Is lettuce good to eat when it turns rusty red?

Lettuce that has turned rusty red may not be harmful, but it can indicate that it is past its peak freshness and may have started to spoil. The red color often results from stress factors like temperature changes or age, and it can affect the taste and texture. If the lettuce is still crisp and doesn't have an off smell or slimy texture, it is generally safe to eat, but it's best to err on the side of caution if you're unsure. Always inspect for any signs of decay before consumption.