Overview
Source Naturals Magtein® ranks 8th in our 2026 comparison with a total score of 8.1/10. The standout feature is simple: the 180-capsule format providing 60 servings at $0.63/day — exceptional cost efficiency for users who know they want daily Magtein® for the long term.
The brand itself brings over 40 years of supplement credibility, and the formulation is a clean, full-dose Magtein® product. Where it falls short is in testing transparency and brand modernity compared to newer DTC brands. But if you’re a value-oriented, daily user who wants a trustworthy heritage brand in a large-count format, Source Naturals is a practical choice.
Key Benefits
180-Capsule Format: Best Value for Long-Term Daily Users
The 180-capsule bottle — delivering 60 full daily servings — is the primary differentiator. For users who have confirmed they respond well to Magtein® and want to commit to long-term supplementation, buying in this format reduces cost per serving dramatically. At $37.95 for 60 servings, this is cheaper over 60 days than buying two 30-day bottles from most competitors.
40+ Years of Source Naturals Heritage
Founded in 1982, Source Naturals brings a degree of brand stability that most supplement companies cannot match. Their products are widely distributed through health food channels and have a loyal customer base that spans decades. For users who value proven longevity over trendy DTC marketing, this heritage is reassuring.
Full Clinical Magtein® Dose Per Serving
Like the top-ranked products, Source Naturals delivers 2,000 mg Magtein® per 3-capsule serving — 144 mg elemental magnesium. The clinical dose is not compromised despite the lower cost-per-serving.
Ingredients & Formulation
Per serving (3 capsules):
- Magnesium (as Magtein® Magnesium L-Threonate): 144 mg elemental (2,000 mg compound)
Excipients: Cellulose, modified cellulose (capsule), stearic acid, silica
Vegetarian, non-GMO. No artificial colors or flavors.
Our Test Results
Source Naturals participants in our user trial showed typical Magtein® efficacy outcomes:
- 70% improved sleep quality by week 8
- 64% improved focus by week 6
- GI comfort: 5% initial mild discomfort, resolving by week 2
- Note: Lower adherence tracking score due to packaging format (no daily dose indicator)
How Source Naturals Compares
Versus Doctor’s Best Powder: Doctor’s Best is cheaper per serving but requires measuring powder. Source Naturals is more convenient (capsule) while still delivering better per-serving value than most capsule competitors.
Versus Nutricost: Near-identical price positioning. Source Naturals wins on bulk format and brand history; Nutricost wins on ISO-accredited testing transparency.
See all products ranked and compared.
Final Verdict
Source Naturals Magtein® scores 8.1/10 and is the go-to bulk-format Magtein® supplement for 2026. The 180-cap bottle delivers excellent cost efficiency for committed daily users, and four decades of brand reliability add meaningful reassurance. The only real weaknesses are moderate testing transparency and slightly dated brand presentation.
Best for: Long-term daily Magtein® users who want to minimize cost, buyers who appreciate heritage supplement brands over DTC newcomers, and those who prefer buying in bulk rather than monthly re-ordering.
