Health for life

Drinking three to four cups of coffee per day may help to prevent type 2 diabetes according to research highlighted in a session report published by the Institute for Scientific Information on Coffee (ISIC), a not-for-profit organisation devoted to the study and disclosure of science related to coffee and health.

Recent scientific evidence has consistently linked regular, moderate coffee consumption with a possible reduced risk of developing type 2 diabetes. An update of this research and key findings presented during a session at the 2012 World Congress on Prevention of Diabetes and Its Complications (WCPD) is summarized in the report.

The report outlines the epidemiological evidence linking coffee consumption to diabetes prevention, highlighting research that shows three to four cups of coffee per day is associated with an approximate 25 per cent lower risk of developing type 2 diabetes, compared to consuming none or less than two cups per day1. Another study also found an inverse dose dependent response effect with each additional cup of coffee reducing the relative risk by 7-8 per cent2.

Whilst these epidemiological studies suggest an association between moderate coffee consumption and reduced risk of developing diabetes, they are unable to infer a causal effect. As such, clinical intervention trails are required to study the effect in a controlled setting. One prospective randomized controlled trial3, tested glucose and insulin after an oral glucose tolerance test with 12g decaffeinated coffee, 1g chlorogenic acid, 500 mg trigonelline, or placebo. This study demonstrated that chlorogenic acid, and trigonelline reduced early glucose and insulin responses, and contribute to the putative beneficial effect of coffee.

The report notes that the association between coffee consumption a reduced risk of type 2 diabetes could be seen as counter intuitive, as drinking coffee is often linked to unhealthier habits, such as smoking and low levels of physical activity. Furthermore, studies have illustrated that moderate coffee consumption is not associated with an increased risk of hypertension, stroke or coronary heart disease4 ,5, 6. Research with patients with CVD has also shown that moderate coffee consumption is inversely associated with risk of heart failure, with a J-shaped relationship7.

Finally, the report puts forward some of the key mechanistic theories that underlie the possible relationship between coffee consumption and the reduced risk of diabetes. These included the Energy Expenditure Hypothesis, which suggests that the caffeine in coffee stimulates metabolism and increases energy expenditure and the Carbohydrate Metabolic Hypothesis, whereby it is thought that coffee components play a key role by influencing the glucose balance within the body. There is also a subset of theories that suggest coffee contains components that may improve insulin sensitivity though mechanisms such as modulating inflammatory pathways, mediating the oxidative stress of cells, hormonal effects or by reducing iron stores.

Coffee is one of the most extensively researched components in the diet. New studies are regularly being added to the already large body of scientific research, which overall suggests that moderate habitual coffee consumption is not associated with detrimental effects on cardiovascular health

Among recent studies, a new review paper1 highlights that for most healthy people, moderate coffee consumption is unlikely to adversely affect cardiovascular health. Furthermore a new paper2 concluded that higher green tea and coffee consumption is inversely associated with risk of CVD and stroke in the general population.

Considerable research has also been devoted to investigating associations between coffee consumption and key risk factors for cardiovascular disease, such as hypertension (high blood pressure) and elevated cholesterol. Most evidence suggests that regular moderate consumption of caffeinated coffee has no long-term effect on blood pressure and does not increase the risk of hypertension.

A recent study suggests that moderate consumption of paper-filtered coffee may have an unfavourable effect on plasma cholesterol3. The wider body of evidence indicates that the impact of coffee on cholesterol is dependent on the brewing method. Unfiltered coffee raises serum cholesterol levels whereas this is not the case with filter coffee because the cholesterol-raising compounds in coffee are retained in the paper filter.

Throughout 2013 coffee and mortality has been a subject of several scientific research papers, which have produced conflicting results. One study4 found a 21% increase in mortality rate in those drinking more than 28 cups of coffee a week. However recent data from a meta-analysis and systematic review5 assessed 23 studies and concluded that coffee consumption is, in fact, inversely related to the risk of mortality.

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More information about this research is available at http://www.coffeeandhealth.org/coffee-and-health-topics/coffee-consumption-and-cardiovascular-health-2/the-latest-research-on-coffee-and-cardiovascular-health/.

References

1 Rebello S.A. & van Dam R.M. (2013) Coffee Consumption and Cardiovascular Health: Getting to the Heart of the Matter. Current Cardiology Reports, 15:403.

2 Kokubo Y. et al. (2013) The Impact of Green Tea and Coffee Consumption on the Reduced Risk of Stroke Incidence in Japanese Population: The Japan Public Health Center-Based Study Cohort. Stroke, published online ahead of print.

3 Correa T.A.F. et al. (2013) Paper filtered coffee increases cholesterol and inflammation biomarkers independent of roasting degree. Nutrition, 29(7-8):977-81.

4 Liu J. et al. (2013) Association of coffee consumtpion with all-cause and cardiovascular disease mortality. Mayo Clinic Proceedings, published online ahead of print.

5 Malerba S. et al. (2013) A meta-analysis of prospective studies of coffee consumtpion and mortality for all causes, cancers and cardiovascular disease. European Journal of Epidemiology, 28(7):527-539.

A large new American Cancer Society study adds to increasing evidence that physical activity reduces the risk of breast cancer in postmenopausal women. Researchers say moderate recreational activity was associated with a 14 percent lower risk and high physical activity with a 25 percent lower risk of breast cancer compared to women who were active at the lowest level. The study appears early online in Cancer Epidemiology, Biomarkers, and Prevention.

A large body of evidence shows that women taking part in regular physical activity have an approximately 25 percent lower risk of breast cancer compared to the most inactive. But still unclear are issues such as whether moderate intensity activity, like walking, imparts a benefit in the absence of vigorous exercise. Also unclear is whether the association differs based on tumor features, such as hormone receptor status, or by individual factors such as a womans body mass index (BMI), weight status, and use of postmenopausal hormones. In addition, while prolonged periods of sitting have been associated with the risk of some cancers, the relation between sitting time and postmenopausal breast cancer risk is not well understood.

To learn more, American Cancer Society researchers led by Alpa Patel, Ph.D. compared exercise and breast cancer status in 73,615 postmenopausal women taking part in in the CPS-II Nutrition Cohort, a prospective study of cancer incidence established by the American Cancer Society in 1992. During the 17-year study, 4,760 women in the study were diagnosed with breast cancer.

About one in ten (9.2 percent) women reported no recreational physical activity at the beginning of the study. Among those who were active, the average expenditure was equivalent to 3.5 hours per week of moderately-paced walking. Physically active women engaged primarily in moderate intensity activities, like walking, cycling, aerobics, and dancing rather than vigorous-intensity activities like running, swimming, and tennis. Among all women, 47 percent reported walking as their only recreational activity. Physically active women tended to be leaner, more likely to maintain or lose weight during adulthood, more likely to drink alcohol, and less likely to currently smoke. They were also more likely to use postmenopausal hormone therapy and to have had a mammogram in the past year.

Among those who reported walking as their only activity, those who walked at least seven hours per week had a 14 percent lower risk of breast cancer compared to those who walked three or fewer hours per week. Consistent with most prior studies, the most active women had 25 percent lower risk of breast cancer than the least active. The associations did not differ by hormone receptor status, BMI, weight gain, or postmenopausal hormone use. Also, sitting time was not associated with risk.

"Our results clearly support an association between physical activity and postmenopausal breast cancer, with more vigorous activity having a stronger effect," said Dr. Patel. "Our findings are particularly relevant, as people struggle with conflicting information about how much activity they need to stay healthy. Without any other recreational physical activities, walking on average of at least one hour per day was associated with a modestly lower risk of breast cancer. More strenuous and longer activities lowered the risk even more."

Current guidelines recommend adults get at least two-and-a-half hours per week of moderate-intensity activity, or 75 minutes per week of vigorous-intensity aerobic activity for overall health. But studies indicate less than half of U.S. adult women are active at these minimum levels. "Given that more than 60 percent of women report some daily walking, promoting walking as a healthy leisure-time activity could be an effective strategy for increasing physical activity among postmenopausal women," added Dr. Patel.