The short answer · Alertness
Take caffeine anhydrous for alertness. This is the one to buy.

Force Factor, ProbioSlim®, Weight Loss Essentials, 120 Vegetable Capsules
4.5· 10,385 ratings· $0.15/serving
Caffeine Anhydrous 100 mg — inside the studied 50-400 mg window
Of 1,136 products scored for Alertness, Force Factor, ProbioSlim®, Weight Loss Essentials, 120 Vegetable Capsules ranks #1 with a DoseRank score of 87. Caffeine Anhydrous is the strongest evidence signal for this outcome.
Retailer links may be affiliate links. Rankings and placement are never paid.
The form“Why Caffeine Anhydrous — not Matcha or Theobromine?”Evidence Strong evidence
Caffeine Anhydrous is the strongest evidence signal for this outcome.
- Caffeine AnhydrousThe pick
Strong evidence · 100 mg
Dehydrated, water-free caffeine; delivers a precise, fast-acting stimulant dose, which is why it dominates pre-workout and weight-management formulas.
- Matcha
Strong evidence · 100 mg
Shade-grown green tea ground to a fine powder; delivers whole-leaf catechins (especially EGCG) plus L-theanine and moderate caffeine in one serving.
- Theobromine
Moderate evidence · 53.6 mg (calculated)
Alkaloid found in cocoa; a mild stimulant and vasodilator related to caffeine but with gentler, longer-lasting effects and minimal jitter.
The dose“Is the dose actually effective?”Dose fit 70
Caffeine Anhydrous at 100 mg lands inside the studied 50-400 mg window.
Caffeine Anhydrous
Studied window 50-400 mg · this pick 100 mg
The ranking“Why should I trust this pick?”Trust 88
Strong trust signals — consistently high marks from verified buyer ratings. Each product gets a DoseRank score blending clinical strength, evidence, dose fit, trust and value. Retailer links may be affiliate links — the scoring model decides placement, never payment from a brand.
- 1,136 products scored
- Never paid placement
- Evidence level: Strong · 92
- 201 brands
- 8 ingredients
The price“Can I do better than $0.15 a serving?”Value 84
$0.15 per serving — low price tier for this outcome. The cheapest ranked pick here is $0.05 per serving.
- 2Nutricost, Caffeine with L-Theanine, 240 CapsulesScore 87 · $0.05/servingiHerb
- 5Nutricost, Caffeine, 200 mg, 120 CapsulesScore 84 · $0.08/servingiHerb
Why not the absolute cheapest? The DoseRank score also weighs clinical strength, evidence, dose fit and trust — the very cheapest listings rarely hold up everywhere else.
Ready?
The #1 pick is $0.15 a serving.Force Factor, ProbioSlim®, Weight Loss Essentials, 120 Vegetable Capsules — in stock at a tracked retailer.
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Force Factor, ProbioSlim®, Weight Loss Essentials, 120 Vegetable Capsules ranks #1 for Alertness with a DoseRank score of 87. The score blends clinical strength, evidence, dose fit, trust signals and value across 1,136 products scored for this outcome.