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The Scoop on Coffee and Reducing Risk for Type 2 Diabetes
Introduction: We love coffee
The world loves coffee. Coffee is one of the most popular and consumed drinks in the world (Van Dam and Hu, 2005). Millions of people drink it everyday. Many people rely on coffee to wake up in the morning, to have energy during the day, and to stay awake at night. Although coffee is very popular, it gets mixed reviews with regards to health. There are many ideas about the effects of coffee on health. How do we know which ones are true and which ones are not true? How much do we really know about the effects of coffee? No one is certain of the comprehensive effects of coffee on health. However, research studies may indicate that drinking a lot of coffee may actually reduce your risk for type 2 diabetes. Research on the effects of coffee on the risk for type 2 diabetes is relatively recent. Several studies have test different cohorts of people who drink a lot of coffee as assessed their risk for type 2 diabetes compared to people who do not drink coffee.
What is type 2 diabetes?
Type 2 diabetes is also known as adult onset diabetes and non insulin dependent diabetes mellitus. It is the most common form of diabetes and accounts for 90-95% of all cases of diabetes in the United States (Mayo Clinic Staff, 2006). Type 2 diabetes occurs when the body does not produce enough insulin or the cells ignore the insulin (Mayo Clinic Staff, 2006). Insulin is important because it takes sugar from the blood into the cells. This process is vital because our bodies use sugar as fuel and energy for our cells.
In type 2 diabetes, glucose builds up in the blood because there is a lack of insulin or the insulin is not able to take the sugar into the cells. This problem is usually due to insulin resistance (dLife Staff, 2006). Insulin resistance occurs when the insulin receptors on the cells prevent the insulin from entering the cells. The insulin cannot get the sugar into the cells because the receptors will not allow insulin to enter the cells. The glucose builds up in the blood and causes high blood sugar. The pancreas continues to produce insulin to try to keep up with increasing blood sugar levels and creates high circulating levels of insulin, hyperinsulinemia (dLife Staff, 2006). This may damage the insulin producing beta cells of the pancreas and, therefore, reduce insulin output (dLife Staff, 2006). This can cause long term health problems such as heart disease, high blood pressure, and kidney failure.
The first step in treatment and prevention of type 2 diabetes involves managing weight by following a healthy diet and exercising regularly (Mayo Clinic Staff, 2006). It is important to monitor blood sugar to stay healthy with type 2 diabetes. Maintaining a healthy weight, eating the right food, and exercising are good ways to maintain a good blood sugar level. If diet and exercise are not enough to control blood sugar, medication is the next step. Pills and insulin injections are usually a last choice in treating diabetes (dLife Staff, 2006). Coffee is not currently suggested as a preventative measure for type 2 diabetes.
What effects of coffee could help to reduce the risk of type 2 diabetes?
There are different theories about the components of coffee that have beneficial effects for type 2 diabetes. Caffeine seems to be an obvious component of coffee. Therefore, it is logical to think that caffeine may affect the risk of type 2 diabetes. However, studies show an inverse relationship between decaffeinated coffee consumption and risk of type 2 diabetes, which suggests that caffeine may not explain the reduced risk of type 2 diabetes (Van Dam, 2006). These results suggest that no one can be certain of the effects of caffeine and the risk for type 2 diabetes.
Chlorogenic acid is a major component of coffee that may provide more of an explanation for coffee’s effect on risk for type 2 diabetes. Chlorogenic acid intake is estimated to be several times higher for people who drink coffee regularly compared to nondrinkers (Van Dam, 2006). Chlorogenic acid has many proposed beneficial effects on glucose metabolism. Van Dam (2006) says that chlorogenic acid “may delay glucose absorption in the intestine through inhibition of glucose-6-phosphate translocase 1 and reduction of the sodium gradient driven apical glucose transport” (73). Coffee might also stimulate the secretion of the incretin hormone glucagon-like peptide-1, which can have beneficial effects on the responsiveness of beta-cells to glucose (Van Dam, 2006). In vitro studies and animal studies show that chlorogenic acid derivates can decrease hepatic glucose output through inhibition of glucose-6-phospatase (Van Dam, 2006). Chlorogenic acid also contributes to antioxidant effects. All of these effects of chlorogenic acid help the body to process sugar and the cells to respond better to insulin, which help treat problems caused by type 2 diabetes.
Two other components of coffee that could reduce risk of type 2 diabetes are lignans and magnesium. There are large amounts of several lignans in coffee that may affect glucose metabolism through antioxidant and (anti)estrogenic properties (Van Dam, 2006). Magnesium is a component of coffee that has been shown to improve beta cell functioning and insulin sensitivity and to be inversely related to type 2 diabetes in men and women (Agardh, 2004). Lignans and magnesium both have effects that help the body process glucose, which is impaired by type 2 diabetes.
What research says about coffee and type 2 diabetes
Research indicates that coffee may actually help to reduce our risk for type 2 diabetes. Several studies followed participants who drank various amounts of coffee and compared their risk for type 2 diabetes.
A study by Tuomilehto et al. (2004) followed 6,974 Finnish men and 7,655 Finnish women without a history of diabetes from 1982-1992. The Finnish population is of interest because they have “the highest per capita coffee consumption in the world with 11.3 kg in 2000”. (Tuomilehto, 2004) They documented 381 cases of type 2 diabetes during their years of observation (Tuomilehto, 2004).
The calculated hazard ratios for type 2 diabetes were 1.00 for 0-2 cups per day, 0.72 for 3-4 cups per day, 0.49 for 5-6 cups per day, 0.47 for 7-9 cups per day, and 0.26 for 10 or more cups per day in women and were 1.00 for 0-2 cups per day, 0.83 for 3-4 cups per day, 0.88 for 5-6 cups per day, 0.86 for 7-9 cups per day, and 0.69 for 10 or more cups per day in men (Tuomilehto, 2004). This shows an inverse and graded association between coffee consumption and risk for type 2 diabetes. They discussed the type of coffee as a possible factor in the results. They found that there was almost a 3 fold increase in the risk of diabetes among men who drank pot-boiled coffee compared with men who drank filtered coffee (Tuomilehto, 2004). This suggests that filtered coffee may be a better type of coffee for reducing risk of type 2 diabetes. Components of coffee that the study suggested could affect glucose regulation include chlorogenic acid on glucose-6-phosphatase, caffeine on insulin secretion on pancreatic beta cells, and magnesium (Tuomilehto, 2004).
They concluded that there is an inverse and graded relationship between coffee consumption and type 2 diabetes (Tuomilehto, 2004). They did not determine the components of coffee that cause this reduced risk.
A study by Agardh et al. (2004) followed 3128 Swedish men without a history of diabetes from 1992-94 and 4821 Swedish women without a history of diabetes from 1996-98. They studied the relationship between coffee consumption and insulin sensitivity and beta cell function by homeostasis model assessment (HOMA) (Agardh, 2004). They documented 107 cases of type 2 diabetes and 339 people with impaired glucose tolerance during the study (Agardh, 2004).
They found that the relative risk of type 2 diabetes and impaired glucose functioning decreased with an increase in coffee consumption in both men and women (Agardh, 2004). The relative risk of type 2 diabetes was reduced by 60% in men and 70% in women for participants drinking 5 cups or more per day as compared to subjects drinking no more than 2 cups per day (Agardh, 2004). The relative risk of type 2 diabetes in high consumers of coffee (5 or more cups per day) was 0.39 for men and 0.32 for women (Agardh, 2004). The impaired glucose tolerance estimates were 0.60 for men and 0.68 for women (Agardh, 2004). Analysis of HOMA parameters showed that coffee consumption of 5 or more cups per day as compared to 2 or fewer cups per day was associated with a reduced relative risk of insulin resistance and low beta cell function in men and women (Agardh, 2004).
They concluded that high coffee consumption is associated with a reduced risk for type 2 diabetes and a reduced relative risk of impaired glucose tolerance in both men and women (Agardh, 2004). The results also suggest an effect on coffee on insulin sensitivity and beta cell functioning from the reduced risk of insulin resistance and improved insulin response with high coffee consumption (Agardh, 2004). Several components of coffee may be involved in the reduced risk of type 2 diabetes, according to these results (Agardh, 2004).
A study by Van Dam et al. (2006) followed a prospective cohort study of U.S. women without a history of diabetes. The researchers were interested in testing the hypothesis that high coffee consumption improved glucose tolerance and lowered risk for type 2 diabetes in younger and middle-aged U.S. women (Van Dam et al., 2006). This hypothesis came from observations that various components of coffee improved glucose metabolism in rats (Van Dam et al., 2006). They followed 88,259 women between 1991 and 2001. They reported 1,263 cases of type 2 diabetes during the years of observation (Van Dam et al., 2006).
The calculated relative risk for type 2 diabetes was 0.87 for one cup per day, 0.58 for 2-3 cups per day, and 0.53 for four or more cups per day (Van Dam et al., 2006). This shows a strong inverse association between the consumption of coffee and the risk for type 2 diabetes. This relationship was independent of caffeine intake. The results observed with decaffeinated coffee suggest that coffee components other than caffeine may contribute to the reduced risk of type 2 diabetes. Women who drank decaffeinated coffee had a lower C-peptide concentration, which suggests a beneficial effect on insulin sensitivity (Van Dam et al., 2006). Coffee also has antioxidants and chrlorogenic acid that may delay glucose absorption (Van Dam et al., 2006).
They concluded that the higher coffee consumption, the lower the risk of type 2 diabetes (Van Dam et al., 2006). They found this to be true for both caffeinated coffee and decaffeinated coffee.
A study by Pereira et al. (2006) followed 28,812 postmenopausal women in Iowa without diabetes or cardiovascular disease from 1986-1997. They wanted to examine the association between caffeinated and decaffeinated coffee and the risk for type 2 diabetes (Pereira et al., 2006). They predicted that coffee may reduce risk for type 2 diabetes with its minerals, phytochemicals, and antioxidants but not caffeine (Pereira et al., 2006).
They reported that regular coffee was more common than decaffeinated coffee, especially for high levels of consumption (Pereira et al., 2006). They found that women who drank 6 or more cups of coffee per day had a 34% reduction in risk of type 2 diabetes compared to those who did not drink coffee (Pereira et al., 2006). The researchers determined that the inverse relationships between coffee consumption and risk for type 2 diabetes were stronger for decaffeinated coffee than for regular coffee (Pereira et al., 2006).
Pereira et al. (2006) concluded that there is a “dose-response inverse association between intake of coffee, particularly decaffeinated coffee, and the risk of type 2 diabetes mellitus” (1314). Caffeine did not seem to affect risk for type 2 diabetes in this study because the decaffeinated coffee had even more of an association with reduced risk for type 2 diabetes than did regular coffee.
A review of 15 epidemiological studies by Van Dam and Hu (2005) examined the association between habitual coffee consumption and risk for type 2 diabetes. Van Dam and Hu (2005) reported that “the inverse association between coffee consumption and glucose intolerance/type 2 diabetes was observed in various populations” (100). They found that risk for type 2 diabetes was lower for people who drank filtered coffee than for people that drank pot boiled coffee (Van Dam and Hu, 2005). Their review supports their hypothesis that coffee consumption reduces risk for type 2 diabetes (Van Dam and Hu, 2005). They did not conclude what components of coffee are responsible for the reduced risk of type 2 diabetes (Van Dam and Hu, 2005). Van Dam and Hu (2005) concluded that studies show a relationship between coffee consumption and reduced risk for type 2 diabetes but that it is too early to recommend drinking coffee as a public health strategy to prevent type 2 diabetes.
Van Dam and Hu (2005) Table Showing Results from Multiple Studies:
Conclusion: Should we drink coffee to help reduce our risk for type 2 diabetes?
The research studies and the systematic review found similar results and concluded that high consumption of coffee is associated with a reduced risk of type 2 diabetes. Researchers are not sure of the components of coffee that cause this reduced risk. Caffeine may contribute to reducing risk for type 2 diabetes but it does not appear to be the primary component of coffee that causes this reduced risk. Decaffeinated coffee was found to be as effective as regular coffee in reducing risk for type 2 diabetes. Some components of coffee that are thought to contribute to reducing risk for type 2 diabetes include chlorogenic acid, magnesium, ligans, and antioxidants. More research is necessary to determine which components of coffee cause a reduced risk in type 2 diabetes and how they cause this reduced risk.
The most recommended and successful ways to reduce your risk for type 2 diabetes are following a healthy diet and exercising regularly. While research shows that coffee may reduce the risk for type 2 diabetes, it is not a recommended method for preventing diabetes. Coffee consumption may be helpful in conjunction with other preventative measures but it not recommended as the primary method of prevention. Keep drinking coffee. It might help reduce your risk for type 2 diabetes.
Van Dam, R. M., Willett, W. C., Manson, J. E. & Hu, F. B. (2006). Coffee,
caffeine, and risk of type 2 diabetes. A prospective cohort study in younger and middle-aged U.S. women. Diabetes Care, 29(2), 398-403.
Tuomilehto, J., Hu, G., Bidel, S., Lindstrom, J. & Jousilahti, P. (2004). Coffee
consumption and risk of type 2 diabetes mellitus among middle-aged Finnish men and women. JAMA, 291(10), 1213-1219.
Pereira, M. A., Parker, E. D. & Folsom, A. R. (2006). Coffee consumption and risk of
type 2 diabetes mellitus. An 11-year prospective study of 28812 postmenopausal women. Arch Intern Med, 166, 1311-1316.
Agardh, E. E., Carlsson, S., Ahlbom, A., Efendic, S., Grill, V., Hammar, N. et al. (2004).
Coffee consumption, type 2 diabetes and impaired glucose tolerance in Swedish men and women. Journal of Internal Medicine, 255(6), 645-652.
Van Dam, R. M. & Hu, F. B. (2005). Coffee consumption and risk of type 2 diabetes. A
systematic review. JAMA, 294(1), 97-104.
Van Dam, R. M. (2006). Coffee and type 2 diabetes: from beans to beta-cells. Nutrition,
Metabolism, and Cardiovascular Diseases, 16(1), 69-77.
dLife Staff. (2006). Type 2 Diabetes. September 15, 2006.
Mayo Clinic Staff. (2006). Type 2 Diabetes. August 1, 2006.
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