Caffeine is a naturally derived stimulant which can be extracted from variety of sources that includes leaves of particular types of plants, nuts and berries. In its pure form, caffeine exists as white crystalline compound that tastes very bitter. Till today, caffeine is largely consumed by human beings in form of Beverages like tea and coffee. Caffeine provides “boost of energy” or a feeling of alertness. Apart from this caffeine is used medically as heart stimulant and is also associated with diuretic activity.
Effects of Caffeine
Caffeine acts as CNS stimulant. It has shown to affect mood, stamina, cerebro-vascular system and gastric as well as tonic activity. As we are dealing hypertension, we will focus mainly on relationship between caffeine and blood pressure. Caffeine acts as stimulant for both heart and brain. After caffeine administration we feel more alert, active and focussed. In order to produce such effect, heart has to pump large amount of blood to the brain, and which may be responsible for rise in blood pressure. On the other hand caffeine has vasoconstricting effect, which leads to narrowing of blood vessels. Heart has to apply more pressure to pass blood through such narrow arteries, and thus blood pressure also increases.
Some researcher suggest that rise in blood pressure on caffeine consumption is due to blockage of hormone adenosine which is responsible for widening of blood vessels and so constricted arteries results in rise in blood pressure. The level of adrenaline and cortisol also increases on caffeine intake which play crucial role in raising blood pressure.
From the above we can conclude that caffeine may lead to high blood pressure, but severity is less as compared to smoking or alcohol induced hypertension. This is because no mortalities from heart attack or strokes have occurred from coffee drinking.
Coffee intake may show spike in blood pressure, but it wears off after some time because of short life span of alcohol. After ingestion, caffeine is completely absorbed within 35-40 mins and its effects start decreasing after 3 hrs. Caffeine also acts as self-limiting agent, as it acts on kidney to promote its own excretion rate and nowhere accumulates in body. On drinking caffeine systolic pressure rises up to 3-14 mmHg whereas diastolic pressure raises by about 5mmHg.
Recommended level of Caffeine
The U.S. Food and Drug administration(USFDA) and American Medical Association classify a “moderate intake” of caffeine as “generally recognised as safe”. Meaning of low, moderate, high and heavy caffeine intake is given below,
- A low to moderate dose is 130mg-300mg per day
- Moderate is 200mg-300mg per day
- High doses are above 400mg per day
- Heavy caffeine doses in more than 6000mg/day
From the above data, we should limit our daily intake of caffeine to moderate level i.e. 200mg per day which means up to two 12oz cup of coffee. Coffee has the highest amount of caffeine. However different products vary significantly in caffeine level like
- One mug of instant coffee has 100mg caffeine
- One mug of filter coffee has 100mg caffeine
- One mug of tea has 75 mg caffeine
- One can of cola has 40mg caffeine
- One can of energy drink has 80mg caffeine
- One 50g bar of dark chocolate has 50mg caffeine.
By drinking around 1or 2 cups of coffee raises blood pressure by 5mmHg. On regular intake of coffee, person develops tolerance and might show no rise in blood pressure.
Benefits of Caffeine
Green Tea is a popular source of vitamins and antioxidants like flavonoid and polyphenols. This flavonoid play important role in treatment of heart diseases as it decreases stiffening in arteries. It is also helpful in treatment of Alzheimer’s disease. Tea and coffee also acts as anticoagulant as it decreases level of platelets, thus prevents blood clot formation.Drinking decaffeinated coffee may protect you from Parkinson’s disease, diabetes and liver cancer.
Precautions while using Caffeine
Avoid drinking coffee during smoking – we know that smoking is one of the major risk factor fo hypertension. If you drink coffee while smoking, your blood pressure may rise up to 10mmHg in few hours.
Avoid coffee if you have occupational stress– Generally people in order to stay active and alert, drink strong coffee during their working hours. You should avoid drinking coffee during combination of stress and coffee if you are suffering from hypertension.
Avoid during pregnancy – Pregnant women should consume less than 200mg of caffeine per day. Heavy caffeine intake can lead to chances of miscarriage.
Decaffeinated coffee can be best choice for patients who are suffering from hypertension. Decaffeinated coffee consists of around 12 mg of caffeine. Excessive intake of decaffeinated coffee may also lead to rise in level of cholesterol. So always consult doctor before drinking decaffeinated drinks.
Caffeine also shares number of traits of notorious drugs like cocaine and heroin- ability to cause addiction. The withdrawal symptom of caffeine includes headache, restlessness, anxiety, restlessness and difficulty to fall asleep.