Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg supplement bottle
Natural Factors

Stress-Relax Suntheanine L-Theanine 100 mg Review

What We Researched
5 active ingredients analyzed · 8 inactive ingredients decoded · 5 brand certifications checked · Last updated: Aug 2026
95
Product Score Excellent
100
Brand Score Excellent

Two independent scores — the product and the brand behind it, never blended into one number. See our methodology.

Product Analysis

Transparency Very Good

Supplement Facts

IngredientAmount% DV
Suntheanine® L-Theanine 200 mg **
Bioavailability Excellent

Absorption Rating

  • Suntheanine® L-Theanine Good
Other Ingredients Excellent

Fillers & Additives

  • Xylitol
  • Natural Flavors
  • Vegetable Magnesium Stearate
  • Cane Sugar
  • Magnesium Stearate
  • Citric Acid
  • Stearic Acid
  • Silica
Efficacy Excellent

Dosage Analysis

  • Suntheanine® L-Theanine 200 mg Effective

Supplement Facts

Ingredient Amount % Daily Value
Calories 15
Total Carbohydrate 4 g 1%‡
Total Sugars 3 g **
Includes 3 g Added Sugars 6%‡
Suntheanine® L-Theanine 200 mg **

Other Ingredients

Inactive ingredients used in manufacturing. All rated for safety.

Xylitol Safe

Provides sweetness with reduced calorie content. Does not promote tooth decay.

Natural Flavors Safe

Improves taste of chewable, gummy, or liquid supplements.

Vegetable Magnesium Stearate Safe

Prevents ingredients from sticking to equipment. Derived from vegetable sources.

Cane Sugar Generally_safe

It is used as a sweetener.

Magnesium Stearate Safe

Prevents ingredients from sticking to manufacturing equipment during tableting.

Citric Acid Safe

Adds tartness and acts as a natural preservative. Also aids in ingredient stability.

Stearic Acid Safe

Helps ingredients flow smoothly through manufacturing equipment.

Silica Safe

Prevents ingredients from clumping and improves powder flow.

Brand Trust Report
Natural Factors

Founded 1950 · Coquitlam, British Columbia, Canada · 832 products · naturalfactors.com

Certifications

5 certifications
B Corp Certified Verified Source
Usp Verified Verified Source
Fda Gmp Inspections Verified Source
Non Gmo Project Verified Source
Usda Organic Verified Source

Transparency

4 claims
Third Party Testing Claim — Verified Source
Testing Lab Disclosure — Verified Source
In House Testing — Verified Source

Violation History

5 incidents
Prop 65 Lead2025-10-31Source
Recall Hi Potency B Complex, RevitalX, Super Multi® IRON FREE2024-07-19Source
Lawsuit Products labeled as containing glucosamine sulfate did not contain the ingredient.2021Source
Prop 65 Lead2016-01-13Source
Recall Natural Factors L-Arginine 500mg2006-04-05Source
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Frequently Asked Questions
Is Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg a good supplement?

Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg received a product quality score of 95/100 in GoodSupp's independent analysis, placing it in the top tier of supplements we've analyzed. The product contains 5 active ingredients Of the 8 inactive ingredients, 7 are rated safe and 0 are flagged for review. The manufacturer, Natural Factors, holds a brand trust score of 100/100 with 5 verified certifications including B Corp Certified, Usp Verified, Fda Gmp Inspections, Non Gmo Project.

What are the ingredients in Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg?

Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg contains 5 active ingredients: Calories (15), Total Carbohydrate (4 g), Total Sugars (3 g), Includes 3 g Added Sugars, Suntheanine® L-Theanine (200 mg). Each ingredient's dosage, form, and safety rating is analyzed independently in GoodSupp's full product breakdown.

Is Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg safe to take?

Natural Factors Stress-Relax Suntheanine L-Theanine 100 mg has been analyzed for ingredient safety across all its components. Always consult your healthcare provider before starting any new supplement, especially if you take medications or have underlying health conditions.

Is Natural Factors a trustworthy supplement brand?

Natural Factors receives a brand trust score of 100/100 based on GoodSupp's independent analysis of certifications, regulatory history, and transparency practices. Founded in 1950 and headquartered in Coquitlam, British Columbia, Canada, the company offers 832 products in their lineup. They hold 5 verified certifications including B Corp Certified, Usp Verified, Fda Gmp Inspections, Non Gmo Project. Third-party certifications are independently verified and indicate the brand meets specific quality, purity, and manufacturing standards. Note: Natural Factors has 5 historical regulatory incidents on record, which are factored into the trust score.

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Disclaimer: GoodSupp provides independent supplement quality analysis for informational purposes only. Scores are generated algorithmically based on ingredient profiles, brand certifications, and public records — read our methodology. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Product data is sourced from manufacturer labels and public databases. GoodSupp is not affiliated with any supplement brand.