This is about as restricted as diets can get and still be regarded as
sane. Many vegetable foods are slightly toxic raw and some are quite toxic
while most animal foods are just plain dangerous uncooked. The most extreme
sect is raw food vegans who also reject all foods of animal (or insect)
origin.
Proponents point out that raw foods must be our natural diet because lighting fires became popular only in very recent times. Before that there was simply no way to cook anything.
Anthropologists and paleontologists now strongly dispute this. It has been found that fire was not first controlled by humans, but by our pre-human ancestors millions of years ago. Many now believe it was the more efficient nutrition of cooked foods that allowed pre-humans to start evolving large, energy consuming brains. In the mean time, our guts became less bulky, as less is needed for cooked food. This short gut is unable to properly digest many raw foods.
Beyond the "no way to cook" issue, there is a lot of disagreement among the sects, particularly between "idealists" and "realists" as well as between "live food" advocates and "juicers". Then there's the split between omnivores and vegans.
Proponents of a vegan raw foods diet maintain that our natural diet was strictly vegetarian as well as raw. Anthropologists and paleontologists firmly deny this was the case. Our ancestors for more than 3 million years back ate every bit of animal flesh they could get their teeth on. They probably also spent plenty of time splitting open rotting logs and eating the grubs, worms and beetles found within - though admittedly eating them raw and as "live food".
Raw food idealists claim for it many health benefits. For one thing, they point out, there are vanishingly few overweight raw foods dieters. They maintain it's a "cleansing" and "detoxification" diet and if adhered to religiously is the formula for perfect health and will cure all diseases. Others say many raw foodists do not take care of real health issues, just blaming them on "insufficient detoxification".
Many practitioners consider the raw foods diet a 100% proposition, holding that any cooked foods whatever are damaging and will interfere with proper absorption of nutrients from raw foods. Others feel anything above 75% raw is just fine.
It is important that raw foods be obtained from organic growers and similarly "clean" sources, as exposure to pesticide residue from conventionally grown food would be much higher than for most people. Foods should be washed thoroughly and carefully.
Care must be take to avoid toxic vegetable foods. For instance sprouts from mung beans and similar can be used, but sprouts from kidney beans and some other beans are much too toxic raw. Nearly all fresh bean seeds are at least somewhat toxic, particularly lima beans and soy beans. Many vegetable foods contain significant amounts of cyanide, which evaporates with cooking.
Many raw foods enthusiasts consume a large amount of their food as juice, because eating that large a volume of whole fresh vegetables is less practical. Many of the great apes spend between 4 and 7 hours a day just chewing, and still need bigger guts for digestion.
Raw nuts are very important to the raw foods diet because so many protein sources are off limits due to toxicity when eaten raw. Among nuts, cashews are a particular problem because they are encased in highly toxic shells. Most "raw" cashews are actually lightly cooked in the shelling process - unacceptable. There is one company in Indonesia that has a method of shelling them cold, but at a significantly higher price.
Not all raw foods enthusiasts are vegetarian, but raw animal foods present some problems. Meats, particularly chicken and turkey, are subject to bacterial contamination and other meats may have parasites. Fish can be obtained suitable for eating raw, but care must be taken there too. For example, salmon, particularly wild salmon, carry parasites that can cause painful (though temporary) infections.
Certified raw milk is pretty safe (where available) if consumed within a short time, but this would not be part of the "natural diet". Milk animals weren't domesticated until long after cooking was established and trying to milk a wild buffalo just isn't safe. Raw eggs would be more natural and seem pretty safe here in "overregulated California", where nearly all cases of illness from raw eggs have been restaurant and institution related where egg pooling is used. Red States, not so much.
Information in this article is based on many publicly available sources. Please refer to our Medical Disclaimer