A Love Affair with Coffee and the Science That Justifies It

Three cups a day. It's more than a habit; it's a ritual, a compass guiding my global explorations. My love for coffee began in the bustling coffee shops of Boston during my undergraduate years as a Barista and grew amidst the vibrant energy of New York City in high school. I fondly recall those cherished moments with my sister during the COVID blues, as we made our ritualistic pilgrimage to Sweet Leaf, just a ten-minute walk away, for our iced vanilla lattes with oat milk. It wasn't merely the caffeine but the atmosphere, the comforting hum of conversation, and the promise of a small, delightful escape.

2019, Sweetleaf, Long Island City, NY

2019, Cafe del Mural, Cartagena, Colombia 

Later, my walks with my dad and our energetic puppy, Lexi, through the diverse neighborhoods of NYC became synonymous with discovering hidden coffee gems. Initially, I was captivated by sweet concoctions, flavored syrups, and the creamy embrace of plant-based milks. But as life took a turn and an eating disorder developed, my coffee order transformed into a black Americano, a means to minimize "empty calories." Ironically, this austerity gave rise to a new appreciation for the taste and quality of my coffee. I began to discern nuanced flavors, bright acidity, and the subtle dance of tasting notes best revealed at room temperature, as a true coffee lover knows that coffee cannot be fully tasted at scalding temperatures or on ice. 

Now, as a global nomad, the excitement of landing in a new city is intrinsically tied to the hunt for exceptional coffee. My pre-trip ritual involves poring over maps, memorizing them with the same fervor I once reserved for the digits of pi (yes, I still remember the first 100 digits from a 6th-grade math competition). I search for specialty coffee shops with a cozy ambiance and a loyal local following. Thankfully, the internet teems with curated guides, making the quest for the perfect brew surprisingly seamless.

2024, Tokyo, Japan 

My recent days in Chișinău, Moldova, have been a testament to this. The city has graced me with a truly special coffee scene. From the expertly crafted brews at Kosmonatvika to the welcoming atmosphere of Coffee Monkey, the passion at Pasio Coffee, the sincerity at Sincer Coffee, and the artistry at Miro Cafe, not a single cafe has disappointed. Now, I have my sights set on Gdańsk, Poland, where Drukarnia, Jozef K, Kompozyt cafe, Lang fuhr, and Fukafe await, each promising a unique experience. With so many enticing options, how does one explore twenty specialty shops in two days without succumbing to jitters from a caffeine overload? 

2025, No. 39, Chiang Mai, Thailand

Amidst this caffeinated exploration, I encountered a researcher discussing coffee's biochemical and physiological benefits. As a devoted coffee lover and global taster (let's just say Kilimanjaro's coffee scene didn't quite ignite the same spark as Armenia's or Chiang Mai's!), along with being a biology major aspiring to work in functional medicine, this resonated with me. I felt compelled to delve into recent studies examining coffee's impact on the human body. Here's what I discovered:

Emerging research highlights coffee's profound influence on our gut. A review in Nutrients suggests that moderate coffee consumption (less than four cups daily) is linked to a more diverse gut microbiota, an increase in beneficial bacteria like Firmicutes and Actinobacteria, and a decrease in Bacteroidetes (Saygili et al., 2024). The phenolic and chlorogenic acids in coffee may even possess antibacterial properties within the gut. Furthermore, caffeine exhibits anti-inflammatory effects, and other coffee components may modulate immune responses. Coffee, including its decaffeinated counterpart, stimulates the release of gastrin and aids in gastric and pancreatic secretion while decreasing esophageal pressure. However, high consumption (over five cups daily) might elevate the risk of gastroesophageal reflux disease. Interestingly, coffee appears to boost ileal and colonic motility independently of caffeine, possibly by acting on muscarinic receptors in gut smooth muscle cells and even influencing the gut-brain axis, potentially impacting visceral pain and CNS functions, perhaps mediated by changes in the gut microbiota (Saygili et al., 2024).

The bioactive compounds within those cherished beans also significantly affect our well-being. Compounds like caffeine, chlorogenic acids (CGAs), trigonelline, melanoidins, and diterpenes found in Coffea Arabica and Robusta have the potential to lower the risk of type-2 diabetes, cardiovascular disease, neurodegenerative diseases, and various cancers (Makiso et al., 2024). These compounds have been shown to enhance lipid and glucose metabolism, inhibit inflammatory mediator production, and combat free radical damage. While three to four cups of filtered coffee per day are generally associated with cardiovascular protection and other health benefits, the caffeine and bioactive compound content can vary based on origin and preparation. The European Food Safety Authority (EFSA) recommends a daily caffeine intake of no more than 400 mg for adults and 200 mg for pregnant women, noting that even a single espresso can exceed the latter limit. They caution that exceeding recommended limits, calcium and vitamin D deficiency, and unfiltered coffee consumption may increase cardiovascular risks, advocating for moderate consumption (Makiso et al., 2024).

The relationship between coffee and cardiometabolic health is a subject of ongoing investigation, but the evidence leans towards protective effects. Phenolic compounds like caffeine and CGAs may boost antioxidant and anti-inflammatory biomarkers, inhibit enzymes linked to cardiometabolic issues, and reduce intestinal absorption of lipids and glucose, potentially improving gut microbiome health (Karagöz et al., 2024). High-molecular-weight compounds in coffee may also positively influence gut microbiota, affecting cholesterol metabolism. However, the ambivalent effects of caffeine on blood pressure and the potential of diterpenes and advanced glycation end-products (AGEs) to increase cholesterol absorption and promote oxidative stress, respectively (Karagöz et al., 2024).

Another recent review suggests a consistent dose-response protective effect of coffee consumption against type 2 diabetes and chronic kidney disease (Ungvari & Kunutsor, 2024). While the impact on heart health is still being researched, coffee may be associated with a reduced risk of stroke. A U-shaped relationship with cardiovascular disease outcomes is possible. Moderate coffee intake (two to five cups daily) is generally linked to a reduced risk of heart failure, although higher consumption might increase this risk. Most evidence shows no significant link between coffee and atrial fibrillation risk. Notably, moderate coffee consumption (one to five cups daily) is associated with a lower risk of all-cause mortality. These benefits appear consistent across different demographics and coffee types, suggesting that moderate consumption, particularly filtered coffee, is generally safe and may offer protection against several cardiometabolic issues, potentially contributing to a longer healthspan (Ungvari & Kunutsor, 2024).

The polyphenols found in coffee are key players in these beneficial effects. Research suggests these polyphenols exhibit strong anti-inflammatory and antioxidant properties  (Chapple et al., 2024). Specific polyphenols have been shown to inhibit inflammatory pathways, reduce the production of reactive oxygen species, promote beta-cell health, improve glucose uptake, and influence pathways involved in insulin secretion, potentially mitigating factors affecting type 2 diabetes pathogenesis (Chapple et al., 2024).

Beyond the physical, coffee also exerts significant effects on our mental well-being. Caffeine boosts alertness and cognitive function by acting on the central nervous and cardiovascular systems (Alimyar et al., 2024). It can positively influence mood and may even help with mild depression when consumed in moderation. However, it is essential to manage caffeine intake due to its complex relationship with sleep. Understanding individual tolerance and optimal dosage is crucial to maximizing its positive impacts. Moderate caffeine consumption may help reduce the risk of several chronic diseases without significantly increasing the risk of coronary heart disease, stroke, cancer, or many women's health issues (Alimyar et al., 2024).

Indian researchers recently suggested that coffee intake may benefit neurological and psychiatric outcomes, potentially reducing the risk of Parkinson's disease, improving cognitive function in older adults, and lowering the risk of depression (Pareek et al., 2024). However, they caution that the evidence isn't entirely consistent, with some studies showing no significant association or even potential adverse effects of high intake, such as increased anxiety. They stress the importance of considering individual responses and the overall diet and lifestyle when evaluating the benefits of coffee (Pareek et al., 2024).

Furthermore, research explores coffee's role in managing type 2 diabetes and its complications. Long-term consumption of both caffeinated and decaffeinated coffee is associated with a decreased risk of type 2 diabetes and its complications  (Mohamed et al., 2024). Coffee intake may also help suppress appetite and mitigate the genetic link between BMI and obesity, attributed to its abundance of bioactive compounds (Mohamed et al., 2024).

The connection between coffee and cancer is also being actively studied. Researchers in GeroScience indicate that coffee consumption is linked to a reduced risk of several cancers, including skin, liver, prostate, and endometrial cancers, with the most significant protective effects observed at three or more cups per day (Kunutsor et al., 2024). Coffee may also lower the risk of cancer recurrence, particularly in colorectal cancer. However, the evidence remains inconclusive for many other cancers, and significantly, coffee consumption has been consistently associated with an increased risk of lung cancer, highlighting the need for personalized dietary recommendations (Kunutsor et al., 2024).

Finally, genetic factors may also influence how we respond to coffee. In Nutrition Journal, Hsieh et al. (2024) found that coffee consumption was associated with a lower odds ratio for metabolic syndrome in Taiwanese adults. Interestingly, they observed an interaction between coffee consumption and a specific genetic variant (rs301 of the LPL gene), suggesting that the protective effect of particular genotypes against metabolic syndrome was more pronounced among coffee drinkers, underscoring the interplay between genetics and lifestyle choices in metabolic health (Hsieh et al., 2024).

2022, Cong CaPhe, Ho Chi Minh, Vietnam

My daily ritual of those three cups isn't just a personal indulgence; it's a constant reminder of the profound connection between our daily choices and our well-being. Just as I meticulously seek out the nuanced flavors in a perfectly brewed cup, I recognize the vital importance of staying attuned to the ever-evolving landscape of health research. This isn't merely an academic pursuit; it's the foundation of how I aim to empower my patients in my future practice in functional medicine. By translating the complexities of studies on something as familiar as coffee, I hope to inspire them to take a more active role in understanding their health and making informed decisions.

2021, Phinista Cafe, Cambridge, Massachusetts 

For my family and fellow coffee enthusiasts, this exploration into the science of our beloved brew is more than just interesting trivia; it's a call to awareness. Understanding how even a seemingly simple habit can intricately impact our bodies underscores the power of knowledge in making proactive choices. And for my future patients, my commitment is unwavering: to remain a dedicated student of health research, to be their informed advocate, and to help them navigate the often-overwhelming world of medical information. Because ultimately, whether it's the comfort of a shared latte with my sister or the potential benefits within each bean, the most enriching discoveries empower us all to live healthier, more informed lives.

References

Alimyar, O., Nahiz, A., Monib, A. W., Baseer, A. Q., Hassand, M. H., Kakar, U. M., ... & Niazi, P. (2024). Coffea plant (caffeine): examining its impact on physical and mental health. European Journal of Medical and Health Research, 2(2), 143-154.

Chapple, B., Woodfin, S., & Moore, W. (2024). The perfect cup? Coffee-derived polyphenols and their roles in mitigating factors affecting type 2 diabetes pathogenesis. Molecules, 29(4), 751.

Hsieh, P. C., Nfor, O. N., Lin, C. C., Hsiao, C. H., & Liaw, Y. P. (2024). Metabolic syndrome risk in adult coffee drinkers with the rs301 variant of the LPL gene. Nutrition Journal, 23(1), 30.

Karagöz, M. F., Koçyiğit, E., Koçak, T., Özturan Şirin, A., Icer, M. A., Ağagündüz, D., & Coreta‐Gomes, F. (2024). Decoding coffee cardiometabolic potential: Chemical composition, nutritional, and health relationships. Comprehensive Reviews in Food Science and Food Safety, 23(5), e13414.

Kunutsor, S. K., Lehoczki, A., & Laukkanen, J. A. (2024). Coffee consumption, cancer, and healthy aging: epidemiological evidence and underlying mechanisms. Geroscience, 1-39.

Makiso, M. U., Tola, Y. B., Ogah, O., & Endale, F. L. (2024). Bioactive compounds in coffee and their role in lowering the risk of significant public health consequences: A review. Food science & nutrition, 12(2), 734-764.

Mohamed, A. I., Erukainure, O. L., Salau, V., & Islam, M. S. (2024). Impact of coffee and its bioactive compounds on the risks of type 2 diabetes and its complications: A comprehensive review. Diabetes & Metabolic Syndrome: Clinical Research & Reviews, 103075.

Pareek, V., Shah, S., Sharma, B., Kumar, S., & Sharma, L. (2024). Coffee and the Brain: A Comprehensive Review of Its Neurological and Psychiatric Effects. Journal of the Indian Academy of Geriatrics, 20(1), 34-39.

Saygili, S., Hegde, S., & Shi, X.-Z. (2024). Effects of Coffee on Gut Microbiota and Bowel Functions in Health and Diseases: A Literature Review. Nutrients, 16(18), 3155. https://doi.org/10.3390/nu16183155

Ungvari, Z., & Kunutsor, S. K. (2024). Coffee consumption and cardiometabolic health: a comprehensive review of the evidence. GeroScience, 46(6), 6473-6510.