Recently, nutritionist Harini Bala took to TikTok to highlight the potential dangers of reheating certain foods, specifically spinach, tea, and rice. Bala emphasized that these common items, when reheated improperly, could pose serious health risks due to the formation of harmful substances or the growth of bacteria.
“In high doses, oxalic acid can crystallize and increase the risk of kidney stones when consumed, especially after reheating spinach” she explained via LadBible. Additionally, reheating spinach can lead to the conversion of nitrates into nitrites, compounds that should not be ingested due to their potential toxicity. There is also a risk of Listeria bacteria being present in improperly heated spinach, which can cause serious health issues such as flu-like symptoms, headaches, confusion, and seizures.
Tea is another item that people often reheat. Bala strongly discourages this practice due to its catechin content breaking down upon reheating. “Reheating it, any type of dormant bacteria can activate inside it,” she stated. The reheating process can also increase the amount of tannins in tea, making the flavor significantly more bitter. Moreover, Bala mentioned that tea contains nitrates, which can convert into nitrites when reheated, and these are toxic.
Rice is perhaps the most concerning of the three foods. Bala warns that when cooled, rice can develop heat-resistant Bacillus cereus bacteria, making it particularly dangerous to reheat. “But if you’re cooking your rice in the morning [leaving it out] and storing it in the fridge at night to eat the next day, there is a huge possibility of Bacillus cereus forming,” she noted. This bacterium can cause vomiting, diarrhea, and abdominal cramps, and its spores are not eliminated by reheating.
The risks associated with reheating rice have been emphasized by health authorities. The NHS has issued guidelines regarding the storage and reheating of food. They advise placing leftover cooked food into small containers to cool quickly, covering it with a lid, tin foil, or cling film, and labeling it with the date. Leftover food should be put into the fridge or freezer as soon as possible, ideally within an hour of cooking. If stored in the fridge, it should be consumed within two days, and if frozen, it should be stored for no more than two months.
One case highlighting the dangers of improper food storage involves a man from Belgium who died after reheating pasta that had been left out for days. An autopsy revealed moderate centrilobular liver necrosis, likely causing his organs to shut down. The report stated, “The spaghetti had been kept at room temperature for several days. This allowed Bacillus cereus to grow to very high concentrations and produced the high toxin concentration… which is likely responsible for the fatal outcome.”
Other reports suggest that reheating certain foods can change their chemical compounds, potentially forming toxic substances associated with kidney damage. Additionally, allowing foods to cool before reheating may encourage the growth of bacteria such as Escherichia coli and Listeria, which are difficult to kill. It’s noted that if spinach is not heated properly, it may contain Listeria bacteria. Studies have shown that spinach leaves are subject to infestations by this bacterium, which can lead to serious health problems.
Bala emphasizes the importance of proper food storage and reheating practices. “You can reheat it if you store it within two hours of cooking in the refrigerator, in an airtight container,” she advises. This practice minimizes the risk of bacteria growth and ensures the food remains safe to consume.
In regards to tea, Bala added, “It also contains nitrates and this will get converted into nitrites when it is reheated and these are toxic.” Furthermore, nitrites can combine with chemicals in the intestines to form compounds that may lead to tumor formation.
The concerns over food reheating extend beyond these three items. Some nutrition experts caution that there are foods that should only be reheated once and never again. Reheating certain foods can produce substances that are potentially toxic to the human body and can be deadly, with risks that could lead to kidney damage.
