It's not bad to heat up lettuce.
You can easily and safely heat up the lettuce in the microwave.
Heating up lettuce is safe and it won't harm the lettuce.
To heat up lettuce in the microwave first clean the lettuce and then set the timing of the microwave (30 seconds should do) and put the lettuce in the microwave.
Once you start the microwave, moisture that is contained in the lettuce is removed.
Since lettuce is composed of 90% water, nothing much will be left of it.
Reheating food is not bad.
However some foods that are reheated may not taste as good as it did when it was freshly cooked.
Many foods can be safely reheated at least once and be perfectly fine to eat.
While almost all foods can be reheated numerous times, it is best practice to avoid reheating the same meal where possible.
Each time food is cooled, stored and reheated, the likelihood of harmful bacteria multiplying increases.
However in most cases the food when reheated is perfectly safe to eat.
But it's best to only reheat food or reheat leftovers once.
Some foods don't do well when reheated and those foods which you really should not reheat include.
Vegetables with High Amounts of Nitrates. If you have spinach or any green leafy vegetables, carrot, turnip or even celery, avoid reheating them in the microwave. ...
Rice.
Eggs.
Chicken.
Potatoes.
Mushrooms.
Cold Pressed Oil.
You can reheat those foods but they don't taste as good or come out very good when reheated.