Bitter Lettuce

Question

Why does lettuce taste bitter? Is something needed in the soil? Some of the cucumbers also taste bitter. Is the fault in the soil?

Answer 1

This will explain about the lettuce:
https://www.gardeningknowhow.com/edible/vegetables/lettuce/bitter-lettuce.htm
And this about the cucumbers:
https://www.gardeningknowhow.com/edible/vegetables/cucumber/what-causes-bitter-cucumber.htm