A video featuring the case was shared on YouTube earlier in January and has shocked several users.
Autopsies revealed the student suffered liver failure, the result of extreme food poisoning caused by a bacteria called Bacillus Cereus.
According to Dr Bernard, who looked into the freakish story on his Youtube channel, AJ put the bowl of stale food in the microwave to heat it up and ate it for lunch, not realising it was five days old.
The student, known only as AJ, became sick on October 1, 2008 when he ate leftover spaghetti with pre-made tomato sauce at his home in Brussels, Belgium.
He was found dead next morning at 11:00 am by his parents.
AJ chalked up his symptoms to food poisoning, so he went to bed without seeking medical help.
In the YouTube clip, Dr. Bernard, a man who said he is a licensed provider trained and based in the United States, surmised the pasta shut down A.J.'s liver.
"B. cereus produces two types of toxins - emetic (vomiting) and diarrhoeal - causing two types of illness".
"Although we can not incriminate B cereus as the direct and unique cause of death, the present case illustrates the severity of the emetic and diarrhoeal syndromes and the importance of adequate refrigeration of prepared food", he said.More news: Mandhana, Mithali lead Indian charge to beat Kiwis by 8 wickets
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Dr Bernard says in the video: "AJ is an otherwise healthy 20-year-old man".
When the spagetti was tested by the National Reference Laboratory for Food-borne Outbreaks, scientists discovered that the meal was so full of toxins, it had caused his liver to fail.
Bernard also noted that A.J.'s case is not typical.
"The final link in this case comes not from the pasta but the stomach medicine that AJ drank after initially vomiting".
'Many people eat pasta, or any other form of noodles, that are leftover for a day or two and they're fine, ' he said, 'but be careful of food left out for more than a few hours. However, it serves as a reminder to be wary of food left out without being refrigerated.
The spaghetti and sauce had been left at room temperature for five days.
As scary as this story may be, it shouldn't stop you from eating leftover pasta or rice again. "If the food smells amusing, it's always better to be safe than sorry", he said.
Food safety experts recommend using a "wide, shallow container", when storing food in the refrigerator.