a well covered subject. anyone4 studying the dr john r. christopher knows thisa subject well.
if your a drug addict and destroyed your liver, then avoid comfrey and all herbs for matter.
dr. christopher made the liver/gallbladder cleanse formula for the drug addicts and then started them on comfrey formulas.
comfrey is a 100% legal herb sold commercially in the u.s.a.
pregnant women develope wonderful babies when they consume comfrey every day. babies develope wonderfully when they consume a little comfrey every day....david christopher states that comfrey never has been a problem, no know cases it ever caused any problems.....but a drug addict with a near dead liver may not do well on "fresh" raw comfrey roots picked in the spring....all commercial comfrey is usually dried powder and the dried powder is a great source of plant calcium and plant calcium one supplement humans do very well on.
simple rule of thumb
"if" your in doubt about an herb or drug or a vitamin, then don't take it! personally i haven't taken an over the counter vitamin for 30 years nor asperin, etc....because those things really are toxic.
comfrey is one of the top 5 herbs for human health on earth.