Vomiting is an unpleasant experience that most of us would prefer to avoid altogether. But it is a common mechanism by which the body rids the upper digestive tract of any irritants. The problem arises when food is vomited repeatedly after a meal. This compromises the body’s nutritional status affects one’s health beyond the primary cause of the vomiting and can even lead to death when serious complications from vomiting sets in. Some of these complications can arise within just a few days of vomiting. Understanding what is causing vomiting after a meal and treating it quickly can therefore be a matter of life or death at times.
Importance of Vomiting
Most people would not think of vomiting as an important mechanism, but it is crucial in protecting the body. If a substance that is toxic enters the digestive tract through the mouth, then the body can immediately expel it through vomiting before it absorbs into the bloodstream. Sometimes the mechanism is not as efficient and a toxin may still be able to enter the circulation before it can be expelled. Vomiting is controlled by the vomit center in the brain. It sends strong impulses through nerves to the digestive tract.
As a result the muscles in the walls of the upper parts of the small intestine, stomach and esophagus contract in a coordinated way to push contents upwards into and out of the mouth. This is known as antiperistalsis since it is working in the opposite direction to the normal movement of food in the digestive tract. Vomiting is usually a violent process to forcefully expel the contents in the digestive tract. When very strong it can lead to projectile vomiting. Regurgitation is a similar process but does not start as low down as the small intestine. It should not be confused with vomiting.
Nausea vs Vomiting
Nausea and vomiting are two different symptoms. Nausea is an unpleasant feeling that you want to vomit. It usually precedes vomiting, and may continue even after having vomited. Most people find that nausea is partly or completely relieved with vomiting. However, nausea may not always lead to vomiting. Similarly vomiting may not always be preceded with a nauseous feeling. Both nausea and vomiting are closely related, especially from its origins in the brain.
The vomiting center in the brain can be directly stimulated or indirectly through the chemoreceptor trigger zone (CTZ). This zone is sensitive to substances in the bloodstream such as drugs and hormones. Therefore nausea and vomiting can be triggered even without eating or without any irritation in the digestive tract. Sometimes it can be a symptom of underlying diseases of other organs like brain injury, kidney disease and liver disease.
Causes of Vomiting After Eating
There are four reasons why eating food may trigger vomiting:
- Food and the digestive processes triggered by eating may irritate the inflamed digestive tract.
- The chemoreceptor trigger zone (CTZ) and/or vomit centers may be stimulated by substances in the blood.
- There is a blockage in the digestive tract impeding the movement of food from the mouth to the rectum.
- Certain foods may aggravate underlying disorders which cause nausea and vomiting.
Gastroenteritis and Food Poisoning
Gastroenteritis and food poisoning are the most common causes of acute vomiting. These are usually due to infections, particularly with viruses or bacteria. Gastroenteritis is usually viral in nature and can be contracted easily from one person to another. It often occurs as outbreaks. Food poisoning is the same type of illness which is transmitted by consuming contaminated food or water. The virus, bacteria or other parasites cause inflammation of the gastrointestinal tract (gut) either directly or by the action of toxins.
Vomiting is not always present in gastroenteritis. Sometimes there is just abdominal pain, nausea and diarrhea. When vomiting does occur, it usually precedes the onset of diarrhea. Vomiting is intense for the first 1 or 2 days, as is the diarrhea. Then it subsides while the diarrhea may continue for a short period of time thereafter. The onset of the nausea and vomiting is usually sudden and there may also be a fever in some of these infections. Dehydration is the main risk.
A number of hormonal disturbances can disturb the CTZ and vomit centers in the brain. It can just cause nausea on its own but sometimes eating food may intensify the nausea and then lead to vomiting. This is mainly seen with an elevated level of certain female hormones as is seen in pregnancy (morning sickness), when using emergency contraceptive pills (the ‘morning after’ pill) and sometimes with severe premenstrual syndrome (PMS). Severe vomiting in pregnancy is known as hyperemesis gravidarum and needs medical treatment.
Migraine, severe headaches and other causes of intense pain like kidney stone pain can trigger nausea and vomiting. These painful conditions are often treated with strong painkillers such as opioid analgesics. It further compounds the situation as these drugs may cause nausea as a side effect. Long term abuse of painkillers may lead to kidney problems which in turn can present with nausea and vomiting. Nervousness and anxiety about situation that is deemed painful can also cause nausea or vomiting even prior to the actual event occurring.
Food Intolerance and Allergies
Nausea and sometimes vomiting after eating a meal are common symptoms in food intolerance and food allergies. The problem in food intolerance is that the body has a deficiency of certain digestive enzymes which makes it difficult to breakdown specific nutrients. Lactose intolerance is one of the most common of the food intolerances. In food allergies, the presence of certain food in the gut triggers an exacerbated immune response (allergic reaction). Sometimes unpalatable foods, overeating or certain foods like very oily meals may trigger vomiting despite there being no problem with the digestive tract.
Obstruction in the Digestive Tract
A blockage in the gut can also cause nausea and vomiting after eating. The movement of food through the gastroinestinal tract is impeded by the obstruction despite the contractions of the the gut. Obstructions may arise with a narrowing of the gut at a specific point (stricture), tumors and other growths, twisting or telescoping of the bowels and when portions of the bowel get trapped in a hernia. There may also be bowel movement symptoms like constipation, sometimes diarrhea and reduced gas production (flatulence).
Drugs, Alcohol and Toxins
A number of pharmaceutical and illicit drugs, poisons and alcohol can cause vomiting after eating. These substances may trigger the CTZ and vomit centers and food exacerbates the situation thereby leading to vomiting. Furthermore these substances can irritate the digestive tract. The stomach acid and digestive enzymes that are secreted with eating food then further irritates the digestive tract and can lead to nausea and vomiting. Chemotherapeutic drugs used in the treatment of cancer, certain antibiotics and non-steroidal anti-inflammatory drugs are among the problem medication that may lead to nausea and vomiting.
Psychological shock, anxiety and eating disorders may all be causes of nausea and vomiting. Eating when in a strained psychological state may trigger or exacerbate nausea and even lead to vomiting. Eating disorders can be complex. In anorexia nervosa a person may refuse to eat and in bulimia a person may purge after eating. However, if forced to eat it may be traumatic for the person. In these instances people with eating disorders may vomit even without manually purging.
A number of non-GI other conditions can lead to vomiting after eating through a variety of mechanisms. This includes: