Overconsumption of any sugar has deleterious effects on our health. However, of the primary types of sugars that our cells can utilize; glucose (common in root vegetables and grains), fructose (common in fruit, honey, agave and corn) and galactose (common in legumes and milk) I propose that fructose has the most detrimental effects on human health. Unlike glucose, which is metabolized by most cells as an energy source, fructose is mainly metabolized by liver cells. As I mentioned in my last post, a study appeared way back in 1988 in the Journal of Diabetes Research and Clinical Practice that showed fructose has a reaction constant 7.5 times higher than glucose as well as a much higher calculated biohazard rating. Supporting research has increased exponentially since then.
In small amounts AND in the presence of adequate antioxidants, the liver has no problem metabolizing fructose. In fact, it converts it into glycogen which is the primary fuel for anaerobic muscles (the ones that get really big when you lift weights). Any fructose left after the muscles have had their fill of glycogen is converted into triglycerides. These “feed” fat cells for later use. Depending on which study you read, this occurs if more than 5-7 grams of fructose is consumed in one sitting. In addition to being converted into triglycerides, the excess fructose initiates a damaging, inflammatory response in the liver along with producing elevated levels of free radicals known as reactive oxygen species (ROS).
Here is a brief summary of the amounts of sugar contained in one cup of various fruits and beverages: Please note that I couldn’t find a breakdown of the glucose to fructose ratio. Source: http://nutritiondata.self.com/
- Coke (26g sugar) – almost all fructose
- Bananas (28g sugar)
- Apples (13g sugar)
- Apple juice (24g sugar) – 15 grams of fructose
- Grapes (23g sugar)
- Apricots (14g sugar)
- Cherries (15g sugar)
- Grapefruit (17g sugar)
- Cantaloupe (14g sugar)
- Pears (16g sugar)
- Plums (16g sugar)
- Blueberries (15g sugar)
- Blackberries (7g sugar)
- Raspberries (5g sugar)
- Peaches (13g sugar)
At first, the inflammation and free radical activity initiated in the liver from fructose results in fat accumulation inside the cells and mildly reduced function. If it continues along this path for any amount of time, a condition called non-alcoholic fatty liver disease, NAFLD, develops. Scores of studies demonstrate that along with obesity, NAFLD incidence has been steadily rising in Westernized, developed countries and in counties that are becoming developed. A study showed a 10-year doubling of NAFLD in one Chinese Population and demonstrated that a similar trend was seen in both Korea and Japan.
Note: I thought it would be interesting to compare fructose consumption and NAFLD incidence in various countries. I spent several hours and had a research assistant spend several more hours trying to find information on fructose sales or consumption in various countries. The information is very difficult and seemingly expensive to obtain. If anyone has access to this type of information, please contact me or enjoy the dissertation subject.
I would like to point out that many of these studies are performed by checking serum levels of the liver enzymes ALT and AST. The pathological changes occur way before these enzymes levels begin to rise. According to Dr. Michael Cave, a professor of hepatology, gastroenterology and nutrition at the Univerisity of Louisville, ALT and AST parameters should be much lower because these enzymes only begin to increase long after the inflammation and fat accumulation starts. To be objective, Dr Cave also presents a strong case for an increase in fatty liver disease as a result of chronic exposures to several persistent organic pollutants and xenobiotics. Several studies show that exposing liver cells to fructose, then adding a xenobiotic, results in accelerated inflammation and disease. It is possible that the rise of fatty liver disease has been a combination of increased fructose intake and exposure to these various environmental pollutants that are now ubiquitous in our environment.
Depending on which study you read, NAFLD is seen in 10-24% of America’s general population and 57-74% of obese individuals. According to the Mayo Clinic’s website, they describe fatty liver disease as “common and for most people causes no signs, symptoms or complications”. However, long before any physical symptoms present, the liver’s various functions diminish. If this continues permanent liver damage occurs along with the cumulative toxicity effects of secondary dysfunction. In addition, any persistent organic compounds that aren’t removed from the blood by the liver accumulate in fat tissue.
Here is a brief summary of the main functions of the liver:
- Eliminating endogenous toxins like testosterone and estrogen
- Eliminating exogenous toxins like gasoline vapors, prescription medications, pesticides, artificial fragrances, hormones from birth control usage that are now in the water supply and BPA from the PVC pipes that carry our water.
- Generating antioxidants like glutathione which not only carry out Phase 2 detoxification in the liver but neutralize pollutants in the lungs and assist with the recycling of neurotransmitters in the nervous system
- Metabolizing fat along with various types of cholesterol
- Generating proteins and enzymes for physiological functions all over the body
It makes me cringe to think what is happening to the livers of those poor souls who become motivated to lose a few extra pounds. They go running five miles per day, lift weights then drink a bunch of carrot juice or eat a banana because they’ve been misinformed into thinking it’s healthy. Not only are they putting an extra burden on their liver to metabolize the fat that is being burned, they also have to detoxify the various persistent organic compounds that are released from that fat. For the final assault they add massive doses of fructose. It would be really interesting to check the liver enzyme levels on NBC’s “The Biggest Loser” contestants before and during the competition. If I were them, I would do things to support the poor liver like eating more protein and vegetables, getting rid of the fruit and adding supplements like phosphatidylcholine, folic acid, B6, B12, alpha lipoic acid and N-acetyl cystiene.
Clearly, we evolved with the ability to eat fruit. For the next post in this series, I will discuss this seeming idiosyncrasy along with how the rise of fructose consumption is causing us to devolve.by