What to watch with Nährstoffcheck and fatigue?

When combining a nutrient check with fatigue, caution is warranted: Many direct-to-consumer tests (e.g., IgG-based food intolerance panels like NutriCheck I) lack scientific validation. IgG levels reflect exposure, not intolerance; medical guidelines advise against their use. Genetic markers (e.g., PPARG rs1801282 for diabetes risk, CLOCK rs1801260 for chronotype, CRP rs1205 for inflammation) have small effect sizes and are not diagnostic for fatigue. True nutrient deficiencies (iron, B12, vitamin D, ferritin) should be assessed by a physician via standard blood work, not by home tests. The 'leaky gut' concept remains controversial, and related panels have no proven clinical utility. Conclusion: Avoid self-diagnosis or supplementation without medical guidance. Evidence: mostly marketing/unclear.