What Are The Health Benefits of Coffee?

What Are The Health Benefits of Coffee?

Title: Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes

Author: Poole et al

Journal: British Medical Journal (2017)

Objective: “To evaluate the existing evidence for associations between coffee consumption and multiple health outcomes.”

Background

Coffee is one of the most commonly consumed drinks in the world and the most consumed stimulant. 50% of Americans consume coffee and it’s an 18$ billion dollar market. The dutch (netherlands) drink the most per person with 260 liters per person per year.

Although evidence generally supports health benefits, it is mixed. Coffee’s more than 1000 bioactive compounds include caffeine, chlorogenic acid, diterpenes, cafestol, kahweol and more which contain antioxidant, anti-inflammatory, antifibrotic and anti-cancer effects.

Researchers have looked at the relationship between coffee and many outcomes including all cause mortality, cancer, cardiovascular disease as well as metabolic, neurological, musculoskeletal, gastrointestinal and liver disease. To best summarize the level of evidence for all these health outcomes, the authors performed a review of existing meta-analyses.

Results

They identified 201 meta-analyses, with 67 unique health outcomes

All Cause Mortality

  • Largest benefit: 3 cups a day associated with 17% reduced risk of death (RR 0.83, 95% CI 0.83 - 0.88)
  • One extra cup per day is associated with a 4% lower risk

Cardiovascular Disease

  • 3 cups per day consistently associated with lower cardiovascular disease, coronary heart disease and stroke risk.
    • Cardiovascular disease mortality: 19% reduction (RR 0.81, 95% CI 0.72 - 0.90)
    • Coronary heart disease mortality: 16% reduction (RR 0.84, 95% CI 0.71 - 0.99)
    • Stroke mortality: 30% reduction (RR 0.70, 95% CI 0.70 - 0.80)
  • Atrial Fibrillation risk: associated with lower risk but not statistically significant
  • Venous Thromboembolism: associated with lower risk but not statistically significant
  • Heart Failure: Largest benefit at 4 cups per day, 11% reduced risk (RR 0.89, 95% CI 0.81 - 0.99) however more than 10 cups per day slightly increased your risk but was not statistically significant (RR 1.01, 95% CI 0.90 - 1.14)
  • Hypertension: No statistically significant estimates of risk
  • Cholesterol: Coffee appeared to have unfavourable effects on lipid panel. Consumers generally had higher total cholesterol, LDL cholesterol and triglycerides as well as lower HDL cholesterol.

Cancer

  • High coffee consumers had an 18% lower risk of developing cancer vs low coffee consumers (RR 0.82, 95% CI 0.74 - 0.89)
  • Even one extra cup per day was associated a 3% lower risk (RR 0.97, 95% CI 0.96 - 0.98)
  • Higher coffee consumption was associated with a lower risk of the following cancers:
    • Prostate
    • Endometrial
    • Melanoma
    • Oral Cancer
    • Leukemia
    • Non-melanoma skin cancer
    • Liver cancer
  • For lung cancer, the evidence is mixed but it appears non smokers have either no increased risk or decreased risk
  • One study found an increased risk of consumption with urinary tract cancer, however other studies did not find an association
  • No significant association found with consumption and the following cancers: colorectal, colon, rectal, ovarian, thyroid, breast, pancreatic, esophageal, laryngeal, lymphoma or glioma

Live and Gastrointestinal Disease

  • Any consumption associated with
    • 29% lower risk of Non alcoholic fatty liver disease (RR 0.71, 95% CI 0.60 - 0.85)
    • 27% lower risk of liver fibrosis (RR 0.73, 95% CI 0.56 to 9.94)
    • 39% lower risk of cirrhosis (RR 0.61, 95% CI 0.45 - 0.84)
  • One extra cupy per day was associated with a 26% reduction in risk from cirrhosis (RR 0.74, 95% CI 0.59 - 0.86)
  • Chronic liver disease was associated with anywhere from 26-65% reduction depending on amount of consumption
  • Gallstone disease: associated with a lower risk

Metabolic Disease

  • Type 2 Diabetes: High consumers associated with a 30% risk of developing type 2 diabetes (RR 0.70, 95% CI 0.65 - 0.75), and one cup/day 6% reduction in risk
  • Metabolic Syndrome: 9% lower risk of developing (RR 0.91, 95% CI 0.86 - 0.95)
  • Gout: Lowers risk
  • Kidney stones: Lowers risk

Kidney disease

  • Urinary incontinence: trend for lower risk, not statistically significant
  • Chronic kidney disease: trend for lower risk, not statistically significant

Musculoskeletal Disease

  • Findings are inconsistent
  • Any fracture or hip fracture: no significant association, however stratified by sex
    • Women: statistically significant increase risk (RR 1.14, 95% CI 1.05 - 1.24)
    • Men: Decreased risk, statistically significant (RR 0.76, 95% CI 0.62 - 0.94)

Neurological Outcomes

  • Parkinson's disease: Lower risk
  • Depression: Lower risk
  • Alzheimer’s disease: 27% decreased risk (RR 0.73, 95% CI 0.55 to 0.97)

Pregnancy

  • Consistently harmful associations with different pregnancy outcomes
    • High vs low consumption had a non-statistically significant increased risk
    • Lower birth weight:  (OR 1.31, 95% CI 1.03 - 1.67)
    • Pregnancy loss (OR 1.46, 95% CI 1.06 - 1.99)
    • Preterm birth (1st or 2nd trimester)
  • No significant association for
    • 3rd Trimester preterm birth
    • Neural tube defects
    • Congenital malformations

Conclusions

Coffee consumption is frequently associated with a benefit to overall health at a variety of consumption levels from one cup a day to multiple cups per day.

Consumption is associated with a overall lower risk of death, developing cardiovascular disease and cancer.

It also protects against gastrointestinal disease, diabetes and metabolic syndrome, parkinsons disease, depression and Alzheimer’s disease.

It may increase the risk of fractures in women and may have some negative effects on the developing fetus. The data is not entirely clear. It appears to have unfavorable effects on your lipid profile.

Overall, this should provide support for your coffee consumption and in my case addiction. Older women and folks with bad cholesterol should be aware of the mixed evidence.

References

Poole, R., Kennedy, O. J., & Roderick, P. (2017). Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. Bmj. doi:10.1136/bmj.j5024

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