An Avoid herb or supplement is recommended (by another source) for my (diagnosed) medical condition.
This will require some discernment on your part.
An herb is generally considered an avoid for a blood type due to particular negative metabolic reactions that may be induced by the herb or indirectly induced as a side effect. If possible, attempt to locate a similarly functioning herb with similar benefits.
Generally, a supplement is considered an avoid because it is bountiful in a well rounded, fresh food based diet for your blood type. Additional supplementation could be considered toxic. However, if you have a diagnosed deficiency of the substance, or a medical condition shown to benefit by supplementation, then the supplement may be taken. It is always wise to consult a nutritionally knowledgeable person who can monitor your health in this situation.
Dr. Peter D'Adamo developed Catechol nutritional supplement to help the body regulate nutritional stress support, while helping to promote a natural state of calm in individuals with blood types O and AB.