The Science of Red Coffee
Why we combined beetroot and coffee — and what happens inside your cells when you drink it.
The problem with coffee
Coffee works. That's not in question. Caffeine crosses the blood-brain barrier, blocks adenosine receptors, and gives you focus. Adenosine is the molecule your brain uses to signal fatigue — block it, and you feel alert.
But caffeine also causes vasoconstriction — it narrows your blood vessels. Your brain gets the "I'm not tired" signal, but your cells are receiving less oxygen. They're still working, still burning ATP, still accumulating adenosine in the background. The debt is building.
When the caffeine wears off — typically 4-6 hours later — all that pent-up adenosine floods back onto its receptors. Your brain suddenly registers fatigue. But now your cells are also depleted: they've been running on reduced oxygen delivery the entire time. The crash isn't just a signal. It's real energy deficit.
This is the trade-off most coffee drinkers accept without knowing it: focus now, depletion later.
What if you could hedge the trade-off?
This is the question that led us to Red Coffee. Not from a marketing angle — from a mechanistic one.
If caffeine's downside is vasoconstriction and cellular oxygen debt, the logical hedge is to restore blood flow through a parallel pathway. Nitric oxide (NO) is the body's primary vasodilator. And dietary nitrate — found in high concentrations in beetroot — is one of the most well-studied ways to increase NO production.
The hypothesis: deliver caffeine for central focus, and dietary nitrate for peripheral oxygenation. Two mechanisms, operating on different systems, in the same cup.
The nitrate-to-NO pathway
Beetroot is one of the richest dietary sources of inorganic nitrate. When you consume it, the pathway is not direct — it depends on an elegant loop involving your gut, your blood, and your mouth.
Step 1: Absorption. Dietary nitrate is absorbed in the gut within 15-30 minutes of consumption.
Step 2: Enterosalivary recirculation. About 25% of circulating nitrate is actively concentrated by your salivary glands and secreted back into your mouth. This takes roughly 30-60 minutes.
Step 3: Bacterial reduction. Facultative anaerobic bacteria on the surface of your tongue reduce nitrate to nitrite. This is a critical step — without these oral bacteria, the pathway is broken.
Step 4: NO conversion. Nitrite is swallowed and converted to nitric oxide in the acidic environment of the stomach, and further conversion occurs in blood and tissues. Peak NO levels are reached approximately 1-3 hours after consumption.
Step 5: Vasodilation. NO activates soluble guanylate cyclase in vascular smooth muscle, producing cGMP, which relaxes blood vessel walls. Blood flow increases. Oxygen delivery to tissues improves.
This pathway has been validated across hundreds of studies. The International Olympic Committee recognises dietary nitrate (primarily via beetroot juice) as one of only five supplements with confirmed ergogenic effects — alongside caffeine, creatine, beta-alanine, and sodium bicarbonate.
Key references: Lundberg et al. (2008) — the enterosalivary nitrate-nitrite-NO pathway; Bailey et al. (2009) — nitrate reduces O₂ cost of exercise and enhances high-intensity tolerance; Jones et al. (2018) — comprehensive review of dietary nitrate and exercise performance.
The dual mechanism: why these two belong together
Caffeine and beetroot nitrate don't compete. They operate on fundamentally different systems:
Caffeine works centrally — in the brain. It blocks adenosine receptors, reducing the perception of fatigue and increasing alertness.
Nitrate-derived NO works peripherally — in blood vessels and muscle tissue. It promotes vasodilation, improves oxygen delivery, enhances mitochondrial efficiency, and reduces the ATP cost of muscle contraction.
This distinction matters. Caffeine gives you focus. NO ensures your cells can sustain the work your focused brain is directing them to do.
Handzlik & Gleeson (2013) tested this directly: in a randomised, double-blinded, placebo-controlled study with trained cyclists, the combination of beetroot juice (8 mmol nitrate) and caffeine (5 mg/kg) produced a 46% improvement in time-to-exhaustion at 80% VO₂max compared to placebo — greater than either supplement alone (beetroot: 23%, caffeine: 15%). The combination also produced lower ratings of perceived exertion.
Lane et al. (2014) found that caffeine improved cycling time-trial performance by 3-4% in both male and female competitive cyclists. And a recent umbrella review of 15 meta-analyses (2025) confirmed that beetroot juice significantly improves VO₂max in healthy adults and time-to-exhaustion across multiple exercise modalities.
The evidence supports what the mechanisms predict: caffeine and nitrate are additive, not redundant.
Key references: Handzlik & Gleeson (2013) — additive ergogenic effects of combined nitrate and caffeine; Lane et al. (2014) — single and combined effects on cycling TT performance; Senefeld et al. (2020) — ergogenic effect of nitrate supplementation meta-analysis (80 RCTs, d = 0.174, p < 0.001).
The crash-softening hypothesis
Here's where Red Coffee's design logic goes beyond what existing research has directly tested — and we want to be transparent about that.
Our hypothesis: if caffeine's crash has two components — a central signal (adenosine rebound in the brain) and a peripheral deficit (cells depleted of oxygen and ATP) — then NO-driven vasodilation can address the peripheral component. When adenosine floods back and the brain registers "tired," the body isn't actually depleted. Cells have maintained oxygen supply. ATP reserves are intact. The landing is softer.
This is mechanistically sound but hasn't been tested as a product-level RCT. The individual mechanisms are well-established (L1 confidence in the LILI framework). The synergy is supported by Handzlik et al.'s findings (L1-L2). The crash-softening prediction specifically is a first-principles extrapolation (L2-L3).
We state this clearly because epistemic honesty is foundational to how we build. We don't claim what hasn't been proven. We do explain what the mechanisms predict — and we design products around those predictions.
VO₂ max and exercise efficiency
The connection between dietary nitrate and exercise performance is one of the most replicated findings in sports nutrition.
A 2020 meta-analysis of 80 randomised controlled trials found that nitrate supplementation significantly improved exercise performance (standardised mean difference: 0.174, p < 0.001). The effect was consistent across multiple outcome measures: time-to-exhaustion, time-trial performance, and power output.
The mechanism: NO improves mitochondrial efficiency — your cells extract more ATP per unit of oxygen consumed. Studies have shown a 3-7% reduction in the oxygen cost of submaximal exercise following nitrate supplementation, meaning you can do the same work with less metabolic cost. NO also enhances blood flow to type II (fast-twitch) muscle fibres, which are typically less well-perfused.
For the everyday coffee drinker, this translates simply: better oxygen utilisation throughout the day, not just during exercise.
Key references: Bailey et al. (2009, 2010) — nitrate reduces O₂ cost of exercise and enhances muscle contractile efficiency; Larsen et al. (2007) — the foundational discovery that nitrate reduces oxygen cost of submaximal cycling; Senefeld et al. (2020) — meta-analysis of 80 RCTs confirming ergogenic effect.
The oral microbiome matters
There's a practical detail that most beetroot products ignore: the entire nitrate-to-NO pathway depends on bacteria in your mouth.
Specifically, facultative anaerobic bacteria on the dorsal surface of your tongue convert nitrate to nitrite. Without this bacterial step, dietary nitrate cannot be efficiently converted to NO.
This has direct implications for how you consume Red Coffee:
Brush your teeth — not your tongue — before drinking. Aggressive tongue scraping or antiseptic mouthwash destroys the very bacteria that activate the NO pathway. Multiple studies have shown that chlorhexidine mouthwash significantly attenuates the blood pressure-lowering and exercise performance-enhancing effects of dietary nitrate.
Wait 30-45 minutes after drinking before brushing. The enterosalivary cycle needs time to complete. Nitrate is being recirculated from blood to saliva during this window.
Antacids and PPIs blunt the pathway. The stomach's acidic environment is where much of the nitrite-to-NO conversion occurs. Proton pump inhibitors reduce gastric acidity and can diminish NO production from dietary nitrate.
Key reference: Woessner et al. (2016) — antiseptic mouthwash attenuates the vascular and blood pressure effects of dietary nitrate.
Timing
Red Coffee is designed around the biology of its two active pathways:
Optimal consumption window: 60-90 minutes after waking. This allows cortisol's natural morning peak (the cortisol awakening response) to begin declining before you introduce caffeine. Adding caffeine at peak cortisol is redundant — you're already alert.
Peak NO: 1-3 hours post-consumption. The enterosalivary cycle takes time. This means the vasodilatory benefit of beetroot ramps up as the morning progresses — exactly when caffeine's vasoconstriction is most active.
Hard caffeine cutoff: 15:00. Caffeine's half-life is approximately 5-6 hours. Consuming it after 3 PM risks disrupting sleep architecture — specifically deep sleep and the autophagy window that depends on it. Within the LILI framework, sleep is the execution layer for cellular repair. Compromising it negates the benefits of any daytime optimisation.
LILI in action
Red Coffee isn't a standalone product decision. It's a product of the LILI framework — the same first-principles model that guides every formulation choice at Akunka.
LILI models your body as oscillating between damage accumulation (driven by ROS from metabolic activity) and repair (driven by autophagy, antioxidant systems, and cellular maintenance). The equation is simple: damage in minus repair out. When repair exceeds damage, your cells get younger locally. When damage exceeds repair, they age.
Every product we build is evaluated through this lens: does it reduce damage input, or does it support repair output?
Red Coffee operates on the damage-reduction side. Caffeine, by enhancing focus and enabling productive activity, supports the behavioural patterns that keep you in a repair-friendly state (structured eating windows, consistent activity, better sleep discipline). Beetroot nitrate, by improving vascular function and mitochondrial efficiency, directly reduces the metabolic cost of daily activity — less ROS generated per unit of work performed.
That's not a marketing story. That's the framework applied to a product.
Two ingredients. Two pathways. One cup.
Most functional coffee brands stack adaptogens, mushrooms, MCT oil, collagen, and a dozen other ingredients — hoping that more means better.
We went the other direction. Two ingredients, chosen because the mechanistic rationale for their combination is specific and evidence-based. Arabica coffee for adenosine receptor blockade. Beetroot for the nitrate-NO vasodilation pathway. Each with decades of research. Together, addressing both sides of the caffeine trade-off.
No kitchen sink. No trend-chasing. Just the two ingredients where the science converges.
References
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Lundberg JO, Weitzberg E, Gladwin MT. The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics. Nature Reviews Drug Discovery. 2008;7(2):156-167.
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Bailey SJ, Winyard P, Vanhatalo A, et al. Dietary nitrate supplementation reduces the O₂ cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. Journal of Applied Physiology. 2009;107(4):1144-1155.
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Bailey SJ, Fulford J, Vanhatalo A, et al. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. Journal of Applied Physiology. 2010;109(1):135-148.
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Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiologica. 2007;191(1):59-66.
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Handzlik MK, Gleeson M. Likely additive ergogenic effects of combined preexercise dietary nitrate and caffeine ingestion in trained cyclists. ISRN Nutrition. 2013;2013:396581.
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Lane SC, Hawley JA, Desbrow B, et al. Single and combined effects of beetroot juice and caffeine supplementation on cycling time trial performance. Applied Physiology, Nutrition, and Metabolism. 2014;39(9):1050-1057.
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Senefeld JW, Wiggins CC, Regimbal RJ, et al. Ergogenic effect of nitrate supplementation: a systematic review and meta-analysis. Medicine & Science in Sports & Exercise. 2020;52(10):2250-2261.
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Woessner M, Smoliga JM, Tarber B, et al. A stepwise reduction in plasma and salivary nitrite with increasing strengths of mouthwash following a dietary nitrate load. Nitric Oxide. 2016;54:1-7.
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Jones AM, Thompson C, Wylie LJ, Vanhatalo A. Dietary nitrate and physical performance. Annual Review of Nutrition. 2018;38:303-328.
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Umbrella Review (2025). Effects of beetroot juice on physical performance in professional athletes and healthy individuals. Nutrients. 2025;17(12):1958. [15 meta-analyses, showing significant improvements in VO₂max (SMD: 0.16), TTE (SMD: 0.37), and Yo-Yo IR1 (SMD: 0.27)]
At Akunka, we publish the science behind every product decision. If you want to go deeper, explore the LILI Framework — the biophysical model that guides everything we build.