Caffeinated drinks, such as tea, coffee and cocoa, can make an important contribution to good health, says a new research review just published.
In this review, which investigates the health aspects of caffeine, Dr Carrie Ruxton, leading independent dietician, concludes that optimal intakes of some caffeinated drinks deliver key benefits in terms of mental function and heart health.
Commenting on the new research, Dr Catherine Hood from the Tea Advisory Panel (TAP) notes: “Caffeinated drinks have been unfairly demonised. In fact, certain caffeinated drinks deliver health benefits because of their moderate caffeine content as well as other nutritional components.
“Black tea, in particular, contains polyphenols, which are a family of natural plant antioxidants. These have beneficial effects on many biochemical processes in the body because they protect cells against harmful free radicals and are anti-inflammatory. Flavonoids, a group of substances within the polyphenol family, are thought to be especially useful, with a number of research studies reporting a link between flavonoid intakes and a decreased risk of heart attack. There are also emerging data which suggest that flavonoids can support brain and mental function.”
Dr Ruxton’s important new review highlights evidence to debunk the many myths surrounding caffeine while demonstrating the key benefits that optimal consumption of caffeinated drinks can deliver. In brief, Dr Ruxton’s paper reveals that:
• Caffeinated drinks, such as tea and coffee, can make an important contribution to health, particularly heart heath and cognitive function.
• Evidence indicates that caffeinated drinks in appropriate amounts do not increase blood pressure or increase the risk of a heart attack.
• Caffeinated drinks in appropriate amounts contribute to healthy hydration.
• Caffeinated drinks provide a range of compounds, such as polyphenols which are associated with health benefits.
• A balanced approach is needed when giving advice about caffeine intake. People who cut out caffeinated drinks, which most British people enjoy, may miss out on the potential health benefits of the compounds they contain.
• Intakes of caffeine up to 400mg a day, which equates to 8 cups of tea, maximise the likelihood of health benefits without any of the possible adverse consequences which have been shown at caffeine intakes of 600mg daily and above.
• The only UK official guideline for caffeine is in relation to pregnancy. Pregnant women are advised to limit caffeine intake to 200mg per day.
• According to Dr Ruxton’s analysis of the literature, all other healthy adults, including athletes, vegetarians, breast feeding mothers and elderly people, can safely consume up to 400mg caffeine a day.
• School aged children can consume up to 95mg a day of caffeine. Caffeinated drinks served unsweetened and with milk, are healthier for the teeth than acidic fruit juices and sugar containing soft drinks. Milk also contributes to daily calcium intakes.
The Tea Advisory Panel:
The Tea Advisory Panel is supported by an unrestricted educational grant from the UK TEA COUNCIL, the trade association for the UK tea industry. The Panel has been created to provide media with impartial information regarding the health benefits of tea. Panel members include nutritionists; dieticians and doctors. For further information please call 0207 7058989 or view all panel biography details by logging on to www.teaadvisorypanel.com
Notes to editors:
Dr Carrie Ruxton is a member of the Independent Tea Advisory Panel
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Julia Riddle at Julia.firstname.lastname@example.org or 020 7052 8859
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Consumption of caffeinated drinks in the UK
Caffeinated beverages have been drunk in the UK for nearly 400 years. Today they are regularly consumed by a large proportion of the UK population. The UK National Diet and Nutrition Survey of nearly 2000 adults revealed that 77% of people drink tea, while 71% drink coffee. According to the most recent National Drinks Survey, the average adult drinks 2.1 cups of tea and 1.1 cups of coffee a day.
Caffeine content of common foods and drinks
Daily caffeine intakes in the UK are approximately 4 mg/kg body weight (i.e. 280mg for a 70kg individual). The main dietary sources are tea, coffee, cocoa products, cola and chocolate.
Caffeine content (mg/portion) of foods and beverages commonly consumed in the UK
Beverage (portion size) Range Average
Tea (190 ml) 1-90 50
Instant coffee (190 ml) 21-120 75
Ground coffee (190 ml) 15-254 100
Espresso coffee (40ml) 140
Hot chocolate (150 ml) 1-6 -
Dark chocolate (bar) - 50a
Cola (330 ml) 11-70 40
Energy drink (250 ml) 27-87 80
Caffeine and health
The link between caffeine and health has been the subject of a large number of studies. These can be difficult to interpret because the sources of caffeine used vary from caffeine pills through to coffee and tea. A UK review of 20 studies found significant health benefits of regular tea drinking (at around 4 cups a day) and heart health, including reduced mortality, lower risk of heart attack and lower cholesterol. Three other studies, which included a total of 90,000 patients, found that drinking 4 cups a day of caffeinated drinks, such as tea, was associated with a lower risk of cardiovascular disease. A further study in 26,500 middle-aged smokers found that men who drank more than 2 cups of tea a day were 20% less likely to have a stroke.
The myth around blood pressure
A lot of the concerns around caffeine and heart health relate to blood pressure. However, Dr Ruxton’s review highlights two observational studies, involving more than 155,000 people, which found no association between caffeine intake and blood pressure. Intervention trials have reported that caffeine consumption in the form of caffeine pills or coffee can increase blood pressure. However, a meta-analysis of 16 controlled trials demonstrated that coffee had less of an effect on blood pressure than caffeine alone. In another study, caffeine pills were more likely to affect blood pressure in people with pre-existing high blood pressure than those with optimal blood pressure. In yet another study, this time comparing the effect of tea with caffeine powder, tea had less of an effect on blood pressure than caffeine alone. Tea polyphenols may have minimised the effect of caffeine in this study, suggests Dr Ruxton.
Caffeine and mental health
Caffeine’s well known effects on mood and performance are believed to be caused by its influence on various chemical transmitters in the brain. Dr Ruxton highlights a recent review that included 23 controlled trials, the majority of which demonstrated benefits for caffeine in the region of 37.5 to 450mg. Benefits included improved alertness, improved short term memory, improved mood and reduced feelings of tiredness. Other compounds in tea and coffee, such as theanine, theobromine and theophylline, have also been shown to influence mood, which is why studies looking at caffeine pills differ in their findings from those looking at caffeinated drinks.
Caffeine and physical performance
Caffeine is well known amongst regular exercisers and sports people for its beneficial effects on physical performance. Such benefits are thought to occur as a result of caffeine’s effect on stimulating fat burning and the consequent preservation of muscle glycogen (carbohydrate) stores. Caffeine may also enhance muscle contractions and increase tolerance to fatigue.
A review of 11 studies found improvements in running and cycling endurance and feelings of fatigue following caffeine consumption, while two meta-analyses also found that caffeine enhanced physical performance. Caffeine has also been found to improve physical endurance and walking in elderly people.
Caffeine and hydration
It is a common misconception that normal consumption of caffeinated drinks causes dehydration. However, evidence from studies of regular caffeine consumption does not back this up. In a review of 8 controlled studies, five found no impact of caffeine on hydration in the range of 98-420mg caffeine a day. Two of the studies did find that urine output increased, but only when caffeine intakes were in the region of 600mg a day. “This suggests that caffeine only presents a risk to hydration at higher intakes, equating to 12 cups of tea or 6 strong cups of coffee a day,” says Dr Ruxton.
Caffeine intake for specific patient groups
Evidence highlighted in Dr Ruxton’s review suggests that, contrary to common misconceptions, caffeinated beverages in appropriated amounts, can deliver benefits for heart health and mental function without risk to other aspects of health. People have long enjoyed, and continue to enjoy, drinks such as tea, and Dr Ruxton’s review emphasises the need to take a balanced approach towards consumption of caffeinated drinks.
The only UK guideline highlighting caffeine intake refers to pregnancy where the Food Standards Agency has identified a daily of limit of 200mg, which equates to 4 cups of tea. For healthy adults, including athletes, breast-feeding women, vegetarians and elderly people, and also people with cardiovascular disease or kidney disease but with normal blood pressure, 400mg a day, which equates to 8 cups of tea a day would appear to be a reasonable limit says Dr Ruxton. Up to this level of intake, caffeinated drinks make a positive contribution to hydration.
There are no official UK guidelines for caffeine intake in children but there is no need for school-aged children to avoid tea and coffee. Dr Ruxton suggests that caffeine intake in children should be limited to 95mg daily, which equates to 1-2 small cups of tea or 1 small cup of weak instant coffee. “Adding plenty of milk to unsweetened tea or coffee provides a source of calcium and is healthier for teeth than acidic fruit juices or sugar-containing soft drinks, notes Dr Ruxton.
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