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Friends are concerned about Will Smith's son, Jaden Smith, who went on a full vegan diet - which means no animal products that provides most of the body's protein.

Vegans subsist on a diet of vegetables, wholegrains, beans, legumes, and fresh fruit. They don't eat eggs, fish or dairy products.

Jaden recently took a food truck to Skid Row to feed the homeless. But insiders say he is unwittingly starving himself to death.

Fans noticed the 21-year-old, who was born under the Cancer zodiac sign, dropped about 40 pounds from his already small frame.

He looks thin and emaciated. But most worrisome is his teeth which are beginning to decay from the effects of his starvation diet. Jaden wears an expensive diamond grill over his teeth to conceal the damage.

When the body doesn't get enough nutrients, the teeth begin to decay, the bones soften from lack of calcium. The muscles atrophy (waste away) from the lack of energy which comes from consuming fast-digesting carbohydrates, like sugar. The patient stops urinating (kidney failure) and the skin turns yellow from jaundice (liver failure). Eventually the internal organs begin to shut down.