Q: I have been told that fructose is a healthy sweetener and that even people with diabetes should use it. I've also been told that some people are dramatically limiting fructose intake to reverse disease processes and protect health. What's the deal? -Nancy S., Wichita, Kan.
A: Years ago, some health professionals recommended fructose for diabetics because it doesn't raise blood sugar levels like so many other sugars. However, we now know that because of the way fructose is metabolized in the body, excess fructose in the diet sets people up for insulin resistance (the central feature of type 2 diabetes), high blood triglycerides, fatty liver disease, and more.
Commercial sweeteners and other sources of carbohydrates, such as fruit, contain varying degrees of the simple sugars fructose and glucose. (One exception to this rule is crystalline fructose, a sweetener derived from corn, that is 100 percent fructose.)
High fructose corn syrup (HFCS) sounds like it should be 80-90 percent fructose, but the most common kind of HFCS used in soft drinks is 55 percent fructose and 45 percent glucose-not very different from the 50/50 mix in regular table sugar.
Our bodies are designed to process fructose in its natural setting, when it's accompanied by fiber and other healthful nutrients found in whole fruit. But because of corn subsidies and sugar tariffs, HFCS and sugar are added into countless foods and drinks today, and our intake of both has skyrocketed. Add to that the amounts of fruits, fruit juices, smoothies, and naturally sweetened foods, such as cereals, that we consume, and our intake of fructose has increased as a percentage of both our caloric intake and of our total consumption. Our current fructose consumption has increased fivefold compared to a hundred years ago, and has more than doubled in the last 30 years. Unfortunately, high amounts, especially in liquid calorie form, lead to bitter health consequences.
Fructose in the Body
Fructose does not stimulate insulin, which in turn does not suppress ghrelin (the "hunger hormone"), and doesn't stimulate leptin (the "satiety hormone"), which means you can consume an enormous amount of fructose calories without your brain realizing that you are full. So, you keep eating (or drinking) the sweet stuff.
The fructose you eat goes right to your liver, the primary organ that can metabolize it. The liver then turns fructose into
triglycerides (a form of fat), which are stored in the liver and also released into the bloodstream. High blood triglyceride levels are a serious heart disease risk factor.
Fructose is broken down in the liver just like alcohol, and produces many of the same side effects of chronic alcohol use, including nonalcoholic fatty liver disease and abdominal fat. Fructose consumption over time also leads to insulin resistance and elevated insulin, which promote weight gain and are underlying factors of type 2 diabetes, metabolic syndrome, heart disease, and many cancers. The metabolism of fructose also leads to uric acid buildup, which causes gout and increases blood pressure. Plus, cancer cells thrive on fructose.
To put it simply, fructose, the sweet component in sugar and other sweeteners, is the primary cause of chronic metabolic disease that kills us slowly, according to sugar expert Robert H. Lustig, MD.
Eating a Low-Fructose Diet
The lesson to take from all this is pretty simple: To stop the dangerous health effects of fructose overload, you have to dampen your sweet tooth and avoid fructose in your diet. Here are some tips:
- Emphasize nonstarchy vegetables; fructose-free, unprocessed meats, fish, and eggs; and good fats, such as avocados, nuts, and olive oil, in your diet.
- Get to know your fruits. All fresh fruits contain fructose, but some contain much more than others. High-fructose fruits include mangoes, grapes, pears, and apples. Limit them in your diet. Low-fructose fruits include strawberries, raspberries, and blackberries; grapefruit; clementines; lemons; limes; and pineapple. While many people are fine with 1-2 daily servings of these lower-fructose fruits, some do best by avoiding fruit altogether.
- Stay away from dried fruits including raisins, figs, dried apricots, dates, and prunes; fruit juices; and fruit smoothies. They seem healthy, but they're concentrated sources of fructose.
- Also avoid sweetened drinks and concentrated sweeteners, including natural sweeteners. Many, such as honey, agave nectar, and fruit juice, are loaded with fructose. Train your taste buds to like foods that aren't sweetened or that use sweet spices such as cinnamon.
- Don't be tempted to use artificial sweeteners. Numerous studies show that they increase weight gain and worsen insulin sensitivity to a greater degree than sugar. Plus, they can be harmful in other ways. Many, for example, are toxic to the nervous system.
- If you feel you must occasionally use a sweetener, experiment with stevia and monk fruit (also known as Lo Han Guo). But if you have insulin issues, high blood pressure, high cholesterol, or diabetes-or if you're a sugar addict or are overweight-it's best to avoid all sweeteners because even these alternatives sometimes can induce cravings.
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What Is Fructose Malabsorption?
Do you experience diarrhea, gas, bloating, abdominal pain, or other digestive symptoms after eating fruit or honey- or agave-sweetened foods ? If you do, you could have fructose malabsorption.
This condition involves an impairment of absorption of fructose in the small intestine, allowing excess fructose to pass into the large intestine, where fermentation causes intestinal distress. It isn't the same thing as small intestine bacterial overgrowth (SIBO) or FODMAPS intolerance (intolerance to sugars in addition to fructose), both of which can cause similar symptoms.
If you suspect that you have difficulty absorbing fructose, avoid foods and drinks made with sweeteners, as well as dried fruit, fruit juices, fruit smoothies, and fruit sauces. If your symptoms improve, try avoiding fruit altogether or choose low-fructose fruit, such as berries and citrus fruits, until you find a quantity of fructose that your gut can handle.