Over-65s who drink four or more caffeinated beverages every day may reduce their risk of heart disease by a whopping 53 per cent, suggests research from the US.
But while the benefits of drinks were found to be dose-dependent, with increasing intake liked to lower risk, lead researcher James Greenberg and his co-workers stressed in the American Journal of Clinical Nutrition that this did not prove a cause-and-effect relationship.
"This study does not provide a valid basis for recommending increased consumption of caffeinate beverage," wrote Greenberg. "Our findings require confirmation in future epidemiological, metabolic, and clinical trial studies."
The apparent benefits were also only seen in people with normal blood pressure and are not applicable to hypertensives, said the researchers.
Writing in the current issue of the American Journal of Clinical Nutrition, Greenberg and his co-workers from the State University of New York and the City University of New York report the results of their epidemiological study of 6594 men and women aged between 32 and 86 using data from the 1971-1973 National Health and Nutrition Examination Survey (NHANES I) and follow-up until 1992.
Intake of caffeinated beverages, including coffee, tea, and caffeinated cola and chocolate, was calculated from food frequency questionnaires, and classified according to average daily intake: less than half a serving, between half and two servings, two to four servings, four or more servings.
During the period of cardiovascular disease monitoring (between 1986 and 1992), in the participants over 65 years of age, 349 passed away from cardiovascular disease, 282 from heart disease, and 67 from cerebrovascular disease.
For this age group, the researchers report that increasing intake of caffeinate beverages was associated with decreasing risk of mortality from these conditions. Indeed, drinking four or more servings per day reduced the risk of heart disease mortality by 53 per cent.
The researchers also point out that, while significant effects were observed in people with normal blood pressure, or blood pressure at the upper limit of the normal range, no effect was observed in people with stage 2 hypertension.
Also, no significant effect was observed amongst the participants younger than 65.
"Our main finding was that, in the prospective NHEFS cohort, participants aged 65 years or over without stage 2 hypertension who reported a higher intake of caffeinated beverages experienced a lower risk of heart disease mortality than did those who reported a lower intake," wrote Greenberg.
"If our findings are confirmed, they may have important ramifications because caffeinated beverages are widely consumed and heart disease is one of the leading causes of death in the elderly," he said.
Indeed, cardiovascular disease (CVD) causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy an estimated €169bn ($202bn) per year.
The researchers noted however that these results do not allow them to conclude if caffeinated beverages or the caffeine content is directly responsible for the apparent protective effect.
"Caffeine is found in coffee, tea, cocoa, and chocolate, all of which contain compounds such as antioxidants and flavonoids," they said. "It is possible that these compounds, which have been shown to preserve cardiovascular function in some studies, are part of the explanation for our findings."
The researchers called for significant further research into this area, and were prudent not to recommend caffeinate beverages for this age group. It seems the global coffee, tea and energy and stimulant drinks industries will have to wait for confirming studies. A Mintel report showed that energy and stimulant drink sales exceeded £1bn (€1.45bn) in the UK in 2005, with a 75 per cent increase in sales volume since 2000.
Source: American Journal of Clinical Nutrition Volume 85, Pages 392-398 "Caffeinated beverage intake and the risk of heart disease mortality in the elderly: a prospective analysis"
Authors: J.A. Greenberg, C.C. Dunbar, R. Schnoll, R. Kokolis, S. Kokolis, J. Kassotis