3–5 Cups of Coffee a Day: What Does Research Say About Longevity and Chronic Diseases?

Is drinking coffee healthy?

If you ask, "Is drinking coffee healthy?", the honest summary is this: most large studies in various countries have found that drinking coffee in moderation, about 3-5 cups per day, is associated with a lower risk of death and a reduced likelihood of developing several major chronic diseases, including heart (cardiovascular) disease, type 2 diabetes, and some types of cancer (Emadi & Kamangar, 2025; Ungvári & Kunutsor, 2024). This conclusion isn't just from one or two small studies, but rather a pattern that repeatedly emerges in many large cohort studies, studies that follow tens to hundreds of thousands of people for years to see who gets sick/dies and what their lifestyle habits are like.

Of course, we need to be careful in interpreting results like this. Most of this evidence comes from observations, not from trials that randomly assign people to "drink coffee" vs. "not drink coffee." This means that even tho the relationship is consistent and makes sense, there's still a possibility that its effects could be "mixed" by other factors, such as exercise habits, diet, or smoking status. In simple terms: accompanying factors can also influence the coffee, making it appear "better" or "worse" than it actually is. Therefore, beside type 2 diabetes (T2DM) and chronic kidney disease (CKD), two areas also supported by genetic approaches, we cannot yet definitively state that "coffee is the main cause of the benefits" without large-scale randomized controlled trials (Barrea et al., 2021; Ungvári & Kunutsor, 2024).

Why can coffee be "friendly" to health?

Coffee isn't just about caffeine. It also contains polyphenols and other bioactive compounds (like chlorogenic acid) that can help reduce inflammation, decrease oxidative stress, and improve how the body processes sugar and fat. This is what makes coffee potentially good for blood sugar, blood vessels, and possibly liver health (Song et al., 2024; Sirotkin & Kolesárová, 2021). Caffeine itself can increase alertness and slightly boost energy expenditure, but many of coffee's benefits are also seen in decaffeinated coffee, so it's clear that caffeine isn't the only factor at play (Emadi & Kamangar, 2025; Ungvári & Kunutsor, 2024).

How many cups does it take to see the benefits?

Many study summaries found non-linear dose-response patterns (often U or J shaped). This means that a little coffee might not be felt, too much can cause side effects (e.g., sleep disturbances, palpitations, or stomach problems), while the middle range, generally 3-5 cups per day, is often the point where the benefits are most consistently seen across various diseases (Emadi & Kamangar, 2025; Ungvári & Kunutsor, 2024). Please note: the definition of "one cup" can vary between studies, and the brewing method also affects the "content" of your coffee.

Which disease has the most obvious benefits?

1. Type 2 diabetes (T2DM). Almost all major summaries agree: moderate coffee drinkers tend to have a lower risk of type 2 diabetes. Interestingly, this finding not only emerged in observational studies but was also supported by a genetic approach called Mendelian randomization, a method that helps assess whether the relationship is closer to cause-and-effect. In layman's terms: there is a causal signal that drinking coffee can indeed help reduce the risk of type 2 diabetes (Ungvári & Kunutsor, 2024; Emadi & Kamangar, 2025).

2. Chronic kidney disease (CKD). Protective signals were also seen for CKD, and, similar to T2DM, there is support from genetic analysis that this relationship is not merely coincidental. The magnitude of the benefits varies across populations, but the direction tends to be consistent (Ungvári & Kunutsor, 2024).

3. Cardiovascular disease (CVD) & stroke. For heart and blood vessel disease, as well as stroke, quite a few large studies have found that moderate coffee drinkers tend to have a lower risk. However, the causal evidence (whether coffee is the primary cause of the benefits) is not as strong as for T2DM/CVD. Nevertheless, from a layperson's perspective, this protective signal is relevant, especially if you drink coffee in a "heart-friendly" way (filtered and without excessive added sugar) (Dewland et al., 2025; Ungvári & Kunutsor, 2024).

4. Certain cancers. Specifically for liver cancer, then the endometrium (uterine lining), and colorectal cancer, some research summaries found a lower risk among moderate coffee drinkers. However, the results across studies can vary, and the causal support is not as strong as for DM2 (Kunutsor et al., 2024; Safe et al., 2023).

How you brew and your "drinking style" matter

It's not just the number of cups that counts; how you enjoy your coffee also matters. For example, unfiltered coffee (like French press) contains substances called diterpenes (cafestol, kahweol) that can increase LDL cholesterol in some people. Meanwhile, filtered coffee tends to reduce this problem because the filter captures some of the diterpenes (Dewland et al., 2025). So, if your focus is heart and blood vessel health, filtered coffee is often a safer choice. Another thing that is often forgotten is sugar and creamer. Many of coffee's benefits will "leak" if every cup is loaded with excessive sugar or sweet creamer. It doesn't mean you can't have any at all, but if your goal is health, reduce sweeteners and get your taste buds used to enjoying the more "pure" taste of coffee (Barrea et al., 2021). For those sensitive to caffeine, such as those who easily experience anxiety, palpitations, or difficulty sleeping, decaffeinated coffee can be a good alternative: the benefits of polyphenols remain, and the "jittery" effects are significantly reduced (Emadi & Kamangar, 2025).

Technical terms in the article

1. The majority of observational evidence. This means researchers observed people's coffee drinking habits and followed them for years, then compared who got sick/died. Advantages: can collect large and long-term data. Disadvantages: many other factors can influence the results (exercise, smoking, diet, economy), making it difficult to say "this is purely because of coffee."

2. Confounding/residual confounding. Imagine you see coffee drinkers often live longer. Is it because of the coffee? It's possible—but it could also be because these people are more active, eat better, or have regular health checkups. Confounding is a "companion factor" that makes the coffee-health relationship appear stronger/weaker than it actually is. Residual confounding is the remaining confounding that persists even after researchers have attempted to control for it. Because it is very difficult to perfectly measure all confounding factors, residual confounding is almost always present (Barrea et al., 2021).

3. Mendelian randomization (MR). This is how researchers are utilizing genetic variations related to coffee drinking habits or caffeine metabolism. Because genes are naturally "randomized" from birth, this approach is more resistant to confounding factors. The MR results strongly support the causal relationship between coffee and T2DM and CKD, while the support for other diseases is not as strong (Ungvári & Kunutsor, 2024).

In summary: the observational evidence is consistent and plausible, but to boldly say "coffee is definitely the cause of the benefits" across all diseases, we need more adequately powered randomized trials. Until then, it's natural for us to interpret coffee as part of a healthy lifestyle, not a "miracle cure."

Who Needs to be extra careful?

1. Pregnant/breastfeeding women. There is a recommended daily limit for caffeine intake. Follow the guidance of local healthcare professionals (Barrea et al., 2021).

2. Patients with uncontrolled arrhythmia/hypertension. Pay attention to your body's response. If you frequently experience heart palpitations or have difficulty stabilizing your blood pressure, consult about your coffee consumption pattern (Dewland et al., 2025).

3. Stomach problems/GERD. The acidity of coffee can trigger symptoms in some people. Try different types/brews or reduce the amount (Barrea et al., 2021).

4. Individual sensitivity. There are genetic factors (e.g., the CYP1A2 enzyme) that influence the speed of caffeine metabolism, which is why the effects of coffee can indeed vary from person to person (Ungvári & Kunutsor, 2024).

Simple practices to make your coffee "healthier"

1. Stay within the range of 3-5 cups per day. This is the range most often associated with benefits, without too many side effects for most adults (Emadi & Kamangar, 2025; Ungvári & Kunutsor, 2024).

2. Choose filtered coffee if you're concerned about LDL cholesterol. Filters help retain diterpenes, which can raise LDL in some people (Dewland et al., 2025).

3. Minimize sugar and sweetened creamers. Let the benefits of polyphenols work; don't "compensate" for them with excessive sugar (Barrea et al., 2021).

4. Pay attention to your drinking schedule. Avoid getting too close to bedtime so that sleep quality is not disturbed; sleep quality is also important for health.

5. Adjust to your body. If you experience palpitations, anxiety, or acid reflux flare-ups, reduce your dosage, switch to decaf, or change your brewing method.

Notes on Coffee "Flavor" and Quality Flavor is not just about taste; the roasting process, brewing method, and bean freshness can change the bioactive compound content in your cup. For example, very dark roasting levels might reduce certain polyphenols, while poor storage can affect overall quality (Bosso et al., 2021). Direct clinical data is still limited, but it's reasonable to choose fresh, cleanly brewed beans with "not too many additives."

Conclusion: Realistic expectations about coffee and health

When asked, "Should I start drinking coffee for my health?", the answer is: if you like coffee and tolerate it, enjoying 3–5 cups per day wisely is a rational and potentially beneficial choice. The available evidence suggests a lower risk of death and a reduced risk of various major diseases, with the strongest support for type 2 diabetes and chronic kidney disease (Emadi & Kamangar, 2025; Ungvári & Kunutsor, 2024). For heart disease, stroke, and some cancers, the direction of benefit is also promising, especially if you choose filtered coffee and don't add excessive sugar (Dewland et al., 2025; Kunutsor et al., 2024; Safe et al., 2023).

However, remember, coffee is not a "shield" against other lifestyles. Eating a balanced diet, staying active, getting enough sleep, and not smoking remain the main foundations. Coffee can be a fun part of a healthy lifestyle, not the only star of the show. If you have certain medical conditions or are unsure about your caffeine tolerance, it's a good idea to discuss it with a healthcare professional. With realistic expectations, a cup of coffee can be a good friend that helps maintain the rhythm of the day, and perhaps, based on numerous studies, contributes to increasing the chances of living longer and healthier (Emadi & Kamangar, 2025; Ungvári & Kunutsor, 2024; Barrea et al., 2021).

References

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• Bosso, H., S.M. Barbalho, R. A. Goulart, & A. M. M. B. Otoboni (2021). Green coffee: economic relevance and a systematic review of the effects on human health. Critical Reviews in Food Science and Nutrition, 63(3), 394–410. https://doi.org/10.1080/10408398.2021.1948817

• Dewland, T. A., R. M. Dam, G. M. Marcus (2025). Coffee and cardiovascular disease, European Heart Journal, 46(36), Pages 3546–3554, https://doi.org/10.1093/eurheartj/ehaf421

• Emadi, R. C. & F. Kamangar (2025). Coffee’s Impact on Health and Well-Being. Nutrients, 17(15), 2558. https://doi.org/10.3390/nu17152558

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• Song, X., M. Singh, K. E. Lee, R. Vinayagam, & S. G. Kang (2024). Caffeine: A Multifunctional Efficacious Molecule with Diverse Health Implications and Emerging Delivery Systems. International Journal of Molecular Sciences, 25(22), 12003. https://doi.org/10.3390/ijms252212003

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