By Sangeeta Pradhan
INDIA New England Nutrition Columnist
The sugar debate, (reminiscent of the fat debate) rages on with folks on either side of the aisle taking strong positions, as is true with most debates- especially those waged over politics, religion and of course…food!
The shocking truth: What, you might ask is all the fuss about? The simple answer is that there is a lot at stake if we maintain the status quo for added sugars in our diet. For starters, did you know that just one 12 oz can of soda contains a whopping 10 teaspoons of sugar??! Would you ever put that much sugar in your cup of morning coffee?! This tops the suggested, added sugar per day guideline set forth by the AHA as I will note in the sequel to this post next week.
Where is the sugar lurking?: According to a Sept 2010 article in the Academy of Nutrition and Dietetics, sugar-sweetened carbonated beverages, energy, fruit and sports drinks in the American diet take the lion’s share of added sugars, contributing a hefty 46%. Grain-based based deserts (13%), dairy desserts ( 7%), candy (6%), and ready-to-eat cereals (4%) along with these beverages, make up the top five sources of added sugars in the American diet.
The fructosification of our food supply: Of note, the consumption of HFCS increased by a staggering 1000% between 1970 and 1990, far exceeding the changes in the intake of any other food or food group. Food manufacturers started lacing their products with this sweetener, primarily because of increased stability, and shelf-life, lower cost secondary to government subsidies, improved palatability and ease of use.
Outcry against fructose: The most vocal advocate against sugar and HFCS in particular, has been Dr. Robert Lustig, American pediatric endocrinologist at the University of California, San Francisco. Dr. Lustig does not mince his words when he calls sugar a “poison” and believes it is a key culprit for obesity in the United States. His talk, “Sugar: The Bitter Truth,” on YouTube has created waves, grabbing a lot of media attention, virtually going viral and receiving to date 5 million hits and rising by the minute.
Sifting through the evidence: All this calls for a closer examination of the current scientific evidence on this hot topic, so let’s get to work, shall we?
A recent, parallel-arm, non-randomized, double-blinded intervention study showed dose-dependent increases in lipoprotein risk factors for cardiovascular disease, demonstrating that the risk of heart disease correlates with consumption of increasing amounts of added sugars.
High fructose corn syrup is a sugar-based sweetener, used in processed foods and drinks in the US. Several different types of high fructose corn syrup are available, with differing amounts of fructose. For example, the most concentrated form contains 90% fructose, and is called HFCS 90.
The most commonly used type is HFCS 55 (55% fructose, 42% glucose). What might come as a surprise to readers is that HFCS 55 is very similar to sucrose (regular table sugar), which is 50% fructose and 50% glucose.
HFCS and sucrose: Not only are HFCS and sucrose or table sugar structurally similar, they also exert the same metabolic effects on the body, as seen in these studies that showed that there are no differences in the metabolic effects of HFCS and sucrose when compared at low, medium, and high levels of consumption.
The increase in plasma triglyceride (a form of fat in the blood) concentrations by sugar-sweetened beverages can be attributed to the fructose rather than glucose in sugar. Several randomized trials of sugar-containing soft drinks versus low-calorie or calorie-free beverages show that either sugar, 50% of which is fructose, or fructose alone increases triglycerides, body weight, visceral fat, muscle fat, and liver fat.
Is fructose as bad as alcohol for the liver?: Fructose is metabolized preferentially in the liver and when the liver is presented with more fructose than it can handle, it coverts it to fat. This leads to a fatty liver and has also been associated with increased triglycerides and lower HDL (a condition called dyslipidemia) and insulin resistance. ( The body is unable to utilize available insulin effectively, as discussed in a previous post). In fact, Lustig goes so far as to draw a parallel between fructose and alcohol, stating that with excessive ingestion, the damage done by fructose is akin to that seen with alcohol.
Fructose and free radicals: Glucose in carbohydrates reacts with substances called amino groups on proteins in a non enzymatic manner called the Maillard reaction. For e. g the “glycated hemoglobin” or Hemoglobin A1C often used to diagnose and monitor sugars in diabetic folks is an example of glucose combining with the protein, hemoglobin in blood. Turns out each “glycation” produces a free radical, which, if not neutralized by an antioxidant, can lead to oxidative damage in your body. Lustig points out in this article that the fructosylation of proteins (when fructose combines with proteins), can occur at 7x the rate of glucosylation of proteins (when glucose combines with proteins), leading to excessive generation of free radicals and subsequent oxidation by these free radicals. Well!! – you guessed it- whenever there is any form of oxidation in the body, it’s cousin, inflammation is never too far, thus leading to inflammation of the liver as well.
The fact that the nation got fatter when fat was declared public enemy # 1 in the 70’s and 80’s, and unfortunately got replaced with (refined carbs) and sugars by food manufacturers to maintain the palatability factor, simply adds credence to Lustig’s argument
The opposite camp: Lustig’s opponents, notably David L. Katz, MD, MPH, FACPM, FACP, director of the Yale University Prevention Research Center says “it would be a mistake to think that HFCS is “the” cause of the obesity epidemic. We would have all the same problems if we replaced it with other varieties of added sugar.”
This article in the American Journal of Clinical Nutrition, also argues that increased caloric intake since 1970 was not due to added sugars and HFCS as Lustig alleges, but due to increased consumption of all nutrients. Fructose-glucose sweeteners ( honey, table sugar, HFCS, fruit sugars and invert sugars), are metabolized through the same pathways regardless of dietary source and finally that there is no longer an association between HFCS and obesity in the United States given that the per capita consumption of HFCS has declined in recent years, whereas obesity rates continue their relentless spiral upwards.
My take: Clearly obesity is a multi-pronged problem, calling for a multi-pronged solution. Just pointing an accusing finger at sugar and HFCS, may be oversimplifying the problem. Removing HFCS from the food supply will not solve the inactivity problem and the fact that we have become increasingly more sedentary, a key contributor to the obesity crisis. That being said, given all the incriminating evidence against this sweet, metabolic menace called sugar, the AHA has set forth very specific guidelines for consumption of “added sugars”.
For more on these guidelines, as well as those recommended by the Academy of Nutrition and Dietetics, please stay tuned for next week’s post as I walk you through practical steps for spotting hidden/added sugars and help you dissect and read “between the lines” of a Nutrition facts label.
Disclaimer: This blog is for informational purposes only and should not be construed as medical advice. Please consult your doctor or registered dietitian for recommendations tailored for your unique needs
(Pradhan is a Registered Dietitian and Certified Diabetes Educator.)