Supplementation with fucoidan increases flu shot effectivity
Edible algae contain fucoidan, the marine equivalent of the beta-glucans in mushrooms, yeast and grains. And like beta-glucans, fucoidan can help the immune system function better. This is evident from a Japanese study, which appeared in the Journal of Nutrition in 2013.Fucoidan
Fucoidan is a sugar chain - or polysaccharide - in edible algae. In Japan, these algae are on the market as wakame. In the study that this report is about, the researchers used fucoidan from the alga Undaria pinnatifida. You can see fucoidan's basic structure below.

The structure of fucoidan is somewhat similar to that of the beta-glucans in mushrooms, yeast and oats. Beta-glucans also stimulate the immune system. You can read more about this here, here, here, here and here.
The researchers used Mekabu Fucoidan, a preparation of Riken Vitamin. You see a jar at the top of the page. Riken did not sponsor the study.
The researchers divided 57 older Japanese, aged 67-102, into 2 groups. After the seventieth year of life, the protective effect of vaccines starts to decrease rapidly by the aging of the immune system.

For half a year, one group of test subjects received a supplement with 300 milligrams of fucoidan every day, while the test subjects in the other group took a placebo.The test subjects received a flu shot 4 weeks after the supplementation started. The vaccine should provide protection against viruses A/Brisbane/59/2007 (H1N1), A/Uruguay/716/2007 (H3N2) and B/Brisbane/60/2008 (B).
5 and 20 weeks after vaccination, the researchers measured the concentration of antibodies against the 3 flu variants in the subjects' blood. Those concentrations were higher in the blood of the subjects in the experimental group.

When the doctors calculated which subjects the vaccination had been successful with, the percentage of protected people appeared to be higher in the experimental group.
In the right column in the table below, the researchers had taken into account immunity that was already present before the vaccination.

"Our study showed a possible adjunctive role of Mekabu Fucoidan in antibody production in the elderly, although further studies on the underlying immunomodulatory mechanisms are needed," the Japanese summarize.

"It is hoped that the popular seaweeds eat daily in Japan, although almost unknown around the world as a nutritional source, will be consumed outside Japan for possible immunopotentiation and for attenuating the burden of infectious diseases in the elderly."
J Nutr. 2013;143(11):1794-8.