If you have a heart condition or otherwise need to monitor your heart rate, you may notice changes during and after a meal. Like the many physiological changes that accompany swallowing and digestion, an increase in your pulse is usually a natural side-effect of eating. Due to the different effects that certain ingredients or types of foods may have on your body, however, an increase in your pulse after eating may be a sign of an allergy or other medical condition.
Eating, swallowing and digestion all affect your nervous system. While the sympathetic branch of your nervous system is active while eating and swallowing, your parasympathetic nervous system takes over during digestion. As the active processes of eating and swallowing trigger the full range of sympathetic nervous effects, your pulse may increase during and shortly after a meal. For your digestive system to do its work, however, your heart rate decreases as your parasympathetic nervous system takes over.
While eating and digesting trigger the release of hormones that can increase your pulse, such effects are limited when you eat a meal that is small or average in size. Larger meals, however, may cause a larger release of such hormones, significantly increasing your heart rate long after a meal despite the inhibition of your sympathetic nervous system. In addition, large meals may contain high amounts of fats, which can increase heart rate by preventing the linings of your arteries from functioning properly. Big meals also cause a large influx of sugars that boost insulin levels, thus increasing your pulse by preventing the relaxation of your heart's arteries that typically occurs after a meal.
Your pulse may increase after consuming caffeine-containing foods, such as coffee, tea, energy drinks, cocoa, chocolate, soft drinks and some candies. As some of these foods may be used as ingredients in other dishes, it is important to inquire about ingredients if you are sensitive to caffeine. Capsaicin, the compound that makes peppers spicy, also causes temporary increases in heart rate after a meal, with your pulse increasing in relation to a dish's spiciness.
A sharp increase in your pulse after a meal may be due to a severe allergic reaction known as anaphylaxis. This typically occurs within minutes of eating an allergen, with the spike in heart rate much more severe than that arising from normal bodily processes. While anaphylaxis may be due to a common food allergy, the Asthma and Allergy Foundation of America states that some lesser-known food additives may also cause allergic reactions. These include sulfites, aspartame, MSG, benzoates, the food colorant tartrazine and a range of preservatives, including nitrates, nitrites, parabens and BHT. While your pulse normally increases slightly after eating, you should seek immediate medical attention if you experience the sharp increase in heart rate that accompanies anaphylaxis.