Two Foods and One Drink You Should Never Reheat, According to a Nutritionist

Many households tend to reheat leftover foods as a convenient way to save time and effort in preparing fresh meals. However, according to experts, certain foods should be avoided when reheating due to potential health risks. This occurs because the chemical compounds in these foods can change when reheated, releasing toxic substances linked to issues such as kidney damage. Additionally, leaving certain foods out before freezing may allow dangerous bacteria like E.coli and listeria to develop. Nutritionist Harini Bala shared a TikTok video listing two foods and one drink that you should avoid reheating in the microwave. Spinach contains oxalic acid, which is harmless when consumed raw but crystallizes and becomes toxic when reheated. High levels of this substance can increase the risk of kidney stones affecting your urinary system. Spinach also contains nitrates, which turn into nitrosamines—compounds linked directly to cancer—when reheated at high temperatures. “Do not reheat spinach; simply consume it immediately after cooking,” advised the nutritionist. Rice is the most dangerous food to reheat. Cooked rice left to cool may contain Bacillus cereus, a bacterium found in soil and vegetables, whose spores are heat-resistant. These spores are generally harmless in small numbers but can cause diarrhea, vomiting, fever, nausea, stomach pain, and cramps when they multiply due to improper temperature control. To reduce contamination risks, Bala suggests storing rice within two hours of cooking in an airtight container. Tea, another popular global beverage, is rich in tannins, a group of antioxidant compounds that help absorb iron from plant-based foods and protect our immune system from infections. Reheating tea diminishes its antioxidant properties while increasing its bitterness due to higher tannin levels. Any ‘inactive bacteria’ in tea could become active with reheating, posing health risks to consumers.