About twenty years ago I went to my doctor because I was putting on weight and feeling tired, she told me that I may have an under active thyroid, so she sent me for a blood test, and said if l do l would be on tablets for the rest of my life. So when l went home I checked my green pharmacy book and read about kelp for an under active thyroid. One week later I went back to my doctor for my results which she confirmed that I had an under active thyroid. I told her I did not want to take the tablets and I was going to try kelp, she suggested that after a month or so I would need another blood test to see how it went. So I went to my local herbal shop and bought powdered kelp, and I really enjoyed it on my avocados. When I went back for another blood test, my doctor said my thyroid had gone back to normal. And I don't take kelp very often.