Green coffee is possibly safe when taken by mouth appropriately. Green coffee extracts taken in doses up to 480 mg daily have been used safely for up to 12 weeks. Also, a specific green coffee extract (Svetol, Naturex) has been used safely in doses up to 200 mg five times daily for up to 12 weeks.
Green coffee also contains caffeine. There is much less caffeine in green coffee than in regular coffee. But green coffee can still cause caffeine-related side effects similar to coffee.
Caffeine can cause insomnia, nervousness and restlessness, stomach upset, nausea and vomiting, increased heart and breathing rate, and other side effects. Consuming large amounts of coffee might also cause headache, anxiety, agitation, ringing in the ears, and irregular heartbeats.
Special Precautions & Warnings:
Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking green coffee if you are pregnant orbreast feeding. Stay on the safe side and avoid use.
Abnormally high levels of homocysteine: Consuming a high dose of chlorogenic acid for a short duration has caused increased plasma homocysteine levels, which may be associated with conditions such as heart disease.
Anxiety disorders: The caffeine in green coffee might make anxiety worse.
Bleeding disorders: There is some concern that the caffeine in green coffee might make bleeding disorders worse.
Diabetes: Some research suggests that caffeine contained in green coffee might change the way people with diabetes process sugar. Caffeine has been reported to cause increases as well as decreases in blood sugar. Use caffeine with caution if you have diabetes and monitor your blood sugar carefully.
Diarrhea: Green coffee contains caffeine. The caffeine in coffee, especially when taken in large amounts, can worsen diarrhea.
Glaucoma: Taking caffeine which is contained in green coffee can increases pressure inside the eye. The increase starts within 30 minutes and lasts for at least 90 minutes.
High blood pressure: Taking caffeine found in green coffee might increase blood pressure in people with high blood pressure. However, this effect might be less in people who consume caffeine from green coffee or other sources regularly.
High cholesterol: Certain components of unfiltered coffee have been shown to increase cholesterol levels. These components can be found in green coffee as well. However, it is unclear if green coffee can also cause increased cholesterol levels.
Irritable bowel syndrome (IBS): Green coffee contains caffeine. The caffeine in green coffee, especially when taken in large amounts, might worsen the diarrhea some people have with IBS.
Thinning bones (osteoporosis): Caffeine from green coffee and other sources can increase the amount of calcium that is flushed out in the urine. This might weaken bones. If you have osteoporosis, limit caffeine consumption to less than 300 mg per day. Taking calcium supplements may help to make up for calcium that is lost. If you are generally healthy and getting enough calcium from your food or supplements, taking up to 400 mg of caffeine daily (about 20 cups of green coffee) doesn’t seem to increase the risk of getting osteoporosis. Postmenopausal women who have an inherited condition that keeps them from processing vitamin D normally, should be especially cautious when using caffeine.