Overnight storage of certain foods might cause bacterial growth, chemical changes, or nutrient loss, making them dangerous to consume.
Some foods are very delicate and should be handled carefully or consumed fresh. Health risks can significantly increase if they are not adequately refrigerated or reheated.
Wood ear fungus and mushrooms, for instance, are best eaten the same day they are cooked.
Complex proteins and high nitrate levels found in these foods can decompose into toxic compounds if they are kept for an extended period of time.

Additionally, reheating them may result in gastrointestinal distress or even severe health consequences.
Additionally, leaving leafy greens at room temperature reduces their nutritional value and safety, particularly for nitrate-rich ones like spinach.
They become less healthful and maybe dangerous if not stored properly as they lose vital nutrients and accumulate increasing nitrite levels with time.
Due to their high protein and moisture content, soy-based goods like tofu and soy milk are vulnerable to bacterial development.
They may potentially get contaminated with Clostridium botulinum, a harmful bacterium that can be lethal or cause serious nerve damage, if improperly stored.
Likewise, shellfish and soft-boiled eggs are high-risk items that should not be stored overnight because of the possibility of bacterial contamination and toxin accumulation.
Always use sealed containers, keep leftovers below 4°C (39°F), and don’t keep them for longer than 24 hours to prevent foodborne illness. Reheating more than once can compromise nutritional quality and safety.
You can preserve the safety and nutritional value of your leftovers by according to these instructions.