Coffee in CKD: aye or nay?

by Robin Rose MD 3/18/25

I have had a long love affair with a cuppa good organic dark roast - my favorite is with cardamom and rose water. But having CKD brings a new set of choices, based on differrent criteria. So I grapple between should I drink coffee or not. I decided to share the conversation going on in my head. Knowledge and data helps this meme of knowing the consequences of your choices.

Coffee is a comforting warm drink and a common daily habit for many people. 400 million cups are ingested daily in the USA alone. .Regular coffee contains multiple potential kidney-modifying compounds,

Caffeine - a stimulant - is a methylxanthine alkaloid which acts as an antagonist of the adenosine receptor - that triggers release of neurotransmitters, such as dopamine, norepinephrine, acetylcholine, gamma-aminobutyric acid, and glutamate. [3,5] This adenosine antagonism of caffeine may prevent constriction of glomerular afferent arterioles, increase renal tissue oxygenation, and prevent renal fibrosis

Methylxanthine, similar to caffeine, can improve the mobilization of intercellular calcium and inhibit phosphodiesterases [enhancing cognitive function]. Caffeine could suppress neuroinflammation and acts as a neuroprotectant by regulating the levels of protein kinase A and the blood supply in the nervous system. [5] Caffeine-derived metabolites may also modulate the gut microbiota and improve depression.  Higher concentrations of methylxanthine can inhibit the uptake of calcium.

Caffeine modifies kidney hemodynamics and natriuresis by inhibiting sodium re-absorption in the proximal and distal tubules - promoting free water and solute excretion [pee it off!] along with modification of the renin-angiotensin-aldosterone system. Responding to this sodium delivered to the distal tubule, caffeine also inhibits the tubuloglomerular feedback response and may help to maintain glomerular filtration rate and renal plasma flow (RPF) - while reducing consumption of renal oxygen (O2).

Cognitive impairment is a common CKD complication. Caffeine intake has been shown to improve cognitive performance Jia et al. [5] found that caffeine only benefited the cognitive function of patients with CKD stages 2 and 3 [early CKD] .Patients with stage 4 and 5 suffer from severely damaged clearance capacity --::> causing accumulation of caffeine metabolites in the blood. These higher levels of metabolites are equivalent to consuming a large amount of caffeine and can be harmful to the nervous system. The group specified that less than 279 mg daily was the sweet spot for coffee's benefit.

There are also polyphenol bioactive compounds, including chlorogenic acid, and diterpenes,[cafestol and kahweol] trigonelline, and melanoidins, [which are Maillard reaction products] serve as plant-based antioxidant, anti-inflammatory, anti-carcinogenic, anti-thrombotic and anti-fibrotic ingredients. These improve the oxidative stress and inflammation that can lead to kidney injury. Coffee can ameliorate oxidative stressdue to its ability to induce mRNA and protein expression and mediate Nrf2-ARE pathway stimulation. Here's a detailed run-down of the components and what they do.

~neuroprotective (caffeine, chlorogenic acids and melanoidins)

~anti-inflammatory (caffeine, chlorogenic acids, melanoidins, diterpenes)

~microbiota modulation (polysaccharides, melanoidins, chlorogenic acids),

~immunostimulatory (polysaccharides)

~antidiabetic (trigonelline, chlorogenic acids)

~antihypertensive (chlorogenic acids)

~hypocholesterolemic (polysaccharides, chlorogenic acids, lipids)

Studies have shown that coffee may protect against liver, neurologic, cardiovascular, neoplastic, and metabolic diseases. For many conditions, the protective effects of coffee are dose dependent - with an upper limit beyond which the benefits of "too much" are less pronounced [and potentially harmful (see below)] --::> more than 3 to 5 cups daily can lead to all-cause and cardiovascular disease death.

THE BENEFITS FIRST

There are quite a few studies that verify the benefit of coffee in CKD. A couple follow.

Kanbay et al [1] looked at 12 studies investigating the relationship between coffee consumption and incident CKD --::> showing that coffee consumption was associated with a significant decrease in the risk for incident CKD outcome. They looked at the incidence of CKD, the progression, and CKD-associated mortality - in relation to coffee consumption and the amount of consumption. In fact, they found that there was a greater benefit in individuals drinking ≥2 cups/day compared to those who drank ≤1 cup/day. Coffee consumption was also associated with a lower risk of albuminuria and overall, the risk of CKD-related death was lower in coffee users.

Hu et al. [2] looked at 14,209 participants [aged 45 to 64 years] from the Atherosclerosis Risk in Communities (ARIC) Study. They only considered people from stage 3 on. The made adjustments for demographic, clinical, and dietary factor - but higher coffee consumption was associated with lower risk for incident CKD compared with those who never consumed coffee. Incredibly, each additional cup of coffee consumed daily decreased the risk for incident CKD by 3%.

Coffee can improve endurance and speed as well as offering a decreased perception of fatigue. The fatigue of CKD may interfere with the renology obligation to make exercise a daily do.

The oxalate load of coffee is low, unlike black tea which is very high [green tea is lower].

Coffee's lipid fraction contains cafestol and kahweol --::> these act as safeguards against some malignant cells by modulating the detoxifying enzymes.

THE DANGERS

~Low caffeine intake refers to below 200 mg/day.

~12 ounces of coffee contains 135 milligrams of caffeine

~Moderate caffeine intake is considered to be between 200 and 400 mg/day

~High intake is above 400 mg/day.

~Recommended dose of caffeine intake for the general population is 400 mg/day or less

~Daily dose of caffeine intake >500–600 mg can harm the cardiovascular and nervous systems by positive inotropic and anxiogenic-like effects --::> leading to tachycardia, and anxiety, increasing the risk of health problems. The recommended dose of caffeine intake was ≤ 279 mg/day for cognitive function in CKD.

Coffee can increase the respiratory rate, heart rate and blood pressure. Temporary elevation of blood pressure is nephron-hazardous. Caffeine as a stimulant can also cause increased blood flow and stress on the kidneys. Excessive caffeine intake has also been linked to kidney stones.

Awareness allows us to choose well. A 12 ounce cup of coffee contains 116 mg of potassium - for those who need to monitor their potassium, this is critical info. High potassium can disrupt cardio-electrophysiology, resulting in arrhythmias. High potassium also contributes to muscle weakness, another known sspect of CKD.

COMT = catechol-O-methyltransferase defect --::> this genetic polymorphism results in a substitution that causes issues with metabolizing catecholamines, including dopamine and norepinephrine, [neurotransmitters involved in mood, motivation, and stress response] and .including those released in response to caffeine [which can increase the release of catecholamines]. Those with lower COMT activity are more sensitive to the effects of caffeine [increased anxiety or other adverse effects]. Those with higher COMT activity might metabolize caffeine more efficiently and experience fewer negative effects.

It is important to remember that CKD causes excessive sympathetic nervous system output - renalase is an enzyme made in the kidneys responsible for breaking down these stress hormones. In CKD it is lower, meaning more sttress hormones that don't get processed and ewliminated. Anything adding to this problem will complicate CKD and its cardiovascular disease twin. Studies have suggested that those with specific COMT genotypes can experience different effects from coffee. 

Some Other Hazards

Acrylamide forms during the roasting of coffee beans, and can be a carcinogen. Mycotoxins have been identified in coffee: ochratoxin A and aflatoxin B1 are both brain and kidney toxic. Proper storage of coffee remains significant to lower this mold issue. Pesticide residues on coffee are not to be ignored in CKD.

Higher levels of the detoxifying enzymes of coffee raise serum cholesterol --::> this poses a threat to coronary health, with heart attack and stroke, insomnia, and cardiovascular complications. Caffeine affects the adenosine receptors--::> its withdrawal is accompanied with muscle fatigue and other problems in those addicted to coffee.

The diterpenoid alcohols in coffee can increase serum homocysteine levels --::> adverse effects on cardiovascular system.

Postmenopausal women should avoid excessive consumption of coffee because it can interfere with hormone replacement benefits.

SO YOU TELL ME?? To drink it or not to drink it? That really is the question. I'm still on the fence for my own case. Everyone has to educate and choose for themselves. Cheers!!

REFERENCES

1. Kanbay M et al. Effect of Coffee Consumption on Renal Outcome: A Systematic Review and Meta-Analysis of Clinical Studies. J Ren Nutr. 2021 Jan;31(1):5-20.

2. Hu EA et al. Coffee Consumption and Incident Kidney Disease: Results From the Atherosclerosis Risk in Communities (ARIC) Study. Am J Kidney Dis. 2018 Aug;72(2):214-222.

3. Tommerdahl KL et al. The Evaluation of Coffee Therapy for Improvement of Renal Oxygenation (COFFEE) Study: A Mechanistic Pilot and Feasibility Study Evaluating Coffee's Effects on Intrarenal Hemodynamic Function and Renal Energetics. Kidney Int Rep. 2022 May 4;7(7):1682-1685.

4. O.J. Kennedy. Am J Kidney Dis.2019; 75(5):753-761.

5. Jia L. et al. Front. Med. October 2022; 9 ; https://doi.org/10.3389/fmed.2022.976244

6. Butt MS, Sultan MT. Coffee and its consumption: benefits and risks. Crit Rev Food Sci Nutr. 2011 Apr;51(4):363-73.

7. Gökcen BB, Şanlier N. Coffee consumption and disease correlations. Crit Rev Food Sci Nutr. 2019;59(2):336-348.

8. Ludwig IA, Clifford MN, Lean ME, Ashihara H, Crozier A. Coffee: biochemistry and potential impact on health. Food Funct. 2014 Aug;5(8):1695-717.