Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets vs Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)
Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets (#2, best premium) vs Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) (#4): in our L-Theanine for Calm Focus scoring the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets totals…
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Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets
$18.87Check price at iHerbRead full review
Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)
$15.95Check price at iHerbRead full reviewTopsFive comparison scores
Side by side
| Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets | Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) | |
|---|---|---|
| Price | $18.87 | $15.95 |
| L-Theanine Per Serving | 200 mg | 200 mg |
| L-Theanine Form | Suntheanine® enzymatically produced L-theanine | Generic L-theanine powder; branded purity process not disclosed |
| Serving Size | 2 chewable tablets | 1 scoop (0.2 g) |
| Servings Per Container | 30 | 500 |
| Caffeine | 0 mg; none listed | 0 mg; none listed |
| Format / Vegan | Chewable tablets; suitable for vegans | Loose unflavored powder; labeled vegetarian |
| Other Ingredients | Organic cane sugar, xylitol, stearic acid, silica, natural tropical flavor, citric acid, magnesium stearate | None |
| Testing / Certification | Isura non-GMO documentation and mass-spec lab verification; no USP/NSF certificate or downloadable current-lot COA on the page | Label states third-party tested and GMP compliant; no named certification or published product-specific COA linked |
How they differ in real use
Built from our l theanine for calm focus scoring, each product's published specifications, and verified owner feedback — not hands-on testing.
Both the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets and the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) made our Top 5 L-Theanine for Calm Focus, at #2 (best premium) and #4. Its Suntheanine form, 200 mg serving, and named Isura verification are strong on the heavily weighted criteria. It ranks below the winner because of its substantially higher active-ingredient cost and added-sugar chewable formulation. Exceptional value, a 200 mg serving, and a one-ingredient label earn fourth place. It remains below the branded products because neither L-isomer process documentation nor a product-specific laboratory report is published on the iHerb page.
We score l-theanine for calm focus on Third-Party Testing (30%), Form & Bioavailability (25%), Dose vs Research (20%), Label Transparency (15%) and Value (10%). On that basis the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets totals 7.9 out of 10 and the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) 6.7. The widest gap is Third-Party Testing, where the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets scores 7 against 3 for the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) — independent certification or a published certificate of analysis. Form & Bioavailability also separates them: 10 for the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus 6 for the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g). The Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) claws back ground on Value and Label Transparency.
On paper, the specifications that actually differ: L-Theanine Form — Suntheanine® enzymatically produced L-theanine on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus Generic L-theanine powder; branded purity process not disclosed on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g); Serving Size — 2 chewable tablets on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus 1 scoop (0.2 g) on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g); Servings Per Container — 30 on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus 500 on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g); Format / Vegan — Chewable tablets; suitable for vegans on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus Loose unflavored powder; labeled vegetarian on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g); Other Ingredients — Organic cane sugar, xylitol, stearic acid, silica, natural tropical flavor, citric acid, magnesium stearate on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus None on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g); Testing / Certification — Isura non-GMO documentation and mass-spec lab verification; no USP/NSF certificate or downloadable current-lot COA on the page on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus Label states third-party tested and GMP compliant; no named certification or published product-specific COA linked on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g). They match on L-Theanine Per Serving and Caffeine.
Pricing as of August 5, 2026: $18.87 for the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets and $15.95 for the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g), a $2.92 difference in the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)'s favor. Owners praise the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets for 200 mg Suntheanine serving directly matches several human-trial doses and isura mass-spec laboratory verification and non-GMO documentation are identified; the most common complaint is costs $0.63 per 200 mg serving, the highest cost in this list. Owners praise the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) for 200 mg serving with no other ingredients and approximately $0.03 per serving and 500 servings per container; the most common complaint is generic L-theanine without a disclosed branded L-isomer process.
Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets
- 200 mg Suntheanine serving directly matches several human-trial doses
- Isura mass-spec laboratory verification and non-GMO documentation are identified
- Vegan chewable format with no caffeine
- Costs $0.63 per 200 mg serving, the highest cost in this list
- Two-tablet serving contains 3 g added sugar plus xylitol and flavoring
Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)
- 200 mg serving with no other ingredients
- Approximately $0.03 per serving and 500 servings per container
- Vegetarian, gluten-free, non-GMO, and caffeine-free labeling
- Generic L-theanine without a disclosed branded L-isomer process
- Measuring a 0.2 g scoop can be less repeatable than using a premeasured capsule
Which should you buy?
The Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets is the better fit for buyers prioritizing Suntheanine and a 200 mg labeled serving and people who prefer chewables over capsules or powder — it is the higher-scoring pick here, chiefly for Third-Party Testing and Form & Bioavailability. The Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) is the better fit for high-volume buyers prioritizing cost per active milligram and buyers wanting a filler-free powder with adjustable portions, and the stronger choice if Value and Label Transparency matter more to you than the overall score. If the $2.92 saving matters more than Third-Party Testing, the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) is the better value. The Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets is a poor fit for buyers avoiding added sugar or xylitol; the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) is a poor fit for buyers prioritizing Suntheanine or AlphaWave.
Choose the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets if
- Buyers prioritizing Suntheanine and a 200 mg labeled serving
- People who prefer chewables over capsules or powder
Skip it if
- Buyers avoiding added sugar or xylitol
- Value-focused buyers seeking a low cost per active milligram
Choose the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) if
- High-volume buyers prioritizing cost per active milligram
- Buyers wanting a filler-free powder with adjustable portions
Skip it if
- Buyers prioritizing Suntheanine or AlphaWave
- People who prefer premeasured capsules
Common questions
Is the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets better than the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)?
In our L-Theanine for Calm Focus ranking the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets scores higher overall, 7.9 to 6.7, with the biggest advantage in Third-Party Testing. The Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g) is stronger on Value and Label Transparency, so it is the better pick if those matter most to you.
How much more does the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets cost than the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)?
$2.92 more as of August 5, 2026: $18.87 for the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets against $15.95 for the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g). Prices move, so the merchant page shows the current figure. What the extra buys is mostly Third-Party Testing — 7 versus 3 in our scoring.
What is the main difference between the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets and the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g)?
The headline spec difference is L-Theanine Form: Suntheanine® enzymatically produced L-theanine on the Natural Factors, Stress-Relax, Suntheanine L-Theanine, 100 mg, 60 Chewable Tablets versus Generic L-theanine powder; branded purity process not disclosed on the Nutricost, L-Theanine, Unflavored, 3.6 oz (100 g). In use, the gap that matters most is Third-Party Testing (7 vs 3 in our scoring): independent certification or a published certificate of analysis.