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Coffee is one of the most consumed drinks in the world. It is obviously very popular, but I hear a lot that women particularly menopausal women saying they have given up coffee because it’s bad for you. Usually this is based on hearsay or something they saw on the Internet, such as "its the number one enemy of menopause" and it "spikes your blood glucose" Now don’t get me wrong, for some giving up coffee may help alleviate some of their menopause symptoms in particular hot flashes, more on that later. But let us see what the scientific research tells us about coffee and its effects on long term health.
Excluding the milk which contains many other valuable nutrients such as protein, calcium and vitamin D and excluding any sweeteners e.g. sugar which I would recommend avoiding. Coffee itself contains over 1000 botanical compounds. The most well-known compound is caffeine (a central nervous system stimulant). Caffeine can negatively impact sleep, so don’t drink your coffee too late in the day. Caffeine, in some people, can also potentially increase anxiety (O’Keefe et al. 2018).
Other less well-known compounds include diterpenes (which can increase serum cholesterol), chlorogenic acid (which improves glucose metabolism), as well as melanoids, quinides, lignans, and trigonelline—all of which confer antioxidant and anti-inflammatory effects (O’Keefe et al. 2013).
The effects of coffee on blood pressure does seem to differ depending on whether you are a regular coffee consumer or not. If you do not normally drink coffee then having a cup can in the short term result in a modest increase in your blood pressure (BP) however, if you are a regular coffee drinker there is no significant effect on blood pressure.7 The lack of impact of regular coffee consumption on blood pressure has been consistently reported in the highest quality of studies and further the long term effects show there is no increased risk of hypertension (HTN) (Mesas et al. 2011; Steffen et al. 2012).
Even with the consumption of up to 6 cups of coffee per day there is no reported increase in risk of hypertension, although these findings were based on observational data meaning other factors could have influenced the results (Winkelmayer et al. 2005).
Observations of various populations indicate that coffee consumption may reduce the likelihood of developing obesity. Interestingly this is particularly true for individuals who are genetically predisposed to develop obesity, where higher coffee consumption is associated with lower body mass index (Wang et al. 2017). Again these studies are observational but they do control for many factors. It is possible that those who drink coffee use it to displace more energy dense (ie more calorie foods) from their diet, after all a black coffee contains minimal energy and the high water content can act to supress appetite in the short term.
Short term studies suggest that caffeine increases both glucose and insulin levels (Wedick et al. 2011),however, paradoxically in the long-term coffee reduces the risk of type 2 diabetes (T2D). This is likely because coffee contains high concentrations of potent antioxidants, without any calories. Intervention studies, where people have been provided with coffee, have shown that coffee consumption can improve glucose metabolism and insulin sensitivity. For example, a 16-week randomized trial found that both caffeinated coffee and decaffeinated coffee improved blood glucose responses following food (Ohnaka et al 2012). Whereas, an 8-week randomized placebo-controlled (i.e. coffee vs a drink made to look and taste like coffee but containing non of the compounds in coffee) study showed that coffee improves levels of adiponectin—an insulin- sensitizing cytokine, important for glucose control (Wedick et al. 2011).
Observational studies have shown every additional cup of coffee per day is linked with a 7% reduction in the risk of type 2 diabetes (Ding et al. 2014; Huxley et al 2009). An even greater reduction in the odds of getting type 2 diabetes was shown for individuals who increased their coffee consumption by one cup or more per day. With the increase associated with an 11% lowered their risk of type 2 diabetes (Bhupathiraju et al. 2014) Conversely, individuals who reduced their coffee intake by 1 cup a day increased their risk of developing Type 2 Diabetes by 17%. However and probably not surprisingly, adding sugar or other sweeteners to coffee can diminish its potential benefits on glucose metabolism (DiNicolanotonio et al 2015; O’Keefe et al. 2016).
Recently, an analysis of the evidence regarding the effects of coffee consumption on all studied health outcomes (Poole et al 2017) concluded that drinking 3 to 4 cups of coffee daily conferred maximal health benefits, including significant risk reductions in all-cause mortality, cardiovascular mortality, and cardiovascular disease (Poole et al 2017). A meta-analysis of 36 studies which included 1,279,804 participants found that moderate coffee consumption (3 to 5 cups per day) was associated with lower risks of adverse cardiovascular events (Ding et al 2014). Drinking more or less than this was not seen to be beneficial (Ding et al 2014). Another study found that daily coffee drinkers (at least 3 cups per day) had a 7% to 12% lower risk of dying prematurely compared to non-drinkers (Gunter et al 2017). Investigators incorporating machine learning in their analysis of data from the Framingham Heart Study reported that coffee consumption was associated with a reduced risk for major adverse cardiovascular events (Stevens et al 2017).Compared to no coffee, every 225 mL (8-oz) cup/day reduced the risk of heart failure (HF) by 7%, stroke by 8%, and coronary heart disease (CHD) by 5%. A different meta-analysis found a U-shaped association between coffee consumption and the occurrence of HF, wherein 4 cups/day of coffee was linked with the lowest risk, whereas less and more intake was linked with greater risk (Motofsky et al 2012).
This effect was most significant among individuals at least 45-years-old, for whom drinking 2 additional cups of coffee per day was linked with a 30% lower risk of mortality during follow-up (Navarro et al 2017).
The research looks positive for coffee consumption and reductions in the risk of many chronic diseases however, there are some considerations we need to note. The apparent health benefits of coffee are predominantly based on observational studies, with very few randomized controlled studies. Observational studies are only able to provide us with associations and an association does not prove causation i.e. we cannot say that it is the coffee producing these beneficial effects as it could well be something else about the coffee drinkers which is improving their health outcomes. The small, short term intervention studies do seem to show beneficial effects but unfortunately the large long-term randomized placebo controlled outcome studies with coffee are not really feasible.
Coffee consumption is not without its risks. The diterpenes in coffee can raise serum cholesterol (Urgent and Katan 1997). In particular, boiled unfiltered coffee can raise cholesterol modestly. However, a standard coffee filter removes diterpenes and thus filtered coffee has largely neutral effects on blood cholesterol (Poole et al 2017). Other adverse effects are predominantly due to the high caffeine content of most coffee preparations, which can lead to insomnia, anxiety, palpitations, tremors, in addition to bone loss and the potential for increased fracture risk, especially among women (O’Keefe et al 2013). For menopausal women many believe that caffeine consumption can increase the severity of hot flashes, the majority of studies seem to support this notion but not all studies show associations between caffeine intake and hot flashes. It should be noted that these studies are based on caffeine, with caffeinated soft drinks showing a greater adverse effect in one study. If you do suffer from hot flashes then try cutting down on your coffee intake, particularly in the afternoon and see if your symptoms persist or alleviate. You could use our free symptoms journal to monitor your symptoms alongside your food intake. As for other symptoms there is some evidence caffeine consumption is associated with a decrease in neurocognitive symptoms (heart palpitations, concentration, memory and depression), but only in premenopausal women and not in postmenopausal women.
The International Agency for Research on Cancer (IARC), which is the cancer agency of the World Health Organization, recently classified the drinking of very hot beverages (hotter than 149 °F or 65 °C) a probable carcinogen (Loomis et al. 2016). Hot coffee is typically served at about 65 °C, so coffee should be allowed to cool to less than scalding hot temperatures before drinking. Additionally, roasted coffee contains acrylamide, a potential carcinogen. However, the level of acrylamide in coffee is very low, and the IARC has recently concluded that coffee is associated with decreased risks for liver cancer and endometrial cancer, and is unlikely to cause breast cancer, prostate cancer, or pancreatic cancer (Loomis et sl 2016).
Finally, regular coffee consumption leads to physical and psychological dependence—another consequence of its high caffeine content. A typical cup of brewed coffee contains from 70 to 165 mg of caffeine.
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