What Is HMG-CoA Reductase?
HMG-CoA reductase is a liver enzyme that controls how much cholesterol the body makes. It plays a central role in cholesterol synthesis and metabolic health.
When this enzyme becomes overactive, cholesterol production increases.
How Refined Carbohydrates Affect Cholesterol Production
When refined carbohydrates are eaten regularly, insulin spikes repeatedly. As a result, HMG-CoA reductase becomes switched on more often. This leads to increased cholesterol production in the liver.
This process explains why diets high in refined carbohydrates often link to raised cholesterol levels.
How Statins and Fibre Act Differently
Statins work by blocking HMG-CoA reductase directly. This reduces cholesterol production through pharmaceutical inhibition of the enzyme.
However, fibre works through a different pathway.
The Role of Fibre and Fermentation
Propionate is a short-chain fatty acid produced when gut bacteria ferment fibre. Propionate naturally turns down HMG-CoA reductase activity. Because of this, cholesterol production decreases at its source.
This is why high-fibre, long-fermented bread can reduce cholesterol synthesis rather than simply clearing cholesterol after it forms.
At The Sourdough School, this principle underpins the Baking as Lifestyle Medicine approach. Long fermentation supports fibre fermentation in the gut, helping regulate metabolic pathways through food rather than medication alone.
This mechanism is also reflected in the design of our Proven Bread programme, where slow-fermented, fibre-rich bread supports health through daily dietary intervention.
