The Link Between Sugar and Heart Disease

Is sugar even worse than saturated or trans fat or sodium, as some nutrition experts and news reports claim? That's difficult to say, but sugar is definitely a major concern, primarily because we're consuming so much more of it than we used to—mainly in the form of added sugar, which is overwhelmingly sucrose (white table sugar) or high-fructose corn syrup, which are liberally added to as much as three-quarters of all packaged foods and beverages in the U.S.—not only "sweets" like candies and cookies, but also staples like breakfast cereal, pasta sauce, ketchup, baked beans, sweetened yogurt, bread, and soups.

Large intakes of added sugar have adverse effects in the body via multiple pathways—notably by increasing inflammation, oxidative stress, and triglycerides, by impairing insulin regulation, and by raising blood pressure.

A sprinkling of recent research

Researchers have found that sugar impacts heart health in several key areas:

• Cardiovascular disease. In an important study in JAMA Internal Medicine, researchers analyzed national data from the past 20 years and found that the 10 percent of people who consumed the most added sugar (25 percent or more of daily calories) were almost three times more likely to die from cardiovascular disease than those consuming the least (less than 10 percent of daily calories), while those with intermediate sugar consumption had a one-third higher risk, on average. Elevated risk was seen regardless of weight, physical activity level, age, sex, race/ethnicity, overall diet quality, and many other factors.
• Blood cholesterol and triglycerides. In a clinical trial in the American Journal of Clinical Nutrition, researchers from UC Davis found that sugary beverages (containing high-fructose corn syrup) significantly raised LDL ("bad") cholesterol, triglycerides, and related risk factors in the blood of young adults in just two weeks. The more sugar they consumed from the beverages, the worse the effects on their risk factors. In the high-sugar group, LDL rose by 16 points and triglycerides by 37 points.
• Diabetes. A review in Mayo Clinic Proceedings confirmed that added sugar, especially fructose, is a "principal driver" of the epidemic of type 2 diabetes, as a result of its contribution to metabolic problems and ultimately insulin resistance. The authors noted that whole foods containing fructose, such as fruits, pose no problem for health and are linked to reduced diabetes risk.
• Obesity-related deaths. Sugary beverages are associated with more than 180,000 obesity-related deaths worldwide each year, according to a 2015 Harvard study. About 25,000 of those deaths occur in the U.S.

What to do

Some simple steps can help reduce sugar intake, such as limiting your consumption of sugar-laden yogurt (add your own fruit to plain yogurt), choosing breakfast cereals with little or no sugar, and avoiding sugary soft drinks and processed foods containing high-fructose corn syrup. Still, if you are generally careful and the rest of your diet is healthful, consuming small amounts of added sugar is unlikely to be harmful. You needn't worry about foods naturally containing sugar, such as fruit (though fruit juice should be limited) or milk.

How much sugar?

The current Dietary Guidelines for Americans, for the first time, recommend a limit on added sugar: no more than 10 percent of a person's daily calories should come from added sugar. That amounts to about 12 teaspoons (50 grams) for someone consuming 2,000 calories a day (1 teaspoon contains about 4 grams of sugar). The recommendations from the American Heart Association are more stringent: no more than 6 teaspoons of added sugar a day for most women and 9 teaspoons for most men.