By Daphne Baldwin Kornrich, MS, RDN, CSOWM, CDN

I feel I can safely say that I am not alone in thinking that I need to start my workday with a cup of coffee. Is it the routine, the aroma, or just taking a moment to sip and enjoy? Sounds nice, but truly it’s about the caffeine. According to the U.S. Food and Drug Administration (FDA) approximately 80% of Americans consume some source of caffeine every day. Caffeine is not only found in coffee and tea but also in soda, energy drinks, chocolate, and many supplements. Caffeine is found naturally in over 60 plant species across the world. The most common sources of caffeine are from coffee beans, tea leaves, cocoa beans, and kola nuts. Guarana is another source of caffeine and is a seed from a South American plant which is processed and added to many energy drinks and supplement (1,2,3,).

How does caffeine affect our brains?

Caffeine is a mild stimulant and the most widely used psychoactive drug in the world! Caffeine in beverages is absorbed quickly in our stomach and reaches our brain and central nervous system which causes us to feel more energetic and alert. It takes about 15-45 minutes for caffeine to be absorbed and peak. Having food in our stomach delays when caffeine peaks in our blood stream. Our liver breaks down caffeine, and caffeine can stay in our blood stream between 1.5-9.5 hours (1,3).

Is it the coffee or caffeine?

There are more than 1,000 bioactive compounds, including caffeine, in coffee. Many of these compounds have been shown to have antioxidative, anti-inflammatory and anticancer benefits. In addition, they may improve the bacteria in our gut and be helpful with the metabolism of fat and blood glucose. Coffee also contains essential micronutrients such as vitamin E, niacin, magnesium, and potassium. (1,2,3,4)

One study in the 2017 British Medical Journal found that people who drank caffeinated or decaffeinated coffee were at lower risk for developing type 2 diabetes and dying from heart disease. They also found strong correlations between those who drank caffeinated coffee and a decrease in developing cancer. Other studies have shown that drinking coffee may have a positive impact on other health issues such as: (1,2,4)

  • Protective against Parkinson’s disease
  • Decrease asthma symptoms
  • Reduce gallstone formation
  • Improve mental function and some studies suggest a lower risk of developing Alzheimer’s disease.
  • Protective against liver disease.

Heart Disease and Caffeine?

For a long time, it seems that the recommendation for people with heart disease was to avoid caffeinated coffee. However, new studies have shown that drinking caffeinated coffee may help decrease heart failure. However, researcher of these studies caution that these studies did have limitations such as not addressing the effect of other caffeinated beverages such as energy drinks, soda, and tea. Researchers also advised there is not enough scientific evidence to tell people to drink coffee at this time compared to the evidence that smoking cessation, losing weight, and increased physical activity has on decreasing risk of heart disease (5).

Negative effects of caffeine:

  • Heart: Caffeine can increase blood pressure, cause palpitations and lead to a rapid heart rate. Those who have these conditions along with people who have arrythmias need to use caution, and it is strongly advised to check with you cardiologist regarding your caffeine intake. Also, avoid caffeine prior to engaging in activities that increase your blood pressure.
  • Fertility: Drinking coffee in more than moderate amounts can affect a woman’s fertility. Drinking excessive amounts of caffeine during pregnancy can increase the risk of a miscarriage and cause developmental issues in newborns. It is recommended that pregnant women limit caffeine intake to 200 mg per day.
  • Insomnia, restlessness, and twitchiness can also be side effects of caffeine consumption, but it varies between individuals and usually related to their ability to metabolize caffeine. If insomnia is an issue think twice before you have that afternoon coffee.
  • Heart burn and reflux can also be caused by caffeine intake especially if you are prone to these conditions. (1,2,3,4,5).


Caffeine sources:   Milligrams of caffeine
Herbal tea 0
Decaf tea: 8 oz 2
Decaf coffee: 8 oz 4
Milk chocolate: 1 oz 6
Dark chocolate: 1 oz 24
Green tea: 8 oz 28
Soda: 12 oz 40
Tea: 8 oz 47
Espresso chocolate: 1.5 oz 65
Coffee: 8 oz 95
Energy drink: 16 oz 170


Caffeine caution:

  • Guarana contains about four times the amount of caffeine found in coffee beans.
  • Caffeine is also found in medications such as cold, allergy, pain, and weight loss medication.
  • Caffeine supplements and energy shots contain about 200 mg of caffeine per dose.
  • American Academy of Pediatrics does not recommend giving caffeine to children.
  • French press coffee and Turkish coffee are not filtered and contain cafestol, which may increase cholesterol levels.
  • Caffeine is mildly addictive and sudden withdrawal or skipping our coffee for a day or two can result in headaches.
  • Smoking can speed up the breakdown of caffeine.
  • Oral contraceptives and pregnancy can slow down the breakdown of caffeine.
  • According to the FDA drinking 400 mg of caffeine per day is considered safe for most people (1, 2, 3, 4).

Take home message:

Enjoy your cup of coffee but stay clear of those fancy coffee drinks with added sugars, creamers, and lots of calories. Drinking coffee in moderation can be part of a healthy lifestyle in conjunction with being physically active, eating more whole foods and consuming less saturated fat, salt, added sugars and including whole grains along with fruits and vegetables. Check with your doctor regarding caffeine intake if you have any health concerns.



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  2. The Power of CoffeeBy Judith CThalheimer, RD, LDN

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Daphne Baldwin Kornrich, MS, RDN, CSOWM, CDN has been a registered dietitian nutritionist for more than 30 years, working in a wide variety of clinical and outpatient settings. She currently specializes in Bariatrics and Weight Management.