Do not eat raw

A lot of vegetables actually contain small amounts of natural toxins to ward of insects and pests. If you eat a varied diet and don't overeat any particular vegetable it is very unlikely that you will be poisoned. Eating a couple of raw mushrooms while you cook or using spinach in a salad occasionally shouldn't be a problem, but if you eat them often it is suggested that you cook them.

Here is a list of some vegetables that you should cook before eating them. Don't stop eating them. Just follow the guidelines and keep using them because once the toxins have been removed they are really good for you!).


Bamboo shots
Contains cyanogenic glycosides which can lead to cyanide poisoning that can cause coma with seizures, apnea and cardiac arrest. Canned bamboo shots can be consumed without further cooking, but fresh bamboo shots should be cooked in slightly salted water for 8-10 minutes to remove the toxin. 

Beans and lentils
Most beans and lentils contain lectins which can cause an upset stomach. Fresh beans: Cook at least 10 minutes at high temperature. Dried beans and lentils: Soak at least 6 hours and then cook at least 10 minutes at high temperature. Canned beans and lentils: Can be consumed without further cooking. Lupini beans should soak at least 7 days, changing the water every day.

Mushrooms
Even the edible kinds of mushrooms contain toxins so it is always a good idea to cook them.

Rhubarb leaves
You can eat the stalk, but do not eat the leaves as they contain oxalic acid and anthraquinones that can cause severe poisoning and lead to fatal kidney damage.


More about the toxins in vegetables:
Food Science Network - University of Guelph, Canada