Wakame

What is wakame?

Wakame (Undaria pinnatifida) is an edible brown seaweed that is widely eaten in Japan and Korea, especially in soups and salads. Like other brown seaweeds it contains fucoidan (a sulfated polysaccharide), the orange pigment fucoxanthin, minerals and iodine. The NIH Office of Dietary Supplements names wakame among the seaweeds that are rich food sources of iodine (ODS iodine fact sheet).

What the research says

Most claims about wakame come from cell and animal studies on fucoidan and fucoxanthin, which show antioxidant, anti-inflammatory and metabolic effects under laboratory conditions. Human data are limited.

One of the better controlled human studies was a randomized crossover trial in 35 healthy adults who took 4.8 g of wakame, 4.8 g of spirulina or a placebo daily for 17 days. Compared with placebo, wakame did not change markers of cholesterol absorption, blood lipids, glucose or blood pressure (van den Driessche et al., 2020). That is a short trial, but it is a useful reminder that effects seen in animals do not always appear in people.

We found no clinical trials of wakame for urinary symptoms, bladder function or the prostate. Claims that wakame “supports normal function of the bladder” or has “strong antibacterial properties” in the urinary tract are not supported by human evidence. Urinary infections need medical diagnosis and treatment, not seaweed.

How it’s used in supplements

Wakame extract is used in some weight management and “detox” products, usually for its fucoxanthin, and in a few prostate formulas as part of a seaweed blend. Amounts are often not listed, which also means the iodine content is unknown.

Because brown seaweeds can carry substantial and variable iodine, people with thyroid disease, those on thyroid or antithyroid medication, and anyone taking several iodine-containing products should be careful. The adult upper limit for iodine from all sources is 1,100 mcg per day (ODS). Eating wakame as food in normal amounts is a different matter from taking concentrated extracts every day.

The bottom line: wakame is a nutritious food with interesting compounds, but the human evidence for health effects is thin and the single controlled trial we found was negative for lipids, glucose and blood pressure. There is no research linking it to prostate or bladder health. If a prostate product lists wakame among its main ingredients, treat that as a source of iodine and minerals rather than as an active prostate ingredient, and judge the product on the rest of its formula and on whether it discloses doses. Men who want the potential benefits of seaweed can simply eat it in normal culinary amounts as part of a varied diet.