Lemons are not "bad", they are sour, which is heating and can increase Pitta.

Anything sour can potentially aggravate the Pitta dosha in the body. Pitta primarily resident in the small intestine and liver. If someone were already suffering from a significant Pitta imbalance, sour tastes would not be advised.

I have a significant amount of Pitta in my constitution and as a result, can not consume large amounts of citrus, such as drinking a full glass of orange juice, because it overheats my digestive tract (sour stomach, loose BMs).

Lemons and citrus are healthy when taken in the proper amounts for one's own constitution. Tweet