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High fructose corn syrup a major culprit in the nation's obesity crisis
03/09/04 11:37 AM
How sweet it isn't
BY KIM SEVERSON
San Francisco Chronicle
An overweight America may be fixated on fat and obsessed with carbs, but nutritionists say the real problem is much sweeter -- we're awash in sugar.
Not just any sugar, but high fructose corn syrup.
The nation eats more sweetener made from corn than from sugar cane or beets, gulping it down in drinks as well as in frozen food and baked goods. Even ketchup is laced with it.
Almost all nutritionists finger high fructose corn syrup as a major culprit in the nation's obesity crisis. The inexpensive sweetener flooded the American food supply in the early 1980s, just about the time the nation's obesity rate started its unprecedented climb.
The question is why did it make us so fat. Is it simply the Big Gulp syndrome -- that we're eating too many empty calories in ever-increasing portion sizes? Or does the fructose in all that corn syrup do something more insidious -- literally short-wire our metabolism and force us to gain weight?
Loading high fructose corn syrup into increasingly larger portions of soda and processed food has packed more calories into us and more money into food processing companies, say nutritionists and food activists. But some health experts argue that the issue is bigger than mere calories. The theory goes like this: The body processes the fructose in high fructose corn syrup differently than it does old-fashioned cane or beet sugar, which in turn alters the way metabolic-regulating hormones function. It also forces the liver to kick more fat out into the bloodstream.
The end result is that our bodies are essentially tricked into wanting to eat more and at the same time, we are storing more fat.
''One of the issues is the ease with which you can consume this stuff,'' says Carol Porter, director of nutrition and food services at the University of California at San Francisco. ``It's not that fructose itself is so bad, but they put it in so much food that you consume so much of it without knowing it.''
A single 12-ounce can of soda has as much as 13 teaspoons of sugar in the form of high fructose corn syrup. And because the amount of soda we drink has more than doubled since 1970 to about 56 gallons per person a year, so has the amount of high fructose corn syrup we take in. In 2001, we consumed almost 63 pounds of it, up from 1 ½ pounds in the mid-'70s -- a more than 4,000 percent spike, according to the U.S. Department of Agriculture.
The USDA suggests most of us limit our intake of added sugar -- that's everything from the high fructose corn syrup hidden in your breakfast cereal to the sugar cube you drop into your after-dinner espresso -- to about 10 to 12 teaspoons a day. But we're not doing so well. In 2000, we ate an average of 31 teaspoons a day, which was more than 15 percent of our caloric intake. And much of that was in sweetened drinks.
So, the answer is to just avoid soda, right? Unfortunately, it's not that simple, because the inexpensive, versatile sweetener has crept into plenty of other places. A low-fat, fruit-flavored yogurt, for example, can have 10 teaspoons of fructose-based sweetener in one serving.
IN FROZEN FOODS
Because high fructose corn syrup mixes easily, extends shelf-life and is as much as 20 percent cheaper than other sources of sugar, large-scale food manufacturers love it. It can help prevent freezer burn, so you'll find it on the labels of many frozen foods. It helps breads brown and keeps them soft, which is why hot dog buns and even English muffins hold unexpected amounts.
The question remains just how much more dangerous high fructose corn syrup is than other sugars.
Fructose, as the name implies, is the sugar found naturally in fruit. It can be extracted, turned into granules and used like sugar in the kitchen. It used to be considered a healthier alternative to sucrose -- plain old table sugar. It's sweeter, so less is needed to achieve the same taste.
Diabetics use it because fructose doesn't stimulate insulin production, so blood sugar levels remain stable.
The process of pulling sugar from cornstarch wasn't perfected until the early 1970s, when Japanese researchers developed a reliable way to turn cornstarch into syrup sweet enough to compete with liquid sugar. After some tinkering, they landed on a formula that was 55 percent fructose and 45 percent glucose -- sweet enough and cheap enough to make most soda companies jump from liquid sugar to high fructose corn syrup by the 1980s.
`FATTEST PEOPLE IN THE WORLD'
Journalist Greg Crister lays out a compelling case against high fructose corn syrup in his 2003 book, Fat Land: How Americans Became the Fattest People in the World. He argues that federal policies that aimed to stabilize food prices and support corn production in the 1970s led to a glut of corn and then to high fructose corn syrup. With a cheaper way to sweeten food, producers pumped up the size and amount of sweet snacks and drinks on the market and increased profits.
Crister writes that despite the food industry's arguments that sugar is sugar, whether fructose or sucrose, no group ``has yet refuted the growing scientific concern that, when all is said and done, fructose . . . is about the furthest thing from natural that one can imagine, let alone eat.''
The latest case against high fructose corn syrup began in earnest a few years ago. Dr. George Bray, principal investigator of the Diabetes Prevention Program at Louisiana State University Medical Center, told the International Congress on Obesity that in 1980, just after high fructose corn syrup was introduced in mass quantities, relatively stable obesity rates began to climb. By 2000, they had doubled.
Further, the American Journal of Clinical Nutrition in 2002 published research that showed that teenagers' milk consumption between 1965 and 1996 decreased by 36 percent, while soda consumption increased by more than 200 percent. Bray argues that without calcium, which nutritionists agree can help the body regulate weight, kids got fatter. He says that he could find no other single combination of environmental or food changes that were as significant to the rise in obesity.
Other studies at UC Davis and the University of Michigan have shown that consuming fructose, which is more readily converted to fat by the liver, increases the fat in the bloodstream in the form of triglycerides.
And unlike other types of carbohydrate made up of glucose, fructose does not stimulate the pancreas to produce insulin. Peter Havel, a nutrition researcher at UC Davis who studies the metabolic effects of fructose, has also shown that fructose fails to increase the production of leptin, a hormone produced by the body's fat cells.
Both insulin and leptin act as signals to the brain to turn down the appetite and control body weight. And in another metabolic twist, Havel's research shows that fructose does not appear to suppress the production of ghrelin, a hormone that increases hunger and appetite.
Other researchers, too, are finding problems with high fructose corn syrup. A study in last month's Journal of the National Cancer Institute suggests that women whose diet was high in total carbohydrate and fructose intake had an increased risk of colorectal cancer. And Dr. Mel Heyman, chief of pediatric gastroenterology and nutrition at UCSF, is seeing sick children whose bodies have been overloaded with fructose from naturally occurring fructose in fruit juice combined with soda and processed food.
''The way the body handles glucose is different from fructose,'' he says. 'It can overload the intestines' ability to absorb carbohydrates by giving it too much fructose. That can cause cramps, bloating and loose stools.''
Like others in the field, he says there is much to discover in how sugar works, but he disagrees that high fructose corn syrup is somehow reprogramming our bodies toward obesity. Rather, he says, we're just eating too much of it.
Nutrition theory holds that the basic make-up of fructose-laced corn syrup is not much different from table sugar. They react about the same in the body, says Dr. Walter Willett, a professor of epidemiology and nutrition at Harvard School of Public Health. ``There are some modest differences in metabolism, but I don't think fructose per se is the culprit.''
Neither do the food companies that use it in copious amounts.
Says Stephanie Childs, a spokesperson for the Grocery Manufacturers Association: ``At the end of the day, how any sweetener affects your weight depends on how many calories you are taking in overall. Overemphasizing one nutrient at the detriment of others is not going to solve the problem.''
Even some leading nutrition reformers aren't convinced that high fructose corn syrup is of itself the issue. The bigger battle, says Michael Jacobson, executive director of the Center for Science in the Public Interest, a consumer advocacy group, is to get added sugars listed on food labels with a percentage of daily value. That means a consumer could look at a package and see that, for example, one soda provides almost all the sugar a person should eat in a day.
''It simply comes down to this,'' he says. ``We're eating too much refined sugars, be it sucrose or high fructose corn syrup or any other refined sugar.''
Heather is the Administrator of the IBS Message Boards. She’s the author of Eating for IBS and The First Year: IBS, and the CEO of Heather's Tummy Care. Join her IBS Newsletter. Meet Heather on Facebook!