10.3 MNT for Food Allergy and Intolerance, Skin, Rheumatic, Musculoskeletal, and Neurologic Disorders
Key Takeaways
A double-blind, placebo-controlled oral food challenge is the reference standard for diagnosing food allergy; skin prick tests and specific IgE show sensitization but not always clinical allergy.
Lactose intolerance is caused by low lactase activity, not an immune reaction, and many affected people tolerate small amounts of milk, yogurt, and cheese.
Gout management limits organ meats, some seafood, alcohol (especially beer), and fructose-sweetened drinks, encourages weight loss and fluids, and allows low-fat dairy.
The classic ketogenic diet for drug-resistant epilepsy provides fat to protein-plus-carbohydrate in a 4:1 or 3:1 ratio by weight.
Wound and pressure injury healing needs adequate energy (about 30-35 kcal/kg), protein (about 1.25-1.5 g/kg), and fluids, with zinc and vitamin C supplements mainly when deficiency is present.
The table of specifications groups allergies, food sensitivities, skin disorders, musculoskeletal (rheumatic) disorders, and nervous and psychiatric disorders together under medical nutrition therapy. Each condition has a few characteristic diet principles that appear in examination questions.
Food Allergy and Food Intolerance
| Feature | Food allergy | Food intolerance |
|---|---|---|
| Mechanism | Immune reaction to a food protein (IgE-mediated or non-IgE) | Non-immune: enzyme deficiency, pharmacologic, or unknown |
| Amount needed | Very small amounts can trigger a reaction | Usually dose-related |
| Symptoms | Hives, swelling, vomiting, wheezing, anaphylaxis | GI symptoms such as bloating and diarrhea |
| Example | Peanut, shellfish, egg, or milk allergy | Lactose intolerance; reactions to MSG or sulfites |
Common allergens: milk, egg, peanut, tree nuts, fish, crustacean shellfish (shrimp, crab), wheat, soy, and sesame. Shellfish allergy is common among Filipino adults.
Diagnosis: detailed history and food diary; skin prick test or specific IgE to show sensitization; the double-blind, placebo-controlled oral food challenge is the reference standard. Diagnostic elimination diets should be short and supervised.
Management:
- Strict avoidance of the confirmed allergen, including hidden sources and cross-contact in kitchens.
- Label reading: allergens must be declared on prepackaged foods.
- Planned substitutes so the diet stays adequate, for example calcium and vitamin D when milk is excluded.
- Emergency plan and epinephrine auto-injector for people at risk of anaphylaxis.
- Prevention in infants: exclusive breastfeeding for 6 months, then introducing complementary foods, including common allergens such as egg and peanut products in safe textures, around 6 months rather than delaying them.
Lactose intolerance: lactase activity falls after weaning in most Asian populations. Many people tolerate about 12 g of lactose (roughly one cup of milk) with meals, and yogurt and aged cheese are better tolerated. Lactase enzyme tablets and lactose-free milk are options.
Running a diagnostic elimination diet: remove only the suspected food or foods for about 2-4 weeks, record symptoms, and then reintroduce each food one at a time under supervision. If symptoms do not improve during elimination, the food is probably not the cause and should return to the diet. Long, broad elimination diets in children risk poor growth.
Skin Disorders
- Atopic dermatitis (eczema): food allergy plays a role in some infants with moderate to severe eczema, but unnecessary elimination diets can cause malnutrition. Test before restricting.
- Acne: high glycemic load diets and, in some studies, milk intake are associated with acne; a balanced low-glycemic diet is reasonable.
- Psoriasis: associated with obesity and cardiovascular risk; weight loss improves severity in people with obesity.
- Pressure injuries and wounds: energy about 30-35 kcal/kg, protein about 1.25-1.5 g/kg, and adequate fluids. Give zinc and vitamin C supplements when deficiency is suspected; routine high doses are not proven. Arginine-enriched supplements may help in some cases.
Rheumatic and Musculoskeletal Disorders
| Condition | Key nutrition points |
|---|---|
| Rheumatoid arthritis | Anti-inflammatory, Mediterranean-style diet; omega-3 fatty acids from fish may reduce joint pain; prevent weight loss and muscle wasting; calcium and vitamin D with steroid therapy; folic acid with methotrexate |
| Osteoarthritis | Weight loss reduces joint load (each kilogram lost reduces knee load by several kilograms with each step); exercise to strengthen muscles |
| Gout | See below |
| Osteoporosis | Adequate calcium (PDRI 750-800 mg/day for adults), vitamin D, protein, and weight-bearing exercise; limit excess alcohol and smoking |
Gout is caused by uric acid crystals in joints. Diet supports medication:
- Limit: organ meats (liver, kidney, isaw), meat extracts and gravies, sardines, anchovies (dilis), mussels, and other high-purine seafood; alcohol, especially beer; and fructose-sweetened drinks.
- Allowed or encouraged: low-fat dairy (associated with lower uric acid), vegetables (including purine-rich vegetables, which do not raise gout risk the way meat does), and plenty of fluids.
- Weight loss lowers uric acid, but crash diets and fasting raise it and can trigger attacks.
Neurologic and Psychiatric Disorders
| Condition | Key nutrition points |
|---|---|
| Epilepsy (drug-resistant) | Classic ketogenic diet with a 4:1 or 3:1 ratio of fat to protein plus carbohydrate by weight; MCT oil or modified Atkins variants; monitor growth, lipids, kidney stones; supplement vitamins and minerals |
| Stroke | Screen for dysphagia; modify texture and liquids (IDDSI); DASH-style diet and sodium restriction for secondary prevention |
| Parkinson's disease | Levodopa competes with large neutral amino acids, so spread protein evenly or follow the prescriber's timing advice; prevent constipation with fiber and fluids; watch for weight loss and dysphagia |
| Dementia | Finger foods, supervised meals, and attention to weight loss and hydration; dysphagia in later stages |
| Migraine | Identify individual triggers such as alcohol or skipped meals; avoid overly restrictive diets |
| Depression and anxiety | Appetite may rise or fall; regular meals; Mediterranean-style patterns linked to lower risk |
| Schizophrenia and bipolar disorder | Antipsychotics often cause weight gain and metabolic syndrome; lithium requires consistent sodium and fluid intake |
Tip
When a question contrasts allergy with intolerance, look for an immune mechanism and reaction to a tiny dose (allergy) versus a dose-related digestive problem (intolerance).
A child reacts with hives and wheezing within minutes of eating a small piece of shrimp. A skin prick test is positive. Which test is the reference standard for confirming clinical food allergy?
A stool test for reducing substances
A lactose breath hydrogen test
A double-blind, placebo-controlled oral food challenge
A hair analysis for food sensitivities and intolerances
A man with recurrent gout asks for diet advice. Which recommendation is most appropriate?
Switch from hard liquor to beer, which is lower in purines
Fast for several days so that weight drops quickly
Replace plain water with fruit-flavored soft drinks
Limit organ meats and alcohol, and drink plenty of fluids
A child with drug-resistant epilepsy starts a classic ketogenic diet in a 4:1 ratio. What does this ratio mean?
Four grams of fat for every one gram of protein plus carbohydrate
Four grams of protein for every one gram of fat
Four meals for every one snack each day
Four grams of carbohydrate for every one gram of fat plus protein combined
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