Sugar may, under some circumstances for some people, increase heart rate. An internet search reveals mixed assertions as to the immediate effects of sugar on heart rate. But research — such as that of D.O. Kennedy and A.B. Scholey presented in a March 2000 study published in Psychopharmocology — and an understanding of the physiology involved in the metabolism of sugar suggest sugar can affect heart rate in the short, medium and long term via varied mechanisms.
Fuel for Thought
Your body requires fuel in order to operate. The food you eat is your fuel. It's digested and converted into glucose, a form of blood sugar, which is then used by cells for the energy required for everything your body does, from thinking to breathing to running.
Some foods, referred to as high glycemic index (GI) foods, are converted into glucose more quickly than other foods. Sugar is a high GI food. When you consume simple processed sugar, it can be converted into blood glucose within minutes. This short time required to convert sugar into blood glucose is one reason people turn to sweets for a quick pick-me-up. Complex carbohydrates such as vegetables and fruit, or proteins including nuts, fish and meat, take much longer to be converted into cellular fuel.
Immediate Effects of Sugar Metabolism
When blood glucose is high, the pancreas releases insulin, which then helps to transport glucose into muscle or liver cells. There, it's used for energy. If there's more glucose present than needed, insulin helps the glucose to be stored in adipose tissues as fat for potential future energy needs.
One immediate effect of the breakdown and conversion of glucose into cellular energy is an increased metabolism, which can manifest itself in the form of increased heart rate, high blood pressure or some other form of arousal such as heightened mental alertness.
The Psychopharmocology study found that study participants had greater increases in heart rate and performed better when given mental tasks following administration of glucose than control subjects who did the same tasks without glucose. People have individualized responses to heightened metabolism, so sugar may not always cause a noticeable change in heart rate for all individuals. In the Psychopharmcology study, subjects who had lower baseline heart rates had the greatest performance enhancements following glucose administration.
While this study seems to indicate that sugar may have an effect on heart rate, this was a small study (14 participants) and additional studies have not been conducted to further evaluate sugar intake on heart rate.
The Sugar Lows
Once insulin has eliminated glucose from the blood, there's a condition of lowered blood glucose. People with diabetes or with other metabolic conditions such as reactive hypoglycemia or postprandial reactive hyperinsulinemia can experience a sudden crash in blood sugar because their pancreas overreacts to the presence of blood glucose and releases too much insulin. The pancreatic reaction triggers a cavalcade of hormone responses, including the release of stress hormones such as epinephrine by the pituitary gland.
These stress hormones stimulate the sympathetic nervous system and cause physiological arousal that can include — among other response — heightened heart rate, increased blood pressure, hyperactivity, anxiety and irritability.
Long-term Health Consequences
Sugar accounts for about 14 percent of Americans' caloric intake, according to the Centers for Disease Control and Prevention. The weighty truth is that the obsession with sugar, along with a growing aversion to exercise, has led to an obesity epidemic. Remember, insulin converts blood glucose it can't use for immediate energy into fat. The extra girth you carry burdens your heart and contributes to escalating cardiac disease — including hypertension, high blood pressure and elevated heart rate.
Epidemiological evidence indicates that sugar may affect heart rate and health by increasing your risk of developing type 2 diabetes and cardiovascular disease, according to an April 2014 study published in JAMA Internal Medicine.
Keeping Your Heart Healthy
You can benefit from the heightened mental and physical energy that food provides without stressing your metabolic system or posing risks to your cardiovascular system. Minimize consumption of simple sugars and starches, and instead consume complex carbohydrates such as fruits, vegetables and whole-grain foods. These foods take longer to release sugars into your blood and provide your brain and body with a steady source of glucose.
- Springer Link: "Glucose Administration, Heart Rate and Cognitive Performance: Effects of Increasing Mental Effort"
- The University of Sydney: "About Glycemic Index"
- Centers for Disease Control and Prevention: "Know Your Limit for Added Sugars"
- JAMA Internal Medicine: "Added Sugar Intake and Cardiovascular Diseases Mortality Among US Adults"