Nausea is a distressful sensation that usually occurs in the upper gastrointestinal tract (stomach and/or small intestine) that may be accompanied by vomiting.
Nausea is not an illness per se, but a possible sign of overeating, food poisoning, parasites, inner ear disorders, excess alcohol consumption, or the flu. It can also be a sign of pregnancy, especially in the first trimester.
Nausea can also be due to a lack of digestive enzymes and/or a toxic colon. Toxins in the liver can also trigger nausea attacks, as can anxiety and emotional stress. All of these potential underlying causes must be screened for and addressed in cases of prolonged nausea.
Excessive intake of zinc in particular or too many vitamins and minerals at one time can cause nausea. To reduce the risk of this happening, take your supplements with your meals unless directed otherwise and limit your zinc intake to 30 mg per day.