FRUCTOSE

Fructose is found in fruits and honey. When fructose and glucose are bonded together, they form sucrose -- commonly known as table sugar. Billed as a "natural" sweetener, fructose is often recommended as a replacement for other sugars in the diet, often being included in weight loss drinks.

Meals high in fructose can reduce fat burning when eaten after exercise.

Researchers from Indiana's Purdue University tested 14 overweight individuals following a 40-minute workout. Subjects were split into two groups, and assigned to follow either a normal or low calorie diet. After six days on each diet, they were then given a meal containing either 50 grams of glucose, or a similar quantity of fructose.

The table below shows how much fat was burned during the three hours after exercise:

As you can see, there was no real difference in oxidation rates during the low calorie diet. However, when subjects were tested following the normal diet, fat oxidation was 38% lower after the high fructose meal.

If you consider fructose a safe, natural sugar, think again. You've been had by one of the biggest nutritional bait-and-switch ploys in years.
 

Fructose and high-fructose corn syrup (HFCS) have been aggressively promoted as natural sugars. After all, we've been taught since childhood that fructose is fruit sugar.
The truth is that fructose and HFCS, as large-scale commercial sweeteners, didn't exist 20 years ago. Now, they're almost as common as sucrose-plain old white sugar. HFCS is routinely added to processed foods and beverages including Coca-Cola, Snapple, and many health food products.
"Fructose is not from fruit. It's a commercial, refined sugar," asserted Robin Rogosin, a buyer and research coordinator at Mrs. Gooch's Natural Foods Market in Beverly Hills, Calif.
In fact, a trail of medical studies dating back a quarter of a century doesn't paint a terribly sweet picture for fructose. High fructose consumption has been fingered as a causative factor in heart disease. It raises blood levels of cholesterol and another type of fat, triglyceride. It makes blood cells more prone to clotting, and it may also accelerate the aging process.
"People should avoid it," urged John Yudkin, M.D., Ph.D., professor emeritus at Queen Elizabeth College, London, and an expert in the health effects of sugar.
Most fructose sneaks into the diet in the forms of sucrose and HFCS. Sucrose breaks down during digestion into equal parts of glucose and fructose. HFCS consists of 55 percent fructose blended with 45 percent glucose.
As is the case with any other refined food, a little fructose won't hurt you. The problem comes with the sheer quantity of "hidden" fructose being consumed through the HFCS and sucrose in processed foods. For example, conventional and "new age" soft drinks almost universally contain 11 percent HFCS by weight-2.2 pounds per case.
"The consumption of fructose has not increased over the last 40 years. We have the data to show that we're not increasing fructose consumption," contended Mark Hannover, Ph.D., a researcher at the A. E. Staley Manufacturing Co. of Decatur, Ill, the second largest maker of HFCS in the United States.
Hannover is right about the past 40 years. But he sidestepped the larger historical context. Overall sugar (sucrose) consumption remained very low - a few pounds a year - until the industrial revolution. Advances in processing made it easy to manufacture from sugar cane and sugar beets, and people began eating more of it.
Although pure fructose has been available in small quantities for decades, its use as common sweetener dates only from the early 1970s. That's when the Finnish Sugar Co. developed a method to efficiently synthesize it from cane and beet sugar. Now, Staley and five other American companies make fructose from corn.
Staley's principal product is HFCS, which has captured a huge chunk of the market once owned by makers of sucrose. The advantage of HFCS, from the standpoint of food manufacturing, is that it's much sweeter than sucrose, it's easier to handle during processing, it has a longer shelf life - and it's cheaper than sucrose.
"We have improved the quality of sweeteners since the advent of HFCS," insisted Hannover. "It's clean microbiologically, it contains few sodium ions, and it's more stable than sugar."
HFCS may be better than sucrose for manufacturing, but it's not any better for health.
Because refined sweeteners - and refined foods, in general - lack bulk, it's easy to consume large quantities of them. Staley grinds up a mind-boggling 500,000 bushels of corn a day and turns them into more than 3 billion pounds of HFCS annually. Amazingly, that's only 20 percent of the 16 billion pounds of HFCS consumed each year in the United States.
These days, our per capita intake of refined sugar is almost 150 pounds a year. HFCS accounts for 51.7 pounds of that, and sucrose for 64.5 pounds, according to the U.S. Department of Agriculture. That translates to about 60 pounds of fructose per person.
There's good reason to believe that, from an evolutionary standpoint, our bodies can't handle such large quantities of sugar, particularly fructose. Eating it poses a health hazard, and it doesn't matter whether it's from HFCS or sucrose. But HFCS may be more dangerous because it sounds more natural - and therefore healthier - than plain old white sugar.
"We felt the healthiest approach was to stay away from refined sugars. That way, we're not offering a lot of empty calories," said Bill Knudsen, whose Chico, Calif., company has steered clear of fructose sweeteners for its health food juices. "A pure fruit juice product is healthier for you than a refined sugar because of the micronutrients that come with the juice."
In medicine, the first alarms about the link between sugar consumption and heart disease were sounded by Yudkin in the late 1960s. At the time, he was chairman of the department of nutrition at Queen Elizabeth College, London. Disturbed by inconsistencies in the evidence linking animal fats to heart disease, Yudkin began searching for another dietary factor.
An expert in carbohydrate metabolism, he initially focused on sucrose consumption. In laboratory and human tests, he found that sucrose increased blood levels of cholesterol, triglyceride, uric acid, insulin, and cortisol - all associated with an increased risk of heart disease. Sucrose also raised blood pressure and increased the fragility of blood platelet cells, making them more prone to clotting.
As dramatic as those findings were, the real surprise came when Yudkin substituted fructose for sucrose in his experiments. "The effects of eating sucrose in the quantities we eat are magnified with fructose. Fructose is the dangerous part," he said. In contrast, glucose did little more than cause cavities.
Although he has been retired for almost 20 years, Yudkin regularly publishes articles and letters about sugar and heart disease in the leading medical journals. In a phone interview, he was surprised to hear that fructose and HFCS had become common sweeteners in the United States. He said they were virtually unheard of in England, where overall sugar consumption has been declining.
Other researchers have confirmed Yudkin's findings, but sucrose and fructose are still recognized as generally safe by the Food and Drug Administration. Many widely used products, like sucrose, were grandfathered in as a safe product when food and drug regulations were created early in 1938, and the safety of fructose was assumed based on the perceived safety of sucrose.
"Fructose is part of the sucrose sugar. Sucrose is affirmed as GRAS (generally regarded as safe)," explained Judy Folke, a spokesperson at the FDA's Food Safety and Applied Nutrition Press Office in Washington,D.C. "Fructose is not GRAS, but it was treated under prior sanction because it had been used for so many years."
But the research suggests that, in retrospect, the FDA may have assumed too much.
For example, fructose has been touted for years as a safe sugar for diabetics because it doesn't trigger a rapid rise in blood sugar. That's true, but the cardiovascular consequences may outweigh the benefits for diabetics, who already face a higher than average risk of developing heart disease.
In a recent study, John Bantle, M.D., of the University of Minnesota sequentially placed 18 Type I (insulin-dependent) and Type II (no insulin-dependent) diabetics on two diets. The only difference between the diets was that one contained carbohydrate as starch, which is digested as glucose, and the other contained carbohydrate as fructose.
When they consumed the fructose, the diabetics had fewer spikes in blood sugar levels. Three of the Type I diabetics were able to reduce their insulin intake, a positive change. However, according to Bantle's report in the Nov. 1992 Diabetes Care, the diabetics' total cholesterol rose an average 7 percent, and their "bad" low-density lipoprotein (LDL) cholesterol rose almost 11 percent. The fructose increased their risk of heart disease.
But fructose doesn't play havoc with only the hearts of diabetics. Bantle noted the same effects in a study of 14 healthy volunteers who sequentially ate a high-fructose diet and one almost devoid of the sugar. While on the fructose diet, the subjects' total cholesterol levels increased by 9 percent and the LDL fraction increased by 11 percent.
"There is some data that if you consume a lot of fructose, you can get an increase in lipoproteins," Hannover told Natural Health. "A lot of this is mediated by consuming fructose with other carbohydrates. We recommend using a blend of carbohydrates - fructose may be the primary carbohydrate with glucose or more complex carbohydrates."
"I'm not trying to ignore the data," he added, "but I'm not trying to blow it out of proportion either."
There's another wrinkle. Add fructose to the typical American high-fat diet - as most people do - and the risk of heart disease increases even more. Sheldon Reiser, Ph.D., of the U.S. Department of Agriculture's Human Nutrition Research Center in Beltsville, Md., studied 21 men eating two kinds of high-fat diets. The diets were the same except for the carbohydrate. One used simple starch, the other 20 percent fructose.
The cholesterol and triglyceride levels of all the men increased while they consumed the high-fructose/high-fat diet, but not while they ate a high-starch/high-fat diet. Ten of the men began the study with high blood levels of insulin - another risk factor for heart disease - and their cholesterol and triglyceride levels rose a whopping 30 to 50 percent.
Should people with moderate to high cholesterol reduce their intake? The answer seems apparent.
"They might benefit from that," Hannover conceded. "We presume you're under a doctor's care, and if you're not, you should be. If I had high cholesterol, it would be on the list of foods to avoid - not on the top of the list, but I wouldn't leave it off either, since there is some data to support this view."
Fructose and other sugars contribute to heart disease in yet another way. Dietary sugars increase what doctors call "spontaneous platelet aggregation", an unnatural tendency toward blood clotting. But according to a study published in the Aug. 1, 1990, Thrombosis Research, fructose promotes abnormal clotting much more than does any other common sugar does.
There's even more. Recent research by Forrest Nielsen, Ph.D., of the USDA's Human Nutrition Research Center in Grand Forks, N.D., found that fructose interferes with absorption of copper, an essential mineral needed to create hemoglobin in red blood cells.
"Copper is affected by fructose," Nielsen told Natural Health. "With a high intake of high-fructose corn syrup, people might show signs of a copper deficiency and may need to enhance their copper intake."
In addition, when five volunteers ate a diet with 20 percent fructose, their total cholesterol and LDL cholesterol shot up. But the combination of suppressed copper and high fructose also increased the number of free radicals, damaged molecules that contribute to cancer and aging.
Does Nielsen think fructose is safe? "I'm not going to damn fructose because in small amounts it's not a bad substance," Nielsen said. But he later acknowledged, "I'm not convinced it's completely safe." There's one more significant side effect of fructose. It cross links - that is, ties up - proteins in what biochemists call the Maillard reaction. This cross linking occurs during the cooking of food, affecting both the taste and the nutritional value of food.
But the Maillard reaction also occurs in the human body, and it's suspected as a factor in diabetes and aging, according to William Dills, Ph.D., a chemist at the University of Massachusetts at Dartmouth. Dills noted in the Nov. 1993 American Journal of Clinical Nutrition that the relationship between the "Maillard reaction-related cross-link in proteins, cells, and tissues and the overall aging process appears indisputable."
All this should not dampen your taste for fresh fruit or fruit juice. The hazards associated with fructose appear to be dose dependent, according to Yudkin and other experts. If you eat predominantly natural foods, and avoid large quantities of processed foods, you have little to worry about.
Fructose accounts for only 5 to 7.7 percent of the wet weight of cherries, pears, bananas, grapes, and apples. That's about 5.5 to 8 teaspoons per pound of fresh fruit. There's even less fructose - 2 to 3 percent, or roughly 2 to 3 teaspoons per pound - in strawberries, blackberries, blueberries, oranges, and grapefruit. Honey, refined by bees, contains 40 percent fructose, but its extreme sweetness deters most people from consuming it in large amounts.
Calls to health food stores around the country indicated a fairy high awareness of fructose as a refined sugar.
Rogosin, at Mrs. Gooch's Natural Foods Market, pointed out that carrying fructose-containing products would be contrary to the chain's mission statement that emphasizes natural foods. "It has known health effects - it increases cholesterol and triglyceride levels," she said.
Tim Connor, a buyer for Nature's Fresh Northwest! in Portland, Ore., pointed out that "there's no question that it's a highly refined sugar." The health food grocery chain carries some products with fructose, though not many.
"We have not taken a no-sugar stance," Connor said. "We have taken a no-excessive-sugar stance. We carry a broader range of products than what's found in more traditional health food or natural food stores."
Is there a safe amount of fructose? Yudkin reiterated that people should avoid it and that they should be wary of sugars hidden in processed foods. "Rather than switch to another sugar," he advised, "they should gradually reduce the amount of sweetness in foods," he said.
And what's the view of the FDA, mandated by Congress to ensure food safety? "We don't have any studies that show health effects (of fructose)", said spokeswoman Folke, after checking with a scientific staff member she declined to name. "We do not have any safety studies on it. If a safety issue had come up, it would be big news."
This article originally appeared in Natural Health magazine. The information provided by Jack Challem and The Nutrition Reporter™ newsletter is strictly educational and not intended as medical advice. For diagnosis and treatment, consult your physician.
 

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