High fructose corn syrup: A recipe for hypertension

A diet high in fructose increases the risk of developing high blood pressure (hypertension), according to a paper being presented at the American Society of Nephrology's 42nd Annual Meeting and Scientific Exposition in San Diego, California. The findings suggest that cutting back on processed foods and beverages that contain high fructose corn syrup (HFCS) may help prevent hypertension.

Over the last 200 years, the rate of fructose intake has directly paralleled the increasing rate of obesity, which has increased sharply in the last 20 years since the introduction of HFCS. Today, Americans consume 30% more fructose than 20 years ago and up to four times more than 100 years ago, when obesity rates were less than 5%. While this increase mirrors the dramatic rise in the prevalence of hypertension, studies have been inconsistent in linking excess fructose in the diet to hypertension.

Diana Jalal, MD (University of Colorado Denver Health Sciences Center), and her colleagues studied the issue in a large representative population of US adults. They examined 4,528 adults 18 years of age or older with no prior history of hypertension. Fructose intake was calculated based on a dietary questionnaire, and foods such as fruit juices, soft drinks, bakery products, and candy were included. Dr. Jalal's team found that people who ate or drank more than 74 grams per day of fructose (2.5 sugary soft drinks per day) increased their risk of developing hypertension. Specifically, a diet of more than 74 grams per day of fructose led to a 28%, 36%, and 87% higher risk for blood pressure levels of 135/85, 140/90, and 160/100 mmHg, respectively. (A normal blood pressure reading is below 120/80 mmHg.)

"These results indicate that high fructose intake in the form of added sugars is significantly and independently associated with higher blood pressure levels in the US adult population with no previous history of hypertension," the authors concluded. Additional studies are needed to see if low fructose diets can normalize blood pressure and prevent the development of hypertension.

Study co-authors include Richard Johnson, MD, Gerard Smits, PhD, and Michel Chonchol, MD (University of Colorado Denver Health Sciences Center). Dr. Richard Johnson reports a conflict of interest as the author of "The Sugar Fix". The authors report no other financial disclosures.

MONDAY, Jan. 26 (HealthDay News) — Almost half of tested samples of commercial high-fructose corn syrup (HFCS) contained mercury, which was also found in nearly a third of 55 popular brand-name food and beverage products where HFCS is the first- or second-highest labeled ingredient, according to two new U.S. studies.

HFCS has replaced sugar as the sweetener in many beverages and foods such as breads, cereals, breakfast bars, lunch meats, yogurts, soups and condiments. On average, Americans consume about 12 teaspoons per day of HFCS, but teens and other high consumers can take in 80 percent more HFCS than average.

“Mercury is toxic in all its forms. Given how much high-fructose corn syrup is consumed by children, it could be a significant additional source of mercury never before considered. We are calling for immediate changes by industry and the [U.S. Food and Drug Administration] to help stop this avoidable mercury contamination of the food supply,” the Institute for Agriculture and Trade Policy’s Dr. David Wallinga, a co-author of both studies, said in a prepared statement.

In the first study, published in current issue of Environmental Health, researchers found detectable levels of mercury in nine of 20 samples of commercial HFCS.

ScienceDaily (Dec. 11, 2008) — A new University of Illinois study suggests that we may pay a price for ingesting too much fructose. According to lead author Manabu Nakamura, dietary fructose affects a wide range of genes in the liver that had not previously been identified.

Chances are you consume quite a bit of fructose. Most Americans do—in refined sugars such as sucrose or table sugar (which is half fructose) and in high-fructose corn syrup, used in products as diverse as soft drinks, protein bars, and fruit juice.

But many scientists believe that high dietary fructose contributes to the development of metabolic syndrome, a group of risk factors that predict heart disease and Type 2 diabetes.

"For this reason, it's important for scientists to understand exactly how consuming high amounts of fructose affects human health," said Nakamura, a U of I associate professor of food science and human nutrition.

Nakamura's lab is continuing to study the metabolism of fructose with an eye to making recommendations about its dietary use.

His study shows that the metabolism of fructose is more complex than the data had indicated. "Our gene-expression analysis showed that both insulin-responsive and insulin-repressive genes are induced during this process. Our bodies can do this, but it's complicated, and we may pay a price for it," he said.

According to the scientist, most carbohydrates are handled fairly simply by our bodies. They are converted quickly to glucose and used for energy or stored as fat. "When we are eating, blood sugar--and insulin production--goes up. When we sleep or fast, it goes down," he said.

The process is not so simple with fructose, he noted. "In order for fructose to be metabolized, the body has to create both fasted and fed conditions. The liver is really busy when you eat a lot of fructose."

Because, unlike glucose, fructose metabolism occurs mainly in the liver, Nakamura wanted to gain a complete picture of gene expression in the liver during fructose metabolism.

In Nakamura's study, 24 rats were fed either a 63 percent glucose or fructose diet four hours a day for two weeks; at the end of this period, half the animals fasted for 24 hours before the scientists performed a gene expression analysis; the other half were examined at the end of a four-hour feeding.

Fructose feeding not only induced a broader range of genes than had previously been identified, there were simultaneous increases in glycogen (stored glucose) and triglycerides in the liver.

"To our surprise, a key regulatory enzyme involved in the breakdown of glucose was about two times higher in the fructose-fed group than in the glucose-fed group," Nakamura said.

The study also suggests that a protein called carbohydrate response element binding protein is responsible for the fructose effect on certain genes that trigger the production of fat, he said.

"We're continuing to assess the risk of fructose insulin resistance and the consequent risk for development of diabetes," he said.

Co-authors of the study, published in a recent issue of Biochimica et Biophysica Acta, are Hyun-Young Koo, Matthew A. Wallig, Takayuki Y. Nara, and B. H. Simon Cho of the University of Illinois and Byung Hong Chung of the University of Alabama at Birmingham.

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