What is NOT absorbed in the jejunum?

The jejunum is the second part of the small intestine and is primarily responsible for the absorption of nutrients from digested food, including carbohydrates, proteins, and vitamins. Bile salts, however, are not primarily absorbed in the jejunum; they are mainly absorbed in the ileum, which is the last segment of the small intestine.

Carbohydrates are broken down into simple sugars and absorbed in the jejunum. Similarly, proteins are digested into amino acids and peptides, which are also absorbed in this part of the intestine. Folic acid, a water-soluble B-vitamin, is readily absorbed in the jejunum as well.

In contrast, bile salts play a crucial role in the emulsification and absorption of dietary fats and fat-soluble vitamins but are specifically reabsorbed in the ileum and not the jejunum. This is a key point of differentiation that underlines why bile salts are the correct answer in this context. The absorption process is designed to maximize the efficiency of nutrient uptake in the jejunum, while certain substances like bile salts are managed differently in the overall digestive system.