We can read that potatoes contain toxic compounds (such as glycoalkaloids). Despite that, would it be still a good idea to eat them raw (e.g. russet baby potatoes)? If so, what are the safe daily amounts (like 0.5kg/day or less is fine)? Better with peels or without, or it doesn't matter?
Raw potatoes are hard to digest, littered with various kinds of bacteria and are toxic.
Most of the toxins can be eliminated by peeling. That still leaves rather hard to digest starches. All in all, eating raw potatoes is not recommended.
As explained in Nutrition Mythbusters page, potatoes can make you sick in a number of ways:
indigestible starch (also called resistant starch),
Starchy foods, such as raw potatoes, unripe (green) bananas, plantains, and some legumes contain a type of starch that is very slowly or incompletely digested in the small intestine. By eating raw potatoes, green bananas or uncooked plantains, large amounts of indigestible starches pass through the small intestine almost intact. When they reach the large intestine, colon bacteria feed on it producing gas. This causes abdominal pain, discomfort, bloating, flatulence and cramps. Cooking potatoes and plantains and ripening bananas breaks down the cellular walls of these resistant starches, making them digestible.
contamination of bacteria present in the soil,
Bacteria such as Listeria, E. coli and Salmonella are found in water and soil. Potatoes may absorb some of these bacteria while growing, as well as during harvest or packaging. Cooking the potatoes destroys the bacteria. Eating the potato raw may cause abdominal cramps, diarrhea, fever and an upset stomach.
toxins present in some potatoes.
Two toxic chemicals (steroidal glycoalkaloids) solanine and chaconine are naturally present in potatoes and are important components of their resistance against pests and pathogens. They can be, however, toxic to humans when taken at high levels. When subjected to stress (sunlight, incorrect handling or bruised, sprouted or damaged in any way) potatoes release these toxins in potentially harmful amounts that can be deadly. Any form of cooking does not reduce the amount of these toxins, and only up to 30% is removed by peeling them.
Although provided that the potatoes are fresh and not damaged, the only safe and beneficial way of having raw potatoes is to juice them (as long as the potato does not contain harmful doses of glycoalkaloids). Peeled potatoes removes most of the resistant starches and is considered safe.
I have only heard of issues of eating green potatoes. I occasionally snack on a potato end while cooking. When I was young I would eat whole raw potatoes as a snack.
I found an article on Live Strong that says they can be eaten raw but there are a variety of reasons not to. It mostly points to the indigestibility but also mentions the toxicity. Most of the other information I can find says similar things. The Risks of eating Raw Potatoes
Raw potatoes are fine, but if they've started to sprout again they are harmful. That's why potatoes are most often cooked, they won't sprout again if that happens.
In a potato plant, there's toxic substances produced by the plant. These are contained in the stem and leaves though. If a potato starts to go green, then it is photosynthesizing, and producing solanine. Solanine is highly toxic, so you don't want to eat it.
TL;DR: they're okay to eat if they haven't gone green yet, but probably not the best idea.