the stomach regulates the release of food into the bowel. When the gastric bypass patient eats a sugary food, the sugar passes rapidly into the intestine, where it gives rise to a physiological reaction called dumping syndrome. The body will flood the intestines with gastric content in an attempt to dilute the sugars. An affected person may feel their heart beating rapidly and forcefully, break into a cold sweat, get a feeling of butterflies in the stomach, and may have an anxiety attack. The person usually has to lie down and could be very uncomfortable for 30–45 minutes. Diarrhea may then follow. Nutritional deficiencies Nutritional deficiencies are common after gastric bypass surgery, and are often not recognized. They include: Secondary hyperparathyroidism due to inadequate absorption of calcium may occur for GBP patients. Calcium is primarily absorbed in the duodenum, which is bypassed by the surgery. Most patients can achieve adequate calcium absorption by supplementation with vitamin D and calcium citrate (carbonate may not be absorbed—it requires an acidic stomach, which is bypassed). Iron frequently is seriously deficient, particularly in menstruating females, and must be supplemented. Again, it is normally absorbed in the duodenum. Ferrous sulfate can cause considerable GI distress in normal doses; alternatives include ferrous fumarate, or a chelated form of iron. Occasionally, a female patient develops severe anemia, even with supplements, and must be treated with parenteral iron. The signs of iron deficiency include: brittle nails, an inflamed tongue, constipation, depression, headaches, fatigue, and mouth lesions. Signs and symptoms of zinc deficiency may also occur such as: acne, eczema, white spots on the nails, hair loss, depression, amnesia, and lethargy. Deficiency of thiamine (also known as vitamin B1) brings the risk of permanent neurological damage (i.e. Wernicke's encephalopathy or polyneuropathy). Signs of thiamin deficiency are heart failure, memory loss, numbness of the hands, constipation, and loss of appetite. Vitamin B12 requires intrinsic factor from the gastric mucosa to be absorbed. In patients with a small gastric pouch, it may not be absorbed, even if supplemented orally, and deficiencies can result in pernicious anemia and neuropathies. Vitamin B12 deficiency is quite common after gastric bypass surgery with reported rates of 30% in some clinical trials. Sublingual B12 (cyanocobalamin) appears to be adequately absorbed. In cases where sublingual B12 does not provide sufficient amounts, injections may be needed. Protein malnutrition is a real risk. Some patients experience troublesome vomiting after