Coffee includes a wide array of components that can have potential implication on health, including caffeine, chlorogenic acids and diterpenes. The information gathered in recent years has generated a new concept of coffee, one that does not match the common belief that coffee is mostly harmful.
While there are still some concerns about coffee consumption during pregnancy and the effects of caffeine on the young (kids), there is a significant positive impact of coffee on the cardiovascular system, and on the metabolism of carbohydrates and fats. It is also important to note that science is not black or white on most topics related to health as there are too many confounding factors to consider. That is why there will never be a definitive study to prove coffee is good or bad.
The good news for those coffee drinkers is that contrary to previous beliefs, the various forms of arterial cardiovascular disease, arrhythmia (irregular heart beat) or heart insufficiency seem unaffected by coffee intake. Coffee is associated with a reduction in the incidence of diabetes and liver disease. Protection seems to exist also for Parkinson's disease among the neurological disorders, while its potential as an osteoporosis risk factor is under debate. Its effect on cancer risk depends on the tissue concerned, although it appears to favour risk reduction and lowering the risk of cancer overall. Overall, coffee consumption seems to reduce mortality(1) and the biggest benefits appear to be as we age. Personally, while it might be beneficial as we age and I love the smell, I don't like the taste so I will stick to my tea.
From a cardiovascular standpoint, coffee consumption reduces the risks of Type 2 diabetes mellitus and hypertension, as well as other conditions associated with cardiovascular risk such as obesity and depression; but it may adversely affect lipid (fat) profiles depending on how the beverage is prepared, especially if prepared with lots of sugar. Moreover, large epidemiological studies suggest that regular coffee drinkers have reduced risks for mortality, both cardiovascular and all-cause mortality. The potential benefits also include protection against neurodegenerative diseases, improved asthma control, and lower risk of some gastrointestinal diseases. A daily intake of about two to three cups of coffee appears to be safe and is associated with beneficial effects for most of the studied health outcomes.
The possible advantages of regular coffee consumption have to be weighed against potential risks (which are mostly related to its high caffeine content) including anxiety, insomnia, tremulousness and palpitations, as well as bone loss and possibly increased risk of fractures (2) and consumption during pregnancy.
Four or More Cups a Day
In a study of 2461 participants with a mean follow-up of 11 years found coffee consumption was inversely associated with all-cause mortality driven by a strong protection among those who drank four or more cups per day. That is, coffee consumption of four or more cups a day was protective (3). To contradict those findings, a study of 43,727 participants' coffee intake was positively associated with all-cause mortality in younger men. After stratification based on age, younger (less than 55 years old) men and women showed a significant association between high coffee consumption (more than 28 cups per week) (4). In this large cohort, a positive association between coffee consumption and all-cause mortality was observed in men and in men and women younger than 55 years. On the basis of these findings, it seems appropriate to suggest that younger people avoid heavy coffee consumption (ie, averaging more than four cups per day).
In contrast, in a prospective study of 34, 670 women with a mean follow-up of 10.4 years, coffee consumption was associated with a statistically significant lower risk of total stroke, cerebral infarction, and subarachnoid haemorrhage. These findings suggest that low or no coffee consumption is associated with an increased risk of stroke in women (5).
Lower Risk of Type 2 Diabetes
Consumption of coffee has also been associated with a lower risk of Type 2 diabetes and short-term metabolic studies have shown that caffeine improves postprandial (after a meal) glycemic (sugar) control. Studies have shown coffee contains chlorogenic acid and quinides, which may reduce body weight and improve glucose tolerance. (6)
In one study, higher coffee consumption had a lower prevalence of Type 2 diabetes (7); similarly in a prospective study, higher coffee consumption was shown to reduce the incidence of diabetes mellitus (8). In a prospective study of 74,749 women and 39,059 men, any sugar-sweetened beverages (SSBs) intake was significantly associated with a higher risk of Type 2 diabetes.
Conversely, the consumption of caffeinated and decaffeinated coffee was associated with a lower risk of Type 2 diabetes. The study concluded that, irrespective of the caffeine content, sugar intake was associated with a higher risk of Type 2 diabetes, and coffee intake was associated with a lower risk of Type 2 diabetes (9). So have coffee with less sugar.
Two cross-sectional studies in Japan showed inverse correlations of coffee consumption with metabolic syndrome and some of its components, which suggest that it is good for reducing the risk of metabolic syndrome, while prospective studies performed in the United States and Europe showed no association. In a study of 554 adults, greater coffee consumption was associated with a significantly lower prevalence of metabolic syndrome. Participants who drank more coffee had a lower risk for high serum triglycerides, but not for increased waist circumference or high blood pressure and moderate coffee consumption (1.5 to more than 3 cups per day) was associated with significantly lower plasma glucose (sugar) (10).
Slows Cognitive Decline
A number of studies have now shown a protective effect of coffee consumption for cognitive decline and people with cardiovascular disorders are at higher risk of cognitive decline and diseases like Alzheimer's. A study of 2,475 women aged 65+ years observed significantly slower rates of cognitive decline with increasing caffeine intake. The rate of difference between the highest and lowest levels of usual caffeine intake (more than 371 mg/day compared to less than 30 mg/day) was equivalent to that observed between those who were seven years apart in age. That is, consumption of caffeinated coffee was significantly related to slower cognitive decline and being seven years younger cognitively. Caffeine intake was also related to moderately better cognitive maintenance over five years in older women with cardiovascular disorders (11).
While the benefits of coffee and caffeine are coming through, it is still important to note some of the potential areas of risk. Caffeine breakdown occurs at different rates in people and is broken down twice as slowly by pregnant women and women on the pill, while newborn babies do not metabolise caffeine at all. As a result, it is worth limiting coffee consumption to no more than two cups of coffee for pregnant women - at least till we have some more science on the topic.
DISCLAIMER: Dr Peter Dingle is a researcher, educator and public health advocate. He has a PhD in the field of environmental toxicology and is not a medical doctor.
References:Cano-Marquinaa, J.J. Tarínb, A. Canoc 2013O'Keefe, et al 2013Hannah Gardener, et al 2013Liu, et al 2013Larsson, Jarmo Virtamo, and Alicja Wolk. 2011Greenberg JA, Boozer CN, Geliebter 2006Kokubo et al. 2010Iso H, Date C, Wakai K, Fukui M, Tamakoshi A, 2006Am J Clin Nutr January 2013 vol. 97 no. 1 155-166)Journal of Epidemiology Vol. 23 (2013) No. 1 P 12-20, Vercambre, et al 2013
Dr Peter Dingle (PhD) has spent the past 30 years as a researcher, educator, author and advocate for a common sense approach to health and wellbeing. He has a PhD in the field of environmental toxicology and is not a medical doctor. He is Australia’s leading motivational health speaker and has 14 books in publication.