4. Contraindication matrix

Across the 196 chapters of the Food Sources v1.5 book, contraindications and risks are scattered throughout. This appendix gathers into a single view the clinically relevant risks, grouped by eight criteria. A dietitian, clinician or donor-diet planner thus gets quick decision support for individual patient screening.

The matrix only contains those foods where the risk is clinically relevant — that is, not merely theoretical but requires management based on an official regulatory body (EFSA / FDA / EMA / Monash / WHO) or a peer-reviewed RCT.

The notation applies to the clinical condition, not to the average healthy consumer. The healthy population can safely consume most of the items.

Clinical relevance: 50—75% of IBS patients show symptomatic worsening with high-FODMAP foods (Monash University evidence base). During the low-FODMAP elimination phase (4—6 weeks) the following are to be avoided, then can be tested in the reintroduction phase.

🟠 — High FODMAP (Monash red) — avoid during the elimination phase:

🟡 — Moderate FODMAP (yellow / titratable):

Clinical relevance: In DAO-deficient patients or those on MAO inhibitors, high-histamine foods or histamine liberators can trigger headache, urticaria, facial flushing, hypotension / hypertension response. Increased attention during antidepressant treatment.

🔴 — Absolute contraindication during MAO-inhibitor (phenelzine, tranylcypromine, moclobemide, selegiline) treatment:

🟠 — High histamine / histamine liberator:

🟡 — Moderate (case-dependent control):

Clinical relevance: For patients with a calcium-oxalate kidney-stone tendency, restriction of high-oxalate foods is recommended. Hyperoxaluria + low urinary calcium + Crohn's disease is an extreme risk.

🟠 — High oxalate content (≥ 100 mg / 100 g):

🟡 — Moderate oxalate (control advised for those prone to kidney stones):

Clinical relevance: A gout attack can be triggered by purine intake. For hyperuricemic patients, moderation of high-purine foods is clinically justified (Choi 2004 NEJM + ACR 2020 guideline).

🟠 — High purine (> 200 mg / 100 g):

🟡 — Moderate purine (moderate consumption advised):

Clinical relevance: In patients with Hashimoto's disease, Graves' disease, autoimmune thyroiditis and L-thyroxine-treated hypothyroidism, high iodine intake can worsen control. EFSA adult UL = 600 µg/day.

🔴 — Absolutely to be avoided (extreme iodine load):

🟠 — High iodine (controlled dosing):

🟡 — Moderate iodine (to be monitored):

Clinical relevance: Methylmercury is neurotoxic to the developing fetal and young-child brain. WHO JECFA = 1.6 µg/kg/week tolerable intake. FDA "Choices to Avoid" prohibited in pregnancy.

🔴 — FDA "Choices to Avoid" — prohibited in pregnancy + childhood:

🟠 — High mercury (max. 1 portion per week in pregnancy):

🟡 — Moderate mercury (monitoring worthwhile):

FDA "Best Choices" — safe even in pregnancy (2—3× per week): Skipjack ("light tuna"), trout, herring, sardine, salmon, cod, sole, plaice, mussel, oyster.

Clinical relevance: Vitamin K-containing vegetables cause warfarin INR disturbance (constant intake recommended, not sudden change). Bleeding-enhancing phytochemicals pose a risk alongside any anticoagulant / antiplatelet treatment (warfarin, DOAC: apixaban, rivaroxaban, dabigatran; ASA, clopidogrel).

🔴 — Absolute contraindication during warfarin:

🔴 — Absolute contraindication alongside CYP3A4-substrate drugs (certain statins, calcium channel blockers, cyclosporine):

🟠 — High vitamin K (warfarin: constant intake mandatory, not sudden):

🟠 — Bleeding-enhancing / antiplatelet effect at high doses:

🟡 — Moderate (stop 2 weeks before surgery):

Clinical relevance: In pregnancy there is an increased risk of Listeria monocytogenes (raw milk, cold-smoked fish), Salmonella (raw egg, sprouts), retinol-A hypervitaminosis (teratogenic > 3 mg/day), high-dose essential oils (uterotonic), mercury and arsenic (fetal neurotoxicity).

🔴 — Absolutely prohibited in pregnancy:

🟠 — To be avoided or only under medical supervision:

🟡 — Moderate (moderate consumption OK under medical supervision):

Patient screening: Before a new donor or patient, review the clinical diagnosis and remove from the list those chapters that the given condition makes advisable to avoid. From the remaining foods, rank by evidence level (Appendix A).

Drug interaction: Alongside anticoagulant / antiplatelet / MAO-inhibitor / CYP3A4-substrate treatment, always review lists 2, 7 and 8.

Pregnancy: Every 🔴 item in list 8 is to be automatically excluded. 🟠 only under medical supervision.

Pediatrics: Infant under 1 year: honey (V.4) is absolutely prohibited (botulism spore). High mercury (list 3 🔴) is also prohibited in childhood.

The matrix was compiled from the contraindication sections of the existing 196 chapters. The source of each item is peer-reviewed (EFSA, FDA, EMA, WHO, Cochrane, Monash University, classic clinical RCTs). The notation level is based on the recommendation of the clinical regulatory authority — not on lay "toxic" lists, and not on general "to be avoided" warnings.

The matrix does not replace individual clinical judgment. For a given patient, the full clinical picture (comorbidity, medication list, allergy history, pregnancy, age) must be weighed. As new evidence is updated, the matrix is also updated.