Research Updates | Other
Finding: The adverse effects of fructose are the result of energy imbalance related to low physical activity.
Summary: After small oral loads, fructose is mostly metabolised in the small bowel, while larger loads reach the portal circulation and are extracted by the liver. When energy output is low a fructose-rich diet stimulates de novo lipogenesis, increases liver fat and blood triglycerides and impairs insulin effects on liver glucose production. All these can be prevented with increased levels of physical activity. During exercise fructose can be converted to glucose and lactate in muscles for energy and can also be stored as muscle glycogen. The authors propose that deleterious effects of fructose are tightly related to imbalance between fructose energy intake and low energy expenditure due to low physical activity.
This explains the conflicting evidence that while excess consumption of fructose is linked to metabolic disease, many physically active people remain healthy while consuming large amounts of fructose.
Citation: Tappy L, Rosset R. Health outcomes of a high fructose intake: the importance of Physical Activity. J Physiol. 2019;597(14):3561-3571 (open access)
See also: Hengist A, Koumanov F, Gonzalez JT. Fructose and metabolic health: governed by hepatic glycogen status? J Physiol. 2019;597(14):3573-3585. This paper proposes that hepatic glycogen storage and hepatic de novo lipogenesis are linked and hepatic glycogen determines the metabolic response of fructose ingestion.