I am being Socratic to show...

If you trace the evolutionary lineage back far enough, some creatures that eventually evolved into H. Sapiens Sapiens lived in trees and ate lots of vegetable matter.  You just have to go back 4 million years or so.  See:

http://www.pnas.org/content/97/25/13506.full

At that time the only source of animal foods was probably insects.

From the paper:

"This suite of traits is distinctive of australopithecines and suggests a dietary shift at or near the stem of hominid evolution. Their thick-enameled, flattened molars would have had great difficulty propagating cracks through tough foods, suggesting that the australopithecines were not well suited for eating tough fruits, leaves, or meat. "

As your meat ages, you will find it may turn to a dark color or drained grey/green color.

Also I think bone marrow maybe.

Is there any single vegetable that is good juiced, all by itself?

 

The general rule (of which there may of course be exceptions) is to eat meat and fruit raw, but to cook vegetables and tubers. 

Be careful eating such foods raw.  They contain anti-nutrients.

From:
http://www.healthy-eating-politics.com/toxins-in-food.html

Hydrazines: volatile carcinogens found in many raw mushrooms, including shiitake and the white button mushrooms common to the grocery store produce section. Mice display a significant increase in the incidence of several types of tumors after they are fed uncooked mushrooms. Cooking the mushrooms destroys a third of the hydrazine compounds.

Spinach is listed below.  Note that the list includes strawberries, pears and peaches (three of my favorite fruits):

Goitrogens: a class of toxins in food which suppress the function of the thyroid gland by interfering with iodine uptake. Long term exposure can cause an enlargement of the thyroid (goiter). Foods containing these substances include soybeans (and soybean products such as tofu), pine nuts, peanuts, millet, strawberries, pears, peaches, spinach, bamboo shoots, radishes, horseradish, and vegetables in the genus Brassica (bok choy, broccoli, brussels sprouts, cabbage, canola, cauliflower, Chinese cabbage, collard greens, kale, kohlrabi, mustard greens, rutabagas, and turnips.

Seeds have phytic acid:
http://www.healthy-eating-politics.com/phytic-acid.html

I stick with certain fruits.  Banana, apple, blueberry, grapefruit, etc.

I still can't understand how people can eat things like raw broccoli etc.

Some cooked vegetables taste good but they always make me tired and sluggish. I get bloatings from all kinds of cabbage. Feels like sh.t. No food. Hmm, so much vegetable food everywhere. It must be a result of animal food shortage and overpopulation, means poverty.

The more poverty the more cabbage.

from their beloved blenders