Seaweed is a replacement for vitamin C? I guess the space aliens have started pouring out of the hollow moon too.

No doubt seaweed is excellent food.  Fucoidan is great for you.  High dose oral vitamin C is an excellent preventive measure for degenerative diseases.

Seaweed contains:  Fucoidan.  Vitamin C.  Fucoidan tightly binds vitamin c, dragging vitamin C around with it.  Weight per weight, edible kelp has more vitamin C than oranges.  Is an orange a substitute for vitamin C?  Not yes and no.  Just simply no.  Oranges are a source of vitamin C.  Seaweed is a source of vitamin C.

Is fucoidan a substitute for ascorbic acid (vitamin C)?  Absolutely not.  Not even a deranged third grader would be puzzled by the fact that vitamin C can only replace vitamin C.  An alternate statement might be: "Fucoidan - A Substitute For Vitamin C."  Nope.  Not to mention the fact that the high molecular weight fucoidan doesn't enter the blood stream (or bind to arteries), that you have to inject intravenously an artificial preparation of low molecular weight fucoidan for any substantial tracing of thromboses, it is the vitamin C in seaweed doing vitamin C things, not seaweed.  Anyone can wander into a normal grocery store and see (not vitamin C) for themselves.  Pick up a pack of dried edible seaweed, look at the nutritional facts, and there it is - 20% of the USRDA of Vitamin C.

This is not Nobel Laureate science, which is why I have nothing whatsoever to do with this strange turn towards completely erroneous self-published, non-peer reviewed....artifacts of vitamin C being inside seaweed itself (and bound to fucoidan).  You can only fathom what insanity is required for this sort of childish and infantile nonsense. 

Only Vitamin C can serve where Vitamin C is needed.  Even in 2016.  It is best stated by Dr. Mark Levine of the US NIH:

Vitamin C: the known, the unknown, and Goldilocks.