Caffeine

Caffeine increases stress and anxiety. In scientific studies on animals it is even used as a means of inducing anxiety. In chronic use it reduces the ability to cope with stress and indeed seems to augment the damaging effects of stress. People who substantially reduce caffeine intake make greatest improvements in reducing anxiety, irritability, sleep disturbance, headaches and abdominal symptoms.

Caffeine or 1, 3, 7-trimethylxanthine is the most widely consumed pharmacologically active substance in the world. Its major action is to stimulate the central nervous system. Caffeine is found in over 60 plant species of which the most well known are cocoa beans, tea and coffee.

Caffeine occurs naturally in tea, coffee, cocoa and chocolate products and is added to soft drinks and a variety of both prescription and over-the-counter drugs. Standard values for the caffeine content of these foods and beverages have been set. Thus an average sized cup (150 ml) of ground roasted coffee contains around 85 mg, instant coffee 60 mg, decaffeinated coffee 3 mg, leaf or bag tea 30 mg, instant tea 20 mg and cocoa or hot chocolate 4 mg caffeine.

A recent review undertaken by Health Canada has considered the numerous studies dealing with caffeine and its potential health effects. It has re-confirmed that for the average adult, moderate daily caffeine intake at dose levels of 400mg/day (equivalent to 6mg per kg of body weight per day in a 65-kg person) is not associated with any adverse effects.

However the data also shows that “reproductive-aged women are a ‘at risk' subgroup who may require specific advice on moderating their caffeine intake. Based on available evidence, it is suggested that reproductive-aged women should consume less than or equal to 300 mg caffeine per day (equivalent to 4.6 mg per kg of bodyweight per day for a 65-kg person)”.

The links between caffeine and health are not completely clear yet.

There is evidence that caffeine affects normal cellular function and has several physiological effects:

• raising blood pressure
• acting as a mild diuretic
• and temporarily averting fatigue.

Source:http://www.nutrition.org.uk/printArticle.asp?dataId=1321

Studies have shown that caffeine can have beneficial performance effects; sustaining attention during the post-lunch dip, at night, after prolonged work and when a person has a cold.
Source:http://www.nutrition.org.uk/printArticle.asp?dataId=1089

Caffeine is a drug that acts as a stimulant to the heart and central nervous system, and is also known to increase blood pressure in the short-term, although there is no conclusive evidence of long-term effects on blood pressure.

Caffeine content:

Caffeine Advice

It's difficult to suggest a safe limit for coffee intake because of the huge variation in caffeine content of different brands and an individual's sensitivity to the drug.

The effects on blood pressure are most likely when caffeine is taken in excessive quantities or by highly sensitive people. In particular, people who are hypertensive (have habitual high blood pressure), are advised to avoid caffeinated drinks.

There is no evidence that coffee does any long-term harm. It has been found that coffee may be beneficial in some areas of health. Early research has found that coffee may reduce the risk of developing gallstones, kidney stones and colorectal cancer.

Tea does contribute slightly to our intakes of minerals, and it helps to replace lost fluids.
(Source:http://www.bbc.co.uk/health/healthy_living/nutrition/drinks_caff.shtml)