Green coffee beans

Is taking green coffee bean extract safe?

Pawel Malczewski
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Short summary

Overall, current studies show a lack of sufficient evidence that green coffee extract (or chlorogenic acid) is unsafe, toxic or unhealthy, even if taken in the long term or in high dosages.
A small number of people, however, have presented some side effects during the studies. Nevertheless, more thorough studies on dose recommendations and safety of this supplement are needed.

In addition, the absorption of some minerals such as iron and zinc may decrease when supplement or drinks containing chlorogenic acid are consumed with food.

PLEASE NOTE: As there is not sufficient evidence on the safety of taking this supplement, pregnant women, children or people on medication should avoid it due to possible untested long term side effects or contraindications. For a quick answer click here.

Explanation

The following explanation is based on studies on the green coffee extract effects sponsored by the supplement companies. Please bear in mind that the results presented may be biased.

There are no specific studies focusing on the daily dosages or safety levels of this product or chlorogenic acid itself. For this reason and the lack of sufficient reports on negative effects, the maximum dosage or recommended daily dosage has not yet been established.

It seems that the supplement companies set the available recommendations based on the chlorogenic acid amounts derived from the usual daily coffee intake.

Some studies conducted so far have identified cases of allergic reaction in green coffee factory workers due to the dust of the processed green coffee beans or contaminants from other products rather than the green coffee extract itself.
Other studies using the actual extract have recorded a small percentage of participants experiencing side effects from the commonly suggested (on the product labels) dosages.

Overall, there are very few reports on the negative side effects of the chlorogenic acid or green coffee extract and it is not entirely clear if these ill effects are due to other factors, chlorogenic acid or combinations.

It is important to note that green coffee extract is a reasonably new product, which in a short time became a new craze on the market and, as in most similar cases, its benefits may be way above the realm.

Yes, it may have a good set of benefits but we need to consider that it can cause some unwanted side effects in some people. The bottom line is that there is not enough evidence to support either conclusion.

Studies on green coffee extract and chlorogenic acid (main active ingredient of the supplement):

  1. Studies showing allergic reactions in workers in coffee factory (not directly linked to the supplement itself, but worth investigating further):
    Some studies showed that allergens associated with green bean coffee are mainly found in the dust generated from processing coffee and primarily affects coffee factory workers. These allergens are destroyed, nevertheless, by roasting the coffee beans. The other allergen found in green coffee beans comes from castor beans, through castor bean contaminated sacks which may be shared between the two products.
    It was also found that green coffee extract inhalation may cause an allergic reaction (bronchoconstriction) in some people. (1)Zuskin E, Kanceljak B, Witek TJ Jr, Schachter EN. Acute ventilatory response to green coffee dust extract. Ann Allergy. 1991 Mar;66(3):219-24. Available here.  A recent study from June 2012 discovered a new coffee allergen called (Cof a 1) that affected 3 out of 17 people working in the coffee processing factory. This allergen has not been linked to chlorogenic acid. However, it was extracted from green coffee extract. (2)Manavski N, Peters U, Brettschneider R, Oldenburg M, Baur X, Bittner C. Cof a 1: identification, expression and immunoreactivity of the first coffee allergen. Int Arch Allergy Immunol. 2012;159(3):235-42. Available here.  These studies found some evidence of the potential side effects from green coffee beans. However, it is unlikely that it is related to the supplement itself.
  2. Study on chlorogenic acid safety shows that it is safe in its purer form:Another study looked at the chlorogenic acid itself and discovered that high purity (92%) chlorogenic acid has not shown allergenic properties. (3)Wu X, Yang H, Lin D, Zhang J, Luo F, Xu X. Comprehensive research and evaluation of chlorogenic acid allergy. Zhongguo Zhong Yao Za Zhi. 2010 Dec;35(24):3357-61. Available here.
  3. Study showing some side effects:One small study (using 200mg of chlorogenic acid per day derived from 400mg of green coffee extract) (4)Svetol. Available here.  found some side effects such as headache and urinary tract infections in 2 out of 17 participants, placing some doubt on the safety of the extract. (5)Blum J, Lemaire B, Lafay S. Effect of a green decaffeinated coffee extract on glycaemia – A Pilot Prospective Clinical Study. NutraFoods. 2007 6(3) 13-17. Available here.
  4. Study showing no side effects (please note the smaller dose)
    140 mg of chlorogenic acid from green coffee extract per day didn’t show side effects in participants with mild hypertension. (6)Watanabe T, Arai Y, Mitsui Y, Kusaura T, Okawa W, Kajihara Y, Saito I. The blood pressure-lowering effect and safety of chlorogenic acid from green coffee bean extract in essential hypertension. Clin Exp Hypertens. 2006 Jul;28(5):439-49. Available here.

NOTE: Absorption of minerals iron and zinc is reduced considerably when chlorogenic acid is taken within about an hour of the meal. It is best to take the supplement over one hour before or two hours after the meal for the maximum absorption of the minerals. (read more..)

Conclusion

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More studies are needed to establish the toxicity levels and long term safety of green coffee extract.

Until we know a little more, if you are using green coffee extract for its claimed benefits you should restrict the dosage to around 200mg per day which seems to be the upper limit used in the studies that haven’t recorded serious side effects.

However, as seen in one study mentioned above, some side effects are still possible and it would be wise to monitor any symptoms when taking this supplement.

Another suggestion is to choose caffeine free supplements to minimize the potential side effects.

References   [ + ]

1. Zuskin E, Kanceljak B, Witek TJ Jr, Schachter EN. Acute ventilatory response to green coffee dust extract. Ann Allergy. 1991 Mar;66(3):219-24. Available here.
2. Manavski N, Peters U, Brettschneider R, Oldenburg M, Baur X, Bittner C. Cof a 1: identification, expression and immunoreactivity of the first coffee allergen. Int Arch Allergy Immunol. 2012;159(3):235-42. Available here.
3. Wu X, Yang H, Lin D, Zhang J, Luo F, Xu X. Comprehensive research and evaluation of chlorogenic acid allergy. Zhongguo Zhong Yao Za Zhi. 2010 Dec;35(24):3357-61. Available here.
4. Svetol. Available here.
5. Blum J, Lemaire B, Lafay S. Effect of a green decaffeinated coffee extract on glycaemia – A Pilot Prospective Clinical Study. NutraFoods. 2007 6(3) 13-17. Available here.
6. Watanabe T, Arai Y, Mitsui Y, Kusaura T, Okawa W, Kajihara Y, Saito I. The blood pressure-lowering effect and safety of chlorogenic acid from green coffee bean extract in essential hypertension. Clin Exp Hypertens. 2006 Jul;28(5):439-49. Available here.

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