The dietitian and the patient need to understand the key gastric neuromuscular abnormalities in the gastroparetic stomach. Then patients with gastroparesis understand the reasons to eat smaller-volume meals of foods that their weak stomachs can mill and empty and thereby achieve nutritional goals and reduce postprandial nausea and noxious fullness, symptoms that can lead to vomiting episodes [12]. We help patients understand that they need to choose foods in a three-step fashion and the choice of steps depends upon the intensity of their nausea and fullness symptoms throughout the day [12]. For example, if a patient is having a difficult day with frequent vomiting, then he or she should choose only liquids, such as Gatorade™, bouillon, or ginger ale that day (see Table 11.1, Step 1). The patient is coached to consume at least 1–1.5 l of an electrolyte solution in small quantities (60–90 ml per hour) on such a day to prevent dehydration and to avoid a visit to the hospital for intravenous hydration. The patient understands gastric accommodation may be impaired and learns that by taking very small sips (60–90 ml or 2–3 oz) of electrolyte-containing liquids every hour that the nausea and vomiting symptoms and dehydration can be limited.

Citrus juices and highly sweetened beverages are to be avoided because they are acidic and may irritate gastritis or esophagitis if present and thereby worsen nausea. Carbonated beverages or sodas are avoided because release of carbon dioxide may increase gastric distension and result in bloating, fullness, or heartburn. Foods that lower LES pressure and thereby increase heartburn include peppermint, chocolate, fat, and caffeine. A chewable vitamin should be taken to maintain vitamin levels. Some patients may tolerate clear liquid caloric supplements such as Ensure Clear™, Boost Breeze™, or Enlive™ during Step 1. Weight should be monitored twice a week at home. If weight is trending downward, then nutritional supplements described in Step 2 below should be added. Overall, the goal of Step 1 is to consume enough electrolyte solutions to maintain hydration and avoid increasing postprandial nausea and vomiting.

In addition to soups, the patient may try smoothies with soy milk, Lactaid™ milk, or almond milk products and vegetables and fruits blenderized into very small particles. Liquid nutrient suspensions require gastric peristaltic contractions for proper emptying from the stomach, but they do not require the trituration that solid foods require before emptying. Thus, the liquid caloric meals can be tasty, require less gastric work to empty than solid foods, and hopefully elicit few postprandial symptoms. Patients are reminded that the supine position may contribute to delayed emptying since ingested nutrients pool in the fundus. Thus, patients are encouraged to remain sitting up after even small-volume meals for at least 1 h. Patients with gastroparesis may consider elevating the head of the bed onto 6–8 in. blocks to prevent regurgitation and gastroesophageal reflux when sleeping. Thus, the goal of Step 2 is to find liquid nutritional foods that are tasty, provide calories to maintain weight, and evoke minimal postprandial symptoms.

If patients tolerate the Step 2 phase and nausea and vomiting are controlled, then they can advance to Step 3. Step 3 emphasizes solid foods that are low in fat and fiber because these foods delay gastric emptying. In other words, the easy foods to empty are basically the starches since starches do not require extensive trituration. Thus, Step 3 includes foods such as rice, pasta, and potatoes. Mashed potatoes would be a choice example for patients to appreciate as a food that requires almost no milling and is easy for their weak stomach to mix and empty. Small portions (e.g., 3–4 oz) of broiled, baked, or grilled lean meats such as chicken, turkey, or fish may be tolerated if diced or chewed thoroughly. Other solid foods recommended in small portions include canned fruit in its own juice, applesauce, or cooked, fork-tender vegetables. Puddings and yogurts are also semisolid foods that require little milling and elicit less postprandial symptoms.

A consultation with a registered dietitian is highly recommended because he or she can calculate patients’ individual nutritional needs, tailor the patients’ diet according to their specific concerns, and ensure that the patients are meeting the individualized nutritional goals at follow-up visits. Based on consultation and follow-up visits, the patient can continue to introduce new foods and add or subtract foods to their list with help of the dietitian. The patient can revise or tailor their diet after he or she has tried various foods or liquids that were suggested. In our practice, there is a wide variation of food tolerances. The spectrum ranges from the patient who can eat every type of food as long as the portion is very small to the patient who can tolerate no foods whatsoever and survives only on enteral feeding. The dietitian must be creative in helping these patients select a nutritious set of foods that also elicits minimal postprandial symptoms.

Patients who follow low fat dietary guidelines may develop essential fatty acid deficiency. Unsaturated fats, which are liquid at room temperature, are considered healthier fats because they can improve blood cholesterol levels and can reduce inflammation [13, 14]. Unsaturated fats are predominantly found in plant foods such as vegetable oils, nuts, and seeds. It may be difficult for patients with gastroparesis to meet daily fat requirements, since 25–30 % of daily calories should be provided in the form of unsaturated fat. The two types of “good” unsaturated fats are listed below and some of these foods may be tolerated by the gastroparesis patient. Monounsaturated fats are found in high concentrations in (a) olive, peanut, and canola oils; (b) avocados; (c) nuts such as almonds, hazelnuts, and pecans; (d) seeds such as pumpkin and sesame seeds; and polyunsaturated fats are found in high concentrations in (a) sunflower, corn, soybean, and flaxseed oils; (b) walnuts; (c) flax seeds; (d) fish; and (e) canola oil (although canola oil is higher in monounsaturated fat, it is also a good source of polyunsaturated fat) [13, 14].

Patients with gastroparesis should avoid most nuts and seeds because they will be difficult to mill and empty; however, patients can try peanut butter or almond butter in small quantities and use small amounts of canola or olive oils when cooking. Baked or broiled fish contain fats, but these foods in small quantities are recommended [10]. Patients with gastroparesis can also increase fat in a liquid form in small volumes of supplements, shakes, or whole milk products sipped throughout the day. High calorie liquid supplements, such as Boost Plus^TM, Boost Very High Calorie^TM, Mighty Shakes^TM, and Ensure Plus^TM can be added from Step 2 if needed to meet daily caloric requirements.

The three-step diet for patients with nausea and vomiting is low in protein and fat and therefore it is not a “complete diet.” Almost 32 % of patients with gastroparesis have diets deficient in calories, vitamins, and minerals; and, unfortunately, only one-third of these patients were taking multivitamins on a daily basis [4]. Patients with idiopathic gastroparesis were more likely to have diets with deficiencies in vitamins B₆, vitamin K, and iron and less likely to have seen a dietitian compared with patients with diabetic gastroparesis. Baseline vitamin levels such as vitamin D, iron panel, zinc, vitamin B12, and folate should be obtained and vitamins or minerals that are deficient should be treated. Laboratory tests should be repeated 3–6 months later to assure repletion. A chewable multivitamin should be added to the daily diet regimen for all patients with gastroparesis. The chewable vitamin should say “complete” on the label. Some of the gummy vitamins lack certain vitamins and minerals. Chewable or gummy vitamins are liquids when they enter the stomach and elicit no gastric symptoms compared with the large standard adult vitamin tablets. Table 11.2 illustrates in more detail a list of foods that are recommended and those to avoid with the three-step gastroparesis diet and sample menus.