Fructose, and especially high fructose corn syrup, has recently been painted as the villain in most every article dealing with obesity.
What is it about fructose that gives it such a bad reputation? Fructose gets its name from fruit sugar, and in its natural form is a simple carbohydrate found in many plants. And fruit, as we know, contains fiber and many vitamins that are part of a healthy balanced diet plan. But commercial fructose is usually derived from sugar cane, sugar beets and corn, and is devoid of that other nutritional value.
In the 40 years since high fructose corn syrup was introduced into our diets in the U.S., the rates of obesity in this country have soared, according to the Centers for Disease Control and Prevention. To gain some perspective, in 1970 about 15 percent of the U.S. population was considered obese. Today, roughly 33 percent of American adults are considered obese.
But is fructose such a bad sugar? Let’s break it down.
Fructose is what we call a simple sugar, or a monosaccharide. It is considerably sweeter than sucrose or table sugar. It is also relatively inexpensive, which has made it an attractive method to sweeten up processed foods from a manufacturing perspective. Diets high in high fructose corn syrup, though, not only contribute to obesity, but also can cause other health issues such as high triglycerides, a type of fat in your blood.
To better understand why fructose creates such havoc in our bodies, we need to look at how it gets metabolized and stored. Sucrose, or table sugar, is made up of 50 percent fructose and 50 percent glucose. It is not good to consume sucrose in excess, but it is metabolized differently in our bodies than fructose alone, causing possibly less “harm” than fructose consumption. When glucose enters the bloodstream, it is metabolized and stored with the help of insulin. Fructose, when consumed by itself, is processed solely by the liver. The liver can get quickly overwhelmed by an abundance of fructose, sending it off to become the dangerous triglyceride. When high fructose corn syrup is manufactured, the fructose is free and un-bound, allowing for complete absorption by the body.
Although the precise pathway for fructose metabolism in the liver is being extensively studied, we do know that it is processed differently than other sugars. Fructose appears to create an almost “confused” metabolic situation in the liver. As fructose enters the liver, the liver reverts to both a fasting and fed state, almost as if it’s not sure how to handle it. This metabolic reaction promotes excess triglyceride and LDL production by the body and also creates an environment for insulin resistance.
There have been several published studies that have helped us to better understand the impact high fructose corn syrup has on the body. One such study, done at Princeton University, showed that rats became obese when they drank water laced with high fructose corn syrup, but did not become obese consuming table sugar, even when their overall caloric intake was the same.
We know, of course, that patients with diabetes need to limit their overall sugar intake. But this sort of research suggests high fructose corn syrup should be a particular concern for people with diabetes. So, given this knowledge, where do we go from here?
Fructose consumption does not by any means have to be kept at zero. Fruits and fruit juices are part of a healthy diet plan. Many experts give a daily fructose recommendation of around 25 grams per day. But today’s average fructose consumption is more than 70 grams daily!
I don’t advocate a lot of fruit juices for my patients, because even though it may not contain high fructose corn syrup, it is still high in fructose. I also feel that eating the actual fruit is a better alternative due to the fiber content of the fruit itself, and in addition, the fruit is simply more filling. If you love fruit juice and still want to incorporate it into your diet plan, some juice is fine. I also recognize that some people are restricted as to the amount of fiber they can consume if conditions like diverticulitis exist. I generally dilute my fruit juice with extra water.
Fructose has also been implicated in a bowel condition labeled fructose malabsorption. Remember that we said that fructose, especially high fructose corn syrup, can get quickly absorbed. Fructose empties more rapidly from the stomach compared to other sugars. If too much fructose gets ingested and overwhelms the digestive tract, unabsorbed fructose combines with water and is rapidly propelled into the colon. This can cause bloating, gas and abdominal discomfort.
This is meant to let you be an informed consumer and to choose your foods wisely. Fruits are healthy and should not be restricted from an average diet. Remember, all things in moderation. Free fructose makes up about 35 percent by weight of honey, apples, pears, and cherries. High fructose corn syrup is by far the most dangerous culprit here. Read your food labels! Fructose is often found in barbecue sauce, soft drinks, dried fruits, breads, crackers, noodles and pastas. If you have any questions, please always defer to your own health care team, as everyone’s dietary concerns are different.
Does high fructose corn syrup worry you? Do you monitor how much you consume? Share your thoughts in the comment section below and check out this related discussion thread.