1.4 Nutrition
Key Takeaways
The six essential nutrient categories are carbohydrates, proteins, fats, vitamins, minerals, and water — each serves specific functions in the body
Macronutrients (carbohydrates, proteins, fats) provide energy measured in calories: carbs and protein yield 4 cal/g, fat yields 9 cal/g
MyPlate guidelines recommend filling half the plate with fruits and vegetables, one-quarter with grains, and one-quarter with protein
Therapeutic diets are prescribed for specific conditions: diabetic diet (carb counting), cardiac diet (low sodium/fat), renal diet (restrict potassium/phosphorus/sodium)
BMI (Body Mass Index) is calculated as weight (kg) / height (m)² and classifies weight status: <18.5 underweight, 18.5-24.9 normal, 25-29.9 overweight, 30+ obese
Medical assistants provide dietary education as directed by the provider, including food diary instructions, portion guidance, and therapeutic diet teaching
Proper nutrition is fundamental to health maintenance and disease management. Medical assistants must understand nutritional principles to support patient education and reinforce provider-directed dietary recommendations.
Essential Nutrients
| Nutrient | Function | Sources | Calories/gram |
|---|---|---|---|
| Carbohydrates | Primary energy source; fuels brain and muscles | Bread, pasta, rice, fruits, vegetables | 4 cal/g |
| Proteins | Build and repair tissues; enzymes and antibodies | Meat, fish, eggs, beans, dairy | 4 cal/g |
| Fats (Lipids) | Energy storage, insulation, hormone production, absorb fat-soluble vitamins | Oils, nuts, butter, avocado | 9 cal/g |
| Vitamins | Regulate body processes; coenzymes | Fruits, vegetables, fortified foods | 0 cal |
| Minerals | Structural components; regulate body processes | Dairy, meat, vegetables, grains | 0 cal |
| Water | Transport, temperature regulation, chemical reactions | Water, beverages, foods | 0 cal |
Key Vitamins and Their Functions
| Vitamin | Function | Deficiency | Food Sources |
|---|---|---|---|
| A | Vision, immune function, skin health | Night blindness | Carrots, sweet potatoes, liver |
| B1 (Thiamine) | Energy metabolism, nerve function | Beriberi | Whole grains, pork, legumes |
| B12 | Red blood cell formation, nerve function | Pernicious anemia | Meat, fish, dairy, eggs |
| C | Collagen synthesis, immune function, antioxidant | Scurvy | Citrus fruits, peppers, strawberries |
| D | Calcium absorption, bone health | Rickets (children), osteomalacia (adults) | Sunlight, fortified milk, fatty fish |
| E | Antioxidant, cell membrane protection | Hemolytic anemia | Nuts, seeds, vegetable oils |
| K | Blood clotting, bone metabolism | Bleeding disorders | Leafy greens, broccoli, liver |
| Folic acid (B9) | DNA synthesis, red blood cell formation | Megaloblastic anemia, neural tube defects | Leafy greens, fortified grains, beans |
Fat-soluble vitamins: A, D, E, K — stored in body fat; can accumulate to toxic levels Water-soluble vitamins: B-complex, C — not stored; excess excreted in urine; need daily intake
Key Minerals
| Mineral | Function | Deficiency | Sources |
|---|---|---|---|
| Calcium | Bones, teeth, muscle contraction, nerve function | Osteoporosis | Dairy, leafy greens, fortified foods |
| Iron | Hemoglobin formation, oxygen transport | Iron-deficiency anemia | Red meat, beans, fortified cereals |
| Potassium | Fluid balance, nerve function, muscle contraction | Muscle weakness, arrhythmias | Bananas, potatoes, oranges |
| Sodium | Fluid balance, nerve impulses | Hyponatremia (rare) | Salt, processed foods |
| Magnesium | Enzyme function, muscle/nerve function | Muscle cramps, weakness | Nuts, whole grains, leafy greens |
| Zinc | Immune function, wound healing | Impaired immunity, slow wound healing | Meat, shellfish, legumes |
Therapeutic Diets
| Diet | Indication | Key Modifications |
|---|---|---|
| Diabetic diet | Diabetes mellitus | Consistent carbohydrate counting, low glycemic index foods, limit simple sugars |
| Cardiac/heart-healthy | Heart disease, hypertension | Low sodium (<2,000 mg/day), low saturated fat, high fiber |
| Renal diet | Chronic kidney disease | Restrict potassium, phosphorus, sodium, and possibly protein and fluid |
| DASH diet | Hypertension | High fruits/vegetables/whole grains, low sodium, low saturated fat |
| Low-residue/low-fiber | Crohn's disease, diverticulitis flare | Limit fiber, raw fruits/vegetables, whole grains |
| High-fiber | Constipation, diverticulosis | Increase fiber to 25-35 g/day, increase fluids |
| Gluten-free | Celiac disease | Eliminate wheat, barley, rye, and cross-contaminated foods |
| Clear liquid | Pre-surgery, acute GI illness | Broth, gelatin, clear juices, popsicles |
| Full liquid | Post-surgery transition | All clear liquids plus milk, cream soups, pudding |
| Soft/mechanical soft | Difficulty chewing/swallowing | Soft, easy-to-chew foods; no raw vegetables or tough meats |
BMI Classification
| BMI | Classification |
|---|---|
| < 18.5 | Underweight |
| 18.5 - 24.9 | Normal weight |
| 25.0 - 29.9 | Overweight |
| 30.0 - 34.9 | Obese (Class I) |
| 35.0 - 39.9 | Obese (Class II) |
| ≥ 40.0 | Morbidly obese (Class III) |
BMI Formula: Weight (kg) ÷ Height (m)² = BMI
Which macronutrient provides the MOST calories per gram?
Carbohydrates (4 cal/g)
Proteins (4 cal/g)
Fats (9 cal/g)
Vitamins (4 cal/g)
A patient with chronic kidney disease would most likely be placed on which type of therapeutic diet?
High-protein, high-sodium diet
Gluten-free diet
Renal diet (restricted potassium, phosphorus, and sodium)
High-fiber diet
Vitamins A, D, E, and K are classified as fat-soluble vitamins. What is the clinical significance of this classification?
They must be taken with water for proper absorption
They are stored in body fat and can accumulate to toxic levels if taken in excess
They cannot be obtained from dietary sources
They are only absorbed when taken on an empty stomach
Sections you finish are checked off in the contents.