Initially Posted: 04/22/2017 | Last Updated: 01/27/2018
Kelp Supplements Reviewed by

Alphabetical list of kelp supplement brands compared in this review


Natural Factors Liquid Kelp


Nature's Answer Kelp Thallus


Nature's Life Icelandic Kelp


Progressive Laboratories Kelp

Puritan's Pride Premium Sea Kelp


Solgar North Atlantic Kelp


Swanson Kelp


Traditional Foods Market Kelp Powder


Vitamin World Sea Kelp

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If you use a kelp supplement, it's important to choose carefully! Tests by revealed that half of the kelp supplements it reviewed contained approximately 200% of their listed amounts of iodine, creating a safety concern. In addition, one of these was contaminated with the toxic heavy metal arsenic. Kelp supplements are primarily used as a source of iodine — an important mineral for healthy thyroid function. Most people get enough iodine through their diets, but those who are on a low salt diet or do not eat dairy or seafood, may be at risk for iodine deficiency.  Fortunately, ConsumerLab also identified several high-quality kelp supplements which contained what they claimed without unacceptable contamination. One of these was chosen as CL's Top Pick among kelp supplements. You must be a member to get the full test results along with's recommendations and quality ratings of kelp supplements. You will get results for 8 supplements — 6 selected by and two which passed the same testing through its voluntary Quality Certification Program, as well as information about one supplement similar to one that passed testing.  In this comprehensive review, you'll discover:
  • Which kelp supplements passed and which failed our testing
  • Which kelp supplements offer the best quality and value, and which is CL's Top Pick
  • Direct comparisons and quality ratings of kelp supplements
  • Clinical evidence for what kelp supplements can and cannot do
  • How much iodine your kelp supplement should provide
  • Who should not take kelp supplements
  • Potential side-effects and concerns with kelp

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