iodine supplements contain amounts far above the upper limit, in some cases thousands of times higher, and advises against kelp or iodine supplements that give more than 500 micrograms a day (ATA, Excess iodine).
| Seaweed | Iodine | Other concern | Source |
|---|---|---|---|
| Kelp supplements | Some contain several thousand times the 1,100 mcg upper limit | Amount varies by product | ATA (ATA, Excess iodine) |
| Bladderwrack | Described as rich in iodine; no figure given | May contain arsenic, cadmium and mercury if harvested from polluted water | MSK (MSK, Bladder wrack) |
| All seaweeds | 16 to 2,984 mcg per gram | Wide variation between species | NIH ODS (NIH ODS, Iodine) |
Without a printed panel the two lines cannot be added up, and the five iodine sources on the label cannot be added together either.
The sales lines03
Four benefit lines, checked one at a time
“Keeps the system toxin-free”
The NCCIH says a 2015 review found no compelling research that detox diets remove toxins from the body (NCCIH, Detoxes and cleanses). No study shows kelp doing so in the urinary system.
“Supports a strong urine flow”
Studies of urine flow use measured flow rates or the symptom index. We found none for kelp, and the NIDDK's list of BPH treatments names medicines and procedures, not seaweed (NIDDK, Enlarged Prostate (BPH)).
“Strengthens prostate cells”
Memorial Sloan Kettering says claims of benefit with bladderwrack have not been confirmed in clinical studies (MSK, Bladder wrack).
“Supports healthy libido levels”
We found no human trial of bladderwrack and libido. The MSK entry lists weight loss and fatigue among purported uses that lack support (MSK, Bladder wrack).
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See packsSafety04
What to know before taking seaweed daily
The main risk is iodine, covered above and on the iodine and thyroid page. Excess can cause a swollen thyroid, an underactive thyroid or an overactive one, and people with existing thyroid disease are more vulnerable (NIH ODS, Iodine) (ATA, Excess iodine).
A second concern is where the seaweed grew. Bladderwrack from polluted water may contain arsenic, cadmium and mercury (MSK, Bladder wrack). A reader cannot see that from a label, which is why a certificate of analysis or independent lab result matters. The seller quotes a lot and analysis reference, but no image shows the document itself, so the batch page explains how to request the document.
Memorial Sloan Kettering also notes a case report linking a 20-herb slimming product that contained bladderwrack to a bladder inflammation with bleeding (MSK, Bladder wrack). A single case report in a multi-herb product proves nothing about bladderwrack alone, but it is a reason to report any new urinary symptom to a doctor rather than push through.
Verdict05
What the evidence supports
What is in its favour
- Traditional food seaweeds with a long record in cooking
- Genuine iodine sources for people who are low (ATA, Iodine deficiency)
What counts against it
- No human evidence for the four benefit lines
- Iodine totals unknown and easy to overshoot (ATA, Excess iodine)
- Possible heavy metals from polluted water (MSK, Bladder wrack)
If your diet is low in iodine, seaweed is an ordinary way to raise it. As a prostate ingredient, neither kelp nor bladderwrack has research to lean on. See the iodine line on its own at the iodine page, and the two other seaweeds on the nori and wakame page.
- ATA Statement on the Potential Risks of Excess Iodine Ingestion and Exposure. American Thyroid Association, 2024.Iodine is needed for normal thyroid function (150 mcg a day for adults). Intake above 1,100 mcg a day is not recommended. Many iodine, potassium iodide and kelp supplements contain amounts far above the upper limit, by up to several thousand times. The ATA advises against taking iodine or kelp supplements that provide more than 500 mcg of iodine a day. Older adults, pregnant and breastfeeding women, infants and people with existing thyroid disease are more vulnerable.
- Bladder wrack. Memorial Sloan Kettering Cancer Center, Integrative Medicine, 2022.Fucus vesiculosus is rich in iodine (no amount given). 'Claims of benefit with use of bladder wrack have not been confirmed in clinical studies.' Purported uses (weight loss, fatigue) lack supporting evidence. A case report links a 20-herb slimming product with bladder wrack to hemorrhagic cystitis. Bladder wrack from polluted waters may contain arsenic, cadmium and mercury.
FAQ06
Prostadine questions people ask
Is kelp good for the prostate?
We found no human trial showing it is. Kelp is a source of iodine, which the thyroid needs, and the American Thyroid Association advises against kelp supplements above 500 mcg of iodine a day (ATA, Excess iodine).
What does bladderwrack do?
Memorial Sloan Kettering says claims of benefit with bladderwrack have not been confirmed in clinical studies, and that purported uses such as weight loss lack supporting evidence (MSK, Bladder wrack).
Can kelp cause thyroid problems?
Too much iodine can. High intakes are linked with goiter, underactive thyroid and overactive thyroid (NIH ODS, Iodine). People with existing thyroid disease should ask a doctor before kelp or bladderwrack supplements.
How much kelp is in Prostadine?
No image or document we hold gives the amount. The info page names kelp third and bladderwrack fourth, which is not a verified order by weight.
Who wrote this07
Written and reviewed by
Pages built from the bottle photos, the info page and linked NIH, FDA, NCI, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by a licensed U.S. retail desk for Prostadine, not by the manufacturer. We earn money when you buy through our order links.
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