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Caffeine - How does it affect your health?

Caffeine - BBDiet dietitian

Every day, millions of people are reaching for a coffee to kick-start the day.

According to Australian Bureau Statistics, nearly half the population are consuming coffee (46%) and tea (38%) each day (1).

Caffeine is one of the most commonly used drugs in the world. Because it is present in so many common foods and beverages, it’s easy to forget that it is a drug. This mind-altering, stimulant drug is the same type of drug as cocaine and nicotine. This addictive drug affects our body by over-stimulating the brain and the nervous system, which then speeding up the heart palpitation, making you feel more alert and increasing muscle tension.

Why is caffeine so popular?

Popular cafe - why is caffeine so popular? BBDiet dietitian

People enjoy the exhilaration it brings to the mind and body. Yes, caffeine gives you that much needed kick in the morning making you feel awake, alert and energetic but the stimulating effect is just temporary. It draws the body’s emergency energy reserves to produce instant energy that only last for a short period. This triggers the yo-yo syndrome, by reaching for another caffeinated drink to get more energy, and then another. The vicious cycle repeats.

What is caffeine?

What is caffeine? BBDiet dietitian

Caffeine is a drug similar to cocaine and nicotine that can cause addiction. It is part of a larger group of drugs related to amphetamines.

Whether it is in the form of coffee, tea, chocolate, pain relievers, or soft drinks, most people are getting caffeine one way or another. Caffeine is also regularly added to gum, jelly beans, beverages, syrup, desserts and more.

How does caffeine affect your health?

Recent studies have shown that caffeine has been implicated in degenerative diseases such as diabetes, cancers, heart disease, high blood pressure and gastro oesophageal reflux disease (GORD) (2,3,4).

How does caffeine affect your health? BBDiet dietitian

Caffeine’s effects upon brain and nervous system are far-reaching. In addition to disrupting sleep, it also has detrimental effects on our health.

Here is an overview of the negative effects of caffeine on the body:

1) Increases the risk of reflux (GORD – Gastro-Oesophagus Reflux Disease)

Caffeine can contribute to reflux because caffeine relaxes a door-like muscle, called the lower oesophageal sphincter (LES) that exists between the lower part of the oesophagus and the stomach.

This sphincter acts as a door that allows food and liquids to pass through the oesophagus into the stomach. When the sphincter is relaxed by the caffeine, it loses the ability to prevent foods from going upwards resulting in foods traveling back into the oesophagus along with acid from the stomach, which leads to heart burn or reflux.

Reflux is one of the commonly seen conditions amongst the patients I see in the clinic. Many of them have been taking nexium for many years as per doctor's advice to help suppress the symptom. Interestingly, majority of the reflux cases are closely associated with caffeine consumption. Most of them found significant relief when cut out caffeine for 7-10 days.

2) Raises Blood Pressure

Caffeine is particularly harmful for people who have already been suffering from hypertension and also for those who normally don’t take caffeine. 250mg of caffeine can elevate the blood pressure significantly within an hour or two as it reaches its highest level in the bloodstream. For those suffering from irregular heart rhythms, caffeine can result in making the heart beat harder and stronger and thus a significant increase in the blood pressure.

3) Irritates Stomach

Caffeine reacts with the acid in your stomach and increases its amount thus causing stomach irritation and heart burn. Caffeine may also cause indigestion and upset your stomach especially when consumed on an empty stomach.

In some cases, people who are sensitive to caffeine may tend to go to the toilet more often than usual or even have diarrhoea. Some people may even use caffeine as a way to help them move their sluggish bowel. However, they are not aware that caffeine is actually upsetting the body and the body is trying hard to get rid of caffeine by flushing it out as soon as it could. As a result, the body is losing more water and nutrients while making the gut more sensitive.

4) Diuretics

As a diuretic, caffeine causes you to lose a lot of water from your body, especially when you are consuming it along with regular exercise. Extra caffeine never gets stored in your body instead it is processed by the liver and then excreted by the body in the form of urine. Every time when you drink a cup of coffee, you will need to drink at least three cups of water to rehydrate your body.

5) Increases Anxiety

Caffeine consumption is linked to increase in anxiety and depression so much so that an individual might have to go for anxiety medication to maintain the situation.

6) Depletes nutrients in the body


Caffeine interferes with iron absorption and can lead to iron deficiency anaemia when consumed in large quantities.

Drinking caffeine at the same time as an iron source can reduce absorption by up to 80%, according to the Nutrition Desk Reference. Any beverage containing caffeine should be separated from iron-containing foods or supplements by at least one hour (5).


Caffeine depletes calcium from the body. For every 150 mg of caffeine consumed, about the amount in one cup of coffee, 5 mg of calcium is lost. This effect occurs even hours after the consumption of caffeine.

One study of postmenopausal women found that those who consumed more than 300 mg of caffeine lost more bone in the spine than women who consumed less. Caffeine also inhibits the amount of calcium that is absorbed through the intestinal tract and depletes the amount retained by the bones. Studies have shown that women with high caffeine intake suffer more hip fractures than those who avoid caffeine or drink in moderation (1 to 2 cups per day) (5).

Other vitamins and minerals

Caffeine may reduce the absorption of manganese, magnesium, zinc, copper, potassium, sodium and phosphate. There is also evidence that caffeine interferes with the action of vitamin A, B, C, D, E and K.

Can caffeine kill you?

Can caffeine kill you? BBDiet dietitian

When caffeine is consumed regularly and in large quantities, the side effects can range from feeling uneasy to severe, sometimes may even result in caffeine overdose.

Consuming high doses of caffeine may lead to:

  • Heart palpitations and rapid heart beat

  • Sweating

  • Anxiety and panic attack

  • Nausea and vomiting

  • Cardiac arrest

According to the Mayo Clinic, if your intake is more than 4 cups of coffee in a day, you may have a 21% increase in your chance of early death (6,7).

A 16-year-old boy died from a caffeine overdose after drinking caffeine-laden soft drinks, coffee and an energy drink in 2017 (8).

Health impacts of caffeine - BBDiet dietitian

Without a doubt, caffeine is a drug. And this is not a metaphor. The composition of caffeine is similar to a drug and therefore classified as one. Caffeine can affect people just like any other substance would and therefore it is important that it be minimised or eliminated from our daily diet for the better.

Withdrawal symptoms vary, but can include lethargy, headache, sweating, muscle ache, irritation, and sometimes anxiety. Symptoms may last approximately up to 7 days. Anyone who wishes to give up caffeine should cut down over a few days rather than at once, with plenty of water and rest, to avoid uncomfortable symptoms.

If you’re worried about your energy dropping because of less caffeine perhaps you can try some alternatives such as ginseng, vitamin B12 supplements, and herbal teas such as peppermint tea to keep your mind fresh in the next couple of days. You would be surprised how energetic you could be without caffeine after overcoming the withdrawal symptoms.


1. Australian Bureau Statistics (ABS). Australian Health Survey: Nutrition First Results - Foods and Nutrients, 2011-12. Available from

2. Van Dam, R.M., Willett, W.C., Manson, J.E., and Hu, F.B. Coffee, caffeine, and risk of type 2 diabetes: a prospective cohort study in younger and middle-aged U.S. women. Diabetes Care. 2006; 29: 398–403

3. Sofi, F., Conti, A.A., Gori, A.M. et al. Coffee consumption and risk of coronary heart disease: a meta-analysis. Nutr Metab Cardiovasc Dis. 2007; 17: 209–223

4. Mesas, A.E., Leon-Munoz, L.M., Rodriguez-Artalejo, F., and Lopez-Garcia, E. The effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals: a systematic review and meta-analysis. Am J Clin Nutr. 2011; 94: 1113–1126

5. Escott-Stump S. 2008. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins.

6. Liu JX, Sui SM, Association of Coffee Consumption With All-Cause and Cardiovascular Disease Mortality. Mayo Clin Proc. October 2013;88(10):1066-1074

7. Healthy Lifestyle – Nutrition and Healthy Eating. Mayo clinic. Available from

8. Caffeine Overdose Killed South Carolina Teen, Coroner Rules. NBC News, May 2017. Available from



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