Sugar intake in the United States has increased by >40 fold since the American Revolution. The health concerns that have been raised about the amounts of
sugar that are in the current diet, primarily as beverages, are the subject of this review. Just less than 50% of the added
sugars (
sugar and
high-fructose corn syrup) are found in soft drinks and fruit drinks. The intake of soft drinks has increased 5-fold between 1950 and 2000. Most meta-analyses have shown that the risk of
obesity, diabetes,
cardiovascular disease, and
metabolic syndrome are related to consumption of beverages sweetened with
sugar or
high-fructose corn syrup. Calorically sweetened beverage intake has also been related to the risk of
nonalcoholic fatty liver disease, and, in men,
gout. Calorically sweetened beverages contribute to
obesity through their caloric load, and the intake of beverages does not produce a corresponding reduction in the intake of other food, suggesting that beverage calories are "add-on" calories. The increase in plasma
triglyceride concentrations by sugar-sweetened beverages can be attributed to
fructose rather than
glucose in
sugar. Several randomized trials of
sugar-containing soft drinks versus low-calorie or calorie-free beverages show that either
sugar, 50% of which is
fructose, or
fructose alone increases
triglycerides,
body weight, visceral adipose tissue, muscle fat, and liver fat.
Fructose is metabolized primarily in the liver. When it is taken up by the liver,
ATP decreases rapidly as the
phosphate is transferred to
fructose in a form that makes it easy to convert to
lipid precursors.
Fructose intake enhances lipogenesis and the production of
uric acid. By worsening blood
lipids, contributing to
obesity, diabetes,
fatty liver, and
gout,
fructose in the amounts currently consumed is hazardous to the health of some people.