Nutrition: Macronutrients.

Macronutrients are nutrients the body needs in large quantities, such as fats, carbohydrates, fiber, protein, and water. The exact quantity of macronutrients needed for an individual depends on multiple factors such as height, weight, sex, physical activity level, and medical conditions. For adequate intake, the Dietary Guidelines for Americans, 2020-2025 (DGA) recommend an overall healthy eating pattern rather than specific macronutrient amounts. A healthy eating pattern includes consumption of minimally processed, nutrient-dense foods and beverages such as vegetables, fruits, grains, dairy, proteins, and oils. Nutrition labels on food packaging can be used to guide food choices. Healthy dietary patterns have been shown to reduce the risk of diet-related chronic diseases. Consumption of foods containing unsaturated fats, complex carbohydrates, and high levels of fiber is recommended. Protein should be obtained from a variety of sources, particularly plant-based sources. Intake of foods and beverages higher in added sugars, saturated fat, and sodium should be limited. Family physicians should obtain a nutrition history for every patient regardless of body mass index. The evaluation should include a diet assessment questionnaire and information about patient nutrition insight and motivation, dietary intake pattern, metabolic demands, comorbid conditions, and dietary supplement and substance use (eg, caffeine, alcohol). Physicians can counsel patients by sharing current DGA recommendations for following a healthy eating pattern.

Nutrition: Micronutrients.

Micronutrients are nutrients the body needs in small quantities, such as vitamins and minerals. Micronutrient deficiencies can occur when an individual is restricting calorie intake for weight loss or management, not consuming an adequate amount of food to meet energy requirements due to poor appetite or illness, eliminating one or more food groups from the diet on a regular basis, or consuming a diet low in micronutrient-rich foods despite adequate or excessive energy intake. Patient groups at risk include older adults, pregnant patients, patients with alcohol use disorder, patients with vegetarian or vegan diets, and patients with increased requirements secondary to medical conditions or long-term drug use that alters nutrient absorption, metabolism, or excretion. The micronutrients that most commonly require supplementation are vitamin D, iron, vitamin A, zinc, folate, and iodine. Results of large-scale randomized trials have shown no overall benefit of multivitamins for the majority of patients. However, a daily multivitamin may be beneficial, particularly for patients who do not consistently consume a well-balanced diet. Although dietary supplements can be helpful in correcting deficiencies, higher than recommended doses can cause adverse effects. Patients should be advised to take recommended dosages of supplements and consult their physician if they notice any adverse effects. Physicians should advise patients to consult drug labels and/or pharmacists about potential supplement interactions with drugs or other supplements.

Nutrition: Malnutrition and Dietary Intake Modification.

The average adult needs 1 to 2 g protein/kg of body weight and 25 to 30 kcal/kg of body weight per day. Caloric needs in adults differ based on height, weight, activity level, and disease state. Malnutrition is defined as an imbalance of nutrition, including lack of adequate calories, protein, and/or other nutrients required for body functioning. Protein-calorie malnutrition is a specific type of malnutrition defined as deficient intake or uptake of protein and energy that leads to physiologic alterations such as inflammation, loss in fat-free mass, and/or decreased response to medical treatment. Worldwide, 20% to 50% of hospitalized patients have malnutrition preadmission, and up to 90% of older adult patients are at increased risk. All patients should be screened for malnutrition within 24 hours of hospital admission. If malnutrition is suspected in the outpatient setting, patients should be screened with assistance from a registered dietitian nutritionist. The treatment strategy for protein and calorie supplementation involves provision of additional calories via oral nutritional supplements, enteral tube feedings, or parenteral nutrition. Oral nutritional supplements are indicated for patients with mild cases of malnutrition who are able to consume food orally. Meal replacement products are a convenient way to modify macronutrient intake, including use as a temporary solution to increase intake in patients with malnutrition and as an intervention for weight loss.

Nutrition: Chronic Disease Management.

Dietary modifications can help to prevent and manage many chronic diseases. The Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets emphasize consumption of fruits and vegetables while reducing intake of red meat. These diets are supported by well-established evidence for patients with cardiovascular disease and hypertension, respectively. Whole-food, plant-based diets have been shown to result in reduced body weight, lower A1c levels, and decreased insulin resistance in patients with diabetes. Patients with diabetes and hypertension should adhere to a heart-healthy diet, such as the DASH diet. For patients with diabetes and at risk of diabetes, key nutritional recommendations include emphasizing intake of nonstarchy vegetables, minimizing intake of added sugars and refined grains, and choosing whole foods instead of processed foods. The Dietary Guidelines for Americans, 2020-2025 recommend that adults limit sodium intake to less than 2,300 mg/day. Patients with chronic kidney or liver disease should follow sodium restriction and protein intake guidelines. Patients with irritable bowel syndrome should follow a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet with fiber supplementation. For patients with gastrointestinal symptoms, fiber can effectively manage constipation and stool irregularity. Probiotic supplements or foods can be useful for digestive problems.