Final answer:
Lemon-yellow skin often signals a deficiency in vitamin C, which can lead to scurvy. Scurvy is now uncommon because vitamin C-rich foods are readily available, but historically, it was a significant health issue, especially among sailors, until its cure was found through citrus fruit consumption.
Step-by-step explanation:
Lemon-yellow skin can indicate a deficiency in vitamin C. This condition, known as scurvy, used to be common among sailors in the 1700s but is now rare due to the wide availability of foods rich in vitamin C, such as citrus fruits and peppers. Deficiency in vitamin C can cause spots on the tongue, poor wound healing, bleeding of the gums, and severe pain.
Although the question mentions lemon-yellow skin, it is important to note that this could also relate to other health issues, such as jaundice, which is associated with liver problems and not vitamin deficiency. However, given the context provided, which details symptoms and historical problems related to scurvy, the correct answer is likely vitamin C. Moreover, the indication that citrus fruits could cure the mentioned symptoms further supports the conclusion that this is a vitamin C deficiency.
John Lind's experiments in the 1700s paved the way for the discovery of vitamins and their roles in preventing diseases like scurvy. Despite the rarity of scurvy today, vitamin C remains vital to health, contributing to the proper formation of collagen and the prevention of various diseases.