Eating seaweed salad may boost the efficacy of vaccinations and help treat cold sores, herpes, Epstein-Barr virus, and shingles. Billions of pounds of seaweed are harvested each year, the “consumption of [which] has been linked to a lower incidence of chronic diseases,” both physical and mental. For example, women who eat more seaweed during pregnancy appear to be less depressed, and have less seasonal allergy symptoms.
But, the problem with these cross-sectional, correlational studies is that you can’t prove cause and effect. Maybe seaweed consumption is just an indicator that they’re following “traditional Japanese dietary customs” in general, which have lots of different aspects that could protect against disease. To know for sure if seaweed could modulate immune function, you have to put it to the test….