META-ANALYSIS: COFFEE IN SUPPORT OF HEALTHY METABOLISM AND BLOOD SUGAR
According to legend, the ancestors of today's Oromo tribal people of northeastern Africa (“Horn of Africa”) have been considered the first who recognized the energizing effects of the coffee plant. The story of Khalid -- the 9th-century Ethiopian goat herder who supposedly discovered coffee when his goats behaved strangely after eating from a coffee plant (later known as coffee Arabica) -- appeared in writing only in late 17th century.
While the aroma of morning coffee does not require special introduction, coffee has now been rediscovered due to preclinical, clinical and epidemiological data in support of healthy effects of daily coffee in prevention of type 2 diabetes mellitus. The worldwide prevalence of type 2 diabetes is increasing and the global number of people with diabetes is estimated to reach 366 million by 2030. The risk of blindness, renal disease and cardiovascular disease among those with type 2 diabetes is 20 to 40 times higher than that of people without diabetes. Those with type 2 diabetes have two to five times higher risk of myocardial infarction and two to three times higher risk of stroke.
Recent meta-analysis (study of studies) evaluated results of 28 epidemiological studies conducted between January 1966 and February 2013 involving 1,109,272 participants, focusing on an association between coffee consumption and risk of type 2 diabetes (J Med Food 2013 Jun;16(6):564-8). The robust inverse association between coffee consumption and diabetes risk was consistent for both genders, among European, US and Asian populations and irrespective whether coffee was caffeinated or decaffeinated, as well as method of coffee preparation and life style of the studied populations (Diabetes Care 2014 Feb;37(2):569-86). The dose-response analysis suggests that incidence of type 2 diabetes decrease by 12 % for every two cups per day increment in coffee intake, 11 % for every two cups per day increment in decaffeinated coffee intake and 14 % for every 200 mg/day increment in caffeine intake (Eur J Nutr 2014 Feb;53(1):25-38). While the caffeine may play a beneficial role in the anti-diabetic properties of coffee, other components are equally if not more beneficial in supporting healthy blood sugar response among habitual coffee drinkers, i.e.polyphenolic compounds like chlorogenic acid, trigonelline (precursor of vitamin B3), caffeoylquinic acid, lignans and guinidines.
Chlorogenic acid, a major coffee component and powerful antioxidant, may reduce gastrointestinal glucose absorption by competitively inhibiting glucose-6-phosphate translocase, an enzyme involved in glucose gastrointestinal transport, while also reducing the liver glucose output. Chlorogenic acid and trigonelline have been shown to reduce early glucose and insulin responses during the challenge with glucose tolerance test, hence indicating mechanism in controlling carbohydrate metabolism (Diabetes Care 2009 Jun;32(6):1023-5). Coffee’s caffeine and chlorogenic acid may prevent accumulation of toxic amyloids in pancreatic islet cells, preventing age-related deterioration of the pancreas, which inhibits healthy production of insulin (Diabetes Care 2009 Jun;32(6):1023-5). The caffeoylquinic acid, rich in coffee’s dark roast, has been reported to decrease oxidative damage and spontaneous DNA strand breaks in peripheral white blood cells, a well-established marker of health risk ((Eur J Nutr 2015 Feb;54(1):149-56). Of interest, medium and dark roast coffee blends exert slightly different metabolic effects, e.g. consumption of four to five cups per day for three months resulted in systolic blood pressure decrease in the dark roast coffee group only, while high-density lipoprotein (HDL or good cholesterol) levels increased in the medium roast coffee group only (Eur J Nutr 2014 Sep 10).
The positive metabolic effects of coffee and components were further supported by its potential role in supporting the liver, a major metabolic organ in the body. Over the past 20 years, an increasing number of epidemiological and experimental studies have demonstrated the positive effects of habitual coffee consumption on chronic liver diseases, e.g. inverse association with liver enzymes in heavy drinkers, improved hepatic steatosis and fibrosis (accumulation of liver fat leading to insulin resistance and type 2 diabetes), and a reduction in liver cirrhosis and the risk of hepatocellular carcinoma. The mechanisms of action through which coffee consumption exerts its beneficial effects may be due to elevated antioxidant capacity through an increase in the antioxidant glutathione as well as modulation of the gene and protein expression of several anti-inflammatory mediators in the liver. The preclinical studies indicate that two diterpenes in coffee -- cafestol and kahweol -- may produce a broad range of biochemical effects resulting in a reduction of the genotoxicity of several carcinogens by induction of conjugating enzymes, an increased expression of proteins involved in cellular antioxidant defense and an inhibition of the expression and/or activity of cytochromes P450 involved in carcinogen activation (Food Chem Toxicol 2002 Aug;40(8):1155-63). (J Clin Gastroenterology 2014 Nov-Dec;48 Suppl 1:S87-90).
.Further addition to understanding of coffee benefits in metabolic health is its impact on cardiometabolic health. The meta-analysis of prospective studies from January 1966 through December 2011 with 140,220 participants evaluating cardiometabolic health among daily coffee drinkers showed a significant positive impact of habitual coffee consumption on cardiovascular health, and on the metabolism of carbohydrates and lipids. Compared with no coffee consumption, the strongest inverse association between coffee consumption and cardiovascular disease was seen in those who had four cups per day (Circ Heart Fail 2012 Jul 1;5(4):401-5).
In summary, regular daily coffee consumption is associated with the reduction in the incidence of diabetes, liver disease and gastrointestinal cancers and improved cardiovascular health. Mounting evidence also appears to show protection seems to exist also for Parkinson's disease, Alzheimer’s disease and in mood disorders -- studies showed that coffee consumption was an independent predictor of non-depressed status in diabetic patients. In general coffee consumption seems to reduce mortality for all causes as compared with the non-coffee-drinking population (Maturitas 2013 May;75(1):7-21). (J Clin Biochem Nutr 2014).
My daily choice is an aromatic and rich cup of black coffee, brewed freshly from medium roast beans.
THE COFFEE CUP OF INDIA – THE COORG COFFEE
Vladimir Badmaev, MD PhD
The Coorg region (southernmost edge of Karnataka, India) is recognized as a heartland of India coffee renowned for its “monsoon-fed coffee beans”, shade-grown under giant Rose Wood, Wild Fig and Jack Fruit trees. This unique growth habitat provides the beans with exotic flavors and aromas. The onset of the coffee season in Coorg region is in February with the air filled with the heavy fragrance of snow white coffee blossoms. In November, the girdles of coffee are dotted with ripe red coffee cherries, or beans.
Coorg is also home to the unique Kodava people, thought to be descendant from migration of Persians and Kurds, or even Greeks from the time of Alexander the Great’s armies. The Coorg region, known as Kodagu, was a state on its own until 1956, when it merged with Karnataka. In mid nineteenth century the first British superintendent, Capitan Le Hardy enthusiastically promoted the cultivation of Coorg coffee encouraging local farming community to give preference to coffee cultivar. The indigenous coffee is a special variety of coffee Arabica known as robusta, obtained with wet process “parchment robusta” or dry process “cherry robusta” and the monsooned coffee with taste preferred by those who like rich and complex flavors. The Coorg coffee is well recognized in India, affectionately called the “Coffee Cup of India”, and abroad --- valued for its taste especially in Italy.