Frequently I tell my patients that fructose is a liver toxin. Their most common response is, “Fructose? You mean corn syrup, don’t you? Surely you can’t mean natural fruit sugar from apples and pears?” Yes, I do mean to include natural fruit sugar – regardless of the source, excess fructose is a liver toxin. The dose of fructose is much higher in soda pop than in whole fruit or carrots, but biochemically speaking, it’s the same molecule, whether it arrives in the sugar bowl, a glass of juice, a can of pop, or in a health food snack bar.
Fructose targets the liver, because that’s pretty much the only part of the body capable of metabolizing it. In the liver, fructose wreaks havoc in several ways: it damages hepatocytes, stimulates production of uric acid, and is metabolized into circulating lipids (triglycerides and low-density lipoprotein, the so-called “bad cholesterol.”) A liver that has been damaged by excessive fructose looks almost exactly the same as a liver that has been damaged by excessive alcohol.
Fructose also causes high blood pressure: Uric acid is one of the bigger culprits behind hypertension. Uric acid constricts blood vessels and causes oxidative damage, in addition to its notoriety in causing gout (painful inflamed joints in the feet). Uric acid is so reliable in this regard, that laboratories testing new blood pressure drugs use fructose to induce hypertension in their laboratory animals. That’s right; a healthy mammal that is overfed on fructose will reliably develop hypertension.
Fructose’s effects in the liver don’t stop at uric acid and hypertension; it also induces fibrosis (formation of scar tissue) in people who have fatty liver disease – which is a surprisingly common condition: about one in five seemingly healthy American has NAFLD, non-alcoholic fatty liver disease. Due to the lack of troubling symptoms, most cases are undiagnosed (and therefore untreated). A new study published in the journal Hepatology in January 2010 points out that heavy intake of fructose is defined as one or more servings of fruit juice (!) or soda pop per day, and is associated with fibrosis of the liver. Heavy fructose consumption is also associated with increased liver inflammation in older adults. How many people are drinking fruit juices every day, believing that it’s good for their health, when in fact it is damaging their livers?
One current fad food (or rather, “foodlike substance,” as journalist Michael Pollan says), is agave syrup, also called agave nectar. Commercial agave syrup is even more nefarious than high fructose corn syrup in terms of its fructose content: HFCS is commonly about 55% fructose, while agave syrup can be as high as 90% fructose in some cases. By comparison, ordinary corn syrup, for example Karo Syrup, has no fructose whatsoever; it is plain dextrose, also known as glucose. I find it stunning that a known liver toxin would be marketed as if it were a health food, but the rules of the game in marketing and advertising are not the same as the rules of biochemistry.
High-fructose anything is not good nutrition, nor is it good for human health; however, it is great for sales – fructose tastes about twice as sweet as glucose, and it has a stronger browning reaction in prepared foods. Sweet, crispy, caramelized, well-browned crusts are selling points when it comes to industrially-prepared “foodlike substances.” If only it were as good for our bodies as it is for the manufacturers’ sales quotas. Just some food for thought! Love your liver if you want to live long and prosper.
To your good health,
Deborah McKay ND
Fructose targets the liver, because that’s pretty much the only part of the body capable of metabolizing it. In the liver, fructose wreaks havoc in several ways: it damages hepatocytes, stimulates production of uric acid, and is metabolized into circulating lipids (triglycerides and low-density lipoprotein, the so-called “bad cholesterol.”) A liver that has been damaged by excessive fructose looks almost exactly the same as a liver that has been damaged by excessive alcohol.
Fructose also causes high blood pressure: Uric acid is one of the bigger culprits behind hypertension. Uric acid constricts blood vessels and causes oxidative damage, in addition to its notoriety in causing gout (painful inflamed joints in the feet). Uric acid is so reliable in this regard, that laboratories testing new blood pressure drugs use fructose to induce hypertension in their laboratory animals. That’s right; a healthy mammal that is overfed on fructose will reliably develop hypertension.
Fructose’s effects in the liver don’t stop at uric acid and hypertension; it also induces fibrosis (formation of scar tissue) in people who have fatty liver disease – which is a surprisingly common condition: about one in five seemingly healthy American has NAFLD, non-alcoholic fatty liver disease. Due to the lack of troubling symptoms, most cases are undiagnosed (and therefore untreated). A new study published in the journal Hepatology in January 2010 points out that heavy intake of fructose is defined as one or more servings of fruit juice (!) or soda pop per day, and is associated with fibrosis of the liver. Heavy fructose consumption is also associated with increased liver inflammation in older adults. How many people are drinking fruit juices every day, believing that it’s good for their health, when in fact it is damaging their livers?
One current fad food (or rather, “foodlike substance,” as journalist Michael Pollan says), is agave syrup, also called agave nectar. Commercial agave syrup is even more nefarious than high fructose corn syrup in terms of its fructose content: HFCS is commonly about 55% fructose, while agave syrup can be as high as 90% fructose in some cases. By comparison, ordinary corn syrup, for example Karo Syrup, has no fructose whatsoever; it is plain dextrose, also known as glucose. I find it stunning that a known liver toxin would be marketed as if it were a health food, but the rules of the game in marketing and advertising are not the same as the rules of biochemistry.
High-fructose anything is not good nutrition, nor is it good for human health; however, it is great for sales – fructose tastes about twice as sweet as glucose, and it has a stronger browning reaction in prepared foods. Sweet, crispy, caramelized, well-browned crusts are selling points when it comes to industrially-prepared “foodlike substances.” If only it were as good for our bodies as it is for the manufacturers’ sales quotas. Just some food for thought! Love your liver if you want to live long and prosper.
To your good health,
Deborah McKay ND
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I was very disappointed with the link "Find Out the Ideal Daily Dose of Vitamin D." I have never found optimal levels of D with blood testing in anyone taking such low dosages recommended in this article.
ReplyDeleteDebbie - I have a feeling that the link you are talking about are placed by blogger. ZRT doesn't ahve control over the content of those articles. But you gave me a good idea for a new blog.
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