Sugar and Your Heart: the Not-So-Sweet Truth

The notion that sugar is unhealthy is neither new nor surprising, but emerging evidence shows just how and why too much of it can disrupt metabolism and fuel maladies ranging from heart disease to cancer.

When it comes to heart disease, high cholesterol and high blood pressure have claimed much of the public attention, but sugar is, without doubt, a central character in fueling cardiovascular damage. In fact, two out of three heart attack patients in the United States have either diabetes or prediabetes.

Sugar can precipitate heart damage both directly and indirectly. Sugar overconsumption can lead to weight gain and obesity — both of which are known causes of high blood pressure and metabolic syndrome — common culprits in cardiovascular disease. In addition, excess sugar gets converted into fat and elevates levels of artery-clogging cholesterol, the leading cause of heart attacks and strokes.

But perhaps the most damning piece of evidence against sugar as an offender in heart health comes from our observations in people with diabetes, a condition in which the body cannot metabolize sugar properly, causing it to build up to dangerous levels. Excess sugar can directly disrupt the work of the heart muscle, leading to a condition known as diabetic cardiomyopathy. Marked by the progressive weakening of the heart muscle and its eventual loss of pumping ability, diabetic cardiomyopathy affects 60 percent of the 380 million people with diabetes worldwide.

Anatomy of Sugar

Sugar comes in two main forms: glucose and fructose. Glucose is the main source of sugar found in pasta, grains, legumes, dairy and vegetables. Fructose is the main source of sugar in fruits and honey. Both fructose and glucose can be added in high concentrations to processed food. Table sugar, known as sucrose, consists of both glucose and fructose. The much-maligned high-fructose corn syrup found in many processed foods, soda and juices is also made up of fructose and glucose, but the fructose content is slightly higher. High-fructose corn syrup packs a caloric punch, but its absence doesn’t mean a food is necessarily low in sugar or healthier. There are plenty of unhealthy foods loaded with sugar that don’t contain high-fructose corn syrup.

Here’s why: Even though sugar calories carry the same charge as calories from other energy sources, such as proteins or fats, emerging evidence shows that sugar and its different forms are metabolized differently by the body and thus may have different downstream effects. Glucose is metabolized as fuel by every cell in the body. Fructose — the dominant ingredient in sugary drinks and candy — is processed primarily by the liver. Research indicates that when the liver is overwhelmed by too much sugar, the excess gets converted into fat. Too much sugar can disrupt the delicate communication between the liver, which processes sugar, and the pancreas, which produces the hormone insulin responsible for removing excess sugar from the blood. That disruption can lead to a condition known as insulin resistance, a precursor to full-blown diabetes, in which the body becomes desensitized to insulin and sugar builds up dangerously in the blood.

The Dose Makes the Poison

To be sure, sugar is not inherently bad. Natural sugars found in fruit, grains and pasta provide a great source of quick energy and should be part of a healthy diet. But regular overconsumption can render sugar toxic. The ancient adage — and a basic principle of toxicology — that “the dose makes the poison” rings particularly true when it comes to sugar.

The Western diet has been quietly infiltrated by sugar. From the fast foods and processed meals high in added sugars to the sugar-laden sodas, sugar is no longer only found in traditional sweet foods. It lurks everywhere, from pasta sauce and ketchup to yogurt and cereal.

To minimize the risk of heart disease and diabetes, the World Health Organization recommends limiting daily sugar intake to 25 grams, or about 5 teaspoons. Yet nearly half of Americans consume about 10 times as much, about half a pound of sugar (225 grams) per day.

The Roots of Sugar Addiction

Our love affair with sugar begins early in life. From candy doled out as reward, to Halloween treats, birthday cakes and Girl Scout cookies, sugar is a powerful presence in American childhood. Even though the tide is turning, sugary sodas remain the default beverage on kids’ menus in far too many restaurants.

The damage of too much sugar consumption in childhood goes well beyond maddening sugar highs and pudgy waistlines.

Over the last 30 years, obesity rates have doubled among children and quadrupled in teens. Although childhood obesity is a multifactorial problem, stemming from lack of exercise, sedentary lifestyles and increased overall calorie consumption, there is no doubt that too much sugar is a key player.

The so-called adult diabetes, or Type 2 diabetes, virtually unseen in children 30 years ago, is now occurring increasingly often in kids. The rates of childhood hypertension have also risen, largely as a result of growing obesity rates and sedentary lifestyles. As a result, it is not uncommon for pediatricians to see overweight and obese teens with changes in the thickness of the heart muscle typically found in middle-aged adults with untreated hypertension and long-standing weight problems.

Even when these conditions do not develop overtly in childhood, we now have evidence that their roots run deep in the earliest years of life. Many of the metabolic and hormonal disruptions that fuel diseases in adult life begin quietly in infancy. The body’s metabolic tone should be set right early on, in the first years of life, putting children on a pathway to lifelong health.

Lowering Diabetes Risk to Improve Heart Health

Minimizing sugar, along with overall calories, is the first step to managing risk. However, regular exercise will give the benefits of healthy diet an added boost. Maintaining a healthy weight and engaging in physical activity cannot only prevent the onset of diabetes, but will also mitigate its effects if and once it develops.

Children with diabetes or prediabetes should aim for at least 60 minutes of physical activity a day. Adults with diabetes are encouraged get 150 minutes of exercise a week.

And keep in mind that an hour of exercise in the morning will not stave off the ill effects of sitting for hours on end for the rest of the day. Research suggests that people who spend hours with little movement are at higher risk for developing blood clots, diabetes and cardiovascular disease. Breaking up long stretches of sitting or immobility by moving around for a few minutes every hour or so will further reduce the risk of ” sitting disease.”

Annual blood pressure and cholesterol checkups are essential, and so are periodic screens for elevated blood sugar — a marker for diabetes — particularly among those deemed at high risk because of family history or being overweight. People of certain ethnicities are far more likely to develop diabetes. These include African-Americans and Asians. Women with history of gestational diabetes and those with polycystic ovary syndrome are also at elevated risk.

More from U.S. News

How to Cope With Gestational Diabetes

Got Diabetes? Why You Must Protect Your Feet

7 Reasons to Choose a Plant-Based Diet

Sugar and Your Heart: the Not-So-Sweet Truth originally appeared on

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