How Fructose Drives Metabolic Disease | Rick Johnson, M.D.

A central metabolic pathway in cells that generates energy. Fructose metabolism, via uric acid, inhibits aconitase, an enzyme in the Krebs cycle, leading to citrate accumulation and fat production.

A condition first linked to fructose consumption by Dr. Johnson's group. It can often be improved by restricting fructose and alcohol, even without significant weight loss.

A hereditary condition where individuals lack fructokinase, causing them to excrete about 10% of ingested fructose in urine and metabolize the rest via glucose enzymes. People with this condition have not been reported to develop type 2 diabetes or obesity.

Table sugar, composed of glucose and fructose bound together. It requires degradation in the gut before absorption, which might differ from high-fructose corn syrup.

An enzyme activated in starvation to raise energy levels. Uric acid inhibits AMPK, further blocking energy production and contributing to a low energy state, mimicking starvation.

An example of an animal that stores fat for water, demonstrating the survival pathway where fat metabolism generates water, especially during periods like hibernation.

An enzyme that removes AMP, a key building block for ATP, making it difficult to replenish ATP after fructose-induced depletion. This leads to uric acid production.

The end product of purine metabolism, generated from ATP breakdown during fructose metabolism. High intracellular uric acid causes mitochondrial oxidative stress, inhibiting ATP production and stimulating fat storage.

An enzyme pathway that converts glucose to sorbitol and then to fructose, activated in high glucose states like diabetes. This is a mechanism by which the body endogenously produces fructose.

A transcription factor located in the osmo-sensitive region of the aldose reductase promoter, activated by increased serum osmolality (e.g., from salt intake) to convert glucose to fructose.

The first and key enzyme in fructose metabolism, also known as ketohexokinase (KHK). It phosphorylates fructose without negative feedback, leading to rapid ATP depletion, especially with high fructose concentrations.

A sweetener where fructose and glucose are already separated, potentially leading to faster absorption and more severe ATP depletion compared to sucrose, where glucose and fructose are bound.

The rate-limiting enzyme in the polyol pathway that converts glucose to sorbitol. It is normally low in the liver but can be induced by high glucose, high uric acid, and increased serum osmolality.

A common strain of laboratory mouse with a propensity for obesity, used in studies to observe the effects of glucose and fructose in drinking water on weight gain and insulin resistance.

A molecule important for vasodilation and blood vessel function. Uric acid raises blood pressure directly by inhibiting nitric oxide through multiple mechanisms.

The process by which fatty acids are broken down to produce ATP. Fructose metabolism, through uric acid and inhibition of enol-A hydratase, blocks this process, stimulating fat storage and reducing fat burning.

A hormone produced in fat cells that signals satiety to the brain. Fructose consumption can lead to leptin resistance, causing animals (and humans) to eat more despite adequate fat stores.

A specific vasopressin receptor, previously of unknown function, now identified as crucial in driving obesity. Blocking this receptor can prevent sugar and salt from causing obesity and metabolic syndrome.

An amino acid used to make nitric oxide. Uric acid can decrease the uptake of L-arginine, contributing to reduced nitric oxide levels and elevated blood pressure.

An artificial sugar that is converted to fructose in the body via the polyol pathway, particularly under high glucose conditions.

A hormone produced by the islets of the pancreas that raises glucose levels and counters the effects of insulin. Its production can be stimulated by the V1b receptor, contributing to insulin resistance.

A hormone produced in the brain that conserves water in response to high salt or sugar concentrations. It also contributes to obesity by stimulating fat storage through the V1b receptor.

An earlier book by Dr. Rick Johnson, which 'Nature Wants Us to Be Fat' follows up on, expanding on the concepts of metabolic disease.

A book written by Dr. Rick Johnson in 2008, initially proposing that a low-fructose diet was the solution to metabolic problems, before the discovery of endogenous fructose production by the body.

Dr. Rick Johnson's follow-up book to 'The Fat Switch', delving deeper into fructose metabolism, uric acid, vasopressin, and their roles in metabolic disease and obesity.

The inventor of Gatorade, who developed sports drinks primarily with glucose, salt, and water to replenish electrolytes and provide muscle fuel during heavy exercise.

Host of The Drive podcast and interviewer of Dr. Rick Johnson. He raises questions and facilitates the discussion on fructose metabolism, metabolic disease, and related topics.

A member of Dr. Johnson's research group who conducted a pair-feeding study comparing sugar and starch diets in mice, which showed that sugar-fed animals developed diabetes and fatty liver even at iso-caloric intake.

A researcher at the University of Florida who collaborated with Dr. Johnson's group on a study showing connections between soft drink consumption, high uric acid, and increased fructokinase expression in NAFLD patients.

A researcher from Princeton whose studies showed that fructokinase in the gut inactivates small amounts of fructose, preventing energy depletion at low concentrations.

A pharmaceutical company actively working on developing fructokinase inhibitors for the treatment of metabolic syndrome and other conditions.

An original sports drink, formulated with glucose, salt, and water to address electrolyte and fuel needs during intense physical activity; later formulations sometimes included small amounts of fructose to enhance glucose uptake.

A pharmaceutical company that developed fructokinase inhibitors, achieving success in a phase two trial which reduced fatty liver and improved insulin resistance, but later stopped progression.

The Journal of the American Medical Association, where a study by Dr. Johnson's group on allopurinol's effect on blood pressure in adolescents was published.

A drug that lowers uric acid levels, used in studies to normalize blood pressure in adolescents with newly discovered hypertension, suggesting a link between uric acid and hypertension.