Decaf and Type 2 Diabetes

Type 2 diabetes is the most common form of diabetes, caused by a combination of inadequate production of insulin and an inability of the body to respond fully to insulin. The majority of scientific studies that have investigated the impact of drinking coffee on Type 2 diabetes point to coffee drinkers having lower risk of developing the disease. In fact, epidemiological studies suggest that drinking more coffee (3-4 cups of per day) is associated with an approximate 25% lower risk of developing type 2 diabetes, compared to consuming none or less than 2 cups per day (Huxley et al. 2009; van Dam & Feskens 2002). A large-scale systematic review on this literature lead by the Harvard School of Public Health concluded that habitual coffee consumption is associated with a substantially lower risk of type 2 diabetes (van Dam & Hu 2005)

There is also good evidence of similar preventive effects with decaffeinated coffee (Greenberg et al. 2006; Salazar-Martinez et al. 2004; Wu 2005) . This effect may be partially explained by CGA, trigonelline, or even magnesium (the exact mechanism has yet to be confirmed) Tajik et al. 2017). CGA has been demonstrated to inhibit glucose absorption (Clifford 2000; Higdon & Frei 2006). A randomized crossover trial study conducted in 2009 found that chlorogenic acid and trigonelline ingestion significantly reduced glucose and insulin after 15 minutes (van Dijk et al. 2009). A meta-analysis conducted in 2014 found a dose-dependent relationship, where the risk for Type 2 diabetes decreased 11% for every 2 cups of coffee/day consumed (Jiang et al. 2014). One study with strong results reported that for those who drank 3–4 cups of decaffeinated coffee containing high contents of CGA, the risk of Type 2 diabetes was reduced by 30%⁷.

Normally, the hormone insulin produced in the pancreas helps move glucose from your blood to your cells to use for energy. Gut hormones are secreted into the blood by specialized gastrointestinal cells, and one of their most important roles is to regulate the insulin secretion immediately after eating. Coffee consumption influences the incretin hormones like peptide 1(GLP-1, which is reduced in Type 2 diabetes)and glucose‐dependent insulinotropic peptide(GIP).

Research by Greenberg et. al. (2010) actually highlighted decaffeinated coffee specifically as being more beneficial than coffee with caffeine: They reported an increase in GLP-1 concentrations after ingestion of decaffeinated coffee —in other words, increasing GLP‐1secretion induced by decaffeinated coffee intake is possibly an important mechanism related to its protective effects.

In another study, Greenberg and Geliebter (2012) conducted a randomized trial to examine effects of caffeine, caffeinated coffee and decaffeinated coffee on hunger and satiety hormone (PYY) response in healthy adults. The trial showed that decaffeinated coffee resulted in higher plasma PYY concentrations than placebo and caffeine. Participants also said they were less hungry for about 3 hours, potentially contributing to the protective nature of decaf coffee consumption against the onset of type2 diabetes. Consumption of regular, caffeinated coffee did not have these same results. These results indicate that decaffeinated coffee consumption.

More recently, a review published in 2016 confirmed the mounting evidence that coffee drinkers who consume 3-4 cups per day exhibit a reduced risk of developing type 2 diabetes (Santos & Lima 2016). The authors of this study attributed the results to possibly both   caffeine and CGA. Supporting this theory are various animal-based studies, which have confirmed an anti-diabetic insulin function strengthening impact of chlorogenic acids (Michels et al. 2005). The sheer number of studies and strength of reviews on this disease has led the link between coffee consumption and decreased risk of diabetes to be one of the strongest evidences to support coffees effect on the body. In addition, it is clear that CGA is one of the primary drivers for this protective effect, so drinking coffee rich in those compounds is a smart choice.

Decaf and Liver Health

There are a host of serious liver diseases which can be positively impacted by drinking coffee. Please see Purity PROTECT for more in depth information on coffee and the liver.

The association between coffee consumption and a decreased risk of liver disease was established over 25 years ago (Klatsky & Armstrong 1992). Since then, a large body of scientific work has elucidated an inverse association between moderate coffee consumption and the risk of developing a range of liver diseases including cancer, fibrosis and cirrhosis. The good news is, these effects have not been found to be exclusively linked to caffeine, which means decaf drinkers can enjoy these benefits as well.

For example, an animal study on decaffeinated espresso found that it was able to reduce liver steatosis and inflammation and fibrosis in rats fed a high fat diet for 12 weeks. This was the first time that a study had showed caffeine was not essential for the anti-fibrotic effects of coffee and that components other than caffeine contribute to the hepatoprotective effect (Vitaglione 2010). Later, two studies independently reported the effects of regular vs. decaffeinated coffee in rats, showing that both types of coffee reduce liver fibrosis (Furtado et al. 2012; Arauz (2013). Research by Ma and others assessed both the preventive and therapeutic effects of chlorogenic acids on mice fed a high fat diet and showed that these compounds blocked the development of fatty liver and the chlorogenic acid treatment reversed the high-fat-diet-induced hepatic steatosis (Ma et al. 2015). This supports the evidence that decaffeinated coffee would still give us the important liver-health related benefits of drinking coffee.

Decaf and Colorectal Cancer

There is solid evidence that drinking decaf coffee can also contribute to a protective effect against colorectal cancer (CRC). There are an estimated 3.5 million individuals living with CRC worldwide, and physicians have no specific dietary or lifestyle recommendations for patients with cancer owing to a lack of convincing evidence to support many of them (Cross & Gunter 2018; Vitaglione 2010). It is the third most common incident cancer in the world and the fourth leading cause of cancer-related death. CRC is a major public health challenge (Ferlay et al. 2015). Multiple studies have pointed to an important association between drinking decaf or regular coffee with a decreased risk of colorectal cancer (Rashmi et al. 2012; Galeone et al. 2010, Michels et al. 2005) .

An exceptionally large and important epidemiological study was published this year by Harvard School of Public Health, which collected data from the Nurses’ Health Study (1984–2012) and Health Professionals Follow-up Study (1986–2012), that followed 1599 patients diagnosed with stage 1, 2, or 3 colorectal cancer. They found that intake of caffeinated and decaffeinated coffee (2+ cups a day) was associated with lower risk of colorectal cancer-specific mortality and all-cause mortality (Hu et al. 2006). Specifically, they found that patients who consumed at least 4 cups of coffee per day had a 52% lower risk of CRC-specific death and 30% reduced risk of all-cause death. Meaning, patients who maintained a high level of coffee consumption both before and after diagnosis had particularly favorable survival. This inverse association between coffee and CRC risk has been hypothesized to be due to a number of factors not including caffeine, such as the anticarcinogenic properties of chlorogenic acids (Arauz et al. 2013), coffee diterpenes (Michels et al. 2005; Cavin et al. 2002) , and other physical and biological actions coffee is involved with in the gut.