It depends on your diet, lifestyle, and specific situation -- but research shows several widespread deficiencies in adults under 30 that dietary intervention alone frequently doesn't resolve. Vitamin D3 insufficiency affects ~40% of young adults regardless of diet quality (it requires sun exposure or supplementation). B12 deficiency is accelerating with plant-leaning eating patterns. Magnesium insufficiency is near-universal under chronic psychological stress. For most people in their 20s, targeted supplementation addressing these gaps provides measurable benefit.*

The evidence-based foundational stack for most people under 30: Vitamin D3 (2,000--5,000 IU based on sun exposure and latitude), Magnesium Glycinate (200--400 mg/day), Omega-3 EPA+DHA (1--2 g combined), and B12 if your diet is plant-leaning. These four address the most prevalent nutritional gaps with the widest documented health impact. From that foundation, add based on specific goals: Ashwagandha for stress/anxiety, Lion's Mane for cognitive support, Probiotics for gut health.*

Creatine Monohydrate is among the most extensively studied supplements in existence -- over 700 human trials across all age groups, including extensive research in healthy young adults. No credible long-term safety concerns have been identified. The persistent myths about kidney damage apply only to people with pre-existing kidney disease; in healthy adults, creatine at standard doses is safe indefinitely. It is one of the few performance supplements that is unambiguously both safe and effective.*

The clinical evidence for KSM-66® Ashwagandha was largely conducted in adults aged 18--50 experiencing chronic stress and anxiety -- overlapping closely with the Gen Z profile. It is not an acute anxiolytic (it doesn't produce immediate calm), but after 6--8 weeks of 600 mg daily, measurable reductions in perceived stress, anxiety scores, serum cortisol, and sleep disturbance are consistently documented. It works by recalibrating HPA axis sensitivity, not by sedating the nervous system.*

Lion's Mane (Hericium erinaceus) is a culinary and medicinal mushroom with centuries of use in traditional Asian medicine and an expanding clinical research base. The safety profile in healthy adults is excellent -- no significant adverse effects have been identified in clinical trials or case series at standard supplement doses. Long-term consistent use is how the NGF-stimulating benefits accumulate. The only documented concern is rare mushroom allergy in susceptible individuals.*

The only way to know definitively is a serum 25(OH)D blood test -- available through your doctor or many direct-to-consumer lab services. Optimal 25(OH)D is generally 40--60 ng/mL; insufficiency is below 30 ng/mL; deficiency is below 20 ng/mL. If you live above 37° latitude, work indoors, wear sunscreen regularly, or have darker skin, you are at significantly higher risk. In the absence of testing, most nutrition researchers suggest 2,000 IU daily as a conservative, generally safe supplementation level.*