Caffeine isn’t an essential nutrient but, like alcohol, it plays an important role in many people’s eating and drinking habits. In terms of health, it’s important to understand what it is, the effect it can have and also the many different products that we find it in.
When caffeine is consumed, it is virtually all absorbed within approximately 45 minutes. Peak volumes of caffeine appear in the blood stream approximately 1 hour after consumption. It’s absorbed into the blood and circulatory system and brain. It is then transported to the liver where it is broken down ready to be eliminated. Caffeine is not stored and does not stay in the bloodstream, but is removed from the body within a few hours of consumption. Once the caffeine has been taken to the liver, the liver’s role is to break it down into products that can be eliminated safely from the body and removed by the urine and faeces. (Caffeine has no biological requirement within the body and is a chemical that the body would prefer not to have).
Caffeine has been associated with some physiological effects and this includes:
- Vitamin and Mineral absorption – Excessive caffeine consumption compromise the body’s ability to utilise B vitamins. It also decreases the absorption of essential minerals, such as calcium, magnesium, iron and zinc. Caffeine causes the excretion of these minerals in the urine, especially calcium, potassium, magnesium, zinc and iron.
- Acidity – Caffeine consumption also raises blood acidity levels, which causes calcium to be pulled from the bones to alkalise the blood, further increasing the risk for osteoporosis. It can also bring on heartburn.
- Increased fat breakdown – Paraxanthine, or 1,7-dimethylxanthine a metabolite of caffeine, is responsible for an increase in the release of glycerol and fatty acids into the blood to be used as a source of fuel by the muscles
- Increased sensitivity – Caffeine can cause increased sensitivity of the fat cells and nervous system, widening and relaxing the blood vessels increasing the amount of oxygen and nutrients to the muscles, increasing its sensitivity.
- Hypothermia – Hypothermia is a condition in which an organism’s temperature drops below that required for normal metabolism and bodily functions. Its link to hypothermia is due to its stimulatory effect increasing the heart rate and so speeding up the effect of excessive cold temperatures/environments on the body.
- Stimulant – Caffeine acts as a psychoactive drug, which means that it has the effect of altering brain function, resulting in temporary changes in perception, mood, consciousness and behaviour. It acts primarily on the central nervous system having the effect of temporarily warding off drowsiness and restoring alertness.
- Diuretic – A diuretic is a drug that elevates the rate of bodily urine excretion; this can lead to dehydration if an individual is not careful to replace this fluid that is excreted.
It’s accepted that moderate amounts of caffeine do not pose any real risks to our health; whereas consistent high intakes may have a detrimental effect. It’s widely agreed that coffee should be avoided by anyone with high blood pressure, gastritis or ulcers, and particularly by pregnant or nursing mothers.
Moderate intakes are considered to be 200-250mg of caffeine; this is the equivalent of 2-3 cups (200mls each) of coffee or 4-5 cups of tea.
- Diet Coke contains 45.6mg of caffeine per 340ml (12oz).
- Brewed coffee contains 112mg of caffeine per 140g (5oz).
- Pro plus contains 50mg of caffeine per tablet.
- Chocolate contains 6mg of caffeine per 28g (1oz).
- Tea contains 6mg of caffeine per 28ml (1oz).
If you were to exclude all sources of caffeine from your diet, it takes about 4-6 days to wash out all the effects of caffeine from your system. Depending on how much caffeine you are consuming, you may experience quite severe headaches as part of the withdrawal process. To reduce the undesirable effects of eliminating caffeine in one go, it is best to gradually reduce intakes.