Making our liver human foie gras

If you were fructose or the food industry that loads us up with fructose, you would be having a really bad year.  The reasons for our increased fructose consumption are that it increases the drive to the brain center which controls our eating behavior and it is inexpensive. 

Most added sweeteners are now derived from corn sugar which is cheap but higher in fructose. The research demonstrating that fructose is the most common cause of fatty liver disease, the most common chronic liver disease, continues to grow.

foie gras is a specialty food made from duck or goose liver.  In most countries where it is enjoyed these birds are specifically groomed for this production.  They are fed high amounts of dried figs and dates by gavage which means force fed through feeding tubes.  The reason for the dried dates and figs is that they contain very high amounts of fructose.  The end effect is that their livers, destined to become foie gras, infiltrate with massive amounts of fat which is supposed to enhance the taste.

Humans either use dietary sugar for immediate energy production as blood levels rise, or store it as fat for later use.  This fat, triglyceride is made in the liver and most is returned to the circulation to be transported to storage in the abdomen.  The purpose of that mechanism is to allow for the storage of extra dietary energy when it is available which can be brought back out of fat storage and converted to usable energy during fasting. 

In essence this system was designed as a two-way highway to go back and forth between feasting and famine.  However, when too much incoming energy is being converted to storage energy, several problems occur.  The first is unhealthy weight gain in the center of the body.  This central/belly fat is highly associated with chronic metabolic disease risks particularly diabetes and heart disease. 

An additional problem also occurs.  Eventually with the chronic excessive triglyceride production these triglycerides cannot be removed from the liver at the pace they are produced causing fatty buildup in the liver itself, or fatty liver disease.  The link to fructose is that fructose causes greater liver triglyceride production and buildup than other dietary sugars.

A recent study uncovered another mechanism by which fructose causes more liver fat production.  Fructose has been shown to cause decreased intestinal barrier function allowing inflammatory bacterial components into the system.  The resulting inflammation accelerates the conversion of fructose into triglycerides in the liver accelerating fatty liver infiltration.(1)

In yet another piece of bad news for fructose, higher overall sugar and fructose consumption appears to contribute to elevated blood cholesterol.  The primary mechanism humans use to remove cholesterol from the blood is by producing LDL receptors in the liver which catch it and bring it into the liver for breakdown.  The old theory of vascular disease related to elevated cholesterol was that we were eating too much of it, the “supply-side theory”.  We were advised to eat a low fat diet (https://banksnutrition.com/2019/11/07/alzheimers-and-eggs/) which means more carbohydrate/sugar diets, and in many ways the problem appears to have worsened.  We now understand why.

Duck or goose liver just doesn’t appeal to me.  Neither does preparing my own liver for fois gras!

1. Todoric et al.  Fructose stimulated de novo lipogenesis is promoted by inflammation.  Nature Metabolism (2020).
2. Zhang et al.  High Dietary Fructose: Direct or Indirect Dangerous Factors Disturbing Tissue and Organ Functions.  Nutrients 2017, 9, 335; doi:10.3390/nu9040335.
3. St-Amand et al.  Two weeks of western diet disrupts liver molecular markers of cholesterol metabolism in rats.  Lipids in Health and Disease (2020) 19:192.