Open Flint Cool Mint pouch tin in afternoon sunlight on a worn green table, beside an open notebook, a pencil and a sprig of mint

THE RESEARCH

Every dose, and the research behind it.

Most focus products list ingredients and skip the amounts. Here's every number in a Flint pouch, the trials those numbers come from, and the gaps.

  • 7 ingredients

  • Every dose on the tin

  • 22 peer-reviewed papers

  • 0 proprietary blends

How to read this page

Every paper here is from a peer-reviewed journal, and every title links to it. Each line says who a trial tested and the dose it used. We don't summarise what the researchers concluded: read the paper and make your own mind up. Under EU law, the only health claims on this page are the authorised ones for the B-vitamins.

What's in one pouch

Ingredient Per pouch NRV
Caffeine 100mg n/a
L-theanine 100mg n/a
Cognizin® citicoline 100mg n/a
Pantothenic acid 3mg 50%
Vitamin B6 0.7mg 50%
Folate 100µg 50%
Vitamin B12 1.25µg 50%

No nicotine. No sugar. No proprietary blend. 20 Cool Mint pouches per tin.

Close-up of five white Flint pouches, showing the soft fabric and sealed ends

Why a pouch, not a drink?

You tuck it under your top lip, and the caffeine absorbs through your gum. There's nothing to brew, open or finish, and the dose is the same every time.

What the research covers. No study has measured caffeine absorption from a pouch yet. The closest is chewing gum. A 2002 trial gave 84 men caffeine as gum or a capsule, at 50, 100 or 200mg. A 2025 trial compared a caffeine mouth spray with coffee and an energy drink. A 2026 trial tested an 80mg caffeine pouch for physical performance, but didn't measure absorption.
Research papers (5)

  1. The rate of absorption and relative bioavailability of caffeine administered in chewing gum versus capsules to normal healthy volunteers.

    Kamimori et al., 2002, International Journal of Pharmaceutics. Tested: 84 healthy men, 12 per group. Used: 50, 100 or 200mg caffeine as gum or capsule, or placebo. Funding: US government (PubMed record).

  2. Sublingual caffeine delivery via oral spray does not accelerate blood caffeine increase compared to ingestion of caffeinated beverages.

    McCarthy et al., 2025, European Journal of Applied Physiology. Tested: 14 adults (6 men, 8 women). Used: 60mg caffeine as a mouth spray, coffee or energy drink. Funding: Mitacs. Authors declare no competing interests.

  3. The Effect of Novel Low-Dose Caffeine Products on Physical Performance.

    Hulton et al., 2026, Nutrients. Tested: 19 adults. Used: an 80mg caffeine pouch, 80mg caffeine gum, or placebo gum. Authors declare no conflicts of interest.

  4. Administration of Caffeine in Alternate Forms.

    Wickham and Spriet, 2018, Sports Medicine. A review of caffeine in gum, bars, gels, mouth rinses and other forms. Funding: not listed on PubMed.

  5. Caffeine pouches: an emerging nicotine-free stimulant trend and its implications for public health.

    Podwiak, 2026, Health Problems of Civilization. A review of caffeine pouches as a product category. Funding: not listed.
Bar chart of caffeine per serving: lowest high-street coffee 33mg, Flint pouch 100mg, highest coffee 325mg. Which? test, 2023

Why 100mg caffeine?

100mg per pouch · the same every time

Caffeine has been studied for alertness and reaction time for decades. Trials of caffeine on its own have used 75 to 150mg. Flint uses 100mg, inside that range and fixed, so you can count your day. For comparison, a 2023 Which? test of high-street coffees found 33mg to 325mg a cup.
Research papers (3)

  1. Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine.

    Haskell et al., 2005, Psychopharmacology. Tested: 24 habitual caffeine consumers and 24 non-consumers. Used: 75mg or 150mg caffeine in a drink, or placebo. Funding: not listed on PubMed.

  2. Faster but not smarter: effects of caffeine and caffeine withdrawal on alertness and performance.

    Rogers et al., 2013, Psychopharmacology. Tested: 369 adults (212 medium-to-high and 157 non-to-low caffeine consumers). Used: 100mg then 150mg caffeine, or placebo. Funding: Biotechnology and Biological Sciences Research Council (UK).

  3. Effects of Different Sources of Low-Dose Caffeine on Mood/Arousal and Cognitive Performance.

    Irwin et al., 2022, Perceptual and Motor Skills. Tested: 22 adults (15 men, 7 women). Used: 80mg caffeine from coffee, an energy drink, a capsule or a mouth strip, or water. Funding: not listed on PubMed.

Why match it 1:1 with L-theanine?

100mg L-theanine · 1:1 with the caffeine

L-theanine is an amino acid found in tea. It has been studied alongside caffeine for attention in at least 8 trials. Those trials ran L-theanine to caffeine at anywhere from 0.67:1 to 2.4:1. Flint sits at 1:1, inside that range, and prints both doses on the tin.
Dot chart of L-theanine to caffeine ratios in nine published trials, from 0.67:1 to 2.4:1, with Flint at 1:1
Ratios used in published trials, with Flint for comparison
Source L-theanineCaffeineRatio
Dodd 2015 50mg 75mg 0.67:1
Flint pouch (not a trial) 100mg 100mg 1:1
Kahathuduwa 2017 200mg 160mg 1.25:1
Kahathuduwa 2018 200mg 160mg 1.25:1
Nawarathna 2025 200mg 160mg 1.25:1
Haskell 2008 250mg 150mg 1.67:1
Owen 2008 100mg 50mg 2:1
Giesbrecht 2010 97mg 40mg 2.4:1
Einöther 2010 97mg 40mg 2.4:1
Research papers (11)

L-theanine with caffeine

  1. A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood.

    Dodd et al., 2015, Psychopharmacology. Tested: 12 habitual and 12 non-habitual caffeine consumers. Used: 75mg caffeine, 50mg L-theanine, both, or placebo. Funding: not listed on PubMed.

  2. Acute effects of theanine, caffeine and theanine-caffeine combination on attention.

    Kahathuduwa et al., 2017, Nutritional Neuroscience. Tested: 20 healthy men. Used: 200mg L-theanine, 160mg caffeine, both, a cup of black tea, or water. Funding: not listed on PubMed.

  3. L-Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging study.

    Kahathuduwa et al., 2018, Nutrition Research. Tested: 9 healthy men. Used: 200mg L-theanine, 160mg caffeine, both, or water. Funding: outside source, not named on PubMed.

  4. High-dose L-theanine-caffeine combination improves neurobehavioural and neurophysiological measures of selective attention in acutely sleep-deprived young adults: a double-blind, placebo-controlled crossover study.

    Nawarathna et al., 2025, British Journal of Nutrition. Tested: 37 sleep-deprived adults aged 22 to 30. Used: 200mg L-theanine with 160mg caffeine, or placebo. Funding: not listed on PubMed.

  5. The effects of L-theanine, caffeine and their combination on cognition and mood.

    Haskell et al., 2008, Biological Psychology. Used: 250mg L-theanine, 150mg caffeine, both, or placebo. Funding: not listed on PubMed.

  6. The combined effects of L-theanine and caffeine on cognitive performance and mood.

    Owen et al., 2008, Nutritional Neuroscience. Tested: 27 healthy adults. Used: 50mg caffeine with and without 100mg L-theanine. Funding: not listed on PubMed.

  7. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness.

    Giesbrecht et al., 2010, Nutritional Neuroscience. Tested: 44 young adults. Used: 97mg L-theanine with 40mg caffeine, or placebo. Funding: outside source, not named on PubMed.

  8. L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness.

    Einöther et al., 2010, Appetite. Used: 97mg L-theanine with 40mg caffeine, or placebo. Industry link: Unilever R&D.

  9. The Cognitive-Enhancing Outcomes of Caffeine and L-theanine: A Systematic Review.

    Anas Sohail et al., 2021, Cureus. A review of the combination trials. Authors declare no competing interests.

L-theanine on its own

  1. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.

    Hidese et al., 2019, Nutrients. Tested: 30 healthy adults. Used: 200mg L-theanine a day for 4 weeks, or placebo. Industry link: funded by Taiyo Kagaku, which supplied the L-theanine; two authors are its employees.

  2. Cognitive and affective effects of L-Theanine: a systematic review and meta-analysis of 31 randomized trials.

    Gerolymos et al., 2026, Molecular Psychiatry. A review of 31 randomised trials. Industry link: one author founded a supplement company.

Why Cognizin®?

100mg per pouch · 300mg across 3 pouches

Cognizin® is a branded form of citicoline, made by Kyowa Hakko Bio in Japan. Citicoline has been studied for attention and memory in healthy adults. The trials we found used 250mg to 500mg a day, taken daily for 4 to 12 weeks. No trial has tested 100mg. 1 or 2 Flint pouches is below the lowest trial dose. 3 pouches gives you 300mg, inside the range.
Bar chart of citicoline per day: Flint 100mg, 200mg and 300mg at 1, 2 and 3 pouches, against published trial doses of 250mg and 500mg
Citicoline per day: trials vs Flint
Source Per day
McGlade 2012 (lower dose) 250mg
McGlade 2012 (higher dose) 500mg
Nakazaki 2021 500mg
Flint, 1 pouch 100mg
Flint, 2 pouches 200mg
Flint, 3 pouches 300mg
Research papers (3)

  1. Improved Attentional Performance Following Citicoline Administration in Healthy Adult Women.

    McGlade et al., 2012, Food and Nutrition Sciences. Tested: 60 healthy women aged 40 to 60. Used: 250mg or 500mg Cognizin® a day for 28 days, or placebo. Industry link: one author from Kyowa, the Cognizin® maker.

  2. Citicoline and Memory Function in Healthy Older Adults: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

    Nakazaki et al., 2021, Journal of Nutrition. Tested: 100 healthy adults aged 50 to 85 with age-related memory complaints. Used: 500mg citicoline a day for 12 weeks, or placebo. Industry link: Kyowa Hakko Bio.

  3. Improvements in concentration, working memory and sustained attention following consumption of a natural citicoline-caffeine beverage.

    Bruce et al., 2014, International Journal of Food Sciences and Nutrition. Tested: 60 healthy adults. Used: a citicoline and caffeine drink, or placebo. Doses aren't given in the published abstract. Funding: US National Institutes of Health (PubMed record).
Flint Cool Mint tin with the four B-vitamins per pouch: vitamin B6 0.7mg, vitamin B12 1.25µg, folate 100µg and pantothenic acid 3mg, each 50% NRV

What the B-vitamins do

This is the only part of the formula with authorised EU health claims. Each vitamin is at 50% of its daily reference value (NRV) per pouch.
  • Vitamins B6 and B12, folate and pantothenic acid contribute to the reduction of tiredness and fatigue.
  • Pantothenic acid contributes to normal mental performance.
  • Vitamins B6 and B12 and folate contribute to normal psychological function.
  • Vitamins B6 and B12 and pantothenic acid contribute to normal energy-yielding metabolism.
  • Vitamins B6 and B12 contribute to the normal functioning of the nervous system.

That's why they're in there: for the tired end of the day.

What we left out

  • Alpha-GPC. It has no EU novel food authorisation, so it can't legally go in.
  • Uridine monophosphate. Its regulatory status in the EU is uncertain.
  • Lion's mane, bacopa and rhodiola. Not in the formula.
  • Nicotine, sugar and a proprietary blend. Never.

How much is too much?

Each pouch has 100mg caffeine. The European Food Safety Authority considers up to 400mg of caffeine a day safe for healthy adults, and up to 200mg in one go. So up to 3 pouches a day, spaced out, and count your coffee too.

EFSA also notes that caffeine close to bedtime can affect sleep, so have your last pouch at least 6 hours before bed.

Flint isn't for under-18s, or anyone pregnant or breastfeeding. If one coffee is already too much for you, Flint will be too.

Source: EFSA Scientific Opinion on the safety of caffeine, 2015. EFSA Journal 13(5):4102.

What the research doesn't cover yet

  • How Flint itself performs in a trial. No trial has tested the Flint pouch. The papers above tested the ingredients, in capsules, drinks and gum, not our pouch.
  • That caffeine, L-theanine or citicoline improve focus. EU law doesn't allow any brand to claim that. The papers above are there for you to read, not as a promise.
  • What happens at 100mg citicoline. No trial has tested it.

Every link last checked 10 October 2026. If one breaks, tell us through the contact form.

Flint Cool Mint pouch tin from above, lid label showing 20 pouches, 100mg caffeine, 100mg L-theanine and 100mg Cognizin

Now you've seen the numbers.

100mg caffeine, 100mg L-theanine and 100mg Cognizin®, every dose on the tin. 14-day returns.

 See the pouch