High-sugar diet increases men’s blood pressure; gout drug protective
“This is the first evidence of a role of fructose in increasing blood pressure and a role in reducing uric acid to protect against increased blood pressure in people,” said Richard Johnson, MD, co-author of study and professor and director of the Division of Renal Diseases and Hypertension, University of Colorado, Denver medical campus in Aurora, Colorado
In the study, excessive consumption of fructose, seemed to increase new onset metabolic syndrome, a set of risk factors associated with the development of cardiovascular disease and type 2 diabetes. Moreover, the drug appeared to halt the drop – most likely by reducing uric acid, which affects blood pressure.
Fructose, one of several dietary sugars, for about half of all the molecules of sugar table sugar and corn syrup, high fructose, a sweetener commonly used in packaged products, because it is relatively cheap and has a long shelf life. Glucose is the other half. The sugar fructose is usually only known to increase uric acid levels.
Patients with high blood pressure, diabetes and kidney disease often have elevated levels of uric acid and gout. But all the ways that these conditions could contribute to the development or worsening of others is not completely understood, “Johnson said.
Johnson and co-author Santos Perez-Pozo, MD, a nephrologist Mathieu Orfila Hospital in Minorca, Spain, who led the study, evaluated 74 men adults, average age 51 years, consuming a diet which included 200 grams (g) of fructose per day in addition to their regular diet. The amount is far superior to ingesting U.S. estimated daily 50 g 70 g fructose consumed by the majority of U.S. adults. Half the men were randomly assigned to get the gout drug allopurinol and the other half acted as controls.
After only two weeks on the diet, high-fructose plus placebo group experienced significant increases in mean arterial pressure of about 6 millimeters of mercury (mm Hg) in systolic blood pressure (the pressure when the heart beats) and about 3 mm Hg increase in diastolic blood pressure (the pressure between beats). They were measured with a strap on the monitors recording blood pressure periodically throughout the day.
In contrast, men in the high-fructose diet, allopurinol also significantly lower uric acid levels and virtually no increase in systolic blood pressure (only 1 mm Hg). The blood pressure of most of the men returned to normal within two months after the conclusion of the study, when participants returned to their normal diet, “Johnson said.
The study also found changes in the incidence of metabolic syndrome. The United States and the international community to define the syndrome slightly differently, so the researchers used two criteria in the study. In general, metabolic syndrome is defined as having three or more of these five risk factors:
Increased waist circumference;
High levels of triglycerides;
Low levels of high density lipoprotein (HDL), a component of total cholesterol thought to have a protective effect;
High blood pressure, and
High fasting blood sugar.
After only two weeks, the incidence of metabolic syndrome than doubled in men who consumed a diet rich in fructose heavy and took the placebo pill. The incidence was 19 percent at baseline to 44 percent by the end of the study, according to the U.S., the National Cholesterol Education Program ATP III (NCEP-ATP III) definition, and 25 percent to 58 percent under the International Diabetes Federation (IDF) definition.
Among males consuming fructose in addition to allopurinol, virtually no change in the rate of metabolic syndrome occurred – perhaps because the drug drop prevents the increase in blood pressure associated with increased fructose consumption.
The study should be viewed as a pilot and more research is needed before doctors believe that reducing uric acid in the clinic, said Johnson, noting that allopurinol can have rare but serious side.
Men in both groups had an increase in fasting triglycerides and an indication of insulin resistance by a method called homeostatic model assessment (HOMA), whereas in the fructose diet increased. The HOMA method was used to quantify insulin resistance and beta cell function. Allopurinol therapy appeared to lower the low density cholesterol (LDL), a component of total blood cholesterol associated with the development of cardiovascular disease, compared with placebo, the researchers reported.
“These results suggest that fructose may be a cause of metabolic syndrome,” Johnson said. “They also suggest that overconsumption of fructose may play a role in the worldwide epidemic of obesity and diabetes.”
Fruit, just 4 and 10 g of fructose per serving, it also contains many beneficial substances including antioxidants, vitamin C, potassium and fiber that is believed to counteract the effects of fructose alone. The main risk to the excessive consumption of fructose in the Western diet comes from sugary drinks and foods high in sugar or syrup, high fructose corn, he said.
“When you give fructose to animals, that absolutely all the characteristics of developing the metabolic syndrome: abdominal fat is received, high triglycerides, low HDL, blood pressure and put up resistance to insulin,” said Johnson. “But you have to give large amounts of fructose to rats to increase uric acid levels, because rats and other animals have an enzyme that breaks down uric acid. Humans lack this enzyme. It turns out that people human get gout, but other animals.
If the enzyme is inhibited in rats that breaks down uric acid, it only takes a small amount of fructose as a result of increased uric acid and metabolic syndrome symptoms appear in animals, he said.
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