Quick Verdict
Vitamin D3
Actually a steroid hormone precursor. Critical for calcium absorption, immune function, hormone production. Widespread d
Evidence: strong (1000+ studies)
Ashwagandha (KSM-66)
Ayurvedic adaptogen herb, most researched for cortisol reduction, testosterone support, and stress resilience.
Evidence: strong (40+ studies)
Side-by-Side Comparison
| Vitamin D3 | Ashwagandha (KSM-66) | |
|---|---|---|
| Category | vitamins | adaptogens |
| Evidence Level | strong | strong |
| Studies | 1000+ | 40+ |
| Dosage | 1000-5000 IU | 300-600 mg |
Stack Compatibility
Vitamin D3: Magnesium (essential cofactor), Vitamin K2 (MK-7), Calcium (if dietary intake low), Zinc
Ashwagandha (KSM-66): Magnesium, L-Theanine, Rhodiola Rosea, Zinc
Which Should You Choose?
Both serve different purposes. Choose based on your priority.