The best replacement for kelp is seaweed.

The best alternatives to kelp are rated as following:
★★★★★  seaweed
★★★  iodine
★★  spirulina
★★  bladderwrack
★★  dulse
★  kale
★  chlorella
★  nori
★  potassium iodide
★  iodine supplement
  kombu
  iodoral
  algae
  sea kelp
  laver
  blue green algae
  irish moss
  dulce
  alfalfa
  fish fertilizer
  lugol's
  fucus
  lugols

Your alternative for kelp is not listed? Suggest!
Speaking about kelp, one probably shouldn't forget about iodine.

Other search terms related to kelp and their ratings are:
★★★★★ iodine
★★ natural selenium & iodine
★ thyroxine
★ lecithin
selenium and iodine
You have in mind a companion for kelp and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of kelp in all years. Click on graph for more.
kelp
seaweed
iodine