Looking forward to your coffee break? Worrying if you are drinking too much? We often seem to be bombarded with conflicting stories telling us that coffee is good for us or bad for us.
We will look at recent studies to see what are the advantages or disadvantages of drinking coffee and ask why it’s liked or detested so passionately. Is coffee a benefit or a danger to our health?
What is in the dark brown liquid?
A typical 200 ml cup of coffee contains:
- Vitamin B2 (Riboflavin): 11% of the Recommended Dietary Allowance (RDA).
- Vitamin B5 (Pantothenic Acid): 6% of the RDA.
- Vitamin B1 (Thiamin): 2% of the RDA.
- Vitamin B3 (Niacin): 2% of the RDA.
- Folate: 1% of the RDA.
- Manganese: 3% of the RDA.
- Potassium: 3% of the RDA.
- Magnesium: 2% of the RDA.
- Phosphorus: 1% of the RDA.
Multiply this by how many cups you drink per day- it can add up to a significant portion of your daily nutrients.
What makes coffee so special?
Coffee contains antioxidants but a study emphasised moderation and recommended only one or two cups a day to be of any benefit. Both caffeinated and decaffeinated versions provided nearly the same levels of antioxidants.
This is a drug found naturally in coffee which stimulates the central nervous system, an effect that may begin as early as 15 minutes after ingesting the caffeine and can last for as long as six hours.
The amount of caffeine in an average coffee various due to the roasting and grinding of the beans as well as the brewing time.
The Foods Standard Agency recommends that pregnant women limit their daily caffeine intake to below 200mg a day.
Coffee at work
The caffeine in the coffee acts as a stimulant making you more alert, less tired and more productive at work. The benefits are felt quickly, usually within fifteen minutes of drinking coffee and the effects can last for hours. A study review suggested that caffeine improves performance in both simple and complex mental tasks as well as moods.
Type 2 Diabetes Protection.
Researchers at the Harvard School of Public Health looked at data from past studies. Diet questionnaires of type 2 diabetes participants (who submitted them every 4 years) found that:
- Participants who increased their coffee intake by more than one cup a day had a lower type 2 diabetes risk than those who did not change their coffee intake.
- Those who reduced their coffee intake showed a higher type 2 diabetes risk.
One theory for the link between coffee and diabetes is that drinking coffee increases blood plasma levels of the protein sex hormone-binding globulin (SHBG). SHBG controls the biological activity of the body's sex hormones (testosterone and oestrogen) which play a role in the development of type 2 diabetes.
Improves Blood Pressure
Usually as we age so our blood vessels stiffen which leads to an increase risk of high blood pressure. However a study of Greek men and woman aged 65 to 100 living on the small island of Ikaria renowned for its aging population, showed that those participants who drank one to two cups of coffee a day had about a 25% greater elasticity in their major blood vessels than people who drank less coffee or none at all leading to lower blood pressure readings.
The data from studies published in Europe regarding the effects of coffee on health disease were analysed by the Beth Israel Deaconess Medical Center, Harvard Medical School, the Harvard School of Public Health, and the University of Alabama. This analysis concluded that participants who drank four cups of coffee per day had an 11% lower risk of heart failure than those who did not drink coffee at all.
No clear reason has been given for this finding but the researchers speculated that there is a connection between the two biggest risk factors for heart failure- diabetes and high blood pressure- both of these are affected by coffee consumption.
Prevents Parkinson’s disease.
This condition affects the whole body and is due to a loss of nerve cells in parts of the brain.
The three main symptoms of Parkinson’s disease are:
- tremor (involuntary shaking of particular parts of the body)
- slow movement
- stiff and inflexible muscles
A study in the US looked at the link between coffee intake and Parkinson’s disease risk. The researchers found that there was a lower incidence of Parkinson’s disease when people drank coffee.
In another study caffeine which is found in abundance in coffee helped to control the tremors of Parkinson’s sufferers.
Prevent Alzheimer’s and improves memory
Drinking between three and five cups of coffee in mid-life has shown to decrease the risk of getting dementia in 65% of people studied in later life. This is mainly due to the caffeine’s effect on the central nervous system and coffees’ antioxidant properties.
Michael Yassa, an assistant professor of psychological and brain sciences at Johns Hopkins found that caffeine has a positive effect on our long-term memory. Their research showed that caffeine taken up to 24 hours enhances certain memories.
Good for your liver
- Researchers from Italy have shown that coffee consumption reduces the risk of liver cancer by about 40%. And some of the results indicate that if you drink three cups a day, the risks are reduced by more than 50%.
- A study undertaken by Dr. Qian Xiao from the National Cancer Institute in the US revealed that participants who drank three or more cups of coffee (normal and decaffeinated) per day had lower levels of all four liver enzymes than non-coffee drinkers.
- Another study in the US found that one cup of coffee a day lowered the incidence of cirrhosis of the liver caused by alcohol abuse by 22%.
Research in the US found that the more coffee consumed the lower the risk of developing basal cell carcinoma (the most common diagnosed form of skin cancer). Decaffeinated coffee did not have any effect speculating that the link lies in caffeine.
Researchers in Washington, USA looked into coffee consumption and prostate cancer survivors. Participants of the study were asked to complete a food frequency questionnaire two years before their prostate cancer diagnosis, and were required to give information regarding their diet and beverage consumption. The study revealed that the men who drank four or more cups of coffee a day had 59% less risk of prostate cancer recurrence and/or progression than those whose coffee consumption was just one cup a week or less.
Research showed that drinking coffee can also reduce womb cancer risks. Elisa V. Bandera, associate professor from Rutgers Cancer Institute of New Jersey, says that “both caffeinated and decaffeinated coffee is associated with "an estimated 7% reduction in risk for every cup of coffee consumed, based on eight studies.”
A specific antioxidant known as chlorogenic acid (CGA) is found in the raw coffee bean.
This CGA has been associated with allowing oxygen to various areas of the body and blocking the cells that cause the hypoxia- deprivation of oxygen in areas of the body.
The retina found at the back of the eye is very prone to a drop in oxygen and susceptible to a variety of diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma all of which can lead to partial or complete blindness. Researchers from Cornell University, USA found that coffee extract and CGA contributed to more oxygen reaching the retina in mice and may prevent retinal degeneration in humans in the future.
Tinnitus or "ringing in the ears"
This subjective condition can be so debilitating that many people are unable to function normally.
Over 65,000 nurses with and without tinnitus were recruited in 1991 for the US Nurses’ Health Study II. Information was collected regarding their medical history, lifestyle and diet. Researchers of the study reported that those who developed tinnitus consumed less caffeine that those who did not report having developed tinnitus. This research showed that higher caffeine consumption was associated with a lower risk of incident tinnitus in women.
a. Researchers looked at over 83,000 Japanese adults and monitored their green tea and coffee consumption for an average of 13 years. They found that: Daily coffee drinkers were at a 20 percent lower risk of stroke compared to those who rarely drank it.
b. Another study published in Stroke: Journal of the American Heart Association stated that women who drink more than one cup of coffee per day appear to have a 22 to 25% lower risk of stroke than those who don't.
In the genes
We may hate or love coffee- we can’t choose. Recent research showed our choice is governed by our genes. Published in the journal Molecular Psychiatry, researchers from top US hospitals analysed over 20 previous studies with a total participation of over 120,000 people. They looked at their coffee consumption and scanned their DNA. The results suggested that people naturally curb their coffee intake to achieve the best effect caffeine can give them. This study showed that genetics can influence our liking or disliking of the drink.
The detrimental effects of caffeine?
Caffeine is a drug found not only in coffee but in other foods such as Coca-Cola, chocolate and pain medication. Genetic disposition may make people more sensitive to the effects of caffeine resulting in health problems. For healthy adults with no medical issues, it is generally agreed that 300mg-400mg of caffeine can be consumed daily without any adverse effects however too much caffeine can result in an overdose.
Caffeine has many effects on the body's metabolism, including stimulating the central nervous system. This can make you more alert and give you a boost of energy. However too much of it may cause some of the following signs and symptoms:
- Jitters, Restlessness, and Nervousness
- Tachycardia (fast heart beat) or cause abnormal heart rhythms
- Insomnia- make it hard to fall asleep or stay asleep
- Cause headaches or dizziness
- Cause dehydration
- Make you dependent on it so you need to take more of it. If you stop using caffeine, you could get withdrawal symptoms.
Caffeine and Pregnancy
There have been a number of studies which have documented the potential risks and benefits associated with coffee consumption in pregnancy. However these have yet to provide definitive conclusions. NHS guidelines state that if you’re pregnant, you should limit the amount of caffeine you have to 200mg a day – the equivalent of two mugs of instant coffee. The British Medical Journal recommends that once pregnancy is confirmed women should make every effort to stop or markedly reduce caffeine consumption. Many women now err on the side of caution and abstain from most or all caffeine whilst pregnant.
If you have a sensitive stomach and suffer from heartburn or reflux, drinking may make your symptoms worse because:
a. coffee is highly acidic and can cause irritation to the lining of the gastrointestinal tract
b. caffeine relaxes the sphincter muscle of the stomach releasing the stomach acid which causes the heartburn
Interaction with medication
The caffeine in the coffee can interfere with the desired effects of certain medication:
a. A study found that taking the osteoporosis drug alendronate with black coffee reduced its absorption by about 60%
b. People who swallowed their thyroid drug with coffee reduced its absorption up to 55%.
c. Certain antibiotics (Cipro, for example), some antidepressants (specifically, MAOIs), and asthma drugs (albuterol and theophylline) slow the rate at which the body breaks down caffeine and gets rid of it. This interaction increases the heart rate and can make you feel jittery.
Drinking coffee is more popular now than tea according to Mintel, the market research specialist; coffee sales in high street stores hit the £1 billion mark in 2013, more than twice the level of tea bags, £480 million.
Drink coffee without lots of cream and sugar to reduce fat and calories. Some coffee drinks contain more than 500 calories.
Unfiltered strong black coffee contains a substance called cafestol that can increase cholesterol levels so it is best to drink filtered or instant coffee.
Most of us who like coffee can carry on drinking it with a clear conscious but be mindful of overdoing the caffeine, sugar and milk or cream.