In one of the best overall raw guides ever written “Diet by Design: Fruits, Nuts and Natural
Foods” (available at it says the following about cacao:
Chocolate and cacao are outright health hazards owing to the chemicals, contaminants, and additives they contain. The chemicals within chocolate are called methylxanthines. They can be further classified as theobromine, caffeine, and theophylline, all of which have deleterious effects on the body. Theobromine is known to cause a host of symptoms including abnormal glandular growth, nervousness, depression, anxiety, insomnia, gastrointestinal problems, and itching. Caffeine is highly suspected of being a carcinogen, and is directly linked to heart and circulatory problems, glandular difficulties, nervous disorders, osteoporosis, birthing abnormalities, and so forth. 

Theophylline causes stomach problems, nausea, vomiting, and nervous disorders.
The processing of cacao beans into powder and chocolate is an unsanitary, risky procedure to say
the least. To be blunt-chocolate and cacao are laced with animal feces and hair, insects, and
molds. The carcinogenic mold called aflatoxin has been found in large quantities on cacao beans.
From an article by Paul Nison