Fascinating substance but unproven

I'm a community health worker. A few of my clients have been on a course of Stemtech supplements. I am concerned that it has become a daily ritual for them at the cost of $80-90 a bottle, to the point that one of my clients stopped his regularly prescribed medications and ended up in hospital. What are your thoughts on these supplements?
- Concerned
Stemtech is a company that sells an extract of blue-green algae via a multilevel marketing company. Blue-green algae is a medical fad from the 1970s, a cure-all once marketed by a company called Cell Tech, which was found guilty in US courts of misleading and deceptive claims and went out of business. Its head of research, Christian Drapeau, went on to form Stemtech.
In the US, Stemtech's products must carry the FDA warning: This product is not intended to diagnose, treat, cure, or prevent any disease.
They are marketed as dietary supplements, not medicines, and so are not held to the same standards of effectiveness and safety as medicines. Yet the Stemtech website recommends it for "anyone wanting to enjoy optimal health ... anyone wanting optimal fitness and performance ... in fact, everyone".
Its New Zealand website gets a lot of mileage out of one citation in a small medical journal. On closer inspection, the study appears weak and of uncertain clinical significance. It gave the product to 12 people, and found a small rise in one type of stem cell for a short period of time. Even if this were accurate, there is no good evidence that increasing your stem cell levels is healthy. In fact, it may be harmful. It could actually accelerate tumour growth and spread. No one knows yet.
Marketing aside, blue-green algae is a fascinating substance, with heaps of vitamins, minerals, and biologically active substances in it.
Some species even contain toxins potent enough to kill dogs who've ingested it while swimming. Perhaps other kinds of blue-green algae are healthy, but that still remains unproven at this point.
My thoughts are that if something's not proven effective, then it should at least be free.
But at a cost of about $1000 a year, it's not that, either.
Gary Payinda MD is an emergency medicine consultant in Whangarei.
Have a science, health topic or question you'd like addressed? Email: drpayinda@gmail.com
(This column provides general information and is not a substitute for the medical advice of your personal doctor.)