Nutrition Foundations | Free Pre-Nursing

Loading progress…

Save your progress across devices

Guest access stays fully free. Create a free account to keep module completion and study preferences synced on every device. No paid subscription is required for Pre-Nursing.

Create free account Sign in

Your progress · Nutrition Foundations

Pre-Nursing stays free. Progress is optional.

0% of modules

Start your first module to build momentum and unlock personalized recommendations.

Mark “Nutrition Foundations” as complete

Suggested next in sequence: medical-terminology

Stay in Pre-Nursing

Ready for exam-style prep

Paid NurseNest plans add full question banks, mocks, and pathway-scoped lessons once you are comfortable with the basics here.

Set a likely route on the study planning page to personalize these links.

Focus on foundations here; we’ll keep exam prep one click away.

Back to Modules

Loading progress…

Nutrition Foundations for Nursing

Understand macronutrients and their caloric values, micronutrients and their roles, fluid requirements, dietary electrolytes, therapeutic diets for common conditions, nutrition label interpretation, and BMI/malnutrition screening in clinical practice.

Macronutrients: Carbohydrates, Proteins, and Fats

Energy sources and their roles in the body

The three macronutrients, carbohydrates, proteins, and fats, serve distinct roles in human physiology. Understanding their caloric density and functions is fundamental to nursing nutrition assessment and patient education.

Carbohydrates, 4 kcal/g

Primary energy source. Simple carbs (glucose, fructose, sucrose) provide rapid energy. Complex carbs (starches, fiber) provide sustained energy and promote GI health. The brain uses ~120g glucose/day. Sources: grains, fruits, vegetables, legumes, dairy. Recommended: 45-65% of total daily calories.

Proteins, 4 kcal/g

Building blocks for tissue repair and growth. Complete proteins (animal sources) contain all 9 essential amino acids. Incomplete proteins (plant sources) must be combined for complete amino acid profile. Functions: enzymes, antibodies, albumin (oncotic pressure), hormones. Recommended: 10-35% of total daily calories, or 0.8 g/kg/day for healthy adults.

Fats, 9 kcal/g

Most calorie-dense macronutrient. Essential for absorbing fat-soluble vitamins (A, D, E, K). Unsaturated fats (olive oil, fish, nuts) are heart-healthy. Saturated fats (animal products) raise LDL cholesterol. Trans fats (hydrogenated oils) are the most harmful. Recommended: 20-35% of total daily calories, <10% from saturated fat.

Macronutrients are nutrients needed in large quantities that provide energy (calories). Carbohydrates provide 4 kcal/g and are the body's preferred energy source, the brain relies almost exclusively on glucose. Proteins provide 4 kcal/g and are essential for tissue repair, immune function, enzyme production, and fluid balance (albumin maintains oncotic pressure). Fats provide 9 kcal/g, the most calorie-dense macronutrient, and are essential for hormone synthesis, cell membrane integrity, absorption of fat-soluble vitamins (A, D, E, K), and insulation. Alcohol provides 7 kcal/g but is not classified as a macronutrient because it offers no nutritional value.

Micronutrients and Fluid Requirements

Vitamins, minerals, and hydration

Micronutrients, vitamins and minerals, are required in small amounts but are essential for metabolic processes, immune function, and disease prevention. Adequate fluid intake is equally critical for cellular function, thermoregulation, and waste elimination.

Fat-Soluble Vitamins (A, D, E, K), stored in body fat

Water-Soluble Vitamins (B-complex, C), not stored, need daily intake

Daily Fluid Requirements

General recommendation: 30 mL/kg/day or approximately 2-3 liters/day for adults. Increased needs: fever (add 500 mL per degree above 37°C), burns, diarrhea, vomiting, drains, high environmental temperature, physical exertion. Restricted needs: heart failure, renal failure, SIADH. Monitor intake and output (I&O). Minimum urine output: 30 mL/hr (0.5 mL/kg/hr) indicates adequate renal perfusion.

Key electrolytes obtained from diet include: Sodium (Na+), found in processed foods, table salt; regulates fluid balance and nerve impulses; normal: 135-145 mEq/L. Potassium (K+), found in bananas, oranges, potatoes, spinach; critical for cardiac function and muscle contraction; normal: 3.5-5.0 mEq/L. Calcium (Ca²+), found in dairy, leafy greens, fortified foods; essential for bone health, muscle contraction, blood clotting; normal: 8.5-10.5 mg/dL. Magnesium (Mg²+), found in nuts, seeds, whole grains; cofactor in 300+ enzymatic reactions; normal: 1.5-2.5 mEq/L. Phosphorus, found in dairy, meat, beans; partners with calcium for bone health; normal: 2.5-4.5 mg/dL.

Therapeutic Diets

Medical nutrition therapy for common conditions

Therapeutic diets are prescribed as part of the treatment plan for specific medical conditions. Nurses must understand diet modifications to provide accurate patient education, monitor compliance, and recognize when dietary intake may worsen a condition.

Nutrition Labels and Screening

Assessment tools and food label literacy

Nurses must be able to interpret nutrition labels for patient education and understand BMI classification and malnutrition screening tools to identify patients at nutritional risk.

Reading a Nutrition Label

% Daily Value (DV):

BMI categories: Underweight (<18.5), Normal (18.5-24.9), Overweight (25.0-29.9), Obese Class I (30.0-34.9), Obese Class II (35.0-39.9), Obese Class III (≥40.0). Malnutrition screening tools include the Malnutrition Screening Tool (MST), Subjective Global Assessment (SGA), and Mini Nutritional Assessment (MNA) for elderly patients. Key lab markers: serum albumin (<3.5 g/dL indicates chronic malnutrition, half-life 18-20 days), prealbumin (<17 mg/dL indicates recent nutritional changes, half-life 2-3 days, more sensitive to acute changes), and transferrin. Unintentional weight loss of >5% in 1 month or >10% in 6 months is clinically significant and warrants nutritional intervention.

Macronutrients — Clinical Applications

From biochemistry to bedside nursing implications

Understanding macronutrient physiology at a clinical level allows nurses to anticipate patient nutritional needs, educate patients about therapeutic diets, and recognize when macronutrient imbalances are contributing to clinical problems.

Macronutrients: Nursing and Clinical Implications

High-Risk Micronutrient Deficiencies in Clinical Populations

Which patients, which deficiencies, and what to watch for

Certain patient populations are at predictable risk for specific micronutrient deficiencies. Recognizing the risk factors, clinical presentations, and nursing implications for each deficiency is a clinical competency that directly affects patient safety.

Vitamin B12 (Cobalamin) Deficiency

At-risk populations: vegans and strict vegetarians (B12 found only in animal products), older adults (gastric parietal cells decline → reduced intrinsic factor → impaired B12 absorption, even with adequate dietary intake), post-gastric bypass or gastric surgery patients (loss of intrinsic factor producing cells), patients taking metformin or PPIs long-term (impair absorption). Clinical presentation: megaloblastic (macrocytic) anemia (large, abnormal RBCs — fatigue, pallor, dyspnea), subacute combined degeneration of the spinal cord (demyelination causing ascending paresthesias, loss of vibration/position sense, gait ataxia), memory loss, depression, confusion. Critical: neurological damage can be IRREVERSIBLE if deficiency is not corrected. Treatment: intramuscular B12 injections for those with absorption problems (oral supplements will not work if intrinsic factor is absent).

Iron Deficiency

Most common micronutrient deficiency worldwide. At-risk populations: women of reproductive age (menstrual losses), pregnancy (increased demand), infants and toddlers, GI bleeding (peptic ulcer, colorectal cancer, IBD), malnutrition. Lab findings: low serum ferritin (storage iron — earliest to drop), elevated TIBC (total iron-binding capacity — transferrin unsaturated), low serum iron, microcytic hypochromic anemia (small, pale RBCs) on CBC. Clinical presentation: fatigue, pallor, dyspnea on exertion, tachycardia, brittle nails, spoon-shaped nails (koilonychia), pica (craving non-food items — ice, clay, dirt). Treatment: oral ferrous sulfate on empty stomach for best absorption — but causes GI upset (nausea, constipation); taking with vitamin C enhances absorption; avoid taking with calcium, antacids, or dairy (reduce absorption). IV iron for severe deficiency or intolerance to oral iron.

Folate (Vitamin B9) Deficiency

At-risk populations: pregnancy (dramatically increased demand for DNA synthesis and cell division), alcohol use disorder (alcohol impairs folate absorption and increases renal excretion), patients on methotrexate or trimethoprim (folate antagonists — block dihydrofolate reductase), poor dietary intake. Clinical presentation: megaloblastic anemia (large, immature RBCs), glossitis (inflamed tongue), neural tube defects (anencephaly, spina bifida) in embryos exposed to deficiency during first 28 days after conception — often before the pregnancy is known. Prevention: all women of childbearing age should take 400–800 mcg folic acid daily, even before conception; neural tube closes in first 28 days. Dietary sources: dark leafy greens (spinach, romaine), legumes, fortified grains, liver.

Vitamin D Deficiency

Synthesis: skin exposure to UVB radiation → precursor → liver converts to 25-hydroxyvitamin D → kidneys convert to active 1,25-dihydroxyvitamin D (calcitriol). At-risk populations: limited sun exposure (northern latitudes, housebound, dark skin with high melanin), liver or kidney disease (impair activation), obesity (sequestered in fat), elderly, breastfed infants without supplementation. Clinical presentation: children — rickets (soft, deformed bones, bowed legs, delayed fontanelle closure); adults — osteomalacia (bone pain, muscle weakness, stress fractures), osteoporosis (increased fracture risk), proximal muscle weakness, immune impairment. Lab: 25-hydroxyvitamin D <20 ng/mL = deficiency; 20–30 = insufficiency. Treatment: 600–800 IU/day maintenance for adults; 1,500–4,000 IU/day for correction of deficiency. Active absorption of calcium from the gut requires vitamin D — deficiency ultimately impairs calcium balance.

Zinc Deficiency

At-risk populations: malnutrition, anorexia, malabsorption (Crohn's disease, short bowel syndrome), burns and major wounds (large losses through wound exudate), alcoholism, vegetarians (plant phytates bind zinc). Clinical presentation: impaired wound healing (zinc is essential for collagen synthesis and cell proliferation), immune dysfunction (recurrent infections), loss of taste (hypogeusia) and smell (hyposmia), hair loss, diarrhea, dermatitis (particularly around body orifices), growth retardation in children. Dietary sources: meat (beef, lamb), shellfish (oysters are highest), legumes, nuts, seeds, dairy. Clinical nursing: high-output wounds with significant exudate in malnourished patients should trigger evaluation for zinc status and appropriate supplementation.

Expanded Therapeutic Diet Reference

Low-sodium (2 g/day): Heart failure, hypertension, CKD, cirrhosis. Avoid canned soups, processed meats, fast food, pickled/cured foods, soy sauce.

Low-potassium: CKD with hyperkalemia. Avoid bananas, oranges, tomatoes, potatoes, spinach, raisins, dates, chocolate. Leaching vegetables (boiling and discarding water) reduces potassium content.

High-potassium: Hypokalemia, diuretic therapy. Encourage bananas, oranges, tomatoes, potatoes, avocados, spinach, prunes.

Renal diet (CKD): Low protein (0.6–0.8 g/kg/day), low K⁺ (<2,000 mg/day), low phosphate (<1,000 mg/day), low sodium, fluid restriction — tailored to individual kidney function and dialysis status.

Consistent carbohydrate (diabetic): 45–60 g carbohydrates per meal, distributed evenly; focus on low glycemic index foods; paired with protein and fat to slow absorption.

Mechanical soft / pureed: Dysphagia, post-oral surgery, poor dentition. Soft cohesive foods; avoid thin liquids if aspiration risk; position upright at 90° during meals and 30 min after.

Enteral nutrition (tube feeding): Indicated when gut is functional but patient cannot eat orally (altered LOC, intubation, severe dysphagia). Routes: nasogastric (NG) — short-term; nasojejunal (NJ) — for high aspiration risk or gastroparesis; PEG (percutaneous endoscopic gastrostomy) — long-term. Nursing: check gastric residuals every 4 hours per protocol (hold feeding if >200–500 mL per institution policy), elevate HOB 30–45°, flush tube before and after medications, monitor for diarrhea, refeeding syndrome risk.

Refeeding Syndrome — A Life-Threatening Complication

Refeeding syndrome occurs when severely malnourished patients (prolonged starvation, anorexia nervosa, alcoholism, prolonged NPO status) are re-introduced to nutrition too rapidly. In starvation, cells adapt to using fat and protein for energy. When carbohydrates are reintroduced, insulin surges → massive intracellular uptake of phosphate, potassium, and magnesium. Serum levels of all three plummet simultaneously. Hypophosphatemia is the hallmark: causes cardiac arrhythmias, respiratory failure (diaphragm weakness), heart failure, hemolytic anemia, and neurological dysfunction. Prevention: identify high-risk patients before feeding, start at 25% of goal calories and advance slowly over 5–7 days, supplement phosphate/K⁺/Mg²⁺ proactively, monitor electrolytes daily during the first week of refeeding.

Nutritional Assessment and Malnutrition

Screening tools, biochemical markers, and nursing interventions

Nutritional assessment is a nursing responsibility performed on admission and throughout the hospital stay. Early identification of malnutrition or nutritional risk allows for timely dietitian referral and intervention before complications develop.

Nutritional Screening Tools

Screening is performed by nursing on admission and periodically during hospitalization. Screening tools: MNA (Mini Nutritional Assessment) — validated for elderly patients (≥65 years), comprehensive 18-question tool; NRS-2002 (Nutritional Risk Screening) — validated for hospitalized adults, assesses BMI, weight loss, dietary intake, and disease severity; MUST (Malnutrition Universal Screening Tool) — used in community and outpatient settings; SGA (Subjective Global Assessment) — comprehensive tool performed by dietitian or advanced clinician, combines history and physical to categorize as well-nourished, mildly/moderately malnourished, or severely malnourished. Any high-risk screening result should trigger dietitian referral within 24–48 hours.

Anthropometric Measurements

BMI = weight (kg) / height (m²). Categories: Underweight <18.5 (malnutrition risk), Normal 18.5–24.9, Overweight 25–29.9, Obese Class I 30–34.9, Obese Class II 35–39.9, Obese Class III (morbid obesity) ≥40. BMI limitations: does not differentiate muscle from fat (athletes may be classified as overweight); does not reflect fat distribution. Waist circumference: central adiposity risk — men >40 inches (102 cm), women >35 inches (88 cm) = increased cardiovascular and metabolic risk. Mid-arm circumference and triceps skinfold thickness: used by dietitians to estimate muscle mass and fat stores — more sensitive for detecting malnutrition than BMI alone. Serial weight measurements: weigh at the same time of day, same scale, same clothing. Weight trends more meaningful than single measurements. Unintentional weight loss: >5% in 1 month or >10% in 6 months = clinically significant malnutrition indicator.

Biochemical Markers of Nutritional Status

Albumin (normal 3.5–5.0 g/dL): half-life 18–20 days — reflects chronic nutritional status over weeks to months. Limitations: affected by inflammation (negative acute-phase reactant — falls during infection/illness regardless of nutrition), fluid status (diluted in edema/overhydration), and liver disease (synthesis site). NOT useful for acute nutritional changes. Prealbumin (transthyretin, normal 17–43 mg/dL): half-life 2–3 days — sensitive to acute nutritional changes over days. More clinically useful for monitoring response to nutritional therapy. Also negative acute-phase reactant — use with C-reactive protein to interpret in context of inflammation. Total lymphocyte count (TLC): <1,500/mm³ suggests impaired immune function from malnutrition. BUN/creatinine ratio: elevated BUN with normal creatinine may indicate protein catabolism or GI bleeding (protein digestion raises BUN). Transferrin (iron-binding protein) and retinol-binding protein are also used but less commonly.

Types of Malnutrition

Protein-energy malnutrition (PEM): the most common type of malnutrition in hospitalized patients. Two classic syndromes: Marasmus — severe calorie deficiency with adaptation. Gradual, chronic starvation. Body consumes fat stores then muscle (cachexia). Patient appears extremely thin, wasted. Albumin often NORMAL (liver adapts). Kwashiorkor — protein deficiency with relatively adequate calories. Acute, often precipitated by severe illness/stress response. Body cannot synthesize proteins. Albumin is LOW → loss of oncotic pressure → massive edema (pitting edema, ascites, moon face, potbelly appearance despite malnourishment). Immune dysfunction severe. Patient may appear well-nourished or edematous — masking underlying protein deficiency. Mixed PEM: elements of both — most common in hospitalized, critically ill patients. ASPEN definition of malnutrition: presence of 2 or more of: inadequate energy intake, weight loss, loss of muscle mass, loss of subcutaneous fat, fluid accumulation, diminished functional status.

Nursing Interventions for Nutritional Support

Admission: complete nutritional screening using facility-approved tool within 24 hours; refer high-risk patients to registered dietitian; document diet history including appetite changes, recent weight loss, chewing/swallowing problems, cultural/religious food restrictions. During hospitalization: document percentage of each meal consumed (e.g., "ate 50% of breakfast, declined lunch, ate 75% of dinner"); obtain daily weights at consistent time and conditions; encourage oral intake — offer preferred foods when possible, ensure dentures are in place, treat pain before meals, position upright; assist with feeding for dependent patients; ensure NPO orders are lifted promptly and advanced appropriately. High-aspiration-risk patients: HOB at minimum 30° for tube feeding (45° preferred); check gastric residuals per protocol; oral care to reduce aspiration pneumonia risk. Refer to speech therapy for dysphagia evaluation before initiating oral feedings post-stroke or post-extubation.

Nutritional Assessment Knowledge Check

1/4

A patient's serum albumin is 2.8 g/dL. The MOST accurate interpretation is:

0/6 matched

components.interactiveLearning.terms

components.interactiveLearning.definitions

1/20

Which macronutrient provides the most calories per gram?

Comprehensive Nutrition Foundations Final Quiz

1/10

A vegan patient reports progressive tingling in the feet and fingers, gait unsteadiness, and a recent diagnosis of macrocytic anemia. The MOST likely deficiency is: