A wide range of macronutrients is compatible with adequate growth and development, maintenance of good health and longevity. The recommended intakes of the macronutrient are easily achievable other than when food is restricted such as during famines. It is recommended to limit the amount of fat and free sugar consumed to avoid excess weight gain. Even small amount of meat protein and a variety of plant protein source generally provides adequate intake of total protein and essential amino acids. Fat source should minimize saturated fatty acids and avoid trans fatty acids, while aiming to acquire PUFA and MUFA. Carbohydrate sources should be derived principally from vegetables, fruit and minimally processed whole grain cereals.
There is two ways that adverse reaction to food can be classified. Either immune mediated (food allergy) or non-immune mediated (food intolerance) the latter being the most common. Eight foods, milk, eggs, peanuts, tree nuts, soy, wheat, fish and shellfish account for 90% of all IgE-mediated food allergies. Celiac disease is a classic example of a non IgE-mediated adverse food reaction. Food intolerance (FI) is much more common that food allergy (FA). Examples of food intolerance include food poisoning, lactose intolerance, as well as toxic, pharmacological, and functional adverse reaction to foods. Quite often these reactions mimic reactions due to FA.
When to start total enteral nutrition (TEN) or total parenteral nutrition (TPN) is based on a patient’s nutritional state and disease severity. Nutritional support is usually started when a patient is unable to attain adequate oral feeding for longer than 10 days. TEN and TPN should supply approximately 25-30kcal/kg/day. TEN should be the method of choice for nutrition support as TPN is associated with metabolic complications including hyperglycemia. Small, frequent, low-fat, low-fiber meals are the first line of therapy with gastroparesis. Micronutrient deficiencies are frequently associated with patients suffering from inflammatory bowel disease and should be replaced accordingly. For patients with short bowel syndrome with a colonic remnant can benefit from a high-complex carbohydrate diet low in oxalate.
Iron deficiency results from decreased intake in the setting of increased loss due to menstruation, child-birth or gastrointestinal bleeding. It is commonly suspected when red blood cells are microcytic and hypochromic. Diets low in animal source foods are deficient in both iron and vitamin B12. Atrophic gastritis and other malabsorption syndroms are the major causes of vitamin B12 deficiency megaloblastic anemia. Folate deficiency megaloblastic anemia is often the result of alcoholism, drug therapy or malabsorption syndrome. Food folate fortification has improved population folate status and decreased neural tube defects in many countries.