Our results indicate the wide variability of lettuces’ nutritional characteristics and emphasize that traditional varieties are a helpful source of agricultural biodiversity. The low content of ascorbic acid, phenolics, and anthocyanins in crisphead lettuce (CL5) is a clear example (49, 67%, and 27% lower, respectively, than the adult mean). The nutritional value of adult lettuce is conditioned by its size, shape, and head structure as phytochemical concentrations are regulated by light. This finding agrees with lettuce’s marked antioxidant capacity and correlates with its pigment contents, especially anthocyanins. Ascorbic acid and phenolic contents were 42% and 79% higher, respectively, in the early stages than in adult lettuces, and red-leaf varieties (CL4 and L11) stood out.

The content of some bioactive compounds and antioxidants (chlorophylls, carotenoids, anthocyanins, ascorbic acid, phenols, antioxidant activity) was monitored in six lettuce landraces and five commercial varieties, and compared across three development stages: microgreen, baby, and adult. Lettuce is a popular leafy vegetable worldwide, and interest in the consumption of first leaves (microgreens) and seedlings (baby leaves) has grown due to the general belief that young plants offer higher nutritional value. Interest in the cultivation of lettuce landraces is increasing because native varieties, as high-quality products, are particularly attractive to consumers.

Therefore, romaine type lettuces with red rather than green leaves may offer a better nutritional choice.

P>Lettuce ( Lactuca sativa L.) is one of the most popular vegetables worldwide, but is often viewed as low in nutritional value.

Iceberg vs romaine