Nausea after eating may be related to a defense against food poisoning, drug side effects, disease or exercise. It is a subjective unpleasant wave-like feeling, which may culminate in vomiting. There are several reasons that nausea my occur. For instance, food intake exposes people to possible viral and bacterial infection, allergies and food intolerance. Spoiled foods smell rancid or sour. Spoiled foods may also taste bitter, but smell and taste do not always detect spoiled or poor quality food. Nausea, emesis and diarrhea help rid the gastrointestinal tract of ingested toxins, and nausea plays a role in a conditioned response to avoid eating offensive substances. Vomiting empties a noxious chemical from the gut.
The Centers for Disease Control and Prevention (CDC) estimates that 76 million food related illness cases occur in the United States every year from foods contaminated with E. coli, salmonella, hepatitis A, Campylobacter, Shigella, Norovirus and Listeria. On an annual basis, approximately 325,000 people are hospitalized with a diagnosis of food poisoning, and 5,000 die. Leafy greens, eggs and tuna are the riskiest foods regulated by the United States Food and Drug Administration (FDA).
High and low intensity exercise immediately after eating and before eating causes nausea. Nausea is greater during exercise when hungry. There is no difference in nausea experienced by men or by women while exercising. Nausea after eating was greater during high intensity exercise than during low intensity exercise.
Pregnancy-induced nausea and vomiting after eating in the first trimester of rapid fetal growth is due to the development of the fetal central nervous system. The developing fetal central nervous system is highly susceptible to toxins. Pregnant women are picky eaters during the first trimester avoiding meat and fish products, which are more likely to contain pathogens that might harm the fetus. Nausea and vomiting after eating in the first trimester is a normal occurrence during pregnancy.
Drug Side Effects
Cyclic vomiting during chemotherapy or as a side effect to medication is mysterious because it is unknown what determines the temporal patterns. Chemotherapy or drugs possibly signals neural systems that modulate the nausea response. Anti-inflammatory drugs ease pain but may irritate the lining of the stomach, which can be relieved with antacids. Antibiotics and other drugs cause nausea when taken on an empty stomach.
The autonomic nervous system with outputs of sweating, salivation, gastric function, and often vasoconstriction is intimately connected to the neural pathways for nausea and vomiting. A common neural pathway for nausea has not been located. Research at the National Institute of Health indicates that brain stem systems for respiration, cardiovascular control and swallowing are involved in nausea and vomiting. Additionally, the respiratory network and sensory pathways for nausea and vomiting are involved in gut-brain communication, but neural circuitry that generates nausea is still unknown.