Americans get more of their antioxidants from coffee than any other dietary source

Professor J. Tuomilehto

According to a new study by researchers at the University of Scranton (Pa.), coffee is the number one source of antioxidants in, the U.S. diet. Their study was described recently at a meeting of the world's largest scientific society. "Americans get more of their antioxidants from coffee than any other dietary source. Nothing else comes close," says study leader Joe Vinson, Ph.D., a chemistry professor at the university. Although fruits and vegetables are generally promoted as good sources of antioxidants, the new finding is surprising because it represents the first time that coffee has been shown to be the primary source from which most Americans get their antioxidants.

Whilst the process of how they are absorbed and utilized is still poorly understood, these latest findings follow a growing number of reports that highlight the potential health benefits of drinking coffee. Antioxidants in general have been linked to a number of potential health benefits, including protection against heart disease and cancer.

For the current study, Vinson and his associates analyzed the antioxidant content of more than 100 different food items, including vegetables, fruits, nuts, spices, oils and common beverages. The data was compared to an existing U.S. Department of Agriculture database on the contribution of each type of food item to the average estimated U.S. per capita consumption.

Coffee came out on top, on the combined basis of both antioxidants per serving size and frequency of consumption. Ample intake of dietary antioxidants, and this includes drinking coffee, may be of great benefit in helping prevent or postpone the onset of degenerative diseases. Results of further research are eagerly awaited.

Coffee and type 2 diabetes - Latest research is good news

There is increasing evidence that drinking coffee may substantially reduce the risk of developing the most common form of diabetes, type 2 diabetes, which is the major contributor to the epidemic rise, worldwide, of this disease. The growing body of published research suggests that alongside other lifestyle measures, such as weight control and exercise, regular coffee drinking may also have a protective effect against developing type 2 diabetes.

In one review article published in 2005, the authors conclude from a systematic review of all key publications on the risk of type 2 diabetes that "habitual coffee consumption is associated with a substantially lower risk of developing type 2 diabetes" (9). With the numbers of people involved, such findings are exciting and significant. It is estimated that in 2000, there were approximately 150 million individuals with the disease and this number is likely to double by 2025 (1). In Europe the number will increase from approx. 16 million in 1994 to 24 million in 2010 (2) and the Centres for Disease Control and Prevention in the USA estimate over 18 million Americans have diabetes, and type 2 diabetes accounts for over 90 percent of that total.

"such findings are exciting and significant"

Results

It is known that, although coffee reduces insulin sensitivity, other components found in coffee such as chlorogenic acids and magnesium may have beneficial effects. A recent study in the Netherlands (3) found that men, who drank seven cups of coffee a day, were 50% less likely to develop diabetes than those who drank two cups a day. Studies published this year produced similar conclusions. A long term US study (4), over a period of 12-18 years, found that compared to non-coffee drinkers, men who drank more than six cups of caffeinated coffee per day, lowered their risk of type 2 diabetes by about half, and women reduced their risk by nearly 30%. The effects were also seen among those who drank decaffeinated coffee, but these were more modest. There was a 25% risk reduction for men and 15% for women.

Similar results were discovered in a major study in Finland (5) that involved more than 14,000 people. As Finland has the highest rate of per capita consumption of coffee in the world, it was possible to determine the risk of diabetes at high levels of consumption. In this study the heavy coffee drinkers i.e. those who drank ten or more cups a day, were even less likely to suffer from the disease. Such high consumption reduced the risk by 79% for women and 55% for men. It was also good news for those who drank more moderate amounts - three to four cups a day - their risk of diabetes was reduced by 29% for women and 27% for men.

How does it work?

The mechanism, or process by which coffee exerts its beneficial effect, is as yet unclear. Coffee is a complex compound and its composition will be affected by many factors including, roasting, blending and brewing. Whilst caffeine is thought to play a significant role, coffee is also a major source of chlorogenic acids, components that exhibit antioxidant properties.

Chlorogenic acids are thought to inhibit one of the enzymes involved in the formation of glucose in the small intestine (6, 7), and the inhibition of this enzyme is a commonly used approach to controlling high blood glucose levels or hyperglycaemia. Such elevated blood levels over time lead to the serious complications of this disease.

Caffeine and another coffee component, theophylline, are also strong stimulants of pancreatic cells, where the body produces its insulin (8). People develop type 2 diabetes because the cells in the muscles, liver and fat do not use insulin properly. Eventually the pancreas cannot make enough insulin to meet the body's needs, so interfering with the body's ability to store energy from food.

Conclusion

Whilst there is a significant evidence to show that drinking coffee can substantially reduce the risk of developing type 2 diabetes, further research is clearly needed to evaluate the true role of coffee in this disease and to have a better knowledge of the beneficial effects of its key components. However from early indications, we can look forward to seeing coffee included in the dietary recommendations for a type 2 diabetes prevention programme.

References

1. King H, Aubert RE, Herman WH. Global burden of diabetes, 19952025: prevalence, numerical estimate, and projections. Diabetes care 1998; 21: 1414-31.
2. Amos AF, McCarty DJ, Zimmet P The rising global burden of diabetes and its complications: Estimates and projections to the year 2010. Diabet Med 1997; 14: S7-S85.
3. Van Dam RM, Feskens EJM. Coffee consumption and risk of type 2 diabetes mellitus. Lancet 2002; 360: 1477-78.
4. Salazar-Martinez E, Willett WC, Ascherio A, Leitzmann M, Manson JE, Stampfer MJ, Hu FB. Coffee consumption and risk of type 2 diabetes in men and women. Ann Intern Med. 2004;140: 1-8.
5. Tuomilehto J, Hu Gang, Bidel S, Lindstrom J, Jousilahti P. Coffee consumption and risk of type 2 diabetes mellitus among middleaged Finnish men and women. JAMA 2004;291: 1213-19.
6. Hauri HP, Wacker H, Rickli EE, Bigler-Meier B, Quaroni A, Semenza G. Biosynthesis of sucrase-isomaltase. Purification and NH2-terminal amino acid sequence of the rat sucraseisomaltase precursor (prosucraseisomaltase) from fetal intestinal transplants. J Biol Chem. 1982;257: 4522-4528.
7. Matsui T, Ueda T, Oki T, Sugita K, Terahara N, Matsumoto K. alpha-Glucosidase inhibitory action of natural acylated anthocyanins. 1. Survey of natural pigments with potent inhibitory activity. J Agric Food Chem. 2001;49: 1948-1951.
8. Tuomilehto J, Tuomilehto-Wolf E, Virtala E, LaPorte R. Coffee consumption as trigger for insulin dependent diabetes mellitus in childhood. BMJ. 1990;300:642643.
9. Van Dam RM, Hu FB, Coffee consumption and Risk of type 2 Diabetes. JAMA 2005; 294 97104

"As type 2 diabetes rarely appears before the age of 40 and many older people stop or lessen coffee drinking, dietary advice may soon be developed that includes coffee as a safe and useful drink in a diabetes prevention programme".


Professor J. Tuomilehto, Diabetes and Genetic Epidemiology Unit, University of Helsinki, Finland.

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