Abstract: While both raw and prepared Rehmannia glutinosa are widely studied, there is currently limited research on fresh R. glutinosa due to its poor storability. In August 2024, China’s National Health Commission approved the use of R. glutinosa as a food ingredient, making fresh R. glutinosa worthy of research. Carbohydrates contribute to the flavor and functional activity of R. glutinosa. Therefore, clarifying the structure and content of functional carbohydrates in fresh R. glutinosa is of great significance for the development of fresh R. glutinosa-based foods. Currently, several key issues exist in the research on fresh R. glutinosa including lack of basic data, unclear understanding of structure-activity relationships, and insufficient insights into how processing affects them. This paper systematically compares the differences in the structure and activity of functional sugars in fresh, raw, and prepared R. glutinosa, preliminarily inferring that fresh R. glutinosa has good antioxidant, anti-inflammatory and antitumor activities, and its antioxidant activity is superior to that of raw and prepared R. glutinosa. Fresh R. glutinosa has a tender, crisp texture and is very juicy. It offers a mild sweetness with a slight bitterness. Thus, fresh R. glutinosa has advantages in texture and taste for the development of functional foods. This review provides a theoretical basis for the development of fresh R. glutinosa-based food products.

Key words: Rehmannia glutinosa; polysaccharides; oligosaccharides; functional activity; medicine and food homology