Blog
Bladderwrack: What We Know and What We Do Not
Bladderwrack, Fucus vesiculosus, is a brown seaweed rich in iodine. Memorial Sloan Kettering says claims of benefit have not been confirmed in clinical studies. It can carry arsenic, cadmium and mercury from polluted water. Prostadine lists it fourth with no amount printed.
Written by the Prostadine label deskUpdated · 4 min read
The basics01
What is bladderwrack?
Bladderwrack, Fucus vesiculosus, is a brown seaweed that grows on rocky shores in the North Atlantic and North Pacific. It is named for the small air bladders along its fronds.
It has been used in folk medicine for centuries and now appears in capsules, powders and tinctures sold for weight, fatigue and thyroid claims. It is the fourth ingredient on the Prostadine info page.
Its main known property is iodine content, which is high. MSK notes that it is rich in iodine, though it gives no figure (MSK, Bladder wrack).
The evidence02
What benefits are claimed, and what is confirmed?
MSK states plainly that claims of benefit with use of bladderwrack have not been confirmed in clinical studies. Purported uses such as weight loss and fatigue lack supporting evidence (MSK, Bladder wrack).
We found no human trial for the prostate or the bladder. Its name may cause some confusion, since the bladder in bladderwrack refers to the air sacs on the plant, not to the organ.
| Claim | Evidence found |
|---|---|
| Weight loss | Lacks supporting evidence (MSK, Bladder wrack) |
| Fatigue relief | Lacks supporting evidence (MSK, Bladder wrack) |
| Prostate or bladder support | No human trial found |
| Iodine source | Rich in iodine; amount varies |
The numbers03
What are the cautions?
The first is iodine. A seaweed this rich can push a daily total toward the 1,100 microgram upper limit, and the thyroid can react to excess (NIH ODS, Iodine).
The second is contamination. Bladderwrack from polluted waters may contain arsenic, cadmium and mercury (MSK, Bladder wrack). Only a lab test on the batch can show whether a given product is clean.
The third is an unusual case report: MSK notes a link between a 20-herb slimming product containing bladderwrack and hemorrhagic cystitis, a painful inflammation of the bladder with bleeding. One case does not prove cause, yet it is part of the picture.
The catch04
Does it interact with medicines?
Through its iodine, it can interact with thyroid medicines and with antithyroid drugs. Seaweeds can also affect how some people respond to blood thinners, though evidence is limited. If you take any of these, ask your pharmacist before using a bladderwrack product.
Because the amounts in Prostadine are unknown, a pharmacist can only judge the combination in general terms, which is another reason to ask the seller for figures.
Safety05
Does bladderwrack affect the thyroid?
Through its iodine, yes, it can. Because it is rich in iodine, a regular dose can raise the total over the upper limit, with the effects the NIH lists: goiter, raised TSH and an underactive or overactive thyroid (NIH ODS, Iodine). Some herbal books suggest it for thyroid support, which is exactly the use that carries the risk.
A person with a thyroid condition should treat it as an iodine product first and a herb second. A blood test for TSH is a simple check if you use it for more than a few weeks, and it costs far less than a mistake.
The American Thyroid Association also warns that older adults and people with thyroid nodules respond differently to extra iodine, and they should be especially careful (ATA, Excess iodine).
What to do06
What to ask before buying
Ask where the bladderwrack is harvested, whether each lot is tested for metals and what its iodine content is per serving. A certificate of analysis answers all three at once.
If the seller cannot give those answers, a plain seaweed salad or a pinch of dried nori gives you iodine, with known sources and no mystery. It also costs less.
On the label07
What it means for the drops
Bladderwrack is one of four seaweeds in the formula, and its benefit for the prostate is unconfirmed. The risks are real if the dose is high or the source is polluted. See the kelp and bladderwrack page for the profile and the testing page for what a lab report should show.
FAQ08
Prostadine questions people ask
Does bladderwrack help the bladder?
The name refers to the plant's air sacs, not the organ. MSK says benefit claims for bladderwrack are not confirmed in clinical studies, and we found no bladder or prostate trial.
Is bladderwrack high in iodine?
Yes. MSK describes it as rich in iodine, though it gives no figure. Seaweeds in general range from 16 to 2,984 micrograms per gram.
Can bladderwrack contain heavy metals?
It can, if harvested from polluted waters. MSK notes arsenic, cadmium and mercury. A lab test on the batch is the only way to know.
What is hemorrhagic cystitis?
A painful inflammation of the bladder with blood in the urine. MSK cites a case linking it to a 20-herb slimming product containing bladderwrack. One case does not prove cause.
Who wrote this09
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.
Keep reading
More about Prostadine
Licensed U.S. retail desk — Prostadine
Ready to try Prostadine?
Check your medicines first, then pick a pack. Three or six bottles ship free in the US and cost less per bottle, and every pack carries the 60-day money-back guarantee.
- Secure checkout
- 60-day money-back guarantee
- Ships from the U.S., free on 3 or 6
