Principles of Diet Therapy

Principles of Diet Therapy

• Disease can affect nutritional status by limiting food consumption, affecting nutrient absorption/metabolism, or increasing nutrient loss.
• Diet therapy modifies a normal diet to meet the requirements of someone who is sick.
• Objectives include maintaining nutritional status, correcting deficiencies, affording rest, adjusting food intake, and changing body weight.

Therapeutic Diet Planning

• Consider the underlying disease, its possible duration, factors in the diet needing alteration, and the patient's tolerance for oral food intake.

Modification of Therapeutic Diets

• Modified diets aim to restore/maintain nutritional status by manipulating dietary aspects.
• Aspects include increasing/decreasing nutrients (protein, calcium, iron, sodium, potassium, vitamin K), restricting/increasing kilocalories
• Texture or consistency can also be modified, such as a diced diet with prethickened liquids for dysphagia.
• Fiber may be restricted or increased, depending on GI function.
• Fluid can be pushed for dehydration or limited for renal/cardiac diseases.
• All modified diets are variations of the general diet to ensure the client still gets essential nutrients.
• Each modified diet has to be planned to provide essential nutrients or have a reason documented for omitting them.

Diet Types for Sick Individuals

• Clear-liquid diets are transparent liquids that can be poured at room temperature, like gelatin, some juices (apple, grape), broth, tea, and coffee.
• Clear-liquid diets are usually inadequate nutritionally and limited in duration.
• Clear-liquid nutritional supplements are available.
• Clear-liquid diets are used preoperatively (bowel surgery), before colonoscopies and postoperatively initially after abdominal surgery or intravenous feeding.
• Clear-liquid diets are also useful for acute GI disturbances when fluid and electrolyte replacement is needed (diarrhea).
• A clear-liquid diet may serve as the first step in oral alimentation for a nutritionally debilitated person.
• The serve to treat temporary food intolerance, relieve thirst, and reduce colonic fecal matter.
• Full-liquid Diet: Any liquid at room temperature including milk, all fruit juices, ice cream, strained soups, and clear-liquid diet items.
• Full-liquid diets are often used postoperatively progressing from clear liquids to solid foods.
• They are also useful in cases of acute gastritis/infections, oral/plastic surgery of the face/neck.
• They can be used for chewing/swallowing dysfunction in acutely ill patients and oesophagal/stomach disorders where solid foods aren't tolerated.
• Soft diets vary between facilities; mechanical soft diets are for clients with few/no teeth.
• A soft diet may also be ordered following surgery when easily digested foods are needed.
• A pureed diet consists of foods processed to meet consistency needs.
• Soft diets can be used when progressing from full fluid to general diets and for postoperative patients unable to tolerate general diets.
• Additional uses include mild GI problems, weakness, inadequate dentition, diarrhoea convalescence, between acute illness and convalescence, and acute infections.

General or Regular Diets

• General or regular diets are unrestricted.
• An "as tolerated" or progressive diet advances from clear-liquid to full-liquid to soft to general as tolerated.

Methods of Nutrient Delivery

• Nutrients may be delivered orally via food or supplements, enterally via feeding tube, or parenterally via veins.
• Enteral Nutrition (EN) involves feeding a formula/liquid through a tube into GI tract.
• EN may be advised when a patient can't eat but their digestive system works normally.
• The tube may pass through the nose into the stomach (nasogastric), duodenum (nasoduodenal), or jejunum (nasojejunal).
• If there's an oesphagus obstruction, enteral feeding involves surgically inserting a tube into the stomach (gastrostomy), duodenum (duodenostomy), or jejunum (jejunostomy).
• Parenteral Nutrition (PN) involves delivering nutrients intravenously.
• PN is used acutely when EN isn't feasible after 7 days in the ICU for previously healthy individuals or there is evidence of protein-calorie malnutrition.
• PN is initiated 5-7 days before major GI surgery and continued afterward if enteral feeding isn't possible.
• PN supplementation may be considered if energy requirements aren't met after 7-10 days via the enteral route alone.
• Peripheral Parenteral Nutrition (PPN): feeding via a vein away from the body's center, terminating in a peripheral site.
• Central Parenteral Nutrition (CPN): feeding via a central vein.
• Total Parenteral Nutrition (TPN) is used when no significant nutrition comes from other routes.
• Partial Parenteral Nutrition (PPN) is used when nutrition is partially enteric.

Planning a Healthy Diet

• Foods provide nutrients needed to maintain the body and support its functions.
• Food choices impact health quality.
• Six basic principles are important in diet planning: adequacy, balance, kcalorie (energy) control, nutrient density, moderation and variety.
• Adequacy: providing enough nutrients to ensure growth, maintenance, and tissue repair; includes carbohydrates, lipids, proteins, water, vitamins, and minerals. Nutrient deficiencies may result from inadequate nutrients.
• Balance: providing foods in proportion to each other and the body’s needs; include various foods as sources of various nutrients (no single foods can provide all nutrients).
• kCalorie (energy) control: balancing consumed energy (energy intake) with energy used by the body (total energy expenditure); energy imbalance leads to weight gain or loss.
• Nutrient density: measuring the nutrients a food provides relative to energy; higher nutrient density means more nutrients and fewer kcalories, helping achieve required nutrient consumption without overeating.
• Fat-free milk is more calcium dense than cheddar cheese (same amount of calcium for half the kcalories) and is better for diet adequacy while controlling kcalories.
• Empty-calorie foods: foods providing energy but little/no protein, vitamins, or minerals.
• Moderation: avoiding excessive nutrient consumption without strict food restrictions; contributes to adequacy, balance, and kcalorie control.
• Variety: selecting various foods from major food groups as diets can be boring if the same foods are included every day.
• Variety increases nutrient adequacy because foods contain different nutrient levels.

Steps in Meal Planning

• Recommended Dietary Allowances (RDA): knowing the RDA for different groups as they reflect the average daily nutrient amount considered adequate for most healthy people.
• Making a food list: preparing one that includes quantities of various food groups to balance the diet and meet the RDA.
• Can be done by selecting foods from all five food groups and deciding their quantities.
• Planning the menu: converting the listed foods into recipes and distributing them across meals

Food Labels

• Food labels help consumers make healthy choices.
• Ingredient List: listing ingredients in descending order by weight
• Serving Sizes: identifying the serving size as labels present nutrition information per serving; consumers should compare it to their actual consumption.
• Nutrition Facts: presenting nutrient information in quantities (e.g., grams) and percentages of Daily Values.
• The Nutrition Facts panel must provide information on total food energy (kcalories), and from fat
• Info on the totals grams and percentage of daily value on total fat, saturated fat, trans fat, cholesterol and sodium must be included
• Nutrient claims: characterizing the quantity of a nutrient in a food, used on labels if they meet regulatory definitions and conditions.
• Health claims: characterizing relationships between a food substance and a disease/health-related condition.
• Structure-Function Claims: statements characterizing the relationship between a food substance and its role in the body; doesn't require approval if it doesn't mention a disease or symptom.

Vegetarian Diets

• Vegetarians exclude meat/other animal-based foods for various reasons, highlighting knowing how to achieve a balanced diet without these.
• Benefits include weight control through diets high in fiber and low in fats.
• Vegetarian tend to have lower blood pressure with diets rich in fiber, fruits, and vegetables and low in fats.
• They also tend to have a reduced risk of heart disease with a diet low in total fat, saturated fat, and cholesterol.
• Lower rates of cancer, particularly colon cancer, may be due to high intakes of fruits and vegetables.
• The principles of planning a vegetarian diet are the same as for planning a normal diet.
• Individuals should include foods such as legumes, nuts, and cereals if they dont consume meat and eggs.
• Iron from plant foods (non-heme iron) is poorly absorbed.
• Vitamin C enhances iron absorption, so consume vitamin C-rich fruits and vegetables.
• Product based on soy beans can interfere with Zinc absorbtion.
• Vegetarians (vegans) may have a risk of vitamin B12 deficiency as its found in animal derived foods.
• Vegans can rely on vitamin B12 fortified foods or supplements.

Nausea and Vomiting

• Nausea & vomiting results from medications, food-borne illnesses, pregnancy, motion and chronic diseases, but a brief period doesn't need special treatment.
• Prolonged vomiting may lead to esophagitis and fluid & electrolyte imbalances, causing malnutrition.
• Dietary strategies to improve nausea include eating small, frequent meals, avoiding drinking during meals, and consuming dry, starchy foods.
• Avoid fatty, greasy, fried, sweet, and spicy foods, or foods with strong odors - cold foods/foods at room temperature may be better tolerated than hot foods.

Constipation

• It is a condition referring to defecation difficulty/infrequent bowel movements over time, diagnosed if bowel movements are fewer than 3 per week.
• Other symptoms include hard/dry stools, bloating, and incomplete stool evacuation.
• Factors that can increase the risk of constipation include low fiber diet, intaking low levels of fluids, low level of physical activity, pregnancy, and medical conditions.
• A habit of delaying going to the toilet increases stool transit time in the colon, leading to more water absorption and harder stool.
• The use of medications like antacids with aluminum/calcium, antihistamines, antidepressants, narcotics, diuretics, antispasmodics, and tranquilizers also contribute to constipation.
• Strategies include gradually increasing fiber consumption to 20-25 grams per day to increase stool volume and water content.
• Using fiber supplements and increasing fluid intake to 1.5-2 liters/day also help.
• Consuming little-to-no fiber foods or exercising less also contribute to constipation.

Diarrhea

• Diarrhea involves passing watery, loose stools frequently, leading to dehydration & electrolyte imbalance if prolonged; chronic diarrhea (2-4+ weeks) causes weight loss & malnutrition.
• Osmotic diarrhea results from unabsorbed solutes in the GI tract attracting water, seen in lactose intolerance, fat malabsorption, or poorly absorbed sugars.
• Secretory diarrhea results from excessive fluid secretion by intestinal cells, caused by foodborne illnesses, intestinal inflammation, or chemical substances.
• Exudative diarrhea occurs when intestinal mucosa damage releases mucus & blood due to inflammation/injury, increasing stool fluid content.
• Rapid intestinal transit diarrhea results from faster intestinal content movement, reducing fluid reabsorption time due to stress, IBS, or resections.
• Foods low in fat, fiber, and lactose are typically recommended when managing diarrhea with frequent, small meals consumed throughout the day.
• Increase of the intake of fluids to replace water and electrolyte loss is also recommended and milk/milk products should be avoided in case of lactose intolerance
• Consuming high caffeine, consuming high fiber, consuming indigestible carbohydrates, consuming fructose (as well as sugar alcohols) should also be avoided.