Green Coffee Beans: Usage, Health Benefits & Side Effects

by on |

Coffee is among the most consumed beverages on earth. Americans, for starters, consume 400 million cups of coffee per day.

There are two main species of coffee; coffee Arabica and Coffee Robusta. Coffee beans are harvested from the coffee berries of the coffee plant.

Black coffee has been a favorite among consumers because of its stimulating effect. Lately, however, green coffee beans have also been gaining popularity.

Green coffee beans became popular around 2012 after it was propagated as an easy fix for weight loss on a popular TV show.

Since then, green coffee beans extracts (GCBE) have become a popular ingredient in weight loss supplements such as slimming aids and fat burners.

Apart from weight loss, green coffee beans have also been linked to other health benefits such as the management of chronic diseases.

Traction aside, can green coffee beans and GCBE help you lose weight or reduce the risk of chronic disease?

In this article, we look at the purported health benefits of green coffee beans from a scientific point of view to establish facts.

What Are Green Coffee Beans?

Green coffee beans are raw or unroasted coffee beans. They retain the green color of coffee beans straight out of the coffee berry.

The difference between green coffee beans and black coffee is the roasting process. Roasting coffee beans reduces the chlorogenic acid composition in the beans.

Chlorogenic acids are among the active ingredients in green coffee beans. Other compounds present in green coffee beans include caffeine, trigonelline, polysaccharides, lipids, and proteins [1].

Most of the health benefits associated with green coffee beans are linked to the chlorogenic acids. The chemical composition of green coffee beans depends on factors like the climate and type of soil where the coffee plant was grown.

Green coffee bean extracts (GCBE) are classified as a dietary supplement by the FDA. They are available in capsule form or as a beverage [2].

Are Green Coffee Beans Safe?

Green coffee beans contain more or less the same amount of caffeine as black coffee. A cup of black coffee (8 ounces) contains between 80mg to 100mg of caffeine.

Most of the side effects linked to the consumption of green coffee beans are similar to those associated with a high dosage of caffeine. The symptoms include anxiety, agitation, headache, sleep arrhythmia, anxiety, insomnia, gastric distress, diuresis, and vomiting.

Bear in mind that studies into the effects of green coffee beans are limited. The limited data is primarily due to limited populations as well as poor methodologies [3].

Given the limited safety information on green coffee beans and GCBE, its safety as a supplement is yet to be established [4]. However, the Natural Medicines Comprehensive Database rates green coffee beans as “possibly safe” if used appropriately [5].

Health Benefits of Green Coffee Beans

Health Benefits of Green Coffee Beans

Below are some of the health benefits associated with green coffee beans supplementation. Let us turn to science to establish whether GCBEs are worth all the hype surrounding them.

1.     Helps with Weight Loss.

Green coffee beans extract is primarily popular because of its purported weight loss function. It is often marketed as an active ingredient in many “fat burners” and slimming aids.

What the science says

A meta-analysis (review) of six randomized clinical trials examining the effects of GCBE supplementation on weight loss was conducted. The clinical trials had included people with normal weight as well as persons with obesity.

The six clinical trials also included a control group on placebo.

The meta-analysis revealed that there was a significantly larger weight loss in the subjects on GCBE supplementation compared to those in the control group.

It also showed that there was more weight loss among the obese subjects compared to subjects with normal weight and mild hypertension [6].

Despite the significant weight loss among overweight subjects, the exact mechanism of action by GCBE was not established by the clinical trials.

Due to the limited populations, inconsistent methodology, and low quality on the currently available data on green coffee beans; the meta-analysis was rendered inconclusive [7].

The results from the above clinical trials and meta-analysis are promising. However, more intensive research needs to be conducted on the effects of GCBE supplementation on weight loss.

2.     It Has Potent Antioxidant Properties. 

Green coffee beans extract is believed to have antioxidant properties that are beneficial to the body’s overall wellness. Popular websites refer to GCBE as a potent antioxidant.

What the science says

Green coffee beans are rich in phenolic compounds with noted high antioxidant activity. The main phenolic compounds found in green coffee beans are chlorogenic acids and caffeic acids.

A research study was conducted to analyze the antioxidant activity of substances present in green coffee beans. Phenolic compounds extracted from green coffee beans was shown to inhibit free radicals like ABTS and DPPH significantly [8].

Free radicals are natural by-products of metabolism processes and are known to cause cell and tissue damage.

In another study, the antioxidant activity of polyphenols from green coffee beans was tested on bread. The results from the study showed that increasing the amount of GCBE on the bread resulted in increased phenolic content coupled with increased antioxidant activity [9].

Green coffee beans are rich in phenols with proven ability to scavenge for free ions and bind strongly to these ions suppressing the formation of radicals. The two processes (scavenging and bonding) protects the cells from oxidative damage [10].

ABTS (mentioned above) is used to test for the scavenging property while DPPH is used to test for a compound’s bonding capacity.

The above findings, therefore, support the efficacy of green coffee beans and GCBE as antioxidant agents.

3.     Has Anti-inflammatory Properties. 

Green coffee beans extracts are common ingredients in skincare products and topical ointments due to their purported anti-inflammatory properties.

What the science says

An inflammatory reaction is a protective reaction to physical stimuli or an infection attacking the body. However, chronic inflammation can lead to cell damage and inhibited cellular function.

A study was conducted to determine the anti-inflammatory effects of Kenyan green coffee beans extracts. In the study, the effect of green coffee beans extract on Nitric oxide (NO) was examined.

Although NO is an inflammatory mediator with anti-inflammatory properties; it is known to go rogue and become pro-inflammatory in abnormal situations [11].

The production of NO was lower in the sample with GCBE compared to the control sample. The findings from the study concluded that GCBE has the potential to be used as natural anti-inflammatory agents [12].

Another study was conducted to examine the topical anti-inflammatory effect of an ointment prepared using methanolic extracts of Coffee Robusta green coffee beans. The results showed that the GCB ointment reduced paw edema within 3-5hours of carrageenan application [13].

Paw edema is a standardized test for anti-inflammatory activity. It entails the application of carrageenan (a substance extracted from seaweed) to induce inflammation [14].

The results yielded from the above research studies affirm the anti-inflammatory property of green coffee beans.

4.     Regulate Blood Sugar Level

Proponents of green coffee beans say that it helps lower blood sugar and reduce fat accumulation. They say that the above-stated functions help reduce the risk of type 2 diabetes.

What the science says

A meta-analysis on the effects of GCBE on Fasting Blood Sugar (FBS), insulin, and insulin resistance was conducted. The meta-analysis involved six published journals on the subject matter.

The meta-analysis results showed that GCBE supplementation reduced fasting blood sugar. FBS is a test to determine how much glucose is in a blood sample after a night of fasting. High FBS levels are indicative of insulin resistance or diabetes.

The meta-analysis results, on the other hand, showed no effect on insulin levels. The results also showed a significant decrease in the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) status after a dose of GCBE greater than 400mg [15].

The researchers theorize that active compounds such as chlorogenic acid and caffeine inhibit the intestinal absorption of glucose. GCBE supplementation shows promising results as an insulin management ingredient.

However, the meta-analysis determined that factors like study design, populations studied, and varying CGBE doses need to be improved in future studies. More thorough research studies and clinical trials need to be conducted on the effects of GCB on insulin and blood glucose.

5.     Helps Reduce the Risk of Cardiovascular Disease. 

Most users of green coffee beans supplements believe GCBE is enriched with compounds that can help reduce the risk as well as manage cardiovascular illnesses.

What the science says

The components found in green coffee beans, such as phenols and chlorogenic acid, have antioxidant properties.

A pilot study was conducted on the effects of green coffee beans on the cardiovascular system.  The results of the study revealed that green coffee significantly improved arterial elasticity while simultaneously reducing systolic and diastolic pressure [16] [17].

From the above findings, it emerged that green coffee beans might play a role in modulating blood pressure. Abnormal blood pressure is often indicative of chronic cardiovascular illnesses.

However, the researchers recommended more research be conducted on larger, more diverse populations over a longer period.

6.     Green Coffee Beans and Cancer

Many people take green coffee beans for their purported non-carcinogenic properties.

What the science says

Chlorogenic acid, a polyphenol found in GCB, is involved in metabolic pathways that may inhibit the development and growth of cancerous tumors [18].

A study was conducted to elaborate on the potential of chlorogenic acid complex (CGA7) as a chemosensitizing chemotherapy agent that suppresses tumor growth.

The cytotoxicity (toxicity to cells) of CGA7 was tested against human cancerous cells from the cervix, liver, colon, and breast. The study involved a control group on placebo.

The cytotoxicity of CGA7 was more pronounced in the colon cancer cells than from cells in any other organ. CGA7 affected the cancerous cells’ viability in a dose-dependent and timely manner [19].

Another study showed that CGA7 can speed up the apoptosis of cancerous cells in the lungs without affecting the lungs’ functions. Apoptosis is the normal degradation of body cells as part of an organism’s growth.

From the above findings, the researchers gathered that CGA7 found in green coffee beans has some potential as a cancer suppression agent. However, the studies on this subject matter are limited.

Researchers recommend further studies into the anti-cancer activity of CGA &, especially, on advanced tumors.

7.     Green Coffee Beans and Neurodegenerative Conditions. 

Green coffee beans are believed to delay the progression of neurological conditions such as Alzheimer’s disease and other types of dementia.

What the science says

Oxidative stress and tissue damage by free radicals are some of the factors that contribute to the progression of neurodegenerative diseases like Alzheimer’s and Parkinson’s disease.

Diabetes and insulin resistance can cause a reduction in the breakdown of amyloid-beta (a pro-Alzheimer’s agent); hence both are risk factors for neurodegenerative conditions.[20].

Green coffee beans have proven anti-oxidative and anti-inflammatory properties that can tackle both oxidative stress and tissue damage.

GCB also contains phenol compounds that regulate blood sugar levels lowering the risk of diabetes-one of the precursors for dementia. Another theory is that caffeine in GCB can block the pathway for beta-secretase secretion in the brain.

Beta secretase causes beta-amyloid accumulation in the brain.

Several studies into the anti-oxidant activity of chlorogenic acid (found in GCB) and its role in reducing the risk of neurodegenerative diseases are promising [21].

However, the mechanism of action by which GCB polyphenols provide neuroprotection is not fully understood. There are also limited human and animal trials.

Further research needs to be conducted to understand the neuroprotective properties and activity of green coffee beans compounds.

Side Effects

So far, the side effects that have been linked to green coffee beans supplementation are similar to those exhibited by excessive consumption of coffee. They include:

  • Anxiety
  • Agitation
  • Headache
  • Sleep arrhythmia
  • Anxiety
  • Insomnia
  • Gastric distress
  • Diuresis
  • Vomiting

Note, however, that data on green coffee beans, in general, is very limited. There is no information on any long-term side effects of GCB yet.

Usage and Dosing Considerations

What Are Green Coffee Beans

Given the limited nature of data on green coffee beans, there is no consensus on its maximum daily recommended dose.

Ideally, the dosage would vary depending on the intended therapeutic use of green coffee beans supplementation.

Some research studies here and there recommended 400 mg of GCB per day to be the maximum.

Based on the above circumstances, it would be best to follow the prescription given on the GCB supplement bottle.

Better still, consult your physician before using green coffee beans supplements for any health therapy.

Risks and Precautions

Apart from the side effects mentioned above, GCB compounds can interfere with the efficacy of Alzheimer’s medication.

If you are on any medication or have a pre-existing condition, consult your doctor before using green coffee beans supplements.

Given the limited research into green coffee beans, it is best to avoid taking GBC supplements while pregnant or breastfeeding.

The same goes for children and teenagers under the age of 18; do not give them green coffee beans supplements.

Conduct due diligence on various brands and their ethical inclinations before purchasing any green coffee beans supplements.

More is not always best; there may not be a recommended GCB maximum dose yet, but do not go overboard.


How much weight can I lose with green coffee beans?

Although green coffee beans have shown promising results when it comes to weight loss, there is no promise of a specific weight loss within any period. Secondly, people react differently to different compounds.

While one person may achieve results, your body may take longer. Third, when it comes to weight loss, other factors like diet and workout regime also play a part.

Do green coffee beans really work?

It depends on the health issue for which you intend to use green coffee beans. Green coffee beans may help improve some health conditions but it may not work for others.

Note that the research on the efficacy of green coffee beans is rather limited. Consult your physician before using green coffee beans supplementation for any health issue.

Which is better: green tea or green coffee beans?

Both green tea and green coffee beans contain polyphenols which have been proven to have many health benefits. The question of which is better will depend on the health issue you intend to manage by taking either substance.

Note, however, that people react differently to different substances. Consult your physician for advice or just go with your personal preferences.

Can I take green coffee beans on an empty stomach?

There is no scientific study on how and when to take green coffee beans as at yet. The information on popular websites is also contradictory.

Your best bet would be to follow the directions given on the GCB supplement bottle or consult your doctor.

When is the best time to take green coffee beans for weight loss?

There is no scientific proof that taking green coffee beans at a specific time will increase your weight loss. Follow the directions given on the green coffee supplement bottle.


Green coffee beans have many health benefits. They are rich in polyphenols that have anti-oxidation properties.

Be that as it may, research data on the efficacy and effects of green coffee beans consumption is limited. Although some of GCB’s purported benefits have been proven by science, further research needs to be conducted.

There are also no recommended dosage considerations.

If you decide to use green coffee beans or GCB supplementation for any therapeutic intervention, ensure you consult a physician first.


Leave a Comment