Chocolate is a poison.
No this isn’t an anti-obesity campaign, it’s true.
Theobromine poisoning or chocolate poisoning is an adverse reaction to the alkaloid theobromine, found in chocolate, and some other foods. The amount of theobromine in chocolate is so small that chocolate can usually be safely consumed by humans. Occasionaly serious side effects result from consuming large quantities, especially for older people. Sometimes a trip to accident and emergency may be necessary.
Serious poisoning is more likely for domestic animals, which metabolize theobromine more slowly than humans, and who are more sensitive to the poison. The commonest fatal reactions are in dogs though cats are more susceptible to the poison, but don’t have taste buds to detect sweetness and so are less likely to eat chocolate in the first place. Birds are reportedly even more vulnerable, a chocolate button being more than enough to kill a sparrow. Mice are slightly less tolerant of Theobromine than humans, and rats slightly more tolerant.
The potentially fatal doses are
Humans 26 Kg about 45 lb. for a normal adult
Dogs 4 kg about 8 lb for a medium sized dog.
Symptoms of illness can occur at lower figures than this, which probably explains why eating too much chocolate makes humans sick. Rather than the sugar intake which is generally assumed to be at fault after eating too many sweets.