Its adverse effects are well documented, and DEET has been shown to have cytotoxic and apoptotic properties in nucleated cells
Vitamin B12, or cobalamin, is a water-soluble vitamin essential for various bodily functions
But "most" is not "all," and several specific populations may find genuine value in a sub-2.5 mg entry point

Comprehensive Skin Improvements The mechanisms produce: Increased Skin Thickness Both epidermis and dermis show measurable thickening, reversing age-related thinning Improved Hydration Enhanced glycosaminoglycan production creates better moisture retention Significant Smoothing Collagen synthesis stimulation reduces wrinkle depth and surface irregularities Increased Elasticity Elastin production enhancement restores youthful bounce and firmness Improved Contrast (Evenness) Reduced hyperpigmentation and more uniform skin tone Enhanced Collagen I Production The primary structural collagen increases substantially Tightened Loose Skin Matrix remodeling restores structural support Barrier Protein Repair Protective skin barrier proteins receive restoration Photodamage Reduction Mottled hyperpigmentation shows correction Photoaging Protection Photoaging protection includes keratinocyte protection from lethal UV-B radiation and blocking UV-induced erythema without increasing UV sensitivity

Multifunctional role of natural products for the treatment of Parkinsons disease: at a glance
Testing and Diagnosis: A proper B12 deficiency diagnosis should always be confirmed by blood tests, as symptoms alone can be misleading