Fructose: Friend or Foe?

Most people think of fructose as a natural fruit sugar. After all, it’s one of the principal sugars (along with glucose and sucrose) in fruits. But in fact, the amount of fructose in most fruits is relatively small, compared with other dietary sources. Fruit also contains many beneficial nutrients, including fiber, which slows the absorption of sugars.

The fructose found in processed foods, however, is another story. Although Americans have actually decreased their intake of sucrose (table sugar), the amount of fructose in the American diet has ballooned over the past 30 years. The reason is that food makers have replaced sucrose (garden-variety table sugar) with “high-fructose corn syrup” (HFCS) to sweeten foods and beverages. Since the early 1980s, the average person’s consumption of HFCS has more than tripled, from about 19 pounds to 60 pounds per person annually.

Despite the natural-sounding ring of fructose, HFCS does not come from fruit. Instead, it’s a highly purified blend of sugars (typically 55 percent fructose and 45 percent glucose) derived from corn. Because the fructose in HFCS is part of a manmade blend (as opposed to the natural compound of sugars found in fruit), the body metabolizes it very differently from other sugars.

Recent Research

• In a study published in the June 2008 Journal of Nutrition, researchers reported that increased consumption of fructose doubled the subjects’ lipogenesis — that is, their ability to make fat — when compared with glucose. In addition, the fructose led to higher levels of triglycerides, a blood fat that is an independent risk factor for heart disease. These findings confirmed other research along the same line.

• Another study, published in the July 2008 Archives of Internal Medicine, found that African-American women who regularly consumed either soft drinks (sweetened with HFCS) or fruit juices were far more likely to develop type 2 diabetes. What’s the problem with fruit juices? They are a more concentrated source of sugar and they lack the fiber of fresh fruit that would blunt increases in blood sugar. Worse, some brands of juice even have added HFCS and more sugars overall than soft drinks!

Tip: Read the ingredients lists on bottles and packages. Pay attention to added syrups, juices, and concentrates used to sweeten; and reject products containing HFCS.

• Fructose might also alter appetite, increasing hunger and cravings for sweet foods. According to some research, fructose decreases levels of leptin, a hormone that normally suppresses hunger. At the same time, it raises levels of ghrelin, a hormone that stimulates hunger. The result? Feeling hungrier, eating more, and packing on pounds.

• Some researchers have argued that the consumption of fructose by children may program developing brains with an intense desire for sweets, leading to a lifelong over-consumption of sweets and an increased risk of overweight, diabetes, and related health problems.

Tip: Don’t give foods or beverages containing HFCS to your children or grandchildren.

What You Can Do

How can you prevent fructose from being a problem in your eating habits? First, make a decision to get your added sweetness from whole fruit. Fruit provides a wealth of good nutrition — especially high-fiber, nonstarchy fruits such as berries, nectarines, and apples. Consider adding some of these (fresh or frozen) to unsweetened yogurt or cream.

Second, make a habit of controlling your sweet tooth and limiting your intake of all added sweeteners — such as HFCS, fructose, sucrose (sugar), glucose, and corn syrup — to improve your control of blood sugar. You’ll have to get good at reading labels.

Third, skip soft drinks and fruit juices altogether. A typical 12-ounce soft drink, sweetened with HFCS, provides the equivalent of 12 teaspoons of sugars and about 150 calories. Some brands of fruit juice are even worse. Those are calories you probably don’t need or should at least be spent on something more nutritious.

Bottom line: If you see the word fructose on a product label, think twice.

1 – Parks EJ, LE Skokan, MT Timlin, et al. 2008. Dietary sugars stimulate fatty acid synthesis in adults. Journal of Nutrition 138:1039-1046.

2 – Havel PJ. 2006. Dietary fructose: implications for dysregulation of energy homeostasis and lipid/carbohydrate metabolism. Nutrition Reviews 63:133-157.

3 – Teff KL, SS Elliott, M Tschop, et al. 2004. Dietary fructose reduces circulation insulin and leptin, attenuated postprandial suppression of ghrelin, and increases triglycerides in women. Journal of Clinical Endocrinology & Metabolism 89:2963-2972.

4 – Bray G. 2004. Reply to NJ Krilanovich. American Journal of Clinical Nutrition 79:538-539.

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