Yes, algin is derived from brown seaweeds like kelp. This is why it is SO important to be sure you get your supplements from a reputable company that tests for heavy metal contaminants, pesticides, etc.

In the U.S., there is no mandatory regulation requiring such tests to be performed, to my knowledge, EXCEPT in California. Proposition 65 requires such testing to make sure products sold within California do not contain any hazardous materials at harmful concentrations.

Nature's Sunshine voluntarily complys with this California law even though they are in another state. In addition, Nature's Sunshine's Quality Assurance Department uses the inductively coupled plasma-mass spectrometer (ICP-MS) to screen raw material for unwanted compounds. This device can detect the presence of elements down to parts per million.

This is exactly why I use Nature's Sunshine products almost exclusively. I depend on Algin for my long-term mercury detox and I've never had any reaction to it (not even before they started complying with Proposition 65).

I don't know if other companies do such careful testing of their raw materials. Based on the feedback I've heard from friends and customers about other products they've tried, it would seem that a lot of other companies don't.

If you're going to use "sea-derived" supplements (i.e. kelp, fish oils, etc.) from another company, make sure you find out what kind of testing they do and if they reject raw materials that contain heavy metal contaminants.