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Solgar L-Lysine vs Nutricost L-Theanine

Side-by-side comparison of scores, ingredients, prices and real customer feedback for Solgar L-Lysine and Nutricost L-Theanine.

Last verified: 26 Mar 2026 · Based on 21 reviews

Back to comparison hub View amino acids guide
80.0
Score Summary

Solgar L-Lysine scores 80.0/100 vs Nutricost L-Theanine at 76.0/100. Solgar L-Lysine wins on effectiveness, ingredient quality, value for money. Nutricost L-Theanine is stronger on certifications.

How Do the Scores Compare?

L-Lysine 1000mg Free Form 5...
Nutricost L-Theanine 200mg,...
L-Lysine 1000mg Free Form 50 Tablets
L-Lysine 1000mg Free Form 5...
Solgar
 Nutricost L-Theanine 200mg, 120 Capsules, Double Strength - Non-GMO, Gluten Free
Nutricost L-Theanine 200mg,...
Nutricost
Overall Score 80.0 76.0
Effectiveness 90.0/100
Best
 82.0/100
Ingredient Quality 80.0/100
Best
 75.0/100
Value for Money 80.0/100
Best
 62.0/100
Side Effects 90.0/100
Best
 90.0/100
Best
Certifications 40.0/100 58.0/100
Best
Best Price £10.40 Holland & Barrett → £8.36 Amazon UK →
Cheapest
Price per Serving N/A £8.36 1 servings
Form Tablet Capsule
Dose 712 g 2.2 Ounces
Third-Party Tested ✗ No ✗ No
Reviews Analysed 5 16

L-Lysine 1000mg Free Form 50 Tablets

Pros

  • ✓Cold sore management: reviewers report reduced swelling, size, and duration when taken early
  • ✓Verified brand quality: Solgar is established in supplementation with consistent user satisfaction
  • ✓Well-tolerated: no reported indigestion or side effects despite large tablet form
  • ✓Measurable dosing: provides exact lysine amounts versus dietary sources

Cons

  • ✗Large tablet size may be difficult for some users to swallow
  • ✗No third-party testing certification noted on product
  • ✗Not vegan-suitable formulation
  • ✗Limited clinical evidence in reviews for claimed general immunity boost (1 mention)

Best For

Individuals with recurrent cold sore outbreaks Those seeking targeted lysine supplementation without multi-amino complexes People preferring tablet form over powders or capsules Users wanting preventive support during high-stress periods
Holland & Barrett £10.40 Amazon UK £22.80
View full review →

Nutricost L-Theanine 200mg, 120 ...

Pros

  • ✓Strong anxiety and stress reduction reported across the majority of reviews
  • ✓Highly effective for smoothing caffeine jitters and improving focus quality
  • ✓Notable sleep improvement, especially when combined with magnesium glycinate
  • ✓Well-tolerated with no side effects reported across all 12 reviews

Cons

  • ✗Price flagged as expensive relative to equivalent products on the market
  • ✗Sleep benefits may take 4–6 weeks to fully manifest for some users
  • ✗Third-party testing claimed in marketing copy but contradicted by product specs
  • ✗Not vegan — capsule shell may contain gelatin

Best For

Coffee and pre-workout users seeking to eliminate jitters Light sleepers or those with difficulty switching off at night People managing mild to moderate daily anxiety or stress Nootropic stackers looking for a clean calming base Anyone sensitive to sedating sleep aids who wants a gentler alternative
Amazon UK £8.36
View full review →

Score Breakdown: Solgar L-Lysine vs Nutricost L-Theanine

Solgar L-Lysine Winner 80.0/100

Solgar's L-Lysine 1000mg receives unanimous 5-star ratings from 4 reviewers, with strong endorsement for cold sore management and immune support.

Effectiveness
L-Lysine 1000mg ..
90.0/100
Nutricost L-Thea..
82.0/100
Ingredient Quality
L-Lysine 1000mg ..
80.0/100
Nutricost L-Thea..
75.0/100
Value for Money
L-Lysine 1000mg ..
80.0/100
Nutricost L-Thea..
62.0/100
Side Effects
L-Lysine 1000mg ..
90.0/100
Nutricost L-Thea..
90.0/100
Certifications
L-Lysine 1000mg ..
40.0/100
Nutricost L-Thea..
58.0/100

What are the key differences?

Solgar L-Lysine is best for: Individuals with recurrent cold sore outbreaks, Those seeking targeted lysine supplementation without multi-amino complexes
Nutricost L-Theanine is best for: Coffee and pre-workout users seeking to eliminate jitters, Light sleepers or those with difficulty switching off at night

Frequently Asked Questions

Which is better, Solgar L-Lysine or Nutricost L-Theanine? ▼
Solgar L-Lysine scores 80.0/100 overall while Nutricost L-Theanine scores 76.0/100. Solgar L-Lysine comes out ahead, scoring higher on effectiveness (90.0 vs 82.0). Solgar L-Lysine is best suited for Individuals with recurrent cold sore outbreaks and Those seeking targeted lysine supplementation without multi-amino complexes. Nutricost L-Theanine is better for Coffee and pre-workout users seeking to eliminate jitters and Light sleepers or those with difficulty switching off at night.
Is Solgar L-Lysine worth the price compared to Nutricost L-Theanine? ▼
Solgar L-Lysine costs £10.40 while Nutricost L-Theanine is £8.36. For value, Solgar L-Lysine scores 80.0/100 vs Nutricost L-Theanine's 62.0/100. Solgar L-Lysine delivers better value relative to its quality. Note that Solgar L-Lysine comes as tablet while Nutricost L-Theanine is capsule, which may affect your preference.
Which has fewer side effects? ▼
Solgar L-Lysine scores 90.0/100 for side effects (higher means fewer reported issues) while Nutricost L-Theanine scores 90.0/100. Both have similar side effect profiles based on user reviews. For certification and testing, Solgar L-Lysine scores 40.0/100 vs Nutricost L-Theanine's 58.0/100. Always consult a healthcare professional before starting any supplement.

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Disclaimer: AIScored provides data-driven comparisons based on publicly available reviews. This is not medical advice. Affiliate links may earn us a commission at no extra cost to you.

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