Overnight foods that are not suitable for eating are: fish, seafood, green leafy vegetables, cold salad and so on. Eating fish and seafood overnight is prone to protein degradation, which will damage liver and kidney function. Green leafy vegetables contain different amounts of nitrate. If they are overcooked or left for too long, not only will the vegetables turn yellow and smelly, but nitrate will also be reduced to toxic nitrite by bacteria, which has carcinogenic effect. Because cold salad is polluted during processing, it is likely to deteriorate even after cold storage and overnight, so it should be prepared immediately and ready to eat.
In addition, overnight seaweed soup is not suitable for drinking, because kelp contains a lot of nitrate, which will be oxidized by air and bacteria overnight to produce toxic and carcinogenic nitrite, which will cause harm to human health after eating.
Hyperthyroidism patients can't eat kelp, because kelp has a high iodine content, which will aggravate the condition. Pregnant women and nursing mothers should not eat more. The reason is that iodine in kelp can enter the fetus and baby through blood circulation, which leads to thyroid dysfunction.
Not only is it best not to drink overnight soup, but many things in life are also best not to eat overnight, such as overnight leafy vegetables, especially some leafy vegetables, which will be decomposed by bacteria to produce nitrite overnight, just like heating, which cannot remove this carcinogen.