Dietitian warns that vegetables should NEVER be heated to prevent potentially deadly bacteria

Many of us depend on leftovers for a quick and easy dinner.

But nutrition experts say there are some foods that should only be reheated once – and never reheated.

There are two reasons why this is the case.

First, the chemical compounds of ingredients can change when they are reheated, releasing toxins linked to problems such as kidney damage.

Second, allowing certain foods to cool before heating them can promote the growth of hard-to-kill bacteria such as E coli and Iisteria.

In a recent video shared with her 23,000 TikTok followers, dietitian Harini Bala revealed three surprising foods you should never reheat.

First on the list is spinach.

Ms Bala said the green leafy vegetable contains a substance called oxalic acid, which is harmless if spinach is eaten in its raw form.

However, when reheated, the oxalic acid ‘crystallizes’, making it ‘poisonous’. In high doses, the substance can increase the risk of kidney stones: clusters of crystals that form in the urinary tract and can become painful.

Ms. Bala added: ‘It also contains nitrates, which are converted into nitrites when heated, which are poisonous.’

Nitries are substances that are thought to combine with chemicals in the intestines to form compounds that increase the risk of developing intestinal tumors.

Other studies have shown that spinach leaves are prone to infestations with listeria, an insect often responsible for foodborne illness.

Experts say that if spinach is not heated properly, the bacteria can still live on it. This can cause fever, flu-like symptoms, headache, stiff neck, confusion and even seizures.

The next favorite to avoid heating up is tea, Ms. Bala said.

Not only will it make the drink more bitter, because it reheats increases the amount of sour-tasting tannins – “any kind of dormant bacteria can become active in there,” she said.

Finally, rice is the riskiest food to reheat, Ms. Bala said.

When cooked rice is cooled, it may contain Bacillus cereus, a spore-forming bacteria commonly found in soil and vegetables.

But the spores are heat resistant, so even heating them up doesn’t eliminate the risk.

Symptoms of illness from Bacillus cereus include vomiting, diarrhea and abdominal cramps.

There are some rules you can follow to limit the risk of contracting the bug, Ms Bala said.

‘If you keep it within two hours, it can be reheated [after cooking it] in the refrigerator in an airtight container.

“But when you cook your rice in the morning [leaving it out] and if you keep it in the refrigerator at night to eat the next day, the chances of Bacillus cereus developing are high.”

Last year, a story surfaced online about a 20-year-old who died from so-called “fried rice syndrome,” which also affects pasta.

The unidentified 20-year-old, from Belgium, died after eating reheated spaghetti that he had left in his kitchen for five days.

He reportedly began experiencing a range of symptoms shortly after eating the pasta, including nausea, abdominal pain, headache, diarrhea and vomiting.

He died within 10 hours.

The autopsy claimed that he suffered from moderate centrilobular liver necrosis, which led to organ shutdown.

Doctors who detailed the case in the Journal of Clinical Microbiology said Bacillus cereus was likely to blame.